JP7544528B2 - Sheet for forming protective film and method for producing same - Google Patents

Description

The present invention relates to a sheet for forming a protective film and a manufacturing method thereof. In particular, the present invention relates to a sheet for forming a protective film provided with a protective film-forming film that is suitably used to protect a workpiece such as a semiconductor wafer or a processed product such as a semiconductor chip obtained by processing the workpiece, and a manufacturing method for the sheet for forming a protective film.

In recent years, semiconductor devices have been manufactured using a mounting method known as flip-chip bonding. In this mounting method, when mounting a semiconductor chip having a circuit surface on which convex electrodes such as bumps are formed, the circuit surface of the semiconductor chip is inverted (face down) and bonded to the chip mounting section. This results in a structure in which the back side of the semiconductor chip, on which no circuit is formed, is exposed.

For this reason, a hard protective film made of an organic material is often formed on the back side of the semiconductor chip to protect the semiconductor chip from shocks during transportation, etc. To form such a protective film, an uncured resin film (hereinafter referred to as "protective film-forming film"), which is its precursor, is used. The protective film-forming film is attached to the back side of the semiconductor wafer and is diced together with the wafer to form chips. By curing the protective film-forming film, a chip with a protective film on the back side is obtained.

As a product form of the protective film-forming film, as shown in FIG. 1, a two-layer structure protective film-forming sheet 10 in which a protective film-forming film 11 is peelably laminated on a first release film 12, or as shown in FIG. 3, a three-layer structure protective film-forming sheet 20 in which a protective film-forming film 11 is sandwiched between two release films (12, 13) is known. The above-mentioned protective film-forming sheet is long and is stored and transported in a roll shape. Such a protective film-forming sheet may be attached to a workpiece (a general term for an adherend such as a semiconductor wafer) by punching the protective film-forming film in advance into a shape substantially the same as the workpiece. In such a punched protective film-forming sheet, a protective film-forming film 16 punched into a predetermined closed shape is laminated on a first release film 12 (FIG. 2) or sandwiched between two release films (12, 13) (FIG. 4).

The punched protective film-forming sheet is manufactured by punching the protective film-forming film into a predetermined closed shape with a punching die, and is used by removing unnecessary parts 17 around the punched protective film-forming film 16. In the case of a two-layered protective film-forming sheet consisting of a protective film-forming film 11 and a first release film 12, the protective film-forming film 11 is completely punched into the predetermined closed shape, and a cut 14 is made in the first release film 12 so as not to completely punch out the film, leaving the protective film-forming film 16 of the predetermined closed shape on the first release film 12, and the unnecessary parts 17 around the cutout are removed. In the case of a three-layer structure protective film forming sheet in which the protective film forming film 11 is sandwiched between two release films (12, 13), the protective film forming film 11 and one of the second release films 13 are completely punched out into a predetermined closed shape, and a cut 14 is made in the other first release film 12 so as not to completely punch out, leaving the protective film forming film 16 in the predetermined closed shape on the first release film 12, and removing the unnecessary peripheral portion 17 and the second release film 13.

A more detailed explanation will be given by taking a two-layered protective film forming sheet as an example. As shown in FIG. 5, a protective film forming sheet 10 consisting of a protective film forming film 11 and a first release film 12 is punched completely into a predetermined closed shape by punching out the protective film forming film 11 into a predetermined closed shape, and a cut 14 is made in the first release film 12 so as not to punch out completely, to produce a punched protective film forming sheet. This process is called the "punching process."

Next, in order to use the punched protective film-forming sheet for application to a workpiece, unnecessary portions 17 are removed from the periphery of the protective film-forming film 16 punched into a predetermined closed shape (Figure 6). This process is called the "waste removal process." As a result, a laminate is obtained that has the protective film-forming film 16 punched into a predetermined closed shape on the first release film 12, which can be used for application to a workpiece.

In the case of a three-layered protective film forming sheet, in the punching process, there is another release film 13 (second release film 13) on the protective film forming film 11, and the second release film 13 is also completely punched out into a predetermined closed shape, and in the waste removal process, the second release film 13 is removed, and the rest is the same as in the case of a two-layered protective film forming sheet.

A sheet for forming a protective film is required to be able to perform the punching process stably (work stability). In particular, the scraping process in which unnecessary parts are removed after punching the protective film-forming film is required to be stable. More specifically, in the scraping process, it is required that the problem of the protective film-forming film 16, which should be left behind, being unintentionally peeled off from the first release film 12 together with the unnecessary parts 17 (hereinafter also referred to as "scrape removal failure") does not occur.

To solve this problem, for example, Patent Document 1 proposes controlling the peeling force between the release film and the protective film-forming film within a predetermined range.

International Publication WO2017/145735

When a waste removal defect occurs, the production line must be stopped and the defective products must be discarded, resulting in lower product yields and increased costs. Therefore, there is a need to further reduce waste removal defects.

The inventors continued to investigate further into the cause of the waste removal failure and came to the following conclusions.

After the punching process and before the scrap removal process, the protective film forming sheet 10 passes through multiple rollers such as guide rollers for the purpose of controlling the tension of the protective film forming sheet. At this time, the protective film forming sheet 10 may be bent so that the upper side of the cut 14 (the surface where the cutter entered) faces the roller 19 as shown in FIG. 7. As a result of bending, the width of the cut 14 narrows, especially in the cut portion that is approximately parallel to the short side direction of the sheet 10, and at the same time, the protective film forming film 16 is crushed and slightly deformed, which may cause the adjacent protective film forming film 16 and unnecessary portion 17 to come into contact and adhere to each other.

After passing through the roller 19, in many cases the protective film-forming film 16 and the unwanted portion 17 separate again, but sometimes they remain attached. If the protective film-forming film 16 and the unwanted portion 17 are removed while still attached, the protective film-forming film 16 that should remain on the first release film 12 will unintentionally peel off from the first release film 12 together with the unwanted portion 17 that should be removed, resulting in poor waste removal.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a sheet for forming a protective film and a method for manufacturing the same that can sufficiently suppress waste removal defects even when the width of the cut during punching is relatively narrow.

The aspects of the present invention are as follows.
(1) a protective film-forming film,
A long sheet having a first release film provided on one surface of the protective film-forming film,
A sheet for forming a protective film, in which the adhesive strength 2 minutes after two protective film-forming films are applied at 23° C. under a load of 2 kgf is 19 N/25 mm or less.
(2) The sheet for forming a protective film according to (1), wherein the surface elasticity of the surface of the first release film in contact with the protective film-forming film is 17 MPa or less.
(3) When the protective film-forming sheet is viewed in plan, a cut is formed in the protective film-forming sheet so that a part of the protective film-forming sheet has a predetermined closed shape,
The sheet for forming a protective film according to (1) or (2), wherein the incision penetrates the protective film-forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.
(4) The sheet for forming a protective film according to (3), wherein the width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.
(5) A method for forming a protective film according to the above (1) or (2) comprising a step of forming a cut so that a part of the sheet for forming a protective film has a predetermined closed shape,
A method for manufacturing a punched sheet for forming a protective film, in which the cut penetrates the protective film-forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.
(6) The method for producing a punched sheet for forming a protective film according to (5), wherein the width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.

The present invention provides a sheet for forming a protective film and a method for manufacturing the same that can sufficiently suppress waste removal defects even when the width of the cut during punching is relatively narrow.

FIG. 1 is a schematic cross-sectional view of a sheet for forming a protective film according to an embodiment. FIG. 2 is a schematic cross-sectional view showing the state after the sheet for forming a protective film according to the embodiment has been punched. FIG. 3 is a schematic cross-sectional view of a sheet for forming a protective film according to another embodiment. FIG. 4 is a schematic cross-sectional view showing a state after punching a sheet for forming a protective film according to another embodiment. FIG. 5 is a schematic perspective view of the protective film-forming sheet after the punching process. FIG. 6 is a schematic perspective view showing the waste removing step. FIG. 7 is a cross-sectional view showing a state in which the sheet for forming a protective film after the punching process passes through rollers. FIG. 8 is a schematic cross-sectional view of an example of a chip having a protective film obtained by forming the protective film-forming film according to this embodiment into a protective film. FIG. 9 is a schematic cross-sectional view for explaining a step of attaching the protective film forming sheet according to this embodiment to a wafer. FIG. 10 is a schematic cross-sectional view for explaining a process of dividing the wafer with the protective film into individual pieces. FIG. 11 is a schematic cross-sectional view for explaining the step of disposing the chip with the protective film on the substrate.

First, let us explain the main terms used in this specification.

The workpiece is a plate-like body to which the protective film-forming film according to this embodiment is attached and processed. Examples of the workpiece include wafers and panels. Specifically, examples include semiconductor wafers and semiconductor panels. Examples of the processed workpiece include chips obtained by dicing a wafer. Specifically, examples include semiconductor chips obtained by dicing a semiconductor wafer. In this case, the protective film is formed on the back side of the wafer and the chip.

The "front surface" of a workpiece such as a wafer refers to the surface on which circuits and convex electrodes such as bumps are formed, while the "back surface" refers to the surface on which circuits, electrodes (for example, convex electrodes such as bumps) are not formed.

In this specification, for example, "(meth)acrylate" is used as a term to refer to both "acrylate" and "methacrylate," and the same applies to other similar terms.

A release film is a film that supports the protective film-forming film so that it can be peeled off. The term film is not limited to a specific thickness, and is used to include the concept of a sheet.

The mass ratios in the descriptions of the protective film-forming film composition and release agent layer composition are based on the active ingredients (solid content), and do not include the solvent unless otherwise specified.

The present invention will be described in detail below based on specific embodiments in the following order:

(1. Protective Film-Forming Film)
The protective film forming sheet 10 in this embodiment is a long sheet having a protective film forming film 11 and a first release film 12 provided on one side of the protective film forming film 11, as shown in Figures 1 and 5, and is usually wound up in a roll.

The protective film forming film 11 is attached to the workpiece and forms a protective film to protect the workpiece or the workpiece processed thereon.

"Making it into a protective film" means making the protective film-forming film 11 into a state having sufficient properties to protect the workpiece or a processed product of the workpiece. Specifically, when the protective film-forming film according to this embodiment is curable, "making it into a protective film" means making the uncured protective film-forming film into a cured product. In other words, the protective film-forming film that has been made into a protective film is a cured product of the protective film-forming film, and is different from the protective film-forming film.

After the workpiece is superimposed on the curable protective film-forming film, the protective film can be firmly adhered to the workpiece by curing the protective film-forming film, forming a durable protective film.

When the protective film-forming film 11 does not contain a curable component and is used in an uncured state, the protective film-forming film according to this embodiment becomes a protective film when it is attached to a workpiece. In other words, the protective film may be the same as the protective film-forming film.

If high protective performance is not required, there is no need to harden the protective film-forming film, so the protective film-forming film may be non-hardenable.

In this embodiment, the protective film-forming film is preferably curable. Therefore, the protective film is preferably a cured product. Examples of cured products include a thermosetting product and an energy ray cured product. In this embodiment, it is more preferable that the protective film is a thermosetting product.

It is also preferable that the protective film-forming film has adhesiveness at room temperature (23°C) or exhibits adhesiveness when heated. This allows the protective film-forming film and the workpiece to be laminated together when they are placed on top of each other. This allows reliable positioning before the protective film-forming film is cured.

The protective film-forming film may be composed of one layer (single layer) or may be composed of two or more layers. When the protective film-forming film has multiple layers, these multiple layers may be the same or different from each other, and the combination of layers that make up these multiple layers is not particularly limited.

In this embodiment, it is preferable that the protective film-forming film is one layer (single layer). If the protective film-forming film is composed of multiple layers, there is a risk of delamination occurring due to differences in thermal expansion and contraction between the layers during processes in which temperature changes occur (during reflow processing or when the device is used), but if it is a single layer, this risk can be reduced.

The thickness of the protective film-forming film is not particularly limited, but is preferably 100 μm or less, more preferably 70 μm or less, even more preferably 45 μm or less, and particularly preferably 30 μm or less. When the thickness of the protective film-forming film is within the above range, even if the punched protective film-forming film and unnecessary parts come into contact with each other or adhere to each other when passing through the rollers after the punching process, the protective film-forming film is easily separated again after passing through the rollers. In addition, the thickness of the protective film-forming film is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. When the thickness of the protective film-forming film is within the above range, the protective performance of the obtained protective film is good.

The thickness of the protective film-forming film means the thickness of the entire protective film-forming film. For example, the thickness of a protective film-forming film composed of multiple layers means the total thickness of all layers that make up the protective film-forming film.

The following describes the protective film formed on the tip as the workpiece. Specifically, the protective film formed by converting the protective film-forming film according to this embodiment into a protective film will be described using the tip 30 with protective film shown in FIG. 8.

As shown in FIG. 8, the chip 30 with protective film has a protective film 32 formed on the back side of the chip 31 (the upper side in FIG. 8), and a convex electrode 33 formed on the front side of the chip 31 (the lower side in FIG. 8).

A circuit is formed on the surface side of the chip 31, and the convex electrode 33 is formed so as to be electrically connected to the circuit. The chip 30 with protective film is arranged so that the surface on which the convex electrode 33 is formed faces the chip mounting substrate. Thereafter, the chip is mounted by electrically and mechanically joining the chip to the substrate via the convex electrode 33 through a specified heating process (reflow process). Examples of the convex electrode 33 include a bump and a pillar electrode.

(1.1 Adhesion between protective film-forming films)
In this embodiment, the adhesive force when the protective film-forming films constituting the protective film-forming sheet are attached to each other is controlled within a predetermined range to suppress the waste removal failure. Specifically, the adhesive force is 19 N/25 mm or less 2 minutes after two protective film-forming films are attached at 23 ° C. with a load of 2 kgf. The adhesive force is preferably 15 N/25 mm or less, more preferably 11 N/25 mm or less. In addition, if the adhesive force is too small, the holding performance of the work may be reduced, so the adhesive force is preferably 0.1 N/25 mm or more, more preferably 1 N/25 mm or more, and particularly preferably 3 N/25 mm or more. The reason why the adhesive force is measured 2 minutes after the protective film-forming films are attached to each other is that in the process in which the protective film-forming sheet passes through the roller 19 in the device that removes the waste and attaches it to the work, the time during which the cut portion is in contact with the roller 19 and stops is approximately 2 minutes.

By controlling the adhesive strength between the protective film-forming films within a predetermined range as described above, even if the protective film-forming sheet is bent after the punching process and the punched protective film-forming film 16 and the unnecessary portion 17 adhere to each other, the protective film-forming film 16 and the unnecessary portion 17 separate again after the protective film-forming sheet passes through the rollers, reducing waste removal defects.

(1.2 Composition for protective film-forming film)
As long as the protective film-forming film has the above-mentioned physical properties, the composition of the protective film-forming film is not particularly limited. In this embodiment, the composition constituting the protective film-forming film (composition for protective film-forming film) is preferably a resin composition containing at least a polymer component (A), a curable component (B), and a filler (E). The polymer component is a component that can be considered to be formed by a polymerization reaction of a polymerizable compound. In addition, the curable component is a component that can undergo a curing (polymerization) reaction. In the present invention, the polymerization reaction also includes a polycondensation reaction.

In addition, the components contained in the polymer component may also be considered as curable components. In this embodiment, when the composition for the protective film-forming film contains a component that corresponds to both such a polymer component and a curable component, the composition for the protective film-forming film is considered to contain both a polymer component and a curable component.

1.2.1 Polymer Component
The polymer component (A) provides the protective film-forming film with film-forming properties (film-forming properties) while providing appropriate tack, thereby ensuring uniform attachment of the protective film-forming film to the workpiece. The weight-average molecular weight of the polymer component is usually in the range of 50,000 to 2,000,000, preferably 100,000 to 1,500,000, and particularly preferably 200,000 to 1,000,000. If the weight-average molecular weight is too low, the adhesive force between the protective film-forming films tends to increase. On the other hand, if the weight-average molecular weight is too high, the compatibility with other components becomes poor, and as a result, uniform film formation is hindered. Examples of such polymer components include acrylic resins, urethane resins, phenoxy resins, silicone resins, saturated polyester resins, etc., and acrylic resins are particularly preferably used.

In this specification, the term "weight average molecular weight" refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC) unless otherwise specified. Measurements by such a method are carried out, for example, using a high-speed GPC apparatus "HLC-8120GPC" manufactured by Tosoh Corporation, connected in this order to high-speed columns "TSK guard column H _XL -H", "TSK Gel GMH _XL ", and "TSK Gel G2000 H _XL " (all manufactured by Tosoh Corporation), under conditions of a column temperature of 40°C, a liquid delivery rate of 1.0 mL/min, and a differential refractometer as a detector.

Examples of acrylic resins include (meth)acrylic acid ester copolymers consisting of (meth)acrylic acid ester monomers and structural units derived from (meth)acrylic acid derivatives. Here, the (meth)acrylic acid ester monomers are preferably (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms, and specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic acid derivatives include (meth)acrylic acid, glycidyl (meth)acrylate, and hydroxyethyl (meth)acrylate.

In this embodiment, it is preferable to introduce a glycidyl group into the acrylic resin using glycidyl methacrylate or the like. The compatibility of the acrylic resin into which the glycidyl group has been introduced with the epoxy resin as the thermosetting component described below is improved, the glass transition temperature (Tg) of the protective film-forming film after curing is increased, and the heat resistance is improved. In this embodiment, it is preferable to introduce a hydroxyl group into the acrylic resin using hydroxyethyl acrylate or the like in order to control the adhesion to the workpiece and the adhesive properties.

The glass transition temperature of the acrylic resin is preferably -70°C to 40°C, more preferably -35°C to 35°C, even more preferably -20°C to 30°C, even more preferably -10°C to 25°C, and particularly preferably -5°C to 20°C. By setting the glass transition temperature of the acrylic resin within the above range, the fluidity of the protective film-forming film and the protective film when heated is suppressed, making it easier to obtain a smooth protective film. If the glass transition temperature is too low, the adhesive strength between the protective film-forming films tends to increase. If the glass transition temperature is too high, the compatibility with other components becomes poor, and as a result, uniform film formation is hindered.

（式中、Ｔｇはアクリル樹脂のガラス転移温度であり；ｍは２以上の整数であり；Ｔｇｋはモノマーｍのホモポリマーのガラス転移温度であり；Ｗｋはアクリル樹脂における、モノマーｍから誘導された構成単位ｍの質量分率であり、ただし、Ｗｋは下記式を満たす。）

（式中、ｍ及びＷｋは、前記と同じである。） When an acrylic resin has m types of structural units (m is an integer of 2 or more), the glass transition temperature of the acrylic resin can be calculated as follows: That is, when m types of monomers from which structural units in the acrylic resin are derived are each sequentially assigned a unique number from 1 to m and named "monomer m", the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox formula shown below.

(In the formula, Tg is the glass transition temperature of the acrylic resin; m is an integer of 2 or more; Tgk is the glass transition temperature of a homopolymer of monomer m; and Wk is the mass fraction of structural unit m derived from monomer m in the acrylic resin, with the proviso that Wk satisfies the following formula.)

(In the formula, m and Wk are the same as above.)

For Tgk, values listed in the Polymer Data Handbook, Adhesive Handbook, Polymer Handbook, etc. can be used. For example, the Tgk of a homopolymer of methyl acrylate is 10°C, the Tgk of a homopolymer of n-butyl acrylate is -54°C, the Tgk of a homopolymer of methyl methacrylate is 105°C, the Tgk of a homopolymer of 2-hydroxyethyl acrylate is -15°C, the Tgk of a homopolymer of glycidyl methacrylate is 41°C, and the Tgk of 2-ethylhexyl acrylate is -70°C.

When the total weight of the composition for protective film-forming films is 100 parts by mass, the content of the polymer component is preferably 5 to 80 parts by mass, more preferably 8 to 70 parts by mass, more preferably 10 to 60 parts by mass, even more preferably 12 to 55 parts by mass, even more preferably 14 to 50 parts by mass, and particularly preferably 15 to 45 parts by mass. By having the content of the polymer component within the above range, the amount of low molecular weight components that increase the adhesive strength between protective film-forming films is limited to an appropriate range, making it easier to design the material for the composition for protective film-forming films.

(1.2.2 Thermosetting component)
The curable component (B) cures the protective film-forming film to form a hard protective film. As the curable component, a thermosetting component, an energy ray curable component, or a mixture thereof can be used. When cured by irradiation with energy rays, the protective film-forming film according to the present embodiment contains a filler and a colorant, etc., which will be described later, and therefore the light transmittance is reduced. If the thickness is too thick, the energy ray curing tends to be insufficient.

On the other hand, thermosetting protective film-forming films can be sufficiently cured by heating even if they are thick, so a protective film with high protective performance can be formed. In addition, multiple protective film-forming films can be heated and thermally cured all at once by using a conventional heating means such as a heating oven.

Therefore, in this embodiment, it is preferable that the curable component is thermosetting. In other words, it is preferable that the protective film-forming film according to this embodiment is thermosetting.

Whether or not a protective film-forming film is thermosetting can be determined as follows. First, a protective film-forming film at room temperature (23°C) is heated to a temperature above room temperature, and then cooled to room temperature to obtain a protective film-forming film after heating and cooling. Next, when the hardness of the protective film-forming film after heating and cooling is compared with the hardness of the protective film-forming film before heating at the same temperature, if the protective film-forming film after heating and cooling is harder, the protective film-forming film is determined to be thermosetting.

As the thermosetting component, for example, epoxy resin, thermosetting polyimide resin, unsaturated polyester resin, and mixtures thereof are preferably used. Thermosetting polyimide resin is a general term for low molecular weight, low viscosity monomers or precursor polymers that form polyimide resins by thermal curing. Non-limiting examples of thermosetting polyimide resins are described in, for example, Sen-i-gakkaishi-journal "Sen-i to Kogyo" (Sen-i to Kogyo), Vol. 50, No. 3 (1994), pp. 106-118.

The epoxy resin, which is a thermosetting component, has the property of forming a three-dimensional network and a strong coating when heated. As such an epoxy resin, various known epoxy resins are used. In this embodiment, the molecular weight (formula weight) of the epoxy resin is preferably 300 or more and less than 50,000, 300 or more and less than 10,000, 300 or more and less than 5,000, or 300 or more and less than 3,000. The epoxy equivalent of the epoxy resin is preferably 50 to 5,000 g/eq, more preferably 100 to 2,000 g/eq, and even more preferably 150 to 1,000 g/eq.

Specific examples of such epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenyl novolac, and cresol novolac; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidyl or alkyl glycidyl epoxy resins in which active hydrogen bonded to nitrogen atoms such as aniline isocyanurate is substituted with a glycidyl group; and so-called alicyclic epoxides in which epoxy is introduced by, for example, oxidizing the carbon-carbon double bonds in the molecule, such as vinylcyclohexane diepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane. Other epoxy resins having a biphenyl skeleton, dicyclohexadiene skeleton, naphthalene skeleton, and the like can also be used.

When a thermosetting component is used as the curing component (B), it is preferable to use a curing agent (C) as an auxiliary in combination. A heat-activated latent epoxy resin curing agent is preferable as a curing agent for epoxy resin. A "heat-activated latent epoxy resin curing agent" is a type of curing agent that does not react easily with epoxy resin at room temperature (23°C) and is activated by heating above a certain temperature and reacts with epoxy resin. Methods for activating a heat-activated latent epoxy resin curing agent include a method of generating active species (anions, cations) through a chemical reaction by heating; a method in which the agent is stably dispersed in epoxy resin near room temperature and becomes compatible and dissolved with epoxy resin at high temperatures to start a curing reaction; a method in which a molecular sieve-encapsulated type curing agent is dissolved at high temperatures to start a curing reaction; and a method using microcapsules.

Among the methods given above, the method in which the compound is stably dispersed in the epoxy resin at room temperature and becomes compatible and soluble in the epoxy resin at high temperatures, initiating the curing reaction, is preferred.

Specific examples of heat-activated latent epoxy resin curing agents include various onium salts, dibasic acid dihydrazide compounds, dicyandiamide, amine adduct curing agents, high melting point active hydrogen compounds such as imidazole compounds, etc. These heat-activated latent epoxy resin curing agents can be used alone or in combination of two or more. In this embodiment, dicyandiamide is particularly preferred.

Phenol resins are also preferred as curing agents for epoxy resins. As phenolic resins, condensates of phenols such as alkylphenols, polyhydric phenols, and naphthol with aldehydes can be used without any particular restrictions. Specifically, phenol novolac resin, o-cresol novolac resin, p-cresol novolac resin, t-butylphenol novolac resin, dicyclopentadiene cresol resin, polyparavinylphenol resin, bisphenol A type novolac resin, or modified products thereof can be used.

The phenolic hydroxyl groups contained in these phenolic resins can easily undergo addition reaction with the epoxy groups of the above epoxy resins when heated, forming a cured product with high impact resistance.

The content of the curing agent (C) is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.2 to 15 parts by mass, and particularly preferably 0.3 to 10 parts by mass, relative to 100 parts by mass of the epoxy resin. By setting the content of the curing agent (C) within the above range, the network structure of the protective film becomes dense, making it easier to obtain the performance of protecting the workpiece as a protective film.

When dicyandiamide is used as the curing agent (C), it is preferable to use a curing accelerator (D) in addition. As the curing accelerator, for example, imidazoles (imidazoles in which one or more hydrogen atoms are replaced by groups other than hydrogen atoms) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole are preferable. Among these, 2-phenyl-4-methyl-5-hydroxymethylimidazole is particularly preferable.

The content of the curing accelerator is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.2 to 15 parts by mass, and particularly preferably 0.3 to 10 parts by mass, relative to 100 parts by mass of the epoxy resin. By setting the content of the curing accelerator (D) within the above range, the network structure of the protective film becomes dense, making it easier to obtain the performance of protecting the workpiece as a protective film.

When the total weight of the composition for protective film-forming film is taken as 100 parts by mass, the total content of the thermosetting component and the curing agent is preferably 3 to 80 parts by mass, more preferably 5 to 60 parts by mass, more preferably 7 to 50 parts by mass, even more preferably 9 to 40 parts by mass, and particularly preferably 10 to 30 parts by mass. When the thermosetting component and the curing agent are mixed in such a ratio, the composition exhibits a suitable tack before curing, and the application work can be performed stably. In addition, after curing, the composition is likely to have the ability to protect the workpiece as a protective film.

When low molecular weight compounds are used as the thermosetting component and curing agent, the tack of the protective film-forming film may increase, and the adhesive strength between the protective film-forming films may increase. Therefore, it is desirable to select the type and amount of the thermosetting component and curing agent so as to control the tack to an appropriate value within the above range.

(1.2.3 Energy Ray-Curable Component)
When the curable component (B) is an energy ray-curable component, the energy ray-curable component is preferably uncured and preferably has adhesive properties, and more preferably is uncured and has adhesive properties.

The energy ray curable component is a component that is cured by irradiation with energy rays, and is also a component that imparts film-forming properties, flexibility, etc. to the protective film-forming film.

As the energy ray curable component, for example, a compound having an energy ray curable group is preferable. Examples of such compounds include known compounds.

When a low molecular weight compound is used as the energy ray curable component, the tackiness of the protective film-forming film increases, and the adhesive strength between the protective film-forming films may increase. Therefore, it is desirable to select the type and amount of the energy ray curable component so as to control the tackiness to an appropriate value.

(1.2.4 Filler)
By containing the filler (E) in the protective film-forming film, the protective film obtained by converting the protective film-forming film into a protective film can easily adjust the thermal expansion coefficient, and this thermal expansion coefficient can be adjusted to the thermal expansion coefficient of the workpiece. By bringing the thickness of the protective film-forming film closer to 0.05 mm, the adhesive reliability of the package obtained by using the protective film-forming film is further improved. In addition, by containing the filler (E) in the protective film-forming film, a hard protective film can be obtained. Furthermore, the moisture absorption rate of the protective film can be reduced, and the adhesive reliability of the package can be further improved.

The filler (E) may be either an organic filler or an inorganic filler, but from the viewpoint of shape stability at high temperatures, it is preferable that it is an inorganic filler.

Preferred inorganic fillers include, for example, powders of silica, alumina, talc, calcium carbonate, red iron oxide, silicon carbide, boron nitride, etc.; beads obtained by shaping these inorganic fillers into spherical shapes; surface-modified products of these inorganic fillers; single crystal fibers of these inorganic fillers; glass fibers, etc. Among these, silica and surface-modified silica are preferred. The surface-modified silica is preferably surface-modified with a coupling agent, and more preferably surface-modified with a silane coupling agent.

The average particle size of the filler is preferably 0.02 to 10 μm, more preferably 0.05 to 5 μm, and particularly preferably 0.10 to 3 μm.

By setting the average particle size of the filler to the above value, the composition for a protective film-forming film is easy to handle. Therefore, the quality of the composition for a protective film-forming film and the protective film-forming film tends to be stable.

In this specification, unless otherwise specified, "average particle size" refers to the particle size (D50) at 50% cumulative value in the particle size distribution curve obtained by the laser diffraction scattering method.

When the total weight of the composition for protective film-forming films is 100 parts by mass, the content of the filler is preferably 15 to 80 parts by mass, more preferably 30 to 75 parts by mass, even more preferably 40 to 70 parts by mass, and particularly preferably 45 to 65 parts by mass.

By setting the filler content to the above value, it is easy to control the adhesive strength between the protective film-forming films within an appropriate range. If the filler content is too low, the tack of the protective film-forming films increases, and the adhesive strength between the protective film-forming films increases excessively. On the other hand, if the filler content is too high, the shape retention of the protective film-forming film decreases, and the film may no longer be able to maintain its shape when bent by the rollers, or the tack of the protective film-forming film and its adhesion to the workpiece may decrease excessively.

In addition, the protective film-forming film preferably contains two or more types of fillers. In other words, the filler (E) is preferably a mixture of two or more types of fillers. "Containing two or more types of fillers" may mean containing two or more types of fillers with different materials, or two or more types of fillers with different average particle sizes.

In this embodiment, it is preferable to include two or more types of fillers with different average particle sizes. By including fillers with different average particle sizes in the protective film-forming film, fillers with smaller average particle sizes are more likely to be placed in the gaps between fillers with larger average particle sizes. As a result, the above effects can be obtained while making it easier to keep the adhesive strength between protective film-forming films within the above range.

When two or more types of fillers with different average particle sizes are included, the average particle size of the filler with the largest average particle size is preferably 1.5 to 100 times, more preferably 2 to 20 times, and even more preferably 3 to 18 times, the average particle size of the filler with the smallest average particle size.

Whether or not a protective film or a protective film-forming film contains two or more types of fillers with different average particle sizes can also be confirmed by observing the cross section of the protective film or the protective film-forming film.

1.2.5 Coupling Agents
The protective film-forming film preferably contains a coupling agent (F). By containing the coupling agent, after the protective film-forming film is cured, the adhesion between the protective film and the workpiece can be improved without impairing the heat resistance of the protective film, and the water resistance (moisture and heat resistance) can be improved. As the coupling agent, a silane coupling agent is preferable from the viewpoint of its versatility and cost merit.

Examples of silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazolesilane. These can be used alone or in combination of two or more.

When the total weight of the composition for protective film-forming films is 100 parts by mass, the content of the coupling agent is preferably 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, or 0.3 to 3 parts by mass.

1.2.6 Colorants
The protective film-forming film preferably contains a coloring agent (G). This conceals the back surface of the workpiece such as a chip, thereby blocking various electromagnetic waves generated in electronic devices and reducing malfunction of the workpiece such as a chip. In addition, when a defect in removing the waste occurs, it can be immediately found by visual inspection.

As the colorant (G), for example, known pigments such as inorganic pigments, organic pigments, and organic dyes can be used. In this embodiment, inorganic pigments are preferred.

Examples of inorganic pigments include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments. Of these, it is particularly preferable to use carbon black. Carbon black can block electromagnetic waves over a wide wavelength range.

The amount of colorant (especially carbon black) in the protective film-forming film varies depending on the thickness of the protective film-forming film. For example, when the thickness of the protective film-forming film is 20 μm, the content of the colorant is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass when the total weight of the composition for the protective film-forming film is 100 parts by mass.

The average particle size of the colorant (especially carbon black) is preferably 1 to 500 nm, more preferably 3 to 100 nm, and even more preferably 5 to 50 nm. If the average particle size of the colorant is within the above range, it is easy to control the light transmittance to the desired range.

(1.2.7 Other Additives)
The composition for the protective film-forming film may contain other additives, such as a photopolymerization initiator, a crosslinking agent, a plasticizer, an antistatic agent, an antioxidant, a gettering agent, a tackifier, a release agent, etc., within the range that does not impair the effects of the present invention.

However, it is preferable that the content of the release agent in the composition for the protective film-forming film is less than a predetermined amount. In this embodiment, it is preferable that the content is less than 0.00099 mass% with respect to the total mass of the protective film-forming film. If the content of the release agent is too high, the adhesive reliability between the protective film and the workpiece tends to decrease. Examples of release agents include alkyd-based release agents, silicone-based release agents, fluorine-based release agents, unsaturated polyester-based release agents, polyolefin-based release agents, and wax-based release agents.

(1.2.8 Control of adhesion between protective film-forming films)
As described above, this embodiment is characterized in that the adhesive strength when the protective film-forming films constituting the protective film-forming sheet are bonded together is controlled within a predetermined range, thereby suppressing waste removal defects.

The adhesion between the protective film-forming films can be controlled by the type and amount of each component that makes up the protective film-forming film.

When the weight average molecular weight of the polymer component (A) is low, the adhesive strength tends to increase. When the glass transition temperature of the polymer component (A) is low, the adhesive strength tends to increase. In addition, when low molecular weight compounds are used as the curable component (B), the curing agent (C), the curing accelerator (D), and the energy ray curable component, the adhesive strength tends to increase. When the amount of the filler (E) is large, the adhesive strength tends to decrease.

The adhesive strength can also be controlled by partially curing the protective film-forming film. For example, the adhesive strength can be reduced by partially curing the curable component (B). The timing of partially curing the protective film-forming film is not particularly limited, and may be, for example, at a stage before passing through roller 19 during punching of the protective film-forming sheet. However, from the viewpoint of setting the peel forces F1 and F2 described below in an appropriate range, and from the viewpoint of adhesion to the workpiece, it is preferable that the protective film-forming film is not partially cured, as in the examples described below.

(2. Protective Film Forming Sheet)
Before use, the protective film-forming film may be rolled up and stored in the form of a two-layered protective film-forming sheet 10 in which a protective film-forming film 11 is releasably laminated on a first release film 12, as shown in Fig. 1. Alternatively, the protective film-forming film may be rolled up and stored in the form of a three-layered protective film-forming sheet 20 (another embodiment) in which the protective film-forming film 11 is sandwiched between two release films (a first release film 12 and a second release film 13), as shown in Fig. 3. The release film is peeled off when the protective film-forming film is used.

The protective film forming sheet is long and is wound up in a roll for storage and transportation. As such a protective film forming sheet, a protective film forming sheet in which a protective film forming film is pre-punched into approximately the same shape as the workpiece is also known. In such a punched protective film forming sheet, a protective film forming film 16 punched into a predetermined closed shape is laminated on a first release film 12 (Fig. 2) or sandwiched between two release films (12, 13) (Fig. 4).

The first release film may be composed of one layer (single layer) or two or more layers of substrate, and the surface of the substrate may be subjected to a release treatment in order to control the release property. That is, the surface of the substrate may be modified, or a material not derived from the substrate may be formed on the surface of the substrate. In this embodiment, the first release film preferably has a substrate and a release agent layer. By having a release agent layer, it is easy to control the physical properties of the surface of the first release film on which the release agent layer is formed. In this embodiment, a coating agent containing a composition for a release agent layer described later is applied to one surface of the substrate, and the coating film is then dried and cured to form a release agent layer. This results in the first release film.

The thickness of the first release film 12 is not particularly limited, but is preferably 30 to 100 μm, more preferably 40 to 80 μm, and even more preferably 45 to 70 μm.

By setting the lower limit of the thickness of the first peelable film 12 to the above value, it is possible to prevent the cutting blade from penetrating the first peelable film 12 and cutting the first peelable film 12 when cutting out the protective film-forming film with the cutting blade. In addition, by setting the upper limit of the thickness to the above value, the protective film-forming sheet 10 passes through rollers such as guide rollers in the device before being unwound, the protective film-forming film 11 is cut out, and transported to the next process, but at that time, it is possible to prevent the protective film-forming film 11 from peeling off from the first peelable film 12.

The thickness of the first release film 12 refers to the thickness of the entire first release film. For example, the thickness of a first release film that is composed of multiple layers refers to the total thickness of all layers that make up the first release film.

Examples of the substrate of the first release film 12 include resin film and paper. Examples of the resin of the resin film include polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene (meth)acrylic acid copolymer, polystyrene, polycarbonate, fluororesin, low-density polyethylene, linear low-density polyethylene, and triacetyl cellulose. Examples of the paper include fine paper, coated paper, glassine paper, and laminated paper. These may be used alone or in combination of two or more types. Among these, polyethylene terephthalate film is preferred from the viewpoints of low cost and rigidity.

At least one surface of the first release film 12 (the surface to be laminated with the protective film-forming film) may be subjected to a release treatment using a release agent layer composition. The thickness of the release agent layer is preferably 30 nm or more and 200 nm or less, and more preferably 50 nm or more and 180 nm or less.

The surface elastic modulus (23°C) of the surface of the first release film 12 in contact with the protective film-forming film 11 is preferably 17 MPa or less, more preferably 14 MPa or less, more preferably 13 MPa or less, and particularly preferably 12 MPa or less. The surface elastic modulus is an index of the ease of deformation of the surface. By setting the surface elastic modulus of the surface of the first release film 12 in contact with the protective film-forming film 11 within the above range, it is possible to suppress the occurrence of lifting (peeling of about 1 to 4 mm) between the protective film-forming film 11 and the first release film 12 when the die is pressed in and then pulled out in the punching process. This is thought to be because the surface of the first release film 12 is relatively soft, so that even if there is compression by the die and decompression due to its detachment, the surface of the first release film follows the deformation of the protective film-forming film. By suppressing the occurrence of lifting, it is possible to further reduce waste removal defects. There is no particular lower limit for the surface elasticity of the surface of the first release film 12 that contacts the protective film-forming film 11, but if the surface elasticity is too low, the peeling force may increase, so it is preferably 3 MPa or more, more preferably 4 MPa or more, and particularly preferably 5 MPa or more.

The surface elastic modulus of the surface of the first release film 12 in contact with the protective film-forming film 11 at 23°C can be measured using an atomic force microscope equipped with a cantilever. That is, a cantilever is pressed against and pulled away from the surface of the first release film 12 in contact with the protective film-forming film 11 to obtain a force curve. The obtained force curve is fitted using the JKR theoretical formula to determine the elastic modulus, which is the surface elastic modulus of the present invention. A specific measurement method will be described in detail in the examples below.

In order to set the release force F1, which will be described later, within an appropriate range and to set the surface elastic modulus of the first release film 12 within the above range, in this embodiment, the release agent layer composition is preferably, for example, an alkyd-based release agent, a silicone-based release agent, a fluorine-based release agent, an unsaturated polyester-based release agent, a polyolefin-based release agent, or a wax-based release agent, and among these, a silicone-based release agent is preferred, and it is particularly preferred to include a silicone-based release agent and a heavy release additive.

As a silicone-based release agent, a silicone release agent containing silicone having dimethylpolysiloxane as the basic skeleton can be used.

The silicone may be any of addition reaction type, condensation reaction type, and energy ray curing type such as ultraviolet curing type and electron beam curing type, but addition reaction type silicone is preferable. Addition reaction type silicone has high reactivity and excellent productivity, and has the advantages of small change in release force after production and no cure shrinkage compared to condensation reaction type.

Specific examples of addition reaction type silicones include organopolysiloxanes that have two or more alkenyl groups having 2 to 10 carbon atoms, such as vinyl groups, allyl groups, propenyl groups, and hexenyl groups, at the ends and/or side chains of the molecule. From the viewpoint of reducing the surface elasticity modulus, it is preferable that the number of alkenyl groups in the addition reaction type silicone is small.

When the total weight of the release layer composition (excluding the catalyst described below) is taken as 100 parts by mass, the content of silicone consisting of dimethylpolysiloxane is preferably less than 100 parts by mass, more preferably less than 90 parts by mass, even more preferably less than 80 parts by mass, and particularly preferably less than 70 parts by mass.

When using such addition reaction type silicones, it is preferable to use a crosslinker and a catalyst in combination.

An example of a crosslinking agent is an organopolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule. From the viewpoint of reducing the surface elasticity, it is preferable that the content of the crosslinking agent in the release layer composition is small.

Specific examples of crosslinking agents include dimethylhydrogensiloxane-methylhydrogensiloxane copolymers endblocked with dimethylhydrogensiloxane, trimethylsiloxy group endblocked dimethylsiloxane-methylhydrogensiloxane copolymers, trimethylsiloxy group endblocked methylhydrogenpolysiloxane, poly(hydrogensilsesquioxane), etc.

Catalysts include fine particle platinum, fine particle platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, platinum group metal compounds such as palladium and rhodium, etc.

By using such a catalyst, the curing reaction of the release agent layer composition can proceed more efficiently.

The content of the silicone-based release agent when the total weight of the release agent layer composition (excluding the catalyst) is taken as 100 parts by mass is preferably 30 to 100 parts by mass, more preferably 50 to 100 parts by mass, from the viewpoint of keeping the surface elastic modulus within the above-mentioned range and keeping the release force F1, which will be described later, within an appropriate range.

The heavy release additive is used to increase the release force F1, which will be described later. Examples of heavy release additives include silicone resins and organosilanes such as silane coupling agents, and among these, it is preferable to use silicone resins.

As the silicone resin, for example, it is preferable to use MQ resin containing M unit, which is a monofunctional siloxane unit [R ₃ SiO _1/2 ], and Q unit, which is a tetrafunctional siloxane unit [SiO _4/2 ]. The three R in the M unit each independently represent a hydrogen atom, a hydroxyl group, or an organic group. In order to easily suppress silicone migration, it is preferable that one or more of the three R in the M unit is a hydroxyl group or a vinyl group, and more preferably a vinyl group. In order to reduce the surface elasticity, it is preferable that the content of the silicone resin (especially MQ resin) in the composition for release layer is small.

When the total weight of the release agent layer composition (excluding the catalyst) is taken as 100 parts by mass, the content of the heavy release additive is preferably 0 to 50 parts by mass, more preferably 5 to 45 parts by mass, and particularly preferably 10 to 40 parts by mass.

From the viewpoint of adjusting the viscosity and improving the applicability to the substrate, the composition for the release agent layer is preferably used as a coating agent containing a diluting solvent together with the various active ingredients described above. In this specification, the term "active ingredient" refers to the components contained in the coating agent containing the target composition, excluding the diluting solvent.

Examples of dilution solvents include organic solvents such as aromatic hydrocarbons such as toluene, fatty acid esters such as ethyl acetate, ketones such as methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and heptane. These dilution solvents may be used alone or in combination of two or more.

The active ingredient (solid content) concentration of the coating agent containing the release layer composition is preferably 0.3 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 0.5 to 3% by mass.

The release agent layer composition may contain additives that are commonly used in release agent layers, as long as the effects of the present invention are not impaired. Examples of such additives include dyes and dispersants.

In the protective film forming sheet 10 according to this embodiment, it is preferable that the protective film forming film 11 is punched into a predetermined shape. That is, when the protective film forming sheet 10 is viewed in plan, it is preferable that a cut 14 is formed in the protective film forming sheet so that a portion of the protective film forming sheet 10 has a predetermined closed shape. Note that it is preferable that the shape of the protective film forming film after punching is smaller than the shape of the workpiece from the viewpoint of preventing the protective film forming film from protruding from the workpiece when the protective film forming film is attached to the workpiece.

(3. Manufacturing method of sheet for forming protective film)
The method for producing the protective film-forming film is not particularly limited. The film is produced using a coating agent containing the above-mentioned composition for the protective film-forming film. The coating agent is prepared by mixing the components constituting the composition for the protective film-forming film by a known method.

The obtained coating agent is applied to the release surface of the first release film 12 using a coating machine such as a roll coater, knife coater, roll knife coater, air knife coater, die coater, bar coater, gravure coater, curtain coater, etc., and dried to obtain a sheet for forming a protective film 10 according to this embodiment having a protective film-forming film 11 on the first release film 12. Note that the coating agent may be applied to another resin film and dried, and the obtained protective film-forming film may be transferred to the first release film. When obtaining a sheet for forming a protective film 20 according to another embodiment, a second release film 13 is attached to the exposed surface of the protective film-forming film 11 laminated with the first release film 12, and a sheet for forming a protective film 20 in which the protective film-forming film 1 is sandwiched between two release films is obtained.

(4. Manufacturing method of punched protective film forming sheet)
A method for punching the protective film-forming sheet 10 to obtain the protective film-forming film 16 punched into a predetermined closed shape on the first release film 12 will be described.

(4.1 Punching process)
First, as shown in FIG. 1, a sheet 10 for forming a protective film that has not been punched is prepared. From the surface of the sheet 10 for forming a protective film on the side of the protective film-forming film 11, a cutter (not shown) is used to make a cut 14 through the protective film-forming film 11 and reach a part of the surface of the first release film 12. The operation of making a cut to reach a part of the surface and not cutting completely is called half-cutting. As a result, a cut 14 is formed on a part of the surface of the sheet 10 for forming a protective film so as to have a predetermined closed shape (see FIG. 2 and FIG. 5). Here, when the protective film-forming film is transferred to a semiconductor wafer, the predetermined closed shape is approximately the same shape as the wafer. That is, the cut 14 is formed so as to have approximately the same shape as the shape of the workpiece to which the protective film-forming film 11 is attached or the area in which the protective film is to be formed. This process is called a "punching process".

By the punching process, the protective film-forming film 11 is divided into a protective film-forming film 16 punched into a predetermined closed shape and an unnecessary portion 17 that continues around it. The protective film-forming film 16 punched into a predetermined closed shape is provided in multiple places along the longitudinal direction of the protective film-forming sheet 10.

In the punching process, a known punching die can be used as appropriate. The punching process is performed by completely cutting the protective film-forming film 11 and half-cutting the first release film 12 so as not to completely cut it.

As shown in Figures 2 and 4, the cross-sectional shape of the cut 14 is almost wedge-shaped, and the width of the cut 14 is wide on the upper surface side of the protective film-forming film 11 where the die enters, and narrows on the lower surface side (the interface between the protective film-forming film 11 and the first release film 12). The width of the cut 14 is not particularly limited, but from the viewpoint of preventing contact or adhesion between the cut-out protective film-forming film 16 and the unnecessary part 17, or from the viewpoint of shortening the time of contact or adhesion, the width D of the cut 14 on the lower surface part of the protective film-forming film 11 (i.e., the upper surface part of the first release film 12) is preferably 8 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. The width D can be measured by cutting the protective film-forming sheet in the thickness direction and measuring the width of the cut on the upper surface part of the first release film 12 in the cross section. The upper limit of the width D is not particularly limited, but considering the width of the cutting blade that can reliably cut the protective film-forming film, it is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less. In order to form such a cut 14, it is preferable to use a cutting die having a cutting blade with a relatively wide blade width at the tip.

The above-mentioned process results in a punched protective film forming sheet 10. When the punched protective film forming sheet 10 is viewed in plan from the top surface of the protective film forming film 11, the cut 14 is formed in the protective film forming sheet so that a portion of the protective film forming sheet has a predetermined closed shape (for example, a shape substantially the same as the planar shape of a semiconductor wafer), and in the thickness direction of the protective film forming sheet 10, the cut 14 reaches a portion of the first release film 12. That is, a cut is also formed on the surface of the first release film 12 that contacts the protective film forming film 11. By allowing the cutting blade to reach the first release film 12, the protective film forming film 11 can be completely cut.

(4.2 Scum removal process)
After the punching process, and before the scrap removal process, the protective film forming sheet 10 passes through a plurality of rollers such as guide rollers for the purpose of controlling the tension of the protective film forming sheet.

In the waste removal process, as shown in FIG. 6, the continuous unnecessary portion 17 is peeled off from the first release film 12, and the punched protective film-forming film 16 is left on the first release film 12. The peeled unnecessary portion 17 is wound up on a disposal roller.

According to the protective film forming sheet 10 of this embodiment, even if the punched protective film forming film 16 and the unnecessary part 17 come into contact and adhere to each other when passing through the roller 19 or the like after the punching process, the adhesive strength between the protective film forming films is low, so that the protective film forming film 16 and the unnecessary part 17 separate again after passing through the roller. As a result, poor scrap removal during the scrap removal process is suppressed.

The punched protective film forming sheet 10 may be wound into a roll for storage and transportation.

(5. Workpiece machining method)
As an example of a method for processing a workpiece using a punched protective film forming sheet according to this embodiment, a method for manufacturing a package in which a protective film-coated chip obtained by processing a wafer to which a protective film-forming film is attached is arranged on a substrate will be described.

The method for manufacturing the device according to this embodiment includes at least the following steps 1 to 9.
Step 1: A step of punching the protective film forming sheet 10. Step 2: A step of the punched protective film forming sheet passing between rollers. Step 3: A step of removing unnecessary parts 17 of the protective film forming sheet 10. Step 4: A step of attaching the protective film forming film 11 of the protective film forming sheet 10 to the back surface of the wafer. Step 5: A step of converting the attached protective film forming film into a protective film. Step 6: A step of peeling off the first release film from the protective film or protective film forming film. Step 7: A step of singulating the wafer having the protective film or protective film forming film on the back surface to obtain a plurality of chips with the protective film or protective film forming film. Step 8: A step of arranging the chips with the protective film or protective film forming film on the substrate. Step 9: A step of heating the chips with the protective film or protective film forming film arranged on the substrate and the substrate.

Steps 1 to 3 are as described above. Step 5 may be performed before step 6, or after any of steps 6 to 9. In other words, the step of converting the protective film-forming film into a protective film may be performed at any stage after the protective film-forming film is attached to the wafer.

The manufacturing method for the device, which includes steps 1 to 9 above, will be explained with reference to the drawings.

As described above, Figures 2, 4 and 5 show the outline of step 1. Figure 6 shows the outline of step 3.
As shown in Fig. 9, the protective film-forming film 11 of the protective film-forming sheet 10 is attached to the back surface of the wafer 21 (step 4). Thereafter, the attached protective film-forming film 11 is made into a protective film to form a protective film 32 (step 5), thereby obtaining a wafer with a protective film. When the protective film-forming film 11 is thermosetting, the protective film-forming film 11 may be heated at a predetermined temperature for an appropriate time. When the protective film-forming film 11 is energy ray-curable, an energy ray-transmitting film may be used as the first release film 12, and energy rays may be incident from the first release film 12 side.

The protective film-forming film 11 may be cured after the dicing process described below, or the chip with the protective film-forming film may be picked up from the dicing sheet and then the protective film-forming film 11 may be cured.

Then, the wafer 21 with the protective film is transferred onto a known dicing sheet 22, and the wafer 21 with the protective film is diced to obtain chips 31 (chips 30 with protective film) having a protective film 32, as shown in FIG. 10 (step 7). Thereafter, the dicing sheet 22 is expanded in the planar direction as necessary, and the chips 30 with the protective film are picked up from the dicing sheet 22 by a suction collet or the like.

The picked up chip 30 with protective film may be transported to the next process, or may be temporarily stored in a tray, tape, etc., and transported to the next process after a specified period of time.

The chip 30 with protective film transported to the next process is transported to the substrate 50 by an adsorption collet as shown in FIG. 11, and is detached from the adsorption collet at the terminal portion on the substrate, and is positioned so that the protruding electrode 33 such as a bump can be connected to the terminal portion such as a pad (process 8). At this time, other chips different from the chip 30 with protective film may also be mounted on the substrate 50. Therefore, multiple chips may be mounted on this substrate.

The chip with the protective film placed in the specified position on the substrate is subjected to a heat treatment (reflow treatment) (step 9). The reflow treatment conditions are preferably, for example, a maximum heating temperature of 180 to 350°C and a reflow time of 2 to 10 minutes.

During the reflow process, the convex electrodes 33 of the protective film-coated chip 30 melt and are electrically and mechanically bonded to the terminals on the substrate, and the protective film-coated chip 30 is mounted on the substrate.

(6. Modifications)
The above embodiment of the present invention has been described with reference to a two-layer structure sheet for forming a protective film having a protective film-forming film 11 on a first release film 12, but a second release film 13 may be laminated on the exposed surface of the protective film-forming film 11. That is, the sheet for forming a protective film may be a sheet for forming a protective film 20 in which the protective film-forming film 11 is sandwiched between the first release film 12 and the second release film 13 (see Figs. 3 and 4). In this case, the second release film 13 may be peeled off before the protective film-forming film 11 is attached to the work.

The material and preferred aspects of the protective film-forming film 11 of the protective film-forming sheet 20 are the same as those in the above embodiment, and the first release film 12 is also the same as that described in the above embodiment.

In addition, in this embodiment, in the protective film forming sheet 20, when the peeling force of the first release film 12 from the protective film forming film 11 is F1 and the peeling force of the second release film 13 from the protective film forming film 11 described later is F2, it is preferable that F1 and F2 satisfy the relationship F1>F2. By satisfying such a relationship, when removing the second release film 13 from the protective film forming sheet 20, the protective film forming film 16 that should remain is not removed together with the second release film 13, making it easier to leave the protective film forming film 16 on the first release film 12, and scrap removal defects can be further suppressed.

Therefore, the first release film 12 is a heavy release film with a strong release strength, and the second release film 13 is a light release film with a weak release strength.

The peeling force F1 is preferably 50 mN/100 mm or more, more preferably 70 mN/100 mm or more, even more preferably 90 mN/100 mm or more, even more preferably 110 mN/100 mm or more, and particularly preferably 130 mN/100 mm or more. By having F1 within the above range, unintentional peeling between the protective film-forming film 11 and the first release film 12 can be suppressed.

The release force can be adjusted by, for example, the type of composition for the release agent layer, the thickness of the release agent layer, etc. The second release film 13 is designed to have a smaller release force than the first release film 12. When the second release film 13 has a release agent layer, the release agent layer is not particularly limited as long as it is made of a material that can impart release properties. For example, the release agent layer of the second release film 13 is obtained by curing a composition for the release agent layer that contains silicone, similar to the release agent layer of the first release film 12.

The composition for the release agent layer of the second release film 13 can be selected from the materials exemplified for the first release film 12, so long as it satisfies the relationship between F1 and F2 above. However, it is preferable that the material exemplified as the heavy release additive is contained in a smaller amount than in the first release film 12, or is not contained at all.

The thickness of the second release film 13 is not particularly limited, but is preferably 10 μm or more and 75 μm or less. The thickness of the second release film is more preferably 18 μm or more, and even more preferably 24 μm or more. The thickness of the second release film is more preferably 60 μm or less, and even more preferably 45 μm or less. From the viewpoint of making the peel force F2 and the peel force 1 satisfy the above-mentioned F1>F2, the thickness of the second release film is preferably equal to or less than the thickness of the first release film, and more preferably less than the thickness of the first release film.

The thickness of the second release film means the thickness of the entire second release film. For example, the thickness of a second release film that is composed of multiple layers means the total thickness of all layers that make up the second release film.

The method for manufacturing the protective film forming sheet 20 is to bond the second release film 13 to the exposed surface of the protective film forming film 11 laminated with the first release film 12, as described in the embodiment.

When punching the protective film forming sheet 20, the die is inserted from the second release film 13 side, and the protective film forming film 11 and the second release film 13 are cut into a predetermined closed shape, as in the above embodiment. As a result, the protective film forming film 11 and the second release film 13 that have been punched are obtained on the first release film 12. The punched protective film forming sheet 20 may be wound into a roll and stored or transported.

In the waste removal process, the second release film 13 and the unnecessary portion 17 are simultaneously wound up and removed. At this time, the second release film 13 after being punched and completely cut is reconnected with a long adhesive tape, making it easier to remove the second release film 13. As a result, the protective film-forming film 16 cut into a predetermined closed shape remains on the first release film 12.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and may be modified in various ways within the scope of the present invention.

The invention will be described in more detail below using examples, but the invention is not limited to these examples.

(Preparation of protective film-forming sheet)
[First release film (heavy release film)]
<Coating agent containing release agent layer composition>
The following raw materials for the release agent layer composition were prepared.
Silicone-based release agent containing an organopolysiloxane having a vinyl group and an organopolysiloxane having a hydrosilyl group (BY24-561, manufactured by Dow Corning Toray Co., Ltd., solid content 30% by mass)
Dimethylpolysiloxane (weight average molecular weight: 2000) (Shin-Etsu Chemical Co., Ltd., X-62-1387, solid content 100% by mass)
MQ resin with vinyl groups as a heavy release additive (Toray Dow Corning Co., Ltd., SD-7292, solid content 71% by weight)
Platinum (Pt) catalyst (Toray Dow Corning Co., Ltd., SRX-212, solid content 100% by mass)

The above raw materials were added to a mixed solvent of toluene and methyl ethyl ketone (toluene/methyl ethyl ketone = 1/1 (mass ratio)) in the mixing ratio (solid content equivalent) shown in Table 1 to adjust the total solid content to 2 mass%, and a coating agent containing a release agent layer composition was prepared.

<Preparation of First Release Film>
A coating agent containing a composition for a release agent layer was applied to a PET film (manufactured by Mitsubishi Chemical, product name: Diafoil (registered trademark) T-100, thickness: 50 μm) so that the film thickness after drying would be 0.15 μm, and then heated and dried to form a release agent layer on the PET film, thereby producing first release films (heavy release films) A to C.

<Measurement of surface elastic modulus>
The surface elasticity of the release-treated surface of the resulting first release film was measured as follows.
A cantilever made of silicon nitride (manufactured by Bruker Corporation, product name: MLCT, tip radius: 20 nm, resonance frequency: 125 kHz, spring constant: 0.6 N/m) was installed on an atomic force microscope (manufactured by Bruker Corporation, MultiMode8). The first release film prepared was placed on the atomic force microscope, and the surface of the release agent layer of the first release film prepared was pressed and pulled off with the installed cantilever at a pressing amount of 2 nm and a scan speed of 10 Hz. This operation was performed at 23 ° C. The force curve obtained by this operation was fitted by the JKR theoretical formula to calculate the surface elastic modulus. The surface elastic modulus was measured at 4096 points in the surface 1 μm × 1 μm of the release agent layer of the first release film, and these values were averaged and rounded off to one decimal place to obtain the surface elastic modulus (MPa). The results are shown in Table 1.

[Second release film (light release film)]
"SP-PET381130 (thickness 38 μm)" manufactured by Lintec was used.

[Coating agent containing composition for protective film-forming film]
The following components were mixed in the compounding ratios (solid content equivalent) shown in Table 2, and diluted with methyl ethyl ketone to a solid content concentration of 50 mass % to prepare a coating agent.

(A) Polymer component (A-1): (meth)acrylic acid ester copolymer obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate (weight average molecular weight: 400,000, glass transition temperature: -1°C)
(A-2) (meth)acrylic acid ester copolymer obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 65 parts by mass of methyl acrylate, 12 parts by mass of glycidyl methacrylate, and 13 parts by mass of 2-hydroxyethyl acrylate (weight average molecular weight: 450,000, glass transition temperature: 2° C.)
(B) Curable component (thermosetting component)
(B-1) Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184 to 194 g/eq)
(B-2) Acrylic rubber microparticle-dispersed bisphenol A type liquid epoxy resin (manufactured by Nippon Shokubai Co., Ltd., BPA328, epoxy equivalent 230 g/eq, acrylic rubber content 20 phr)
(B-3) Dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., Epicron HP-7200HH, softening point 88 to 98° C., epoxy equivalent 255 to 260 g/eq)
(C) Curing agent: Dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation)
(D) Curing accelerator: 2-phenyl-4,5-dihydroxymethylimidazole (Curesol 2PHZ, manufactured by Shikoku Chemical Industry Co., Ltd.)
(E) Filler (E-1) Epoxy group-modified spherical silica filler (manufactured by Admatechs Co., Ltd., SC2050MA, average particle size 0.5 μm)
(E-2) Silica filler ("YC100C-MLA" manufactured by Admatechs Co., Ltd., average particle size 0.1 μm)
(F) Silane coupling agent: γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403, methoxy equivalent 12.7 mmol/g, molecular weight 236.3)
(G) Colorant: Carbon black (manufactured by Mitsubishi Chemical Corporation, MA600B, average particle size 28 nm)

The prepared composition for the protective film-forming film was applied to the release-treated surface of the first release film (any of A to C above) and dried at 100°C for 2 minutes to form a protective film-forming film with a thickness of 20 μm. Next, a second release film was attached to the protective film-forming film to obtain a three-layered protective film-forming sheet in which release films were formed on both sides of the protective film-forming film. The attachment conditions were a temperature of 60°C, a pressure of 0.4 MPa, and a speed of 1 m/min. Next, the protective film-forming sheet was cut to a width of 208 mm and wound up to a length of 50 meters to form a roll body.

The following measurements and evaluations were carried out using the obtained protective film forming sheet.

[Adhesion between protective film layers]
The protective film-forming film was exposed from the sheet for forming a protective film as described below, and the protective film-forming films were attached to each other to measure the adhesive strength.

<Fixing protective film-forming film onto adhesive tape>
I. The second release film of the protective film-forming sheet having a three-layer structure of second release film/protective film-forming film/first release film was peeled off.
II. An adhesive tape manufactured by Lintec Corporation (product name PET50PL Thin: acrylic adhesive layer/50 μm PET substrate) was attached to the exposed protective film-forming film at 23° C. to prepare a laminate sample of “PET substrate/acrylic adhesive layer/protective film-forming film/first release film.”
III. The laminate sample was cut into a rectangular shape with a width of 25 mm and a length of 250 mm.

<Fixing protective film onto SUS plate>
I. Double-sided tape with a PET film core was attached to the entire surface of a SUS plate (0.5 mm thick x 70 mm x 150 mm).
II. The second release film of the protective film-forming sheet having a three-layer structure of second release film/protective film-forming film/first release film was peeled off.
III. The exposed protective film-forming film was attached to the entire surface of the adhesive side of the double-sided tape to obtain a laminate sample of "SUS plate/double-sided tape/protective film-forming film/first release film."
IV. The first release film was peeled off to expose the protective film-forming film.

<Adhesive Strength Measurement>
The first release film was peeled off from the laminate sample of "PET substrate/acrylic adhesive layer/protective film-forming film/first release film" to expose the protective film-forming film. The laminate of "PET substrate/acrylic adhesive layer/protective film-forming film" and the laminate of "SUS plate/double-sided tape/protective film-forming film" were laminated so that the protective film-forming films faced each other, and were bonded together at 23°C using a 2 kg roller.

The adhesive strength was measured by the following measurement method after leaving the patch unattached for 2 minutes (±20 seconds) from application.
Using a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS"), the peel strength was measured over a measurement distance of 70 mm at a peel speed of 300 mm/min, a temperature of 23° C., and a peel angle of 180°. The average of the measured values over a 50 mm measurement distance excluding the first 10 mm and the last 10 mm was taken as the "adhesion strength between protective film-forming films."

[Peeling force F1 of first release film from protective film-forming film]
The second release film was peeled off from the obtained protective film-forming sheet. A good adhesive surface of a good adhesive PET (PET25A-4100, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was attached to the surface of the protective film-forming film exposed by peeling by thermal lamination (70° C., 1 m/min) to prepare a laminate sample. The laminate sample was cut into a width of 100 mm to prepare a measurement sample. The back surface of the first release film of the measurement sample was fixed to a hard support plate with double-sided tape.

Using a universal tensile tester (Shimadzu Corporation, product name "Autograph (registered trademark) AG-IS"), the protective film-forming film/good adhesion PET composite (integrated) was peeled from the first release film at a peel angle of 180° and a peel speed of 1 m/min, and the load at that time was measured. The measurement distance was a total of 100 mm, and the average of the measured values over the 80 mm excluding the first 10 mm and the last 10 mm was taken as the peel force F1. The results are shown in Table 2.

[Peeling force F2 of second release film from protective film-forming film]
The obtained sheet for forming a protective film was cut into a width of 100 mm to prepare a measurement sample. The back surface of the first release film of the measurement sample was fixed to a hard support plate with double-sided tape.

Using a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph (registered trademark) AG-IS"), the second release film was peeled off from the measurement sample, and the load at that time was measured under the same conditions as in the measurement of F1, and this was taken as the peel force F2.

The obtained peel forces F1 and F2 were compared and it was confirmed that F1 was greater than F2 for all samples.

[Punching and waste removal of protective film sheets]
Using a RAD-3600F/12 manufactured by Lintec with specifications for 200 mm wafers, a die was inserted from the second release film side of the protective film-forming sheet, and the protective film-forming film and the second release film were punched into a circle (inner diameter 198 mm). At this time, a cut was made in the first release film so as not to punch it completely (punching process). Four types of die with different cutting blade widths were used to perform half cuts with different cut widths. 40 punching processes were performed.

After the punching process, the protective film forming sheet was run between a number of rollers. After that, the circularly punched portion was left on the first release film, and the second release film and unnecessary portions around the circularly punched portion were removed (waste removal process). At this time, the second release film after being punched and completely cut was reconnected with a long adhesive tape, and then the second release film was removed .

<Cutting width>
The protective film-forming sheet after the scrap removal process was cut in the thickness direction so that the cut portion of the first release film would not be deformed, and the protective film-forming sheet was held flat, and the cross section was observed with a scanning electron microscope (SEM, "VE-9800" manufactured by KEYENCE Corporation). The width of the cut remaining in the first release film at the interface between the first release film and the protective film-forming film was measured.

Of the 40 circular parts, the 20th one was selected, and measurements were taken at six equally spaced points on the circumference of one of the circles (connecting the points forms a regular hexagon). The smallest value of the six points was taken as the "cut width." The value was rounded off to one decimal place.

The wider the cut, the less the protective film will stick to itself, making it easier to remove the waste.

<Evaluation of scrap removal ability>
During the scrap removal process, the number of the protective film-forming films of the circular parts that were lifted up along with the unnecessary parts was counted among the 40 circular parts. The fewer the number of lifted pieces, the less the protective film-forming films adhered to each other, and the smoother the scrap removal was.

The above results are summarized in Table 3.

From Table 3, it was confirmed that when the adhesive strength between the protective film-forming films was 19 N or less, the protective film-forming films did not adhere to each other after the punching process, and scrap removal could be performed smoothly. In addition, as in Example 7, it was found that when the cut width was narrow, the protective film-forming films tended to adhere to each other after the punching process, making it difficult to remove the scraps smoothly.

As described above, the present invention provides a sheet for forming a protective film and a method for manufacturing the same that can sufficiently suppress waste removal defects even when the width of the cut during punching is relatively narrow.

10... Sheet for forming protective film (this embodiment)
11... protective film-forming film 12... first release film 13... second release film 14... incision 16... punched protective film-forming film 17... unnecessary part 19... roller 20... protective film-forming sheet (other embodiments)
21...wafer 22...dicing sheet 30...chip with protective film 31...chip 32...protective film 33...projecting electrode 50...substrate

Claims (10)

A curable protective film-forming film;
A long sheet having a first release film provided on one surface of the protective film-forming film,
A sheet for forming a protective film, in which the adhesive strength 2 minutes after two protective film-forming films are applied at 23° C. under a load of 2 kgf is 19 N/25 mm or less. A single-layer protective film-forming film;
A long sheet having a first release film provided on one surface of the protective film-forming film,
the protective film-forming film is releasably laminated on the first release film,
A sheet for forming a protective film, in which the adhesive strength 2 minutes after two protective film-forming films are applied at 23° C. under a load of 2 kgf is 19 N/25 mm or less. A long sheet having a first release film, a second release film, and a protective film-forming film sandwiched between the first release film and the second release film,
A sheet for forming a protective film, in which the adhesive strength 2 minutes after two protective film-forming films are applied at 23° C. under a load of 2 kgf is 19 N/25 mm or less. A protective film-forming film containing a filler;
A long sheet having a first release film provided on one surface of the protective film-forming film,
A sheet for forming a protective film, in which the adhesive strength 2 minutes after two protective film-forming films are applied at 23° C. under a load of 2 kgf is 19 N/25 mm or less. A protective film forming film,
A long sheet having a first release film provided on one surface of the protective film-forming film,
The adhesive strength after 2 minutes from sticking two protective film-forming films under a load of 2 kgf at 23° C. is 19 N/25 mm or less,
The protective film-forming film is a sheet for forming a protective film, which is releasably laminated on a first release film,
A step of attaching the protective film-forming film of the protective film-forming sheet to the back surface of the workpiece in a state in which the protective film-forming film is on the first release film;
A step of converting the attached protective film-forming film into a protective film; and
A sheet for forming a protective film used in a method for processing a workpiece, the method including a step of peeling off a first release film from a protective film or a protective film-forming film. 6. The sheet for forming a protective film according to claim 1, wherein the surface elasticity of the surface of the first release film in contact with the protective film-forming film is 17 MPa or less. When the protective film-forming sheet is viewed in plan, a cut is formed in the protective film-forming sheet so that a part of the protective film-forming sheet has a predetermined closed shape,
The sheet for forming a protective film according to any one of claims 1 to 6 , wherein the cut penetrates the protective film-forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film. The sheet for forming a protective film according to claim 7 , wherein the width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more. The method includes a step of forming a cut so that a part of the sheet for forming a protective film according to any one of claims 1 to 6 has a predetermined closed shape,
A method for manufacturing a punched sheet for forming a protective film, in which the cut penetrates the protective film-forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film. The method for producing a punched sheet for forming a protective film according to claim 9 , wherein the width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.

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