JP5629097B2 - Dry film resist roll - Google Patents

Description

  The present invention relates to a dry film resist roll, and more particularly, to an alkali developable dry film resist roll suitable for manufacturing printed circuit boards, lead frames, semiconductor packages, and the like.

  In recent years, electronic devices used in personal computers, mobile phones, and the like have become lighter, thinner, and smaller, and a narrow pitch pattern is required for packages such as printed wiring boards or lead frames, BGAs, and CSPs. In the field of manufacturing printed wiring boards, lead frames, semiconductor packages, etc., and precision processing of metals, photopolymerizable resin compositions as resist materials such as etching resists or plating resists, and dry film resists using the same It is known to use. The dry film resist is generally prepared by laminating a photopolymerizable resin composition layer on a support and further laminating a protective layer as necessary on the photopolymerizable resin composition layer. The photopolymerizable resin composition layer used here is generally of an alkali development type using a weak alkaline aqueous solution as a developer.

To prepare a printed wiring board using a dry film resist, the protective layer is first peeled off, and then a dry film resist is laminated on a permanent circuit creation board such as a copper-clad laminate or a flexible board using a laminator or the like. Then, exposure is performed through a wiring pattern mask film or the like. Next, the support is peeled off as necessary, and the unexposed portion of the photopolymerizable resin layer is dissolved or dispersed with a developer to form a resist pattern on the substrate.
After forming the resist pattern, the process of forming a circuit is roughly divided into two methods.

  The first method is a method in which after removing a copper surface such as a copper-clad laminate not covered with a resist pattern by etching, the resist pattern portion is removed with an alkaline aqueous solution stronger than the developer. In this case, a method (tenting method) in which through holes (through holes) are covered with a cured film and then etched is used frequently for the convenience of the process.

  The second method is to perform copper plating on the same copper surface as in the first method, and after removing plating of solder, nickel, tin, etc. if necessary, remove the resist pattern portion in the same manner. This is a method (plating method) for etching a copper surface such as a copper-clad laminate that has appeared. For etching, an acidic etching solution such as cupric chloride, ferric chloride, copper ammonia complex solution, sulfuric acid / hydrogen peroxide aqueous solution or the like is used.

  Usually, such a dry film resist roll is rolled into a product and distributed in the market. The photosensitive resin composition in the dry film resist has adhesiveness and fluidity. is there. Therefore, the photosensitive resin composition oozes out from the roll end surface during storage, and the problem is that the roll cannot be rewound during use due to adhesion between the layers at the roll end, or even if the roll can be rewound, the rewinding workability is remarkably deteriorated. There was a problem.

  In order to solve such a problem, Patent Document 1 and Patent Document 2 propose a laminate element that covers a roll end by bringing a sheet-like desiccant into contact with the roll end of a photoresist film. In addition, it is described that these methods prevent bleeding from the end of the photosensitive layer during winding and storage. However, the techniques described in these patent documents do not sufficiently prevent the bleeding.

Japanese Patent No. 2730630 JP 2001-188319 A

  The problem to be solved by the present invention is to provide a dry film resist roll that suppresses bleeding of the resist and has excellent adhesion resolution as a resist material such as an etching resist or a plating resist.

  The present inventor has intensively studied to solve the above problems, and as a result of repeated experiments, it has been found that the use of a desiccant containing calcium oxide significantly suppresses the exudation of the resist. Invented.

That is, the present invention is as follows.
[1] A dry film resist roll comprising a dry film resist having a photosensitive layer wound in the form of a roll and provided with a desiccant on the end surface of the film roll, the photosensitive layer containing a photosensitive resin composition, The photosensitive resin composition is such that (a) the carboxyl group content is 100 to 600 in terms of acid equivalent and the weight average molecular weight is 5000 to 500,000 with respect to the total amount of the composition: 20 to 90% by mass, (b) a photopolymerizable unsaturated compound: 3-70% by mass, and (c) a photopolymerization initiator: 0.1-20% by mass, and the desiccant contains calcium oxide. A dry film resist roll characterized by that.

  [2] The unsaturated compound capable of photopolymerization (b) is represented by the following formula (1):

{Wherein R ₁ and R ₂ are each independently H or CH ₃ , A is C ₂ H ₄ , B is C ₃ H ₆ , and n ₁ and n ₂ are 1 It is an integer of ~ 29, _{n 3} and _{n 4} is an integer of _{0~29, n} 1 + n ₂ is an integer from 2 to _30, n 3 + _{n 4} is an integer of 0 to 30, The arrangement of repeating units of-(A-O)-and-(B-O)-may be random or block. } The dry film resist roll according to [1], which is a compound represented by:

  [3] The dry film resist roll according to [1] or [2], wherein the (c) photopolymerization initiator contains a 2,4,5-triarylimidazole dimer.

  [4] A resist pattern forming method including a step of forming a photosensitive resin layer on a substrate using the dry film resist roll according to any one of [1] to [3], an exposure step, and a development step.

  The dry film resist roll of the present invention is used as a resist material such as an etching resist or a plating resist in the field of manufacturing printed wiring boards, lead frames, semiconductor packages, etc., or precision processing of metal, etc. It is suppressed and has excellent adhesion resolution.

Hereinafter, the present invention will be specifically described.
In the dry film resist of the present invention, (a) a binder resin having a carboxyl group content of 100 to 600 in terms of acid equivalent and a weight average molecular weight of 5,000 to 500,000 in the photosensitive layer: 20 to 90% by mass, ( b) Photopolymerizable unsaturated compound: 3 to 70% by mass, and (c) Photopolymerization initiator: 0.1 to 20% by mass. This photosensitive layer may be prepared using a photosensitive resin composition. Therefore, this photosensitive layer contains a photosensitive resin composition. Moreover, this photosensitive resin composition is (a) Resin for binders: 20-90 mass% with respect to this composition whole quantity, (b) Unsaturated compound which can be photopolymerized: 3-70 mass%, and ( c) Photopolymerization initiator: 0.1 to 20% by mass is contained. The (a) binder resin, ((b) the photopolymerizable unsaturated compound, and (c) the photopolymerization initiator may each contain one or more compounds.

  About the quantity of the carboxyl group contained in (a) resin for binders used for this invention, an acid equivalent is 100-600, Preferably it is 300-400. An acid equivalent means the mass of the polymer which has a 1 equivalent carboxyl group in it.

  The carboxyl group in the polymer is necessary for imparting developability and releasability to an aqueous alkali solution to the photosensitive layer. When the acid equivalent is less than 100, the development resistance is lowered and adversely affects the resolution and adhesion. On the other hand, when it exceeds 600, the developability and the peelability are lowered. The acid equivalent is measured by a potentiometric titration method using Hiranuma automatic titrator (COM-555) manufactured by Hiranuma Sangyo Co., Ltd. and 0.1 mol / L sodium hydroxide.

  The weight average molecular weight of the (a) binder resin used in the present invention is 5,000 to 500,000. When the weight average molecular weight exceeds 500,000, the developability deteriorates. When the weight average molecular weight is less than 5000, the tenting film strength decreases and edge fuse occurs. The weight average molecular weight is preferably 10,000 to 40,000 because the resolution is improved when i-line monochromatic exposure is performed using a projection exposure machine.

  The weight average molecular weight was measured by Gel Permeation Chromatography (GPC) manufactured by JASCO Corporation (pump: Gulliver, PU-1580 type, column: Shodex (registered trademark) manufactured by Showa Denko KK (KF-807, KF-806M). , KF-806M, KF-802.5) 4 in series, moving bed solvent: tetrahydrofuran, use of calibration curve with polystyrene standard sample), as a weight average molecular weight (polystyrene conversion).

  The resin for binder (a) used in the present invention is obtained by copolymerizing two or more monomers selected from the group consisting of the following two types of monomers.

  The first monomer is a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. For example, as the first monomer, (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester and the like can be mentioned.

  The second monomer is non-acidic, has one polymerizable unsaturated group in the molecule, has various properties such as developability of the photosensitive layer, resistance in etching and plating processes, and flexibility of the cured film. Selected to retain properties. Examples of such compounds include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. , 2-hydroxypropyl (meth) acrylate, (meth) acrylonitrile and the like. In a preferred embodiment of the present invention, a vinyl compound having a phenyl group (for example, styrene) is used to obtain high resolution.

  (A) Resin for binder used in the present invention is a radical polymerization initiator such as benzoyl peroxide or azoisobutyronitrile in a solution obtained by diluting a mixture of the above monomers with a solvent such as acetone, methyl ethyl ketone, or isopropanol. It is preferable to synthesize | combine by adding a suitable quantity and superheated stirring. Moreover, you may synthesize | combine (a) resin for binders, dripping a part of mixture into a reaction liquid. Moreover, after completion | finish of reaction, a solvent may be added and (a) binder resin may be adjusted to a desired density | concentration. Furthermore, as synthesis means, bulk polymerization, suspension polymerization, or emulsion polymerization may be used in addition to solution polymerization.

  The ratio of the (a) binder resin to the total amount of the photosensitive resin composition used in the present invention is in the range of 20 to 90% by mass, preferably 30 to 70% by mass.

  (A) When the ratio of the binder resin is less than 20% by mass and more than 90% by mass, the resist pattern formed by exposure and development has characteristics as a resist, such as tenting, etching, and the like. It does not have sufficient resistance in various plating processes.

  In the present invention, compounds represented by the following formulas (1) to (4) can be used as the photopolymerizable unsaturated compound (b).

  In a preferred embodiment of the present invention, from the viewpoint of resolution, the photosensitive layer is represented by the following formula (1) as (b) a photopolymerizable unsaturated compound:

{Wherein R ₁ and R ₂ are each independently H or CH ₃ , A is C ₂ H ₄ , B is C ₃ H ₆ , and n ₁ and n ₂ are N is an integer of 1 to 29, n ₃ and n ₄ are integers of 0 to 29, n ₁ + n ₂ is an integer of 2 to 30, and n ₃ + n ₄ is an integer of 0 to 30 And the sequence of-(A-O)-and-(B-O)-repeating units may be random or block. } At least one photopolymerizable unsaturated compound selected from the group consisting of compounds represented by:

In the compound represented by the above formula (1), when n ₁ + n ₂ and n ₃ + n ₄ exceed 30, the double bond concentration in the negative photosensitive layer (A) becomes relatively low, which is sufficient. Sensitivity cannot be obtained. n ₁ + n ₂ is preferably ₄ to 14, and n ₃ + n ₄ is preferably 0 to 14.

  Specific examples of the compound represented by the above formula (1) used in the present invention include polyalkylene glycol dimethacrylate in which an average of 2 mol of propylene oxide and an average of 6 mol of ethylene oxide are added to both ends of bisphenol A, respectively. Polyethylene glycol dimethacrylate (NK ester BPE-500, manufactured by Shin-Nakamura Chemical Co., Ltd.) in which an average of 5 moles of ethylene oxide is added to both ends of bisphenol A, respectively. From the viewpoint of resolution, the content of the compound represented by the above formula (1) in the photosensitive resin composition is preferably 1% by mass to 50% by mass.

  In another embodiment of the present invention, the photosensitive layer is represented by the following formula (2) as (b) a photopolymerizable unsaturated compound:

{Wherein R ₃ and R ₄ are H or CH ₃ , which may be the same or different, and n ₅ , n ₆ and n ₇ are integers of 3-20. . } Is contained.

The compound represented by the above formula (2) is used when n ₅ , n ₆ and n ₇ are smaller than 3, the boiling point of the compound is lowered and the odor of the resist is increased. Becomes difficult. On the other hand, when n ₅ , n _6, and n ₇ exceed 20, the concentration of the photoactive site per unit weight decreases, so that practical sensitivity cannot be obtained.

  Specific examples of the compound represented by the above formula (2) used in the present invention include, for example, a diglycol of glycol obtained by adding ethylene oxide to both ends at an average of 3 moles on polypropylene glycol with an average of 12 moles of propylene oxide added. Methacrylate is mentioned.

  In another embodiment of the present invention, the photosensitive layer is represented by the following formula (3) as (b) a photopolymerizable unsaturated compound:

{Wherein R ₅ is a diisocyanate residue having 4 to 12 carbon atoms, R ₆ and R ₇ are H or CH ₃ , which may be the same or different, and m ₁ , M ₂ , m ₃ and m ₄ are integers from 0 to 15, and — (OC ₃ H ₆ ) _m1 — (OC ₂ H ₄ ) _m3 — and — (OC ₃ H ₆ ) _m2 — (OC ₂ H ₄ ) The arrangement of repeating units of _m4 − may be random or block, and in the case of a block, either may be on the acryloyl group side. } May be contained.

In the compound represented by the above formula (3), when m ₁ , m ₂ , m ₃ and m ₄ exceed 15, sufficient sensitivity cannot be obtained.

  Specific examples of the compound represented by the above formula (3) used in the present invention include, for example, a diisocyanate compound such as hexamethylene diisocyanate, tolylene diisocyanate, or 2,2,4-trimethylhexamethylene diisocyanate, and one molecule. Examples thereof include urethane compounds with compounds having a hydroxyl group and a (meth) acryl group (for example, 2-hydroxypropyl acrylate, oligopropylene glycol monomethacrylate, oligoethylene glycol monomethacrylate, oligoethylenepropylene glycol monomethacrylate, etc.). . Specifically, a reaction product of hexamethylene diisocyanate and oligopropylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Blenmer PP1000), hexamethylene diisocyanate and oligoethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Blemmer PE-) 200), a reaction product of hexamethylene diisocyanate and oligoethylenepropylene glycol monomethacrylate (manufactured by NOF Corporation, Blemmer 70PEP-350B). In the present specification, the diisocyanate residue includes a urethane bond derived from a diisocyanate compound as a raw material.

  In another embodiment of the present invention, the photosensitive layer is represented by the following formula (4) as (b) a photopolymerizable unsaturated compound:

{Wherein R ₈ is H or CH ₃ , R ₉ is a hydrogen atom or an alkyl group having 1 to 14 carbon atoms, A is C ₂ H ₄ , and B is C ₃ H ₆ M ₅ is an integer of 1 to 12, m ₆ is an integer of 0 to 12, m ₇ is an integer of 1 to 3, and — (A—O) — and — (B The arrangement of repeating units of —O) — may be random or block. } Is contained.

In the compound represented by the above formula (4), when m ₅ and m ₆ exceed 12, sufficient sensitivity cannot be obtained, and even when m ₇ exceeds 14, sufficient sensitivity cannot be obtained.

  Specific examples of the compound represented by the formula (4) used in the present invention include, for example, polypropylene glycol added with an average of 2 mol of propylene oxide and polyethylene glycol added with an average of 7 mol of ethylene oxide to nonylphenol. 4-normal nonyl phenoxy hepta ethylene glycol dipropylene glycol acrylate, which is an acrylate of a compound, or 4-normal nonyl phenoxy octaethylene glycol acrylate, which is an acrylate of a compound obtained by adding polyethylene glycol added with an average of 8 moles of ethylene oxide to nonyl phenol ( And Toagosei Co., Ltd., M-114).

  As the photopolymerizable unsaturated compound (b) used in the present invention, in addition to the above compounds, the following photopolymerizable unsaturated compounds can be used in combination. For example, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 2-di (p-hydroxy) Phenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate, polyoxyethyltrimethylolpropane triacrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol penta (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A di Glycidyl ether di (meth) acrylate, and β- hydroxypropyl-beta '- (acryloyloxy) propyl phthalate.

  The ratio of (b) the photopolymerizable unsaturated compound to the total amount of the photosensitive resin composition is in the range of 3 to 70% by mass. If this ratio is less than 3% by mass, the sensitivity is not sufficient. On the other hand, if it exceeds 70% by mass, the photopolymerizable layer protrudes during storage. Preferably, this proportion is 10-60% by weight, more preferably 15-55% by weight.

  Next, (c) the photopolymerization initiator used in the present invention will be described.

  In a preferred embodiment of the present invention, from the viewpoint of high resolution, (c) the photopolymerization initiator includes a 2,4,5-triarylimidazole dimer. As the triimidazole dimer, the following formula (5):

  {In the formula, X, Y and Z each independently represent hydrogen, an alkyl group, an alkoxy group or a halogen group; and p, q and r are each independently an integer of 1 to 5. . } And the following formula (6):

  {In the formula, X, Y and Z each independently represent hydrogen, an alkyl group, an alkoxy group or a halogen group; and p, q and r are each independently an integer of 1 to 5. . }, At least one 2,4,5-triarylimidazole dimer selected from the group consisting of compounds represented by:

  Furthermore, as the 2,4,5-triarylimidazole dimer, for example, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-bis -(M-methoxyphenyl) imidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, and the like. In particular, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer is preferable.

  In a further preferred embodiment of the present invention, (c) 2,4,5-triarylimidazole dimer represented by the formula (5) and / or (6), benzophenone and / or as a photopolymerization initiator Use in combination with benzophenone derivatives. Such a benzophenone derivative is particularly preferably p-aminophenyl ketone from the viewpoint of sensitivity. Examples of p-aminophenyl ketone include p-aminobenzophenone, p-butylaminophenone, p-dimethylaminoacetophenone, p-dimethylaminobenzophenone, p, p'-bis (ethylamino) benzophenone, p, p'- Examples thereof include bis (dimethylamino) benzophenone [Michler's ketone], p, p′-bis (diethylamino) benzophenone, p, p′-bis (dibutylamino) benzophenone, and the like.

  In addition to the compounds shown above, other photopolymerization initiators can be used in combination. In the present specification, the photopolymerization initiator may be a known compound that is activated by various actinic rays, such as ultraviolet rays, and starts polymerization.

  Other photopolymerization initiators include, for example, quinones such as 2-ethylanthraquinone and 2-tert-butylanthraquinone, aromatic ketones such as benzophenone, benzoin ethers such as benzoin, benzoin methyl ether and benzoin ethyl ether, Examples include acridine compounds such as 9-phenylacridine, benzyldimethyl ketal, and benzyldiethyl ketal. For example, combinations of thioxanthones such as thioxanthone, 2,4-diethylthioxanthone, and 2-chlorothioxanthone and tertiary amine compounds such as dimethylaminobenzoic acid alkyl ester compounds are also included.

  Moreover, oxime esters such as 1-phenyl-1,2-propanedione-2-O-benzoyloxime and 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) oxime are also included. Furthermore, N-aryl-α-amino acid compounds can also be used, and among these, N-phenylglycine is particularly preferable.

  In this invention, the ratio of the photoinitiator (c) with respect to the photosensitive resin composition whole quantity is 0.1 mass%-20 mass%. If this ratio is less than 0.1% by mass, sufficient sensitivity cannot be obtained. On the other hand, if this ratio exceeds 20% by mass, fogging due to light diffraction through a photomask during exposure tends to occur. As a result, the resolution deteriorates.

  Further, the photosensitive layer of the present invention may contain coloring substances such as dyes and pigments. Examples of such coloring substances include fuchsin, phthalocyanine green, auramin base, chalcoxide green S, paramadienta, crystal violet, methyl orange, Nile Blue 2B, Victoria Blue, Malachite Green (Eizen (registered by Hodogaya Chemical Co., Ltd.)) Trademarks) MALACHITE GREEN), Basic Blue 20, Diamond Green (Eizen (registered trademark) DIAMOND GREEN GH manufactured by Hodogaya Chemical Co., Ltd.) and the like.

  The photosensitive layer of the present invention may contain a coloring dye that develops color when irradiated with light. Examples of such a coloring dye include a combination of a leuco dye or a fluorane dye and a halogen compound.

  Examples of the leuco dye include tris (4-dimethylamino-2-methylphenyl) methane [leuco crystal violet], tris (4-dimethylamino-2-methylphenyl) methane [leucomalachite green], and the like.

  Halogen compounds include amyl bromide, isoamyl bromide, isobutylene bromide, ethylene bromide, diphenylmethyl bromide, benzal bromide, methylene bromide, tribromomethylphenyl sulfone, carbon tetrabromide, tris (2,3 -Dibromopropyl) phosphate, trichloroacetamide, amyl iodide, isobutyl iodide, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, hexachloroethane, triazine compounds and the like.

  Examples of the triazine compound include 2,4,6-tris (trichloromethyl) -s-triazine and 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine.

  Among such coloring dyes, a combination of tribromomethylphenylsulfone and a leuco dye or a combination of a triazine compound and a leuco dye is useful.

  In order to improve the thermal stability and storage stability of the photosensitive layer of the present invention, it is also preferable to contain a radical polymerization inhibitor in the photosensitive resin composition.

  Examples of such radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, 2,2 Examples include '-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), diphenylnitrosamine and the like.

  Further, the photosensitive layer of the present invention may contain an additive such as a plasticizer as necessary. Examples of such additives include phthalic acid esters such as diethyl phthalate, p-toluenesulfonamide, polypropylene glycol, polyethylene glycol monoalkyl ether, and the like.

  In the dry film resist of the present invention, the melt viscosity at 70 ° C. of the photosensitive layer is preferably from 10,000 Pa · sec to 150,000 Pa · sec from the viewpoint of resolution. From the viewpoint of extending the life by suppressing bleeding by a desiccant, the melt viscosity is more preferably from 10,000 Pa · sec to 100,000 Pa · sec, and even more preferably from 10,000 Pa · sec to 50,000 Pa · sec. In the range of the melt viscosity, the bleeding into the resist when combined with the desiccant is particularly suppressed.

  The melt viscosity of the photosensitive layer is measured by CAPILLARY RHEOMETER CFT-500D (manufactured by SHIMADZU).

  Although the thickness of the photosensitive layer varies depending on the application, it is 5 to 100 μm, preferably 5 to 50 μm, for use in producing a printed circuit board. In the present invention, the thinner the photosensitive layer, the better the resolution, while the thicker the photosensitive layer, the better the film strength.

  By laminating the photosensitive layer on the support layer, the dry film resist of the present application is formed. The support layer used here is preferably a transparent layer that transmits active light. As the support layer that transmits active light, polyethylene terephthalate film, polyvinyl alcohol film, polyvinyl chloride film, vinyl chloride copolymer film, polyvinylidene chloride film, vinylidene chloride copolymer film, polymethyl methacrylate copolymer film , Polystyrene film, polyacrylonitrile film, styrene copolymer film, polyamide film, cellulose derivative film and the like. These films can be stretched if necessary.

  The haze of the support layer is preferably 5.0 or less. A thinner thickness is more advantageous in terms of image formation and economy, but a thickness of 10 to 30 μm is common to maintain strength.

  If necessary, a protective layer can be laminated on the surface opposite to the photosensitive layer laminated with the support layer. An important characteristic of this protective layer is that the protective layer has a sufficiently lower adhesion to the photosensitive layer than the support layer and can be easily peeled off. Examples of such a protective layer include a polyethylene film and a polypropylene film.

  The dry film resist roll of the present invention is formed by providing a desiccant containing calcium oxide on the end face of a film roll obtained by winding the dry film resist into a roll. When calcium oxide is used as the desiccant, the effect of extending the life by suppressing bleeding is particularly large compared to other desiccants.

  The desiccant may be kneaded into a resin to form a sheet, or sandwiched between thermoplastic resins to have a sandwich structure.

  The desiccant may be used after being sealed with a moisture-permeable donut-shaped bag-like film. When sealed and used with a moisture-permeable donut-type film, it is preferable because calcium oxide can be prevented from coming into direct contact with the resist end face, and dust from the desiccant can be prevented from adhering to the resist.

  As an example of such a desiccant, “ring-shaped parc ace” manufactured by Yabashi Mine Parc Co., Ltd., and the like can be given.

  A process for producing a printed circuit board using this dry film resist is performed by a known technique, and will be briefly described below.

  When there is a protective layer, the protective layer is first peeled off, and the photosensitive layer is then heat-pressed and laminated on the metal surface of the substrate, ie, the printed circuit board substrate. The heating temperature at this time is generally 40 to 160 ° C.

  Next, if necessary, the support layer is peeled off and image exposure is performed with active light through a mask film.

  Next, when there is a support layer on the photosensitive layer, this is removed as necessary, and subsequently, an unexposed portion of the photosensitive layer is developed and removed using an alkaline aqueous solution. As the alkaline aqueous solution, an aqueous solution of sodium carbonate, potassium carbonate or the like can be used. These alkaline aqueous solutions are selected according to the characteristics of the photosensitive layer, but generally 0.5 to 3% by mass of sodium carbonate aqueous solution is used.

  Next, a metal image pattern is formed on the metal surface exposed by development by performing either a known etching method or a plating method.

  Thereafter, the cured resist pattern is peeled off with an alkaline aqueous solution that is generally stronger than the alkaline aqueous solution used in development. Although there is no restriction | limiting in particular also about the aqueous alkali solution for peeling, The aqueous solution of 1-5 mass% sodium hydroxide and potassium hydroxide is generally used. In addition, when a plating step is provided as in the semi-additive method, the copper surface that appears under the resist pattern may be etched after the resist pattern is removed.

  When producing a lead frame using the dry film of the present invention, a photosensitive layer is laminated on one side or both sides of a metal plate such as copper, copper alloy, or iron-based alloy instead of the copper-clad laminate or flexible substrate. Etching is performed after exposure and development. Finally, the cured resist is peeled off to obtain a desired lead frame.

  In addition, when manufacturing a semiconductor package using the dry film resist of the present invention, a photopolymerizable resin layer is laminated on a wafer on which circuit formation as an LSI has been completed, exposed and developed, and then copper, Apply columnar plating such as solder. Next, the cured resist is peeled off, and the thin metal layer other than the columnar plating is removed by etching to obtain a desired semiconductor package.

Examples of the present invention will be specifically described below.
(Example 1, Comparative Examples 1-2)
<Photosensitive layer>
The compositions of the photopolymerizable resin compositions used in the examples and comparative examples are shown in Table 1 below.
Hereinafter, a method for producing samples for evaluation of Examples and Comparative Examples, an evaluation method for the obtained samples, and evaluation results will be described.

1. Production of Evaluation Samples Photopolymerizable resin laminates in Examples and Comparative Examples were produced as follows.

<(A) Preparation of resin for binder containing carboxyl group>
First, the binder shown below was prepared.
(Synthesis example)
In a 1000 cc four-necked flask equipped with a nitrogen inlet, stirring blades, Dimroth, and thermometer, 300 g of methyl ethyl ketone was placed under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. Next, a total of 400 g of methacrylic acid / styrene / benzyl methacrylate was prepared at a composition ratio of 30/20/50 (mass ratio). A solution in which 3 g of azobisisobutyronitryl was dissolved in 30 g of methyl ethyl ketone was prepared, and the solution was added dropwise to the prepared solution over 2 hours with stirring. Thereafter, polymerization was performed for 6 hours (primary polymerization). Thereafter, a solution obtained by dissolving 6 g of azobisisobutyronitrile in 30 g of methyl ethyl ketone was added dropwise in 3 portions every 4 hours, followed by stirring with heating for 5 hours (secondary polymerization). Next, 240 g of methyl ethyl ketone was added, and the polymerization reaction product was taken out of the flask to obtain a binder solution. The binder had a weight average molecular weight of 55,000, a dispersity of 1.8, and an acid equivalent of 290. The resin solid content measured after sufficiently removing methyl ethyl ketone in the obtained binder solution was 41%.

<Production of dry film resist roll>
A photopolymerizable resin composition having the composition shown in Table 1 was prepared, stirred and mixed well, and uniformly applied to the surface of a 19 μm-thick polyethylene terephthalate film having a width of 500 mm and a length of 200 m as a support, and dried at 95 ° C. After drying for 4 minutes in the machine and pasting a 23 μm thick polyethylene film as a protective layer on the surface of the photosensitive layer, the film was wound around a core to obtain a dry film resist roll. The thickness of the photosensitive layer was 25 μm.

  In Example 1, a calcium oxide-containing desiccant sheet (manufactured by Yabashi Mine Park Co., Ltd., trade name: Ring-shaped Parc Ace) processed into a donut shape was installed on both end faces of the dry film resist roll.

  In Comparative Example 1, a calcium chloride-containing desiccant sheet (trade name: ID sheet, thickness 1 mm, manufactured by ID Corporation) processed into a donut shape was installed on both end faces of the dry film resist roll.

  In Comparative Example 2, no desiccant was installed on both end faces of the dry film resist roll.

<Evaluation of seepage life from edge of photosensitive layer>
The dry film resist rolls of Example 1 and Comparative Examples 1 and 2 were placed in a polyethylene tube, and then stored in a constant temperature and humidity layer at 20 ° C. and 50%. The state of the end face was checked every day, and the day before the first oozing was confirmed on the entire end face was defined as the life.

<Board surface preparation>
As a resolution evaluation substrate, the surface of a 1.6 mm thick copper clad laminate on which 35 μm rolled copper foil is laminated is jet scrubbed at a spray pressure of 0.20 MPa (Nippon Carlit Co., Ltd., Sac Random R (registered trademark) # 220). ) Was used.

<Laminate>
Laminating at a roll temperature of 105 ° C with a hot roll laminator (ALA-70, manufactured by Asahi Kasei Co., Ltd.) on a copper clad laminate that has been leveled and preheated to 60 ° C while peeling off the polyethylene film of the photopolymerizable resin laminate. did. The air pressure was 0.35 MPa, and the laminating speed was 1.5 m / min. It was.

<Exposure>
With a super high pressure mercury lamp (manufactured by Oak Manufacturing Co., Ltd., HMW-201KB), a 21-step tablet manufactured by Stöffer was exposed at an exposure amount of 7 steps.

<Development>
After peeling off the polyethylene terephthalate film, a 1 mass% Na ₂ CO ₃ aqueous solution at 30 ° C. was sprayed for a predetermined time to dissolve and remove the unexposed portion of the photopolymerizable resin layer. At this time, the minimum development time was defined as the minimum time required for the photopolymerizable resin layer in the unexposed portion to be completely dissolved.

2. Resolution Evaluation Method A substrate for resolution evaluation that had passed 15 minutes after lamination was exposed through a line pattern mask in which the width of the exposed area and the unexposed area was 1: 1. Development was performed with a development time twice as long as the minimum development time, and the minimum mask width in which a cured resist line was normally formed was defined as a resolution value.

3. Evaluation results The evaluation results of Examples and Comparative Examples are shown in Table 1 below.

  The dry film resist roll of the present invention suppresses resist exudation and has excellent adhesion resolution, so that it can be used in the fields of manufacturing printed wiring boards, lead frames, semiconductor packages, etc., and precision processing of metals. Used as a resist material such as a plating resist.

Claims (4)

  A dry film resist roll comprising a dry film resist having a photosensitive layer wound in the form of a roll and provided with a desiccant on the end face of the film roll, the photosensitive layer containing a photosensitive resin composition, The resin composition is (a) a binder resin having a carboxyl group content of 100 to 600 in terms of acid equivalent and a weight average molecular weight of 5,000 to 500,000, based on the total amount of the composition: 20 to 90% by mass (B) a photopolymerizable unsaturated compound: 3 to 70% by mass, and (c) a photopolymerization initiator: 0.1 to 20% by mass, wherein the desiccant contains calcium oxide. A dry film resist roll. (B) The photopolymerizable unsaturated compound is represented by the following formula (1):

{Wherein R ₁ and R ₂ are each independently H or CH ₃ , A is C ₂ H ₄ , B is C ₃ H ₆ , and n ₁ and n ₂ are 1 It is an integer of ~ 29, _{n 3} and _{n 4} is an integer of _{0~29, n} 1 + n ₂ is an integer from 2 to _30, n 3 + _{n 4} is an integer of 0 to 30, The arrangement of repeating units of-(A-O)-and-(B-O)-may be random or block. } The dry film resist roll of Claim 1 which is a compound represented by these.   The dry film resist roll according to claim 1 or 2, wherein the (c) photopolymerization initiator contains a 2,4,5-triarylimidazole dimer.   A method for forming a resist pattern, comprising a step of forming a photosensitive resin layer on a substrate, an exposure step, and a development step using the dry film resist roll according to claim 1.