JP7582297B2 - Marking film for semiconductor encapsulation, release film for semiconductor encapsulation, semiconductor package, and method for manufacturing semiconductor package - Google Patents

Description

The present disclosure relates to a marking film for semiconductor encapsulation, a release film for semiconductor encapsulation, a semiconductor package, and a method for manufacturing a semiconductor package.

As electronic devices become lighter, thinner, and smaller, semiconductor packages are becoming smaller and thinner. The above-mentioned semiconductor packages are obtained by encapsulating semiconductor elements with a thermosetting resin encapsulant, but as semiconductor packages become thinner, the encapsulating resin layer that encapsulates the semiconductor elements is also becoming thinner.

In resin-sealed semiconductor packages, various types of identification information such as manufacturing lot numbers and logos are printed on the surface of the sealing resin layer. One method of printing on the surface of the sealing resin layer is a printing method using ink whose main component is a thermosetting resin or an ultraviolet-curing resin. However, printing with ink can require the application, curing and washing of the ink, which can complicate the manufacturing process of semiconductor packages or make it difficult to ensure the durability of the ink.

To solve these problems, a laser marking method is sometimes used, in which the surface of the encapsulating resin layer is engraved with a laser. Laser marking is a technology in which the surface of the encapsulating resin layer is scraped off with a laser beam to print. With the laser marking method, the encapsulating resin layer is directly engraved, so additional processes such as cleaning are not required, making production more efficient than with printing methods and improving the durability of the printed area.

In addition, encapsulating sheets that exhibit good laser marking properties have been proposed (see, for example, Patent Documents 1 and 2). In the encapsulating sheets described in Patent Documents 1 and 2, a resin layer that exhibits excellent laser marking properties and an encapsulating resin layer that encapsulates a semiconductor element are laminated together.

Patent No. 4682796 JP 2015-043378 A

The encapsulating resin layer that encapsulates the semiconductor element is located as the outermost layer of the semiconductor package, and therefore is required to have an excellent appearance. On the other hand, since the encapsulating resin layer contains a large amount of filler, the amount of colorant added may be small. In addition, carbon black, which is widely used as a colorant, is conductive, and therefore may not be added in high concentration to the encapsulating resin layer from the viewpoint of reliability. For these reasons, the encapsulating resin layer may not be black enough, resulting in a poor appearance of the semiconductor package.
In addition, since the encapsulating sheets disclosed in Patent Documents 1 and 2 have a laminated structure of a resin layer having excellent laser marking properties and an encapsulating resin layer for encapsulating a semiconductor element as described above, the type of encapsulating material is limited to the material constituting the encapsulating resin layer, resulting in poor freedom in the selection of encapsulating materials.
Furthermore, when a colored layer with excellent laser marking properties is disposed on the surface of the sealing resin layer to improve the appearance of the semiconductor package, the laser-marked printed portion of the colored layer may discolor due to heat generated during laser irradiation. Discoloration of the printed portion may reduce the contrast with the non-printed portion, resulting in reduced visibility and design.

One aspect of the present disclosure has been made in consideration of the above-mentioned conventional circumstances, and aims to provide a marking film for semiconductor encapsulation in which discoloration of the printed portion is suppressed. Another aspect of the present disclosure aims to provide a release film for semiconductor encapsulation in which discoloration of the printed portion is suppressed, as well as a semiconductor package and a method for manufacturing the semiconductor package using this release film for semiconductor encapsulation.

Specific means for achieving the above object are as follows.
<1> A marking film for semiconductor encapsulation, comprising a colored layer containing a resin having a non-aromatic cyclic structure.
<2> The marking film for semiconductor encapsulation according to <1>, comprising two types of colored layers having different colors, at least one of which contains the resin having a non-aromatic cyclic structure.
<3> The marking film for semiconductor encapsulation described in <1> or <2>, wherein the colored layer containing the resin having a non-aromatic cyclic structure contains a colorant, a thermosetting resin, and a curing agent, and the resin having a non-aromatic cyclic structure is the thermosetting resin.
<4> The marking film for semiconductor encapsulation according to <3>, wherein the curing agent includes a curing agent that does not contain an aromatic ring in the molecule.
<5> A release film for encapsulating a semiconductor, comprising: a substrate; a release layer; and a colored layer containing a resin having a non-aromatic cyclic structure, in this order.
<6> The release film for semiconductor encapsulation according to <5>, further comprising two types of colored layers having different colors on the release layer, at least one of the colored layers being a colored layer containing the resin having a non-aromatic cyclic structure.
<7> The release film for semiconductor encapsulation according to <5> or <6>, wherein the colored layer containing the resin having a non-aromatic cyclic structure contains a colorant, a thermosetting resin, and a curing agent, and the resin having a non-aromatic cyclic structure is the thermosetting resin.
<8> The release film for semiconductor encapsulation according to <7>, wherein the curing agent contains a curing agent that does not contain an aromatic ring in the molecule.
<9> A semiconductor package comprising: a semiconductor element; an encapsulating resin layer that encapsulates the semiconductor element; and a colored layer provided on a surface of the encapsulating resin layer, the colored layer being a layer derived from the colored layer of the release film for semiconductor encapsulation according to any one of <5> to <8>.
<10> A method for producing a semiconductor package, comprising a step of encapsulating a semiconductor element in a state in which the semiconductor element and the semiconductor encapsulation release film are disposed in a mold so that the semiconductor element faces the colored layer in the semiconductor encapsulation release film according to any one of <5> to <8>.

According to one aspect of the present disclosure, it is possible to provide a semiconductor encapsulation marking film in which discoloration of the printed portion is suppressed. Also, according to one aspect of the present disclosure, it is possible to provide a semiconductor encapsulation release film in which discoloration of the printed portion is suppressed, as well as a semiconductor package and a method for manufacturing a semiconductor package using this semiconductor encapsulation release film.

Hereinafter, the embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to the numerical values and their ranges, and do not limit the present disclosure.
In the present disclosure, the term "step" includes not only a step that is independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.
In the present disclosure, the numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple types of corresponding substances. When multiple types of substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In the present disclosure, the particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.
In the present disclosure, the terms "layer" and "film" include cases where the layer or film is formed over the entire area when the area in which the layer or film is present is observed, as well as cases where the layer or film is formed over only a portion of the area.
In this disclosure, the term "lamination" refers to stacking layers, where two or more layers may be bonded together or two or more layers may be removable.
In the present disclosure, "(meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acrylate" means at least one of acrylate and methacrylate.

In the present disclosure, the average thickness of a layer or film is defined as the arithmetic mean value of thicknesses measured at five points on the layer or film of interest.
The thickness of the layer or film can be measured using a micrometer or the like. In the present disclosure, when the thickness of the layer or film can be measured directly, it is measured using a micrometer. On the other hand, when the thickness of one of the layers or the total thickness of the layers in a state where the layers are stacked, the thickness may be measured by observing the cross section of the measurement target using an electron microscope.

In this disclosure, the "average particle size" is determined as the particle size (50% D) at which the cumulative volume from the small particle size side reaches 50% in a particle size distribution curve of cumulative volume measured by a laser diffraction scattering particle size distribution measurement method. For example, it can be measured using a particle size distribution measurement device that uses a laser light scattering method (for example, "SALD-3000" manufactured by Shimadzu Corporation).

<Marking film for semiconductor encapsulation>
The marking film for semiconductor encapsulation (hereinafter, sometimes referred to as "marking film") of the present disclosure has a colored layer containing a resin having a non-aromatic cyclic structure. A portion (printed portion) of the colored layer that has been removed by a laser marking method or the like is recognized as identification information.
The marking film of the present disclosure is suppressed from discoloring the printed portion. Although the reason is not clear, it is presumed that the resin having a non-aromatic cyclic structure is less susceptible to oxidation due to heat during laser marking and the associated yellowing, and therefore discoloration of the printed portion is more likely to be suppressed.

The components constituting the colored layers of the marking film of the present disclosure are not particularly limited as long as at least one of the colored layers contains a resin having a non-aromatic cyclic structure, and the colored layers can be formed by combining various materials used in the technical field. When the marking film of the present disclosure has two or more colored layers, it is sufficient that at least one of the colored layers contains a resin having a non-aromatic cyclic structure, and all of the colored layers may contain a resin having a non-aromatic cyclic structure.

In the present disclosure, the term "non-aromatic cyclic structure" refers to a cyclic structure that does not exhibit aromaticity. Examples of non-aromatic cyclic structures include alicyclic structures and heterocyclic structures that do not exhibit aromaticity.
Specific examples of the alicyclic structure include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cubane structure, a norbornane structure, a tetrahydrodicyclopentadiene structure, an adamantane structure, a diadamantane structure, a bicyclo[2.2.2]octane structure, a decahydronaphthalene structure, and a spiro ring structure such as a spiro[5.5]undecane structure.
Specific examples of the heterocyclic structure not exhibiting aromaticity include a pyrrolidine structure, a piperidine structure, a piperazine structure, a morpholine structure, a tetrahydrofuran structure, a tetrahydropyran structure, and an isocyanuric acid structure.

The colored layer may contain, for example, a colorant, a thermosetting resin, and a curing agent. The colored layer may contain other components such as a curing accelerator, a thermoplastic resin, and an inorganic filler. When the colored layer contains a resin having a non-aromatic cyclic structure, the resin having a non-aromatic cyclic structure may be a thermosetting resin.
When the marking film has two or more colored layers, the colorants contained in each colored layer may be the same or different, and are preferably different. When the marking film has two types of colored layers with different colors, at least one of the colored layers may be a colored layer containing a resin having a non-aromatic cyclic structure.

The average thickness of the colored layer is preferably from 3 μm to 100 μm, and more preferably from 5 μm to 60 μm.
When the colored layer has two or more layers, it is preferable that the average thickness of the entire colored layers is within the above range.

- Coloring agent -
The colored layer may contain a colorant. As the colorant, various organic pigments, inorganic pigments, etc. can be used. As the colorant, black pigments, white pigments, yellow pigments, magenta pigments, cyan pigments, red pigments, blue pigments, green pigments, etc. can be mentioned. Among these, black pigments and white pigments are preferable from the viewpoint of visibility of various information printed on the sealing resin surface.
Examples of black pigments include carbon black such as acetylene black and ketjen black, titanium black, and aniline black.
Examples of white pigments include basic lead carbonate (2PbCO ₃ .Pb(OH) ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), and strontium titanate (SrTiO ₃ ).

The content of the colorant in the colored layer can be appropriately set depending on the type of the colorant.
When a black pigment is used as the colorant, the content of the colorant in the colored layer is preferably 0.5% by mass to 12% by mass, and more preferably 1% by mass to 10% by mass.
When a white pigment is used as the colorant, the content of the colorant in the colored layer is preferably 15% by mass to 60% by mass, and more preferably 20% by mass to 50% by mass.
The marking film may have two types of colored layers having different colors. When the marking film has two types of colored layers having different colors, it is preferable that the two types of colored layers are a combination of a colored layer containing a white pigment and a colored layer containing a black pigment.
When a colored layer containing a white pigment and a colored layer containing a black pigment are transferred in this order onto the surface of a semiconductor package, the surface of the semiconductor package onto which the colored layer has been transferred can be irradiated with laser light to sublimate the resin in the colored layer containing the black pigment, thereby making it possible to scrape off the surface of the colored layer. At this time, the colored layer containing the white pigment appears from the area where the colored layer containing the black pigment has been scraped off, making it possible to print with high contrast and good visibility.
In this case, it is preferable that the colored layer containing the white pigment contains a resin having a non-aromatic cyclic structure. The influence of discoloration of the resin tends to be greater in the colored layer containing the white pigment. By containing the colored layer containing the white pigment and the resin having a non-aromatic cyclic structure, discoloration in the colored layer containing the white pigment (especially yellowing of the colored layer) tends to be suppressed.

The lasers used in the laser marking method are mainly carbon dioxide lasers and YAG lasers. Since the laser used in the laser marking method is often a YAG laser, it is preferable to use carbon black, which is easily volatilized by a YAG laser, as the black pigment contained in the coloring layer. In addition, a _YVO4 laser can also be used as the laser used in the laser marking method.

- Thermosetting resin -
The colored layer may contain a thermosetting resin. Examples of the thermosetting resin include epoxy resin, triazine resin, phenol resin, melamine resin, cyanate ester resin, and modified products of these resins. These resins may be used alone or in combination of two or more.
From the viewpoint of heat resistance, the thermosetting resin is preferably at least one selected from the group consisting of epoxy resins, phenolic resins, and triazine resins, and more preferably an epoxy resin.

As the epoxy resin, bifunctional epoxy resins such as bisphenol A type epoxy resins, novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins can be used. In addition, generally known epoxy resins such as multifunctional epoxy resins, glycidylamine type epoxy resins, heterocyclic epoxy resins, and alicyclic epoxy resins can be used. These epoxy resins may be used alone or in combination of two or more types.

The epoxy equivalent of the epoxy resin is preferably 80 g/eq to 220 g/eq, more preferably 90 g/eq to 210 g/eq, and further preferably 100 g/eq to 200 g/eq.
The epoxy equivalent of the epoxy resin is measured by perchloric acid titration in accordance with JIS K7236:2009.

Examples of bisphenol A type epoxy resins include Mitsubishi Chemical Corporation's product names: Epicoat 807, 815, 825, 827, 828, 834, 1001, 1004, 1007, 1009, etc., Dow Chemical Company's product names: DER-330, 301, 361, etc., and Shin-Nihon Kagaku Epoxy Manufacturing Co., Ltd.'s product names: YD8125, YDF8170, etc.

Examples of phenol novolac type epoxy resins include Epicoat 152, 154, etc., manufactured by Mitsubishi Chemical Corporation, EPPN-201, etc., manufactured by Nippon Kayaku Co., Ltd., and DEN-438, etc., manufactured by The Dow Chemical Company. Examples of o-cresol novolac type epoxy resins include EOCN-102S, 103S, 104S, 1012, 1025, 1027, etc., manufactured by Nippon Kayaku Co., Ltd., and YDCN701, 702, 703, 704, etc., manufactured by Shin-Nikka Epoxy Manufacturing Co., Ltd.

Examples of polyfunctional epoxy resins include Mitsubishi Chemical Corporation's product name: Epon 1031S, Chiba Specialty Chemicals' product name: Araldite 0163, Nagase Chemicals' product names: Denacol EX-611, 614, 614B, 622, 512, 521, 421, 411, 321, etc. Examples of amine-type epoxy resins include Mitsubishi Chemical Corporation's product name: Epicoat 604, etc., Shin-Nikka Epoxy Manufacturing Co., Ltd.'s product name: YH-434, etc., Mitsubishi Gas Chemical Company, Inc.'s product names: TETRAD-X, TETRAD-C, etc., and Sumitomo Chemical Co., Ltd.'s product name: ELM-120, etc.

Examples of heterocycle-containing epoxy resins include those manufactured by Ciba Specialty Chemicals under the trade name Araldite PT810, those manufactured by UCC under the trade names ERL4234, 4299, 4221, 4206, and those manufactured by Nissan Chemical Industries, Ltd. under the trade name TEPIC-PAS.

Examples of alicyclic epoxy resins include those manufactured by Daicel Corporation under the product names EHPE-3150, CEL2021P, and CEL2000.

When the resin having a non-aromatic cyclic structure is an epoxy resin, the epoxy resin is preferably a heterocycle-containing epoxy resin, an alicyclic epoxy resin, etc., and from the viewpoint of solubility in solvents, an alicyclic epoxy resin is more preferable.

The content of the thermosetting resin in the colored layer is preferably 0.1% by mass to 80% by mass, more preferably 1% by mass to 60% by mass, and further preferably 5% by mass to 50% by mass.
When the colored layer has two or more layers, it is preferable that the content of the thermosetting resin in each colored layer is within the above range.

- Hardener -
The colored layer may contain a curing agent. A commonly used known curing agent may be used as the curing agent. When the thermosetting resin is an epoxy resin, examples of the curing agent include amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenols having two or more phenolic hydroxyl groups in one molecule, such as bisphenol A, bisphenol F, and bisphenol S, and phenolic resins, such as phenol novolac resins, bisphenol A novolac resins, and cresol novolac resins.
Among these, phenol resins, acid anhydrides, amines, etc. are preferred from the viewpoint of the curing properties of the epoxy resin.

Examples of phenolic resins used as curing agents include those manufactured by DIC Corporation under the trade names Phenolite LF-2882, Phenolite LF-2822, Phenolite TD-2090, Phenolite TD-2149, Phenolite VH-4150, and Phenolite VH-4170, and those manufactured by Mitsui Chemicals, Inc. under the trade names XLC-LL and XLC-4L. These may be used alone or in combination of two or more types.

Examples of acid anhydrides used as curing agents include phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, himic anhydride, methyl himic anhydride, chlorendic anhydride, succinic anhydride, trimellitic anhydride, pyromellitic anhydride, trialkyltetrahydrophthalic anhydride maleic anhydride, benzophenonetetracarboxylic dianhydride, hydrogenated methylnadic anhydride, dodecenylsuccinic anhydride, etc. These may be used alone or in combination of two or more.

Examples of amines used as a curing agent include chain aliphatic amines, cyclic aliphatic amines, aliphatic aromatic amines, and aromatic amines.
Specific examples of amines used as curing agents include aromatic amine curing agents having one aromatic ring, such as m-phenylenediamine, 1,3-diaminotoluene, 1,4-diaminotoluene, 2,4-diaminotoluene, 3,5-diethyl-2,4-diaminotoluene, 3,5-diethyl-2,6-diaminotoluene, and 2,4-diaminoanisole; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-methylenebis(2-ethylaniline), and 3,3'-diethyl-4,4'-diaminodiphenylmethane. aromatic amine curing agents having two aromatic rings, such as 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane; hydrolysis condensates of aromatic amine curing agents; aromatic amine curing agents having a polyether structure, such as polytetramethylene oxide di-p-aminobenzoate, polytetramethylene oxide di-para-aminobenzoate; condensates of aromatic diamines and epichlorohydrin; and reaction products of aromatic diamines and styrene.

As a curing agent, from the viewpoint of further suppressing discoloration of the printed area, a curing agent that does not contain an aromatic ring in the molecule is preferable, an acid anhydride that does not contain an aromatic ring is more preferable, and hexahydrophthalic anhydride is even more preferable.

As for the compounding ratio of the thermosetting resin and the curing agent, from the viewpoint of keeping the unreacted portions of each to a minimum and allowing the curing reaction to proceed sufficiently, the ratio of the equivalent number of the thermosetting functional group contained in the thermosetting resin to the equivalent number of the functional group contained in the curing agent (equivalent number of thermosetting resin/equivalent number of curing agent) is preferably set in the range of 0.6 to 1.4, more preferably in the range of 0.7 to 1.3, and even more preferably in the range of 0.8 to 1.2.
When the colored layer has two or more layers, it is preferable that the ratio in each colored layer (equivalent number of thermosetting resin/equivalent number of curing agent) is within the above range.

- Hardening accelerator -
The colored layer may contain a curing accelerator. As the curing accelerator, it is preferable to use various imidazoles. Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Imidazoles are commercially available from Shikoku Chemical Industry Co., Ltd. under the trade names 2E4MZ, 2PZ-CN, 2PZ-CNS, and 2P4MHZ-PW.
In addition, an organic phosphine compound can also be used as the curing accelerator. Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkylalkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine, dialkylarylphosphine, and alkyldiarylphosphine.
When the colored layer contains a curing accelerator, the content of the curing accelerator in the colored layer is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 8% by mass, and even more preferably 0.2% by mass to 6% by mass.

- Thermoplastic resin -
The colored layer may contain a thermoplastic resin. Examples of the thermoplastic resin include polyimide resin, (meth)acrylic resin, urethane resin, polyphenylene ether resin, polyetherimide resin, phenoxy resin, modified polyphenylene ether resin, polystyrene resin, polyethylene resin, polyester resin, polyamide resin, butadiene rubber, acrylic rubber, polycarbonate resin, polyphenylene ether resin, and mixtures thereof, but the thermoplastic resin is not limited to these specific examples.
The thermoplastic resin is preferably a resin having no aromatic ring.
When the colored layer contains a thermoplastic resin, the content of the thermoplastic resin in the colored layer is preferably 0.1% by mass to 30% by mass, more preferably 0.5% by mass to 25% by mass, and even more preferably 1% by mass to 20% by mass.

The weight average molecular weight (Mw) of the thermoplastic resin is preferably from 10,000 to 3,000,000, more preferably from 50,000 to 2,500,000, and even more preferably from 100,000 to 2,000,000.
In the present disclosure, the weight average molecular weight is a value determined by conversion using a standard polystyrene calibration curve by gel permeation chromatography under the following apparatus and measurement conditions. A set of five samples (PStQuick MP-H, PStQuick B [product name, manufactured by Tosoh Corporation]) was used as the standard polystyrene to create the calibration curve.
Apparatus: High-speed GPC apparatus HLC-8320GPC (detector: differential refractometer) (manufactured by Tosoh Corporation, product name)
Solvent used: tetrahydrofuran (THF)
Column: Column TSKGEL SuperMultipore HZ-H (product name, manufactured by Tosoh Corporation)
Column size: Column length 15 cm, column inner diameter 4.6 mm
Measurement temperature: 40°C
Flow rate: 0.35 mL/min Sample concentration: 10 mg/5 mL THF
Injection volume: 20 μL

- Inorganic filler -
The colored layer may contain an inorganic filler. Examples of the inorganic filler include crystalline silica, amorphous silica, aluminum oxide, calcium carbonate, magnesium carbonate, aluminum nitride, and boron nitride. These inorganic fillers may be used alone or in combination of two or more. Among them, silica fillers such as crystalline silica and amorphous silica are preferred from the viewpoint of versatility. Silica fillers are commercially available under the product names R972, R972V, and R972CF from Nippon Aerosil Co., Ltd., SO-E1, SO-E2, SO-E5, SO-C1, SO-C2, SO-C3, and SO-C5 from Admatechs Co., Ltd., and PLV-6, PLV-4, TFC-12, TFC-24, USV-5, and USV-10 from Tatsumori Co., Ltd.
The average particle size of the inorganic filler is preferably 0.01 μm to 20 μm, more preferably 0.1 μm to 10 μm, and even more preferably 0.2 μm to 2 μm.
When an inorganic filler is contained in the colored layer, the content of the inorganic filler in the colored layer is preferably 1% by mass to 90% by mass, more preferably 3% by mass to 80% by mass, and even more preferably 5% by mass to 70% by mass.

The proportion of the resin having an aromatic ring in the entire resin contained in the colored layer is preferably 80% by mass or less, more preferably 55% by mass or less, and even more preferably 5% by mass or less.
In the present disclosure, the ratio of the resin having an aromatic ring refers to the ratio of the resin having an aromatic ring to the total resin contained in the colored layer when the colored layer has one layer, and refers to the ratio of the resin having an aromatic ring to the total resin contained in all the colored layers when the colored layer has two or more layers.

The colored layer of the marking film may be provided on a substrate. The substrate used for the marking film may be the same as the substrate used for the semiconductor encapsulation release film described below.

(Method of manufacturing marking film for semiconductor encapsulation)
The marking film can be manufactured by a known method. For example, the marking film can be manufactured by applying a colored layer forming composition containing the components constituting the colored layer to one side of the substrate and drying it. The details of the colored layer forming composition and the details of the case of applying the colored layer forming composition to the substrate are the same as those of the manufacturing method of the semiconductor encapsulation release film.

<Release film for semiconductor encapsulation>
The semiconductor encapsulation release film (hereinafter sometimes referred to as "release film") of the present disclosure has, in this order, a substrate, a release layer, and a colored layer containing a resin having a non-aromatic cyclic structure. A portion of the colored layer that has been removed by a laser marking method or the like (printed portion) is recognized as identification information.

The release film of the present disclosure suppresses discoloration of the printed portion. The reason for this is not clear, but is presumed to be as follows.
A semiconductor package is manufactured by encapsulating a semiconductor element using an encapsulant in a state where the semiconductor element and the release film are arranged in a mold so that the semiconductor element and the colored layer of the semiconductor encapsulation release film face each other. When encapsulating a semiconductor element using an encapsulant, a pressure treatment is performed under a predetermined temperature condition. After the pressure treatment, a colored layer is transferred to the surface of the encapsulation resin layer that encapsulates the semiconductor element (i.e., the surface of the semiconductor package). The resin having a non-aromatic cyclic structure contained in the colored layer is less likely to be oxidized by heat during the laser marking method and yellowing due to the heat. Therefore, it is presumed that when a printed portion is formed on the transfer layer on the surface of the semiconductor package by the laser marking method, discoloration of the printed portion is more likely to be suppressed.

The release film of the present disclosure has a substrate, a release layer, and a colored layer, and may have other layers as necessary.
Hereinafter, various materials constituting the semiconductor encapsulation release film of the present disclosure will be described.

(Substrate)
The release film has a substrate. The substrate is not particularly limited and can be appropriately selected from resin-containing substrates used in the technical field. From the viewpoint of improving conformability to the shape of the mold, it is preferable to use a resin-containing substrate having excellent stretchability.
Considering that the encapsulation of semiconductor elements with an encapsulant is carried out at high temperatures (approximately 100° C. to 200° C.), it is desirable for the base material to have heat resistance at or above this temperature. In addition, in order to prevent the occurrence of wrinkles in the encapsulating resin and tears in the release film when the release film is attached to a mold and when the resin flows during molding, it is desirable to select the base material taking into consideration the elastic modulus, elongation, etc. at high temperatures.

From the viewpoint of heat resistance and elastic modulus at high temperatures, the substrate preferably contains a polyester resin, such as polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, and copolymers and modified resins thereof.
The substrate is preferably a polyester resin molded into a sheet, more preferably a polyester film, and from the viewpoint of conformability to a mold, still more preferably a biaxially oriented polyester film, and particularly preferably a biaxially oriented polyethylene terephthalate film.
The average thickness of the substrate is not particularly limited, and is preferably 5 μm to 100 μm, and more preferably 10 μm to 70 μm. When the average thickness of the substrate is 5 μm or more, the substrate is easy to handle and tends to be less prone to wrinkles. When the average thickness of the substrate is 100 μm or less, the substrate is excellent in conformity to the mold during molding, and thus tends to suppress the occurrence of wrinkles and the like in the molded semiconductor package.

(Release Layer)
The release film has a release layer. The components constituting the release layer are not particularly limited, and various materials used in the technical field can be used in combination.
The release layer may contain, for example, resin particles and a binder, and may contain other components as necessary.

-Resin particles-
The type of resin constituting the resin particles is not particularly limited. The resin particles preferably contain at least one selected from the group consisting of acrylic resin, polyolefin resin, polystyrene resin, polyacrylonitrile resin and silicone resin. From the viewpoint of releasability to a semiconductor package, the resin particles more preferably contain at least one selected from acrylic resin, polystyrene resin and polyacrylonitrile resin.
From the viewpoint of uniformity of the surface appearance of the semiconductor package, the resin particles are preferably insoluble or poorly soluble in organic solvents (e.g., toluene, methyl ethyl ketone, and ethyl acetate) that can be used in preparing the composition for forming the release layer. Here, "insoluble or poorly soluble in organic solvents" means that the gel fraction after dispersing the resin particles in an organic solvent such as toluene and holding at 50°C for 24 hours in a gel fraction test conforming to JIS K6769:2013 is 97% or more.

The average particle diameter of the resin particles is preferably 1 μm to 55 μm. When the average particle diameter of the resin particles is 1 μm or more, it is possible to form sufficient unevenness on the surface of the release layer, and the uniformity of the appearance of the surface of the molded semiconductor package is improved, and flow marks of the encapsulant tend to be suppressed. In addition, when the average particle diameter of the resin particles is 55 μm or less, it is not necessary to excessively increase the average thickness of the release layer in order to fix the resin particles in the release layer, which is preferable from the viewpoint of cost.
The upper limit of the average particle size of the resin particles is preferably 55 μm, more preferably 50 μm, from the viewpoint of the surface appearance of the semiconductor package, and the lower limit of the average particle size of the resin particles is more preferably 2 μm, even more preferably 3 μm, from the viewpoint of cost.

The shape of the resin particles contained in the release layer is not particularly limited and may be spherical, elliptical, irregular, etc.

The content of the resin particles in the release layer is preferably 5% by volume to 65% by volume.
When the content is 5% by volume or more, it is possible to form sufficient irregularities on the surface of the release layer, and the uniformity of the appearance of the surface of the molded semiconductor package is improved, and the effect of suppressing flow marks of the encapsulant tends to be sufficiently obtained. From this viewpoint, the lower limit of the content of the resin particles is preferably 10% by volume, and more preferably 20% by volume.
In addition, when the content is 65% by volume or less, the resin particles are easily fixed by the binder in the release layer described later, the possibility of the resin particles falling off is reduced, contamination of the surface of the molded semiconductor package can be suppressed, and it tends to be economically preferable. From this viewpoint, the upper limit of the resin particle content is preferably 60% by volume, and more preferably 50% by volume.

-binder-
The type of binder that may be contained in the release layer is not particularly limited. When the release layer contains a binder, the resin particles are fixed in the release layer.
From the viewpoints of releasability from the semiconductor package, heat resistance, and the like, the binder is preferably an acrylic resin or a silicone resin, and more preferably a cross-linked acrylic resin (hereinafter also referred to as a "cross-linked acrylic copolymer").

The acrylic resin may be an acrylic copolymer obtained by copolymerizing a low glass transition temperature (Tg) monomer such as butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, etc., as a main monomer with a functional group monomer such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, acrylonitrile, etc., as necessary. In addition, a crosslinked acrylic copolymer can be produced by crosslinking the above acrylic resin using a crosslinking agent.
Examples of the crosslinking agent used in the production of the crosslinked acrylic copolymer include known crosslinking agents such as isocyanate compounds, melamine compounds, epoxy compounds, etc. In order to form a network structure that spreads gently in the acrylic resin, the crosslinking agent is preferably a multifunctional crosslinking agent having a trifunctional or tetrafunctional functionality.

The crosslinked acrylic copolymer produced using the above-mentioned crosslinking agent has a gently spreading network structure. Therefore, when this crosslinked acrylic polymer is used as a binder in a release layer, the extensibility of the release layer is improved and the inhibition of the extensibility of the base material is suppressed, so that the conformability of the release film to the mold during compression molding can be improved.
From this viewpoint, the amount of the crosslinking agent used in the production of the crosslinked acrylic copolymer is preferably 3 parts by mass to 100 parts by mass, more preferably 5 parts by mass to 70 parts by mass, relative to 100 parts by mass of the acrylic copolymer. When the amount of the crosslinking agent is 3 parts by mass or more, the strength of the binder is ensured, and contamination tends to be prevented. When the amount of the crosslinking agent is 100 parts by mass or less, the flexibility of the crosslinked acrylic copolymer is improved, and the stretchability of the release layer tends to be improved.

-Other ingredients-
The release layer may further contain a solvent, an anchoring enhancer, a crosslinking promoter, an antistatic agent, a colorant, and the like, as necessary.

--Average thickness of release layer--
The average thickness of the release layer is not particularly limited and is appropriately set in consideration of the relationship with the average particle diameter of the resin particles used. The average thickness of the release layer is preferably 0.1 μm to 100 μm, and more preferably 1 μm to 50 μm.
If the average thickness of the release layer is not extremely thinner than the average particle diameter of the resin particles used, it is not difficult to fix the resin particles in the release layer, and the resin particles are not likely to fall off. Therefore, the surface of the molded semiconductor package is not likely to be contaminated by the release layer. In addition, if the average thickness of the release layer is not extremely thicker than the average particle diameter of the resin particles used, it is likely to have the effect of improving the uniformity of the surface appearance of the molded semiconductor package and the effect of suppressing flow marks of the encapsulant. In addition, it is not likely to be economically disadvantageous.
In the present disclosure, the average thickness of the release layer means the average thickness in a dry state, and the release layer of the release film can be measured by the above-mentioned method for measuring the average thickness of a layer.

(Colored Layer)
The release film has one or more colored layers. The details of the components constituting the colored layers are the same as those of the marking film described above.
The release film may have two different colored layers on the release layer, at least one of which contains a resin having a non-aromatic cyclic structure.
The semiconductor encapsulation release film of the present disclosure preferably has a substrate, a release layer, a colored layer containing a black pigment, and a colored layer containing a white pigment, in this order. When a semiconductor package is molded using a semiconductor encapsulation release film of this configuration, a colored layer containing a white pigment and a colored layer containing a black pigment are transferred to the surface of the semiconductor package in this order. By irradiating the surface of the semiconductor package to which the colored layer has been transferred with laser light, it is possible to sublimate the resin in the colored layer containing the black pigment and scrape off the surface of the colored layer. At this time, the colored layer containing the white pigment appears from the area where the colored layer containing the black pigment has been scraped off, making it possible to print with high contrast and good visibility.

(Other configurations)
The substrate is a layer that contacts the mold surface, and depending on the material used, a larger peeling force may be required to peel the release film from the mold. When a material that is difficult to peel from the mold is used for the substrate, it is preferable to adjust the substrate so that the release film is easily peeled from the mold. For example, the surface of the substrate opposite to the surface on which the release layer is provided, that is, the surface on the mold side of the substrate, may be subjected to a surface treatment such as a matte finish to improve releasability from the mold, or a new release layer (second release layer) may be provided. The material of the second release layer is not particularly limited as long as it satisfies the heat resistance, releasability from the mold, etc., and the same material as the release layer may be used. The average thickness of the second release layer is not particularly limited, and is preferably 0.1 μm to 100 μm.

Furthermore, if necessary, an anchoring improving layer (primer layer), an antistatic layer, etc. may be provided between the release layer and the substrate, between the substrate and the second release layer, etc.

A protective film may be provided on the colored layer of the semiconductor encapsulation release film. Examples of the protective film include plastic films such as polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene film, polypropylene film, polymethylpentene film, and polyimide film.

(Method for producing semiconductor encapsulation release film)
The semiconductor encapsulation release film can be manufactured by a known method. For example, a release layer-forming composition containing a component constituting the release layer is applied to one side of a substrate, dried to form a release layer on the substrate, and then a colored layer-forming composition containing a component constituting the colored layer is applied to the release layer, dried to form a colored layer on the release layer, thereby manufacturing the semiconductor encapsulation release film.
As another method, a release layer is formed on one substrate by applying a release layer forming composition containing the components constituting the release layer to one side of the substrate and drying it. Meanwhile, a colored layer forming composition containing the components constituting the colored layer is applied to one side of the other substrate and dried to form a colored layer on the other substrate. Then, the release layer on the one substrate and the colored layer on the other substrate are bonded together so that they are in contact with each other, thereby producing a semiconductor encapsulation release film.
The solvent used for preparing the composition for forming the release layer or the composition for forming the colored layer is not particularly limited, and is preferably an organic solvent capable of dispersing or dissolving each component constituting the release layer or the colored layer. Examples of the organic solvent include toluene, methyl ethyl ketone, and ethyl acetate.
The other substrate may be a film that can be a protective film provided on the colored layer as needed, and examples of such films include plastic films such as polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene film, polypropylene film, polymethylpentene film, polyimide film, etc. The surface of the other substrate may be subjected to a surface treatment such as a release treatment as needed.

The method for applying the release layer-forming composition or the colored layer-forming composition is not particularly limited, and any known coating method such as roll coating, bar coating, kiss coating, or comma coating can be used.
The method for drying the applied release layer forming composition or color layer forming composition is not particularly limited, and any known drying method can be used. For example, a method of drying at 50° C. to 150° C. for 0.1 to 60 minutes may be used.

<Semiconductor package and manufacturing method thereof>
The semiconductor package of the present disclosure comprises a semiconductor element, an encapsulating resin layer that encapsulates the semiconductor element, and a colored layer provided on a surface of the encapsulating resin layer, the colored layer being a layer derived from the colored layer of the semiconductor encapsulation release film of the present disclosure.

The semiconductor package of the present disclosure may be manufactured by any method. For example, the semiconductor package of the present disclosure may be manufactured by a process of encapsulating a semiconductor element in a state in which the semiconductor element and the release film are arranged in a mold so that the semiconductor element and the colored layer of the semiconductor encapsulation release film of the present disclosure face each other.
After the step of sealing the semiconductor element, the colored layer may be subjected to laser marking.
In the step of encapsulating the semiconductor element, the semiconductor element may be encapsulated by compression molding or transfer molding, with compression molding being preferred.

Usually, in the compression molding of a semiconductor package, a release film for semiconductor encapsulation is placed on the mold of a compression molding device, and the release film for semiconductor encapsulation is made to conform to the shape of the mold by vacuum suction or the like. Then, an encapsulant for the semiconductor package (e.g., epoxy resin, etc.) is placed in the mold, a semiconductor element is placed on it, and the encapsulant is hardened by compressing the mold while heating, thereby molding the semiconductor package. Then, the mold is opened, and the molded semiconductor package is taken out. In this manner, a semiconductor package can be manufactured.
At this time, the colored layer of the semiconductor encapsulation release film is transferred to the surface of the encapsulation resin layer of the semiconductor package.
The thermosetting resin contained in the colored layer is preferably an epoxy resin. Since the sealing material of the semiconductor package often contains an epoxy resin, the adhesion between the sealing resin layer and the colored layer is easily improved by containing an epoxy resin as a thermosetting resin in the colored layer. Therefore, the occurrence of wrinkles and the like in the colored layer is more easily suppressed, and the appearance of the surface of the semiconductor package is more excellent.

The present disclosure will be described below based on examples, but the present disclosure is not limited to the following examples. In the following examples, parts and percentages indicate parts by mass and percentages by mass, unless otherwise specified.

[Example 1]
(Preparation of release film)
A primer layer solution having a solids concentration of 1% was prepared by mixing 65 parts of acrylic resin (monomer components: ethyl acrylate, butyl acrylate, and acrylonitrile), 35 parts of tin catalyst (di-n-octyltin dilaurate), and tolue.
Next, 100 parts of acrylic resin (monomer component: acrylic acid alkyl ester), 17 parts of polyisocyanate as a crosslinking agent, 10 parts of filler (acrylic resin particles, average particle diameter: 10 μm), and toluene were mixed to prepare a release layer solution with a solid content concentration of 15%. As a substrate, a primer layer solution was applied to one side of a biaxially oriented polyethylene terephthalate film with an average thickness of 25 μm using a roll coater, and then the release layer solution was applied and dried in layers so that the average thickness after drying was 10 μm to form a release layer, thereby obtaining a release film. The drying temperature was 100° C., and the drying time was 2 minutes.

(Preparation of First Colored Layer)
Thermoplastic resin (acrylic acid ester polymer, monomer components: butyl acrylate and acrylonitrile, weight average molecular weight 900,000), thermosetting resin A (alicyclic epoxy resin, containing cyclohexane structure, epoxy equivalent: 175 g/eq), curing agent A (hexahydrophthalic anhydride), black pigment (carbon black, average particle size: 0.5 μm), curing accelerator (2-phenyl-4-methyl-5-hydroxymethylimidazole), silica filler (average particle size: 0.5 μm), and methyl ethyl ketone were mixed to prepare a solution of a composition for forming a first colored layer having a solid content concentration of 35.0%. The composition ratio based on mass of the composition is shown in Table 1. The unit is "parts by mass".

A solution of the composition for forming the first colored layer was applied using a comma coater onto a polyethylene terephthalate film with an average thickness of 38 μm, and then dried at 85°C for 2 minutes to produce a black first colored resin film with an average thickness of 10 μm.

(Preparation of second colored layer)
A thermoplastic resin (acrylic acid ester polymer, monomer components: butyl acrylate and acrylonitrile, weight average molecular weight 900,000), a thermosetting resin A (alicyclic epoxy resin, containing a cyclohexane structure, epoxy equivalent: 175 g/eq), a curing agent A (hexahydrophthalic anhydride), a white pigment (titanium oxide, average particle size: 0.4 μm), a curing accelerator (2-phenyl-4-methyl-5-hydroxymethylimidazole), a silica filler (average particle size: 0.5 μm), and methyl ethyl ketone were mixed to prepare a solution of a composition for forming a second colored layer having a solids concentration of 38.0%.

A solution of the composition for forming the second colored layer was applied using a comma coater onto a polyethylene terephthalate film with an average thickness of 38 μm, and then dried at 85°C for 2 minutes to produce a white second colored resin film with an average thickness of 10 μm.

The first colored resin film and the second colored resin film were bonded together using a roll laminator at 80°C and 0.4 MPa with the black first colored layer and the white second colored layer in contact with each other, producing a marking film in which the black colored layer and the white colored layer were laminated.

[Preparation of colored layer-integrated release film]
The release film and the marking film were laminated together using a roll laminator under conditions of 80° C. and 0.4 MPa with the release layer and the black colored layer in contact with each other to produce a release film integrated with the colored layer.

(Compression molding process)
A semiconductor bare chip was set on the upper mold of a compression molding die, a colored layer integrated release film was attached to the lower mold, and the semiconductor bare chip and the colored layer of the colored layer integrated release film were arranged so that they faced each other. An encapsulant (manufactured by Hitachi Chemical Co., Ltd.: product name "CEL-9750ZHF10") was supplied onto the colored layer integrated release film. The colored layer integrated release film was fixed to the lower mold of the compression molding die by vacuum, and then the die was clamped, and the encapsulant was molded (compression molded) to obtain a semiconductor package. The die temperature was 165°C, the molding pressure was 6.86 MPa (70 kgf/cm ² ), and the molding time was 180 seconds.

(Hardening)
Next, the semiconductor package was thermally cured at a curing temperature of 175° C. under atmospheric pressure for a curing time of 300 minutes.

(Laser marking)
The semiconductor package was printed under the following conditions: The laser marking conditions were as follows:
Laser marking device: Product name "MD-H9800", manufactured by Keyence Corporation Wavelength: 1064 nm
Intensity: 2W
Scan speed: 700 mm/sec
Q-switch frequency: 50 kHz
Characters (120 characters in a 10 mm x 11 mm cell, the characters are not particularly limited) and rectangles (15 mm x 15 mm) were marked.

[Examples 2 to 4 and Comparative Examples]
Thermosetting resin B (heterocyclic epoxy resin, containing isocyanuric acid structure, epoxy equivalent: 135 g/eq), thermosetting resin C (heterocyclic epoxy resin, containing isocyanuric acid structure, epoxy equivalent: 105 g/eq), thermosetting resin D (novolac type epoxy resin, epoxy equivalent: 200 g/eq), thermosetting resin E (bisphenol F type epoxy resin, epoxy equivalent: 160 g/eq), curing agent A (hexahydrophthalic anhydride), and curing agent B (novolac type phenolic resin) were used to prepare a colored layer-integrated release film in the composition ratio shown in Table 1. Other semiconductor packages were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2. In Table 1, "first layer" means the first colored layer, and "second layer" means the second colored layer.

(Evaluation Method)
- Visibility -
The characters formed by laser marking were rated as A when they were visible to the naked eye (visual distance: about 60 cm), and B when they were not visible.

- Hue -
The hue of the rectangle formed by laser marking was evaluated using a spectrophotometer (handy colorimeter NR3000, manufactured by Nippon Denshoku Industries Co., Ltd.) to evaluate the yellowness index b* in the CIE L*a*b* color system defined in JIS Z 8781-4:2013.
A: b*≦5
B: 5<b*≦9
C: 9<b*

-Heat resistance-
After heat curing, the semiconductor package was visually and microscopically observed to evaluate whether or not the colored layer had peeled off.
A: No peeling B: Peeling

From Table 2, it can be seen that the release film for semiconductor encapsulation of the present disclosure, which has a colored layer containing a resin having a non-aromatic cyclic structure, suppresses yellowing of the printed area due to laser marking and provides excellent visibility to the semiconductor package.

All publications, patent applications, and technical standards described in this specification are incorporated by reference into this specification to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims (6)

A colored layer including a resin having a non-aromatic cyclic structure and a white pigment ,
the colored layer containing the resin having a non-aromatic cyclic structure and the white pigment contains a colorant, a thermosetting resin, and a curing agent, the colorant being the white pigment, and the resin having a non-aromatic cyclic structure being the thermosetting resin;
The marking film for semiconductor encapsulation , wherein the curing agent contains a curing agent that does not contain an aromatic ring in the molecule . The semiconductor encapsulation marking film according to claim 1, which has two different colored layers, at least one of which contains a resin having a non-aromatic cyclic structure and a white pigment. The present invention has a substrate, a release layer, and a colored layer including a resin having a non-aromatic cyclic structure and a white pigment, in this order;
the colored layer containing the resin having a non-aromatic cyclic structure and the white pigment contains a colorant, a thermosetting resin, and a curing agent, the colorant being the white pigment, and the resin having a non-aromatic cyclic structure being the thermosetting resin;
The release film for semiconductor encapsulation , wherein the curing agent contains a curing agent that does not contain an aromatic ring in the molecule . A release film for semiconductor encapsulation as described in claim 3, which has two types of colored layers of different colors on the release layer, and at least one of the colored layers is a colored layer containing a resin having a non-aromatic cyclic structure and a white pigment. 5. A semiconductor package comprising: a semiconductor element; an encapsulating resin layer that encapsulates the semiconductor element; and a colored layer provided on a surface of the encapsulating resin layer, the colored layer being a layer derived from the colored layer of the semiconductor encapsulation release film according to claim 3 . 5. A method for manufacturing a semiconductor package, comprising a step of encapsulating a semiconductor element in a state in which the semiconductor element and the semiconductor encapsulation release film are placed in a mold so that the semiconductor element faces the colored layer in the semiconductor encapsulation release film according to claim 3 or 4.