JP2013080757A - Laminate structure for printed wiring board and method of manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate structure for a printed wiring board capable of performing fine and quick via hole formation without denaturation of a surface layer around a via hole periphery when the via hole reaching a substrate is formed by irradiation with an ultraviolet laser, and also to provide a method of manufacturing a printed wiring board using the same.SOLUTION: A laminate structure for a printed wiring board includes: a substrate; a second cured coated film layer formed on the substrate; and a first cured coated film formed between the second cured coated film layer and the substrate. The second cured coated film is formed of a thermosetting resin composition including (C) a polyimide resin having a multi-branched structure and (D) a multifunctional cycloaliphatic epoxy resin, and the first cured coated film is formed of the thermosetting resin composition including at least one kind of a component having ultraviolet absorption.

Description

  The present invention relates to a laminated structure used for a printed wiring board and the like and a method for manufacturing a printed wiring board using the same.

  In recent years, with the miniaturization and high density of electronic devices such as information communication devices, printed wiring boards have also become smaller and thinner, and the demand for higher density and miniaturization of wiring patterns has increased. ing. When forming a via hole (through hole) reaching a substrate having a diameter of about 50 to 250 μm with respect to such a resin insulating layer on the substrate, a carbon dioxide laser is generally used (Patent Document 1, etc.) reference).

  Further, when forming a fine via hole having a diameter of about 30 to 50 μm, an ultraviolet laser is used (see Patent Documents 2 to 4). At that time, for the purpose of increasing the processing speed of the ultraviolet laser, in order to increase the ultraviolet absorptivity of the resin insulating layer, an ultraviolet absorber or the like may be included in the component of the resin insulating layer (see Patent Document 5).

  In such ultraviolet laser processing, a laser beam having a high energy density is irradiated onto the resin insulating layer and the part is removed, but at the same time, a laser beam having a low energy density is also irradiated onto the resin insulating layer. In particular, in a resin insulating layer having a high UV absorption property, the surface layer portion around the via hole is denatured, so that the physical properties of the coating film are significantly deteriorated. This is because the resin insulating layer is only one layer, and therefore, in addition to the formation of a desired via hole, there is a problem that the surface layer portion around the periphery of the via hole is modified.

  In addition, when an ultraviolet laser is used, if the resin insulating layer has a low ultraviolet absorptivity, the removability is poor and the number of times of irradiation increases, so that the processing speed is slow and the processing cannot be performed quickly. On the other hand, in the case of using a carbon dioxide laser, although the processing speed of the resin insulating layer is high, it is not appropriate because the formation of a via hole of 50 μm or less cannot be stably formed from the wavelength and diffraction limit.

  To solve the above problem, a method of removing the resin layer by changing the focal position of the laser beam (defocusing) has been disclosed (see Patent Document 6 and the like). In addition, a method of processing with an ultraviolet laser in a state where a plastic film is laminated on a resin insulating layer to form two or more layers is disclosed (see Patent Documents 7 to 8, etc.).

International Publication No. 2009-0666759 Japanese Patent Laid-Open No. 11-266068 (Claims etc.) JP 2004-240233 A (Claims etc.) International Publication No. 2009-096507 (Claims etc.) JP 2002-121360 A (Claim 1 etc.) JP 2006-203074 A (Claims etc.) JP 2004-079991 A (Claims etc.) JP 2001-323075 A (Claims etc.)

  However, although the method described in Patent Document 6 can reduce the generation of a resin degradation product called smear generated during laser processing, it does not show that the surface layer portion around the periphery of the via hole is not modified. However, it does not solve the above problem. Further, in the methods described in Patent Documents 7 and 8, it is necessary to separately provide a step of peeling the film after laser processing. In addition, a thin film having a thickness of less than 20 μm has a small effect of suppressing denaturation, and has a thickness of 20 μm or more. In the case of a film, a large number of laser irradiations are required to remove the film, which causes a problem of a decrease in productivity. As described above, in the conventional method, there is a problem that it is difficult to satisfy both the fact that the surface layer portion around the periphery of the via hole is not modified and the formation of a fine and quick via hole.

  Accordingly, an object of the present invention is to form a fine and quick via hole without modifying the surface layer portion of the periphery of the via hole when a via hole reaching the substrate is formed by ultraviolet laser irradiation in the resin insulating layer on the substrate. Another object of the present invention is to provide a laminated structure for a printed wiring board and a method for producing a printed wiring board using the same.

  As a result of intensive studies, the present inventors have used a first cured coating layer using a thermosetting resin composition having ultraviolet absorptivity and a thermosetting resin composition having no ultraviolet absorptivity. The present invention has been completed by finding that the above-mentioned problems can be solved by using a laminated structure for a printed wiring board including the second cured coating layer.

  That is, the laminated structure of the present invention for a printed wiring board includes a substrate, a second cured coating layer formed on the substrate, and between the second cured coating layer and the substrate. And the second cured coating film comprises (C) a polyimide resin having a multi-branched structure and (D) a polyfunctional alicyclic epoxy resin. The first cured coating film is formed from a thermosetting resin composition containing at least one component having ultraviolet absorptivity.

  In the laminated structure for a printed wiring board according to the present invention, the first cured coating film includes (A) a polyimide resin having a linear structure, (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring, and (E ) It is preferably formed of a thermosetting resin composition containing a component having at least one of ultraviolet absorbers among ultraviolet absorbers.

  In the laminated structure for a printed wiring board of the present invention, it is preferable that the first cured coating film and the second cured coating film are insulating permanent protective films.

  In the laminated structure for a printed wiring board of the present invention, the polyimide resin having the linear structure (A) is preferably an aromatic polyimide resin having a reactive functional group.

  In the laminated structure for a printed wiring board according to the present invention, the (B) epoxy resin having a polycyclic aromatic hydrocarbon ring may be at least one of a naphthalene type epoxy resin and an anthracene type epoxy resin. preferable.

  In the laminated structure for a printed wiring board of the present invention, the film thickness of the second cured coating film is preferably thinner than the film thickness of the first cured coating film.

  In the method for producing a printed wiring board of the present invention, the laminated structure for printed wiring board is irradiated with an ultraviolet laser to remove the first cured coating film and the second cured coating film. A reaching via hole is formed.

  According to the present invention, when a via hole reaching the substrate is formed by ultraviolet laser irradiation with respect to the resin insulating layer composed of the first cured coating film and the second cured coating film on the substrate, the surface layer portion at the periphery of the via hole It is possible to form a fine and quick via hole without degeneration.

It is a schematic cross section which shows the through-hole and wiring groove | channel formation process by the ultraviolet laser processing of the laminated structure of this invention. It is a schematic cross section which shows the through-hole formation process by the ultraviolet laser processing of the board | substrate provided with the conventional resin insulation layer.

Hereinafter, the present invention will be described in detail.
The laminated structure for a printed wiring board according to the present invention is formed between a substrate, a second cured coating layer formed on the substrate, the second cured coating layer, and the substrate. And a first cured coating layer. The first cured coating film has ultraviolet absorption by having the following constitution, and the second cured coating film has no ultraviolet absorption by having the following constitution, or has extremely low ultraviolet absorption. Here, the ultraviolet ray refers to a wavelength of 200 to 400 nm. The laminated structure for a printed wiring board of the present invention is useful as a printed wiring board. That is, through holes are formed by laser processing, preferably ultraviolet laser processing, and plating treatment is performed, so that it can be used as a printed wiring board having a high-density and fine wiring pattern.

  As a result of the study by the present inventors, by adopting the configuration of the present invention, the second cured coating film and the first cured coating film are removed by ultraviolet laser irradiation, and a fine and quick via hole can be formed. It became clear that This is because when irradiated with an ultraviolet laser, the laser light is transmitted through the second cured coating film, but the first cured coating film having ultraviolet absorptivity absorbs the laser light. And when a coating film decomposes | disassembles and vaporizes and is removed, it is thought that the 2nd cured coating film is simultaneously removed so that it may be extruded from the 1st cured coating film side. And since a laser beam permeate | transmits a 2nd cured coating film, generation | occurrence | production of the modification | denaturation of a through-hole periphery is suppressed in the layer of a 2nd cured coating film.

<First cured coating film>
The first cured coating film is formed of a thermosetting resin composition containing at least one component having ultraviolet absorptivity.
The thermosetting resin composition used for the first cured coating film includes (A) a polyimide resin having a linear structure, (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring, and (E) an ultraviolet absorber. It is preferable that at least any one of these is included.
In addition, when (E) only an ultraviolet absorber is included as a component which has ultraviolet absorptivity, it is necessary to include a thermosetting resin component in a thermosetting resin composition.

（式中、Ｒ_３は、芳香族環を有する４価の有機基を表し、Ｒ_４は、芳香族環を有する２価の有機基を表す。） The (A) polyimide resin having a linear structure as a component having ultraviolet absorptivity preferably contains a cyclic imide bond in the resin skeleton, and has a high absorptivity in the ultraviolet region. Moreover, the aromatic polyimide resin which has a reactive functional group is preferable, and it is preferable that it is soluble in an organic solvent. Here, the aromatic polyimide resin is preferably a resin having a structural unit represented by the following general formula, and preferably has a reactive functional group similar to the following in the molecule.

(In the formula, R ₃ represents a tetravalent organic group having an aromatic ring, and R ₄ represents a divalent organic group having an aromatic ring.)

  (A) Specific examples of the polyimide resin having a linear structure include V-8005 (manufactured by DIC); GPI-NT, -HT (manufactured by Gunei Chemical Industry Co., Ltd.); Rika Coat SN-20, -PN-20, -CN-20 (made by Shin Nippon Rika Co., Ltd.) etc. are mentioned. These may be used individually by 1 type and may be used in combination of 2 or more types.

  In addition, the polyimide resin which has the said (A) linear structure can also use polyimide resin other than having described in the specific example, if it has ultraviolet absorptivity.

  The content of the polyimide resin having such a linear structure (A) in the composition is preferably 10 based on the total solid content of the thermosetting resin composition for forming the first cured coating film. It is -90 mass%, More preferably, it is 20-60 mass%. If the polyimide resin having the linear structure (A) is less than 10% by mass, the heat resistance is lowered, so the effect of the present invention may not be exhibited. If it exceeds 90% by mass, the curability becomes insufficient. The function as a cured coating film may not be expressed.

  The epoxy resin having a polycyclic aromatic hydrocarbon ring (B) as a component having ultraviolet absorptivity is an epoxy resin containing a polycyclic aromatic hydrocarbon ring in which two or more aromatic rings are condensed in the resin skeleton. That is. Among these epoxy resins having a polycyclic aromatic hydrocarbon ring, naphthalene type epoxy resins or anthracene type epoxy resins having particularly high absorbability in the ultraviolet region are preferable in that good ultraviolet laser processability can be obtained. .

  Specific examples of the epoxy resin having the (B) polycyclic aromatic hydrocarbon ring include naphthalene type epoxy resins such as HP-4032, HP-4032D, HP-4700, HP-4710, HP-4770, EXA-4700. , EXA-4710, EXA-7311, EXA-9900 (all manufactured by DIC); ESN-175, ESN-355, ESN-375 (all manufactured by Nippon Steel Chemical Co., Ltd.); YX-8800 (as anthracene type epoxy resin) Mitsubishi Chemical Corporation). These may be used individually by 1 type and may be used in combination of 2 or more types.

  (B) The content of the epoxy resin having a polycyclic aromatic hydrocarbon ring in the composition is preferably based on the total solid content of the thermosetting resin composition for forming the first cured coating film. It is 10-90 mass%, More preferably, it is 20-60 mass%.

  Examples of the ultraviolet absorber (E) as a component having ultraviolet absorptivity include benzophenone derivatives, benzoate derivatives, benzotriazole derivatives, triazine derivatives, benzothiazole derivatives, cinnamate derivatives, anthranilate derivatives, dibenzoylmethane derivatives and the like. It is done. For example, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-ethylhexyl salicylate, phenyl Salicylate, pt-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-t- Butyl-4-hydroxybenzoate, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2 ′ -Hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- 2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy- 3 ', 5'-di-t-amylphenyl) benzotriazole, hydroxyphenyltriazine, bisethylhexyloxyphenol methoxyphenyltriazine, etc., and specific examples include CHIMASSORB81, TINUVIN120, -NP, -234, -320, -326, -327, -328, -329, -1577ED (manufactured by BASF Japan); Sumisorp 200, -250, -300, -340, -350 (manufactured by Sumitomo Chemical Co., Ltd.); ADK STAB LA-31, -32, -36 (made by ADEKA) etc. are mentioned.

Moreover, the photoinitiator generally used for the photoresist as said (E) ultraviolet absorber can also be used. Examples of such a photopolymerization initiator include α-aminoalkylphenone compounds, acylphosphine oxide compounds, oxime ester compounds, benzophenone compounds, and the like. Specific examples of the photopolymerization initiator include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-dimethylamino-2- (4-methyl-benzyl)- 1- (4-morpholin-4-yl-phenyl) -butan-1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2- (acetyloxy Iminomethyl) thioxanthen-9-one, 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], 1- (9-ethyl-6- (2-methyl) Benzoyl) -9H-carbazol-3-yl), ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (0-acetyloxime), , 4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, and the like. As specific examples of commercially available products, Irgacure-369, -379, -907, -OXE01, -OXE02, CGI-242 (BASF Japan); N-1919 (ADEKA); EAB (Hodogaya Chemical) Etc.).
Said (E) ultraviolet absorber may be used individually by 1 type, and may be used in combination of 2 or more type.

  (E) The content of the ultraviolet absorber is preferably 0.5 to 10% by mass, more preferably, based on the total solid content of the thermosetting resin composition for forming the first cured coating film. Is 3-7% by mass. If the ultraviolet absorber is less than 0.5% by mass, the laser processability may not be sufficiently improved, and if it exceeds 10% by mass, the physical properties as the resin insulating layer may be deteriorated.

In addition, when (A) a polyimide resin having a linear structure and (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring are used in combination as a component having ultraviolet absorptivity, the first cured coating film is formed. The compounding amount in the whole thermosetting resin composition is the total amount of (A) a polyimide resin having a linear structure and (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring, and is used for the first cured coating film. It is preferably 40 to 80 parts by mass with respect to 100 parts by mass of the thermosetting resin composition. When the blending amount is less than 40 parts by mass, since the amount of resin in the entire composition is low, it is difficult to control the fluidity of the composition, and printability may be deteriorated. On the other hand, when the blending ratio exceeds 80 parts by mass, the blending amount of the inorganic filler or the like may be relatively decreased, and the mechanical strength of the resin insulating layer may be decreased.
When the component having ultraviolet absorptivity includes (E) only the ultraviolet absorber, the thermosetting resin component includes an epoxy resin, a phenol resin, an amino resin, an unsaturated polyester resin, a polyurethane resin, a silicone resin, or A known and commonly used thermosetting resin such as a thermosetting polyimide resin can be used.

  It is preferable that the film thickness of the 1st cured coating film using the said thermosetting resin composition is 10-30 micrometers, More preferably, it is 10-20 micrometers. The cured coating film is preferably leveled (smoothed). When the film thickness is less than 10 μm, it is not preferable because it is easily damaged by laser irradiation such as cracks. On the other hand, when the film thickness exceeds 30 μm, the thickness of the substrate increases, and the substrate cannot be made thinner.

<Second cured coating film>
The thermosetting resin composition used for the second cured coating film includes (C) a polyimide resin having a multi-branched structure and (D) a polyfunctional alicyclic epoxy resin.
(C) The polyimide resin having a multi-branched structure has an isocyanurate ring in the resin skeleton, and has a structure in which branching occurs from the isocyanurate ring, and has no or extremely low ultraviolet absorptivity. It is a polyimide resin. Further, the resin structure does not include a structure that brings about ultraviolet absorption such as a polycyclic aromatic group such as a naphthalene ring or an anthracene ring, and preferably has a urethane bond, an imide ring, and an isocyanurate ring, and , Having a reactive functional group that reacts with an epoxy group. By having a reactive functional group, curing by heating becomes possible. Further, it is preferably soluble in an organic solvent. Examples of the reactive functional group include functional groups having active hydrogen such as a carboxyl group, an amino group, and a hydroxyl group. Since it has an imide structure, a cured coating film having high heat resistance can be obtained. Therefore, it can be expected to suppress decomposition, dissolution, expansion, and denaturation due to heat generation caused by laser processing.

（式中、Ｒ_１は炭素原子数６〜１３の環式脂肪族構造を有する有機基を示し、Ｒ_２は数平均分子量７００〜４，５００の線状炭化水素構造を示す。）

Specific examples of suitable (C) polyimide resins having a multi-branched structure include, for example, a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2). And what has any 1 or more types of the terminal structure shown by the following general formula (3), (4) and (5) is mentioned.

(Wherein R ₁ represents an organic group having a cyclic aliphatic structure having 6 to 13 carbon atoms, and R ₂ represents a linear hydrocarbon structure having a number average molecular weight of 700 to 4,500.)

(C) Specific examples of the polyimide resin having a multi-branched structure include V-8000 (manufactured by DIC).
In addition, the polyimide resin which has the said (C) multi-branched structure can also use polyimide resin other than what was described in the specific example, as long as it does not have ultraviolet absorptivity or is remarkably low.

  The content of such (C) polyimide resin is based on the total solid content of the thermosetting resin composition for forming the second cured coating film (minus the solvent from the entire composition), Preferably it is 50-90 mass%, More preferably, it is 50-75 mass%. If the polyimide resin having the above-mentioned (C) multi-branched structure is less than 50% by mass, the heat resistance is lowered, so the effect of the present invention may not be exhibited. If it exceeds 90% by mass, the thermosetting property is poor. The physical properties of the resin insulating layer may be deteriorated.

The (D) polyfunctional alicyclic epoxy resin is a resin having a structure including a carbocycle having no unsaturated bond in the skeleton and having two or more epoxy groups as functional groups.
Specific examples of the (D) polyfunctional alicyclic epoxy resin include Celoxide 2021, -2021P, -2080, -2081, -2083, -2085, Epolide GT-301, -302, -401, -403, EHPE. -3150 (manufactured by Daicel Chemical Industries); Cyracure UVR-6105, -6107, -6110, -6128 (manufactured by Dow Chemical Company); YX8000, YX8034 (manufactured by Mitsubishi Chemical Corporation); ) And the like. These may be used individually by 1 type and may be used in combination of 2 or more types.

  (D) The content of the polyfunctional alicyclic epoxy resin is preferably 10 to 40% by mass, more preferably 10 based on the total solid content of the composition for forming the second cured coating film. -25% by mass.

  Moreover, the compounding quantity in the whole thermosetting resin composition for forming the 2nd cured coating film of (C) polyimide resin which has a multi-branch structure, and (D) polyfunctional alicyclic epoxy resin is (C ) The total amount of the polyimide resin having a multi-branched structure and (D) the polyfunctional alicyclic epoxy resin, and from 40 parts by mass to 95 parts by mass with respect to 100 parts by mass of the thermosetting resin composition used for the second cured coating film. It is preferable that it is a mass part. When the blending amount is less than 40 parts by mass, since the amount of resin in the entire composition is low, it is difficult to control the fluidity of the composition, and printability may be deteriorated. Further, when the blending ratio exceeds 95 parts by mass, the blending amount of additives for enhancing the physical properties of the coating film is relatively decreased, so that the mechanical strength of the resin insulating layer may be decreased.

  The film thickness of the second cured coating film using the thermosetting resin composition is preferably 5 to 20 μm, more preferably 5 to 10 μm. When the film thickness is less than 5 μm, the effect of suppressing the modification of the surface layer portion around the via hole by the laser irradiation is not preferable. On the other hand, when the film thickness exceeds 20 μm, the thickness of the substrate increases, and the substrate cannot be made thinner. Moreover, it is preferable that the film thickness of a 2nd cured coating film is thinner than the film thickness of a 1st cured coating film.

(A) a polyimide resin having a linear structure constituting the thermosetting resin composition used in the first cured coating film used in the present invention, (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring, (C) Polyimide resin having a multi-branched structure and (D) polyfunctional alicyclic epoxy resin constituting the thermosetting resin composition used for the cured coating film are preferably liquid, but are solid or crystalline at room temperature. It may be a conductive solid. In that case, it is dissolved in an organic solvent and used as a resin varnish.
The organic solvent can be used appropriately when adjusting the viscosity for obtaining the printability of the composition, as well as for adjusting the resin varnish as described above.

  Any known organic solvent can be used. As such a solvent, ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, and the like can be used. More specifically, ketones such as methyl ethyl ketone, acetone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, diethylene glycol Glycol ethers such as monoethyl ether acetate, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl Ether acetate, propylene glycol ethyl ether acetate, propylene glycol buty Esters such as ether acetate, methyl lactate, ethyl lactate, butyl lactate; amides such as γ-butyrolactone, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide; ethanol, propanol, Examples include alcohols such as ethylene glycol and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. Especially, (A) linear structure Amides such as γ-butyrolactone, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, and (C) a polyimide resin having a multi-branched structure. For diethylene glycol monoethyl ether acetate Glycol ethers etc., has good solubility, preferred. These organic solvents may be used individually by 1 type, and may be used in combination of 2 or more types.

  The thermosetting resin composition used for the first cured coating film and the second cured coating film used in the present invention further includes a thermosetting catalyst, an inorganic filler, a colorant, a thickener, an antifoaming agent, and a leveling. It can contain known and commonly used additives such as an agent and an adhesion-imparting agent. However, additives having ultraviolet absorptivity cannot be used in the thermosetting resin composition used for the second cured coating film.

  The thermosetting catalyst is used to further improve the thermosetting properties of the thermosetting resin composition. For example, amine compounds such as dicyandiamide and aromatic amines, imidazoles, phosphorus compounds, acid anhydrides, bicyclics Amidine compounds can be used. Specifically, imidazole, 1-benzyl-2-phenylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2 -Imidazoles such as phenylimidazole, 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy- Amine compounds such as N, N-dimethylbenzylamine and 4-methyl-N, N-dimethylbenzylamine, phosphorus compounds such as triphenylphosphine, and the like can be used. More specifically, as imidazole compounds, 1B2PZ, 2E4MZ, 2MZ-A, 2MZ-OK, 2PHZ, 2P4MHZ (manufactured by Shikoku Kasei Kogyo Co., Ltd.); As a bicyclic amidine compound and a salt thereof, DBU, DBN, U-CAT SA102, U-CAT5002 (manufactured by San Apro) and the like can be mentioned. These may be used singly or in combination of two or more.

For the content of the thermosetting catalyst, a normal blending ratio is sufficient. For example, 0.1 to 10 parts by mass is preferable with respect to 100 parts by mass of the epoxy resin component that is a thermosetting component.
The inorganic filler is used to suppress curing shrinkage of the resin insulating layer and improve properties such as adhesion and hardness. Examples of inorganic fillers include barium sulfate, barium titanate, amorphous silica, crystalline silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, and nitride. Aluminum etc. are mentioned. These may be used singly or in combination of two or more.

  Next, a preferred example of a method for manufacturing a printed wiring board in which a laminated structure for a printed wiring board according to the present invention is produced using the above-described thermosetting resin composition and via holes are formed by ultraviolet laser processing will be described. . Manufacturing conditions such as temperature, time, and coating film thickness are not limited to the following and can be appropriately changed as desired.

  After the substrate is subjected to pretreatment such as buffling polishing and chemical polishing, the thermosetting resin composition for the first cured coating film adjusted to the viscosity suitable for the printing application method with an organic solvent is 10 μm in dry film thickness. Print to ~ 20 μm. Next, the organic solvent contained in the composition is volatilized and dried at a temperature of 40 ° C to 100 ° C. Furthermore, it can be heat-cured for 30 minutes to 120 minutes at a temperature of 170 ° C. to 230 ° C. to form a first cured coating film (see FIG. 1A).

  Subsequently, the thermosetting resin composition for the second cured coating film, which is similarly adjusted, is printed so that the dry film thickness is 5 μm to 10 μm. Next, the organic solvent contained in the composition is volatilized and dried at a temperature of 40 ° C to 100 ° C. Furthermore, the second cured coating film can be formed by heat curing at a temperature of 150 ° C. to 230 ° C. for 30 minutes to 120 minutes. At this time, the second cured coating film is leveled (smoothed), and the first cured coating film is formed on the substrate, and the second cured coating film is formed on the first cured coating film. A laminated structure is completed (see FIG. 1B).

  The above-mentioned substrates mainly include printed circuit boards and flexible printed circuit boards in which circuits are formed in advance, paper-phenolic resin, paper-epoxy resin, glass cloth-epoxy resin, glass-polyimide, glass cloth / non-woven cloth-epoxy. Use of copper-clad laminates of all grades (FR-4 etc.) using composite materials such as resin, glass cloth / paper-epoxy resin, synthetic fiber-epoxy resin, fluororesin / polyethylene / PPO / cyanate ester it can.

  Examples of the printing method include a dip coating method, a flow coating method, a roll coating method, a bar coater method, a screen printing method, and a curtain coating method. It is also possible to form a film by coating and drying on a carrier film, winding up as a film to form a dry film, and laminating on a substrate. Further, partial printing may be performed by using a mask or the like in order to provide wiring or a mounting portion at the time of application.

  As the drying and heating method, a method using a hot-air circulation type drying furnace, an IR furnace, a hot plate, a convection oven or the like equipped with a heat source of a heating method using steam, and a countercurrent contact of hot air in the dryer, and a nozzle A method of spraying more on the support can be applied.

  Next, the resin insulating layer is subjected to ultraviolet laser processing to remove the second cured coating film and the first cured coating film, thereby forming a via hole in which the conductor layer of the substrate is exposed (see FIG. 1C).

The ultraviolet laser is a laser having an oscillation wavelength in the ultraviolet region (having a wavelength of 200 nm to 400 nm). In the present invention, the YLF crystal is a medium third harmonic laser (351 nm), YAG or YVO ₄ crystal is a medium. It is particularly preferable that the medium is a third harmonic laser (355 nm).

  As the ultraviolet laser irradiation method, there are pulse irradiation and continuous irradiation, but pulse irradiation is preferable because damage to the periphery of the via hole is less. Moreover, the repetition frequency of pulse irradiation is preferably 1 kHz to 500 kHz, and more preferably 10 kHz to 100 kHz.

  If it is less than 1 kHz, it takes a long time for laser processing, which may lead to a decrease in productivity. On the other hand, when the frequency exceeds 500 kHz, for example, in the case of a nanosecond laser, the irradiation time per pulse is shortened, so that the periphery of the via hole of the second cured coating film may be damaged such as cracks. The focal position of the ultraviolet laser is preferably the surface of the second cured coating film. If the focal position is within the second cured coating film or at a position separated from the coating film, a desired processed shape may not be obtained.

  The irradiation energy of the ultraviolet laser is shown as irradiation energy [μJ / pulse] per pulse. In the present invention, 0.5 μJ / pulse to 50 μJ / pulse is preferable, and more preferably 1 μJ / pulse to 10 μJ / pulse. pulse. In this case, the pulse width is 1 microsecond or less. If it is less than 0.5 μJ / pulse, the resin insulating layer is hardly removed, so that it is difficult to form a via hole, which is not preferable. On the other hand, when it exceeds 50 μJ / pulse, not only the resin insulating layer may be penetrated, but also the substrate surface may be removed, or the processed diameter may be larger than a desired processing diameter.

  The number of times of irradiation of the ultraviolet laser needs to be performed until a via hole can be formed, and the number of times of irradiation is proportional to the film thickness of the resin insulating layer. Specifically, when forming a via hole, the laser irradiation necessary to reach the conductor layer by removing the second cured coating film having a thickness of 5 to 10 μm and the first cured coating film having a thickness of 10 to 20 μm. The number of times is preferably 1 to 100 times, and more preferably 1 to 50 times. If the number of times of irradiation is too large, damage such as cracks may occur in the second cured coating film and conductor layer.

  The shape of the via hole formed by the ultraviolet laser is the ratio between the diameter D of the second cured coating film surface and the diameter d of the conductor layer surface (via hole bottom surface), that is, the formula (d / D) × 100 [%]. Indicated by In this invention, 50% or more is preferable, More preferably, it is 70% or more. If it is less than 50%, the bottom surface of the via hole is too thin, and a problem of poor adhesion of solder or metal plating may occur. On the other hand, if it exceeds 100%, the via hole becomes reverse tapered, which is not preferable.

  The diameter of the via hole formed by the ultraviolet laser is preferably 10 μm to 70 μm, more preferably 10 μm to 45 μm, in the diameter D of the second cured coating film surface. By using the laminated structure for a printed wiring board of the present invention, for example, a printed wiring board corresponding to a narrow pitch circuit wiring that cannot be handled by a carbon dioxide laser used for general purposes and a composition used therefor can be provided. .

  The via hole formed by the ultraviolet laser can be used as a solder resist pattern, and desmear treatment that decomposes and removes residual components after ultraviolet laser processing using a chemical solution for desmear treatment such as permanganate solution, Manufacture a board. Note that a double-sided substrate and a multilayer substrate are similarly subjected to desmearing after forming a resin insulating layer using a thermosetting resin composition and forming a via hole with an ultraviolet laser.

  Via holes are subjected to metal plating or preflux treatment on the printed wiring board thus manufactured, and then electronic components such as semiconductor chips to be mounted are bonded and mounted by gold bumps or solder bumps.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, the value which shows the compounding quantity of each component is a mass reference | standard all unless there is particular notice.

<Example 1>
(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
UV-absorbing linear polyimide resin (V-8005, manufactured by DIC) 333 parts of varnish obtained by dissolving dimethylacetamide to a non-volatile content of 15%, anthracene type epoxy resin (YX-8800, manufactured by Mitsubishi Chemical Corporation) 167 parts of varnish dissolved in dimethylacetamide so as to have a nonvolatile content of 30%, 1 part of 1-benzyl-2-phenylimidazole (1B2PZ, manufactured by Shikoku Chemicals), 30 parts of silica, 15 parts of barium sulfate, silicone-based surface A tension adjuster (BYK-310, manufactured by BYK-Chemie Co., Ltd.) 0.05 parts was blended, premixed with a stirrer, kneaded using a three-roll mill, and thermosetting for the first cured coating film. A resin composition was prepared.
Since the epoxy resin and the polyimide resin itself have high ultraviolet absorptivity by preparing the thermosetting resin composition for the first cured coating film, the ultraviolet absorptivity can be obtained without adding an ultraviolet absorber or the like. A thermosetting resin composition having the following characteristics could be prepared.

(Preparation of resin composition having no UV absorption (for second cured coating film))
188 parts of varnish in which branched polyimide resin (V-8000, manufactured by DIC) is dissolved in diethylene glycol monoethyl ether acetate so as to have a nonvolatile content of 40%, alicyclic epoxy resin (Celoxide 2021, manufactured by Daicel Chemical Industries), 25 parts Were premixed with a stirrer and kneaded using a three-roll mill to prepare a thermosetting resin composition for a second cured coating film.

(Manufacture of laminated structures for printed wiring boards)
The thermosetting resin composition for the first cured coating film was applied onto a 0.8 mm thick copper-clad laminate that had been buffed, dried in a hot air circulating oven at 80 ° C. for 30 minutes, and then 230 The first cured coating film was formed by curing at 0 ° C. for 1 hour. Thereafter, the thermosetting resin composition for the second cured coating film is applied onto the first cured coating film, dried at 80 ° C. for 30 minutes in a hot air circulating drying oven, and then at 170 ° C. for 1 minute. It was cured by heating for a time, and the second cured coating film was laminated on the first cured coating film to produce a test piece of a laminated structure for a printed wiring board. At this time, the cured coating film on the substrate is leveled, and the unevenness of the cured coating film before the ultraviolet laser irradiation is not observed.

Ultraviolet laser (YVO ₄ laser triple harmonic, wavelength: 355 nm, repetition frequency: 50 kHz, pulse energy: 0.4 μJ / pulse, so as to be perpendicular to the cured coating film of the laminated structure for printed wiring board. (Pulse width: 30 ns, beam shape: Gaussian).

<Example 2>
A test piece was prepared in the same manner as in Example 1 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 1 below, and ultraviolet laser irradiation was performed.

<Example 3>
A test piece of the laminated structure for printed wiring board was prepared by the same method as in Example 1 except that the preparation of the first resin composition for cured coating film was changed as follows, and irradiated with an ultraviolet laser. Carried out.

(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
333 parts of varnish obtained by dissolving linear polyimide resin (V-8005, manufactured by DIC) having ultraviolet absorptivity with dimethylacetamide so as to have a nonvolatile content of 15%, naphthalene type epoxy resin (manufactured by HP-4032, DIC) 100 parts of varnish dissolved with dimethylacetamide so as to have a nonvolatile content of 50%, 1 part of 1-benzyl-2-phenylimidazole (1B2PZ, manufactured by Shikoku Chemicals), 30 parts of silica, 15 parts of barium sulfate, silicone surface tension 0.05 part of a regulator (BYK-310, manufactured by BYK Chemie) was blended, premixed with a stirrer, kneaded using a three-roll mill, and thermosetting resin for the first cured coating film. A composition was prepared.

<Example 4>
A test piece was prepared in the same manner as in Example 3 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 1 below, and ultraviolet laser irradiation was performed.

<Example 5>
A test piece of the laminated structure for printed wiring board was prepared by the same method as in Example 1 except that the preparation of the first resin composition for cured coating film was changed as follows, and irradiated with an ultraviolet laser. Carried out.

(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
UV-absorbing linear polyimide resin (V-8005, manufactured by DIC) 333 parts of varnish obtained by dissolving dimethylacetamide to a non-volatile content of 15%, bisphenol A type epoxy resin (E828, manufactured by Mitsubishi Chemical Corporation) 50 Parts, 1 part of 1-benzyl-2-phenylimidazole (1B2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.), 30 parts of silica, 15 parts of barium sulfate, 0.05 part of a silicone-based surface tension adjuster (BYK-310, manufactured by BYK Chemie) Were premixed with a stirrer and kneaded using a three-roll mill to prepare a thermosetting resin composition for a first cured coating film.
Even if the epoxy resin does not have ultraviolet absorptivity by the preparation of the thermosetting resin composition for the first cured coating film, it contains a linear polyimide resin, and therefore has a high ultraviolet absorptivity. A functional resin composition could be prepared.

<Example 6>
A test piece was prepared in the same manner as in Example 5 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 1 below, and ultraviolet laser irradiation was performed.

<Example 7>
The test piece of the laminated structure for printed wiring boards in the same manner as in Example 1 except that the preparation of the resin composition for the first cured coating film and the curing temperature of the laminated structure for printed wiring boards were changed. Were prepared and irradiated with an ultraviolet laser.

(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
67 parts of varnish obtained by dissolving anthracene type epoxy resin (YX-8800, manufactured by Mitsubishi Chemical Corporation) with dimethylacetamide so as to have a nonvolatile content of 30%, trihydroxyphenylmethane type epoxy resin (EPPH-501H, manufactured by Nippon Kayaku Co., Ltd.) 63 parts of varnish dissolved in propylene glycol monomethyl ether acetate so that the nonvolatile content is 80%, 67 parts of phenoxy resin (YX8100H30, manufactured by Mitsubishi Chemical Corporation), 70 parts of silica, 35 parts of barium sulfate, 1-benzyl-2-phenyl 1 part of imidazole (1B2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.), 62 parts of varnish obtained by dissolving phenol novolac resin (HF-1M, manufactured by Meiwa Kasei Co., Ltd.) with diethylene glycol monoethyl ether to a non-volatile content of 65%, propylene glycol monomethyl ether acetate 30 parts of PGMAc (manufactured by Daishin Chemical Co., Ltd.) and 0.05 parts of a silicone-based surface tension modifier (BYK-310, manufactured by BYK Chemie) were premixed with a stirrer and then mixed using a three-roll mill. It knead | mixed and the thermosetting resin composition for 1st cured coating films was prepared.

  By preparing the thermosetting resin composition for the first cured coating film, since the anthracene type epoxy resin has ultraviolet absorptivity, a thermosetting resin composition having high ultraviolet absorptivity could be prepared. .

(Manufacture of laminated structures for printed wiring boards)
Test of laminated structure for printed wiring board in the same manner as in Example 1 except that the thermosetting resin composition for the first cured coating film was cured by heating at 170 ° C. for 1 hour. A piece was prepared and irradiated with an ultraviolet laser.

<Example 8>
A test piece was prepared in the same manner as in Example 7 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 1 below, and ultraviolet laser irradiation was performed.

<Example 9>
A test piece of the laminated structure for printed wiring board was prepared by the same method as in Example 1 except that the preparation of the first resin composition for cured coating film was changed as follows, and irradiated with an ultraviolet laser. Carried out.

(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
Dissolve 50 parts of bisphenol A type epoxy resin (E828, manufactured by Mitsubishi Chemical Corporation) and trihydroxyphenylmethane type epoxy resin (EPPH-501H, manufactured by Nippon Kayaku Co., Ltd.) with propylene glycol monomethyl ether acetate so that the nonvolatile content is 80%. 63 parts of varnish, 67 parts of phenoxy resin (YX8100H30, manufactured by Mitsubishi Chemical Co., Ltd.), 70 parts of silica, 35 parts of barium sulfate, 1 part of 1-benzyl-2-phenylimidazole (1B2PZ, manufactured by Shikoku Chemicals), phenol novolac resin 62 parts of varnish obtained by dissolving HF-1M (manufactured by Meiwa Kasei Co., Ltd.) with diethylene glycol monoethyl ether to a non-volatile content of 65%, 30 parts of propylene glycol monomethyl ether acetate (PGMAc, manufactured by Daishin Chemical Co., Ltd.), benzophenone ultraviolet Absorbent ( AB, manufactured by Hodogaya Chemical Co., Ltd.) and 15 parts of a silicone-based surface tension modifier (BYK-310, manufactured by BYK Chemie) were each mixed and premixed with a stirrer, and then a three-roll mill was used. And kneaded to prepare a thermosetting resin composition for the first cured coating film.
Even when the epoxy resin does not have ultraviolet absorptivity by the preparation for the first cured coating film, a thermosetting resin composition having high ultraviolet absorptivity is prepared because it contains a benzophenone-based ultraviolet absorber. did it.

<Example 10>
A test piece was prepared in the same manner as in Example 9 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 1 below, and ultraviolet laser irradiation was performed.

<Comparative Example 1>
A test piece of the laminated structure for printed wiring board was prepared in the same manner as in Example 1 except that the preparation of the second resin composition for cured coating film was changed as follows, and irradiated with an ultraviolet laser. Carried out.

(Preparation of resin composition having no UV absorption (for second cured coating film))
50 parts of polyfunctional alicyclic epoxy resin (Celoxide 2021 manufactured by Daicel Chemical Industries), 25 parts of polyfunctional alicyclic epoxy resin (hydrogenated epoxy / YX-8000 manufactured by Mitsubishi Chemical), triarylsulfonium salt photoacid Three parts of a roll mill after blending 1 part of a generator (CPI-100P, manufactured by San Apro) and 0.05 part of a silicone-based surface tension adjuster (BYK-310, manufactured by Big Chemie), respectively, and premixing with a stirrer Was used to prepare a thermosetting resin composition for the first cured coating film.

<Comparative example 2>
A test piece was prepared in the same manner as in Comparative Example 1 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 2 below, and ultraviolet laser irradiation was performed.

<Comparative Example 3>
In the preparation of the thermosetting resin composition, a printed wiring board was prepared in the same manner as in Example 1 except that a thermosetting resin composition having ultraviolet absorptivity was prepared for the second cured coating film. A test piece of a laminated structure for a sample was prepared and irradiated with an ultraviolet laser.

(Preparation of resin composition having ultraviolet absorptivity (for first cured coating film))
167 parts of varnish obtained by dissolving linear polyimide resin (V-8005, manufactured by DIC) with dimethylacetamide so that the nonvolatile content is 15%, anthracene type epoxy resin (YX-8800, manufactured by Mitsubishi Chemical Corporation) is 30% nonvolatile 83 parts of varnish dissolved in dimethylacetamide, 0.5 part of 1-benzyl-2-phenylimidazole (1B2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.), silicone surface tension adjuster (BYK-310, manufactured by BYK Chemie) 0.02 part was blended and premixed with a stirrer, and then kneaded using a three-roll mill to prepare a thermosetting resin composition for a first cured coating film.

<Comparative example 4>
A test piece was prepared in the same manner as in Comparative Example 3 except that the film thicknesses of the first cured coating film and the second cured coating film were changed as shown in Table 2 below, and ultraviolet laser irradiation was performed.

<Comparative Example 5>
In the production of the laminated structure for a printed wiring board, a test piece of the laminated structure for a printed wiring board containing a plastic film was produced by a method using a plastic film instead of the second cured coating film. The ultraviolet laser irradiation was performed under the same conditions as in Example 1 above.

(Manufacture of laminated structures for printed wiring boards)
The thermosetting resin composition for the first cured coating film described in Example 1 is made of a polyethylene terephthalate (PET) film (G2-16, Teijin) so that the dry coating film (cured coating film) has a thickness of 20 μm. The film was applied onto a film having a thickness of 16 μm manufactured by DuPont Films, and dried at 80 ° C. for 30 minutes to obtain a film with a dry coating film. Using a vacuum laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) on a 0.8 mm thick copper-clad laminate that has been buffed with a dry coated film, 1 minute at 120 ° C. at 5 kgf / cm ² , 1 Torr, After heating and laminating, leveling at 10 kgf / cm ² and 130 ° C. for 1 minute with a hot plate press machine, it was cured by heating at 170 ° C. for 1 hour in a hot-air circulating dryer, and then on the copper-clad laminate. The test piece of the laminated structure for printed wiring boards in which the 1st cured coating film and the PET film were each formed on the 1st cured coating film was produced.

<Comparative Example 6>
A test piece of a laminated structure for a printed wiring board containing a plastic film was produced in the same manner except that the thickness of the plastic film of Comparative Example 5 was changed. Ultraviolet laser irradiation was performed under the same conditions as in Example 1 above.

(Manufacture of laminated structures for printed wiring boards)
A test piece of a laminated structure for a printed wiring board was prepared in the same manner as in Comparative Example 5 except that the PET film was changed (Lumirror 38R75, manufactured by Toray Industries, Inc., film thickness 38 μm).

<Comparative Example 7>
In the production of the laminated structure for printed wiring board, only the first cured coating film using the thermosetting resin composition having ultraviolet absorptivity was formed to prepare a test piece of the laminated structure for printed wiring board. Here, the thermosetting resin composition having ultraviolet absorptivity was prepared in the same manner as in “Preparation of resin composition having ultraviolet absorptivity” in Example 1 above. The ultraviolet laser irradiation was performed under the same conditions as in Example 1 above.

(Manufacture of laminated structures for printed wiring boards)
In the formation of the first cured coating film described in Example 1, the first cured coating film was formed on the copper-clad laminate in the same manner except that the thickness of the cured coating film was 20 μm. The test piece of the laminated structure for printed wiring boards was formed.

<Comparative Example 8>
In the production of a laminated structure for a printed wiring board, only a first cured coating film using a thermosetting resin composition having no ultraviolet absorptivity was formed to prepare a test piece of the laminated structure for a printed wiring board. . Here, the thermosetting resin composition having no ultraviolet absorptivity is prepared by the same method as in “Preparation of resin composition having no UV absorptivity” in Example 1, and the first curing is performed. It was for coating film. The ultraviolet laser irradiation was performed under the same conditions as in Example 1 above.

(Manufacture of laminated structures for printed wiring boards)
In the formation of the second cured coating film described in Example 1, the second cured coating film was formed on the copper-clad laminate in the same manner except that the thickness of the cured coating film was 20 μm. The test piece of the laminated structure for printed wiring boards was formed.

(Performance evaluation of test pieces according to Examples 1 to 10 and Comparative Examples 1 to 8)
(Adhesion test)
In accordance with JIS K5600-5-6: 1999, a cross-cut is made on the resin insulation layer of the test piece, a cellophane tape is applied to the cured coating film, and a peeling test is performed to peel it off, and then the resin insulation layer The state of peeling was visually observed and evaluated according to the following criteria.
○: No peeling (good adhesion between substrate and coating film and coating film)
Δ: Peeled on a part of the resin insulation layer ×: Peeled on most of the resin insulation layer The results are shown in Tables 1 and 2 below.

(Solvent resistance test)
After being immersed in isopropyl alcohol for 60 minutes at room temperature and normal pressure, a peeling test similar to the adhesion test was performed, and then the state of peeling of the resin insulation layer was visually observed and evaluated according to the following criteria.
○: No peeling Δ: Peeling part of the resin insulation layer ×: Peeling most part of the resin insulation layer The results are shown in Tables 1 and 2 below.

(Heat resistance test)
After immersing the test piece in a 260 ° C. solder bath for 10 seconds and repeating this three times, after performing the same peeling test as the adhesion test, the state of peeling of the resin insulation layer was visually observed, and the following criteria It was evaluated with.
○: No peeling Δ: Peeling part of the resin insulation layer ×: Peeling most part of the resin insulation layer The results are shown in Tables 1 and 2 below.

(Laser processability 1 (number of times of UV laser irradiation))
The number of ultraviolet laser irradiations when forming the via hole was evaluated according to the following criteria.
Standard: Irradiation required for the ratio [formula (d / D) × 100 [%]] of the via hole diameter D on the surface of the resin insulation layer and the via hole diameter d on the surface of the copper-clad laminate (via hole bottom surface) to exceed 70% Number of times. However, only the resin insulation layer (or PET film and resin insulation layer) was processed, and the copper-clad laminate was not damaged. The shape of the via hole was measured using a laser microscope.
○: Number of irradiation times of 40 or less Δ: Number of irradiation times exceeding 40 and 100 times or less X: The number of irradiation times exceeding 100 times does not satisfy the standard. The via hole diameter R on the surface of the resin insulating layer formed with 40 or less irradiations was 30 μm.

(Laser processability 2 (presence or absence of alteration in the surface layer around the via hole))
The presence or absence of alteration in the surface layer around the periphery of the via hole when the via hole was formed was evaluated according to the following criteria.
Reference | standard: The presence or absence of the dent and swelling (unevenness | corrugation) of thickness 0.5 micrometer or more was confirmed in the via-hole periphery. For observation and measurement, a digital microscope (KH-1300, manufactured by Hilox) and a laser microscope (VK-8500, manufactured by Keyence) were used.
○: No alteration (unevenness) ×: Alteration (irregularity) The results are shown in Tables 1 and 2 below.

(Desmear resistance)
Using an oxidizing agent treatment solution (manufactured by ATOTECH), swelling treatment at 80 ° C. for 10 minutes with Welling Dip Securiganth P (containing NaOH), roughening treatment at 80 ° C. for 10 minutes with Concentrate Compact CP (containing KMnO ₄ ), and The reduction treatment was carried out at 40 ° C. for 5 minutes using Reduction Solution Security P500 (containing H ₂ SO ₄ ). Then, the 2nd cured coating film surface (via-hole periphery) was observed with the laser microscope, and the following references | standards evaluated. The results are shown in Tables 1 and 2.
○: No peeling of the coating film on the periphery of the via hole Δ: Partial peeling of the coating film on the periphery of the via hole is observed x: Most peeling of the coating film on the periphery of the via hole is observed

＊１：硬化塗膜の代わりにプラスチックフィルムを使用。
＊２：硬化塗膜が第１の硬化塗膜（一層）のみから形成。

* 1: Plastic film is used instead of the cured coating film.
* 2: The cured coating film is formed only from the first cured coating film (one layer).

  As is apparent from the results shown in Table 1, in Comparative Examples 1 and 2 using a polyfunctional alicyclic epoxy resin that does not have ultraviolet absorptivity, the heat resistance of the second cured coating film is inferior, Alteration in the surface layer occurred. Moreover, in Comparative Examples 3 and 4 in which the resin composition used for the second cured coating film has ultraviolet absorptivity, the deterioration occurred in the surface layer portion around the via hole. Further, in Comparative Examples 5 and 6 using a plastic film instead of the second cured coating film, and in Comparative Example 8 in which only the first cured coating film using a resin composition having no ultraviolet absorptivity is formed, ultraviolet rays are used. A large number of laser irradiations were required.

  Deformations such as dents and bulges are observed at the periphery of the via hole. When a cured coating using a resin composition having a high UV-absorbing property is applied to the surface of the resin insulation layer, a laser beam having a low energy density is emitted. This is because it has been denatured by hitting the peripheral edge.

On the other hand, in Examples 1 to 10, the resin insulating layer is removed by irradiating with an ultraviolet laser to reach the substrate, and at this time, the surface layer portion around the via hole is not modified such as a dent and a bulge. In addition, since a fine and quick via hole with a via hole diameter of about 30 μm was formed, the laser processability was good, and the adhesion and heat resistance were also excellent.
Therefore, the printed wiring board and the manufacturing method thereof according to the present invention can form a fine and quick via hole without modifying the surface layer portion around the periphery of the via hole.

  INDUSTRIAL APPLICABILITY The present invention can be used as a printed wiring board corresponding to a narrow pitch circuit that can meet demands for higher density and miniaturization.

1 Substrate (copper-clad laminate)
1a Conductor layer (circuit wiring)
1b Insulating layer 2 First cured coating film (resin insulating layer)
3 Second cured coating (resin insulation layer)
4 Laser light 5 Via hole 6 Denatured part of the surface layer

Claims (7)

A substrate,
A second cured coating layer formed on the substrate;
A first cured coating layer formed between the second cured coating layer and the substrate;
The second cured coating film is formed from a thermosetting resin composition containing (C) a polyimide resin having a multi-branched structure and (D) a polyfunctional alicyclic epoxy resin,
The laminated structure for a printed wiring board, wherein the first cured coating film is formed of a thermosetting resin composition containing at least one component having ultraviolet absorptivity.   The first cured coating film is at least one of (A) a polyimide resin having a linear structure, (B) an epoxy resin having a polycyclic aromatic hydrocarbon ring, and (E) an ultraviolet absorber. The laminated structure for a printed wiring board according to claim 1, which is formed of a thermosetting resin composition containing   The laminated structure for a printed wiring board according to claim 1 or 2, wherein the first cured coating film and the second cured coating film are insulating permanent protective films.   The laminated structure for a printed wiring board according to claim 2, wherein the polyimide resin having a linear structure (A) is an aromatic polyimide resin having a reactive functional group.   The laminated structure for a printed wiring board according to claim 2, wherein the epoxy resin (B) having a polycyclic aromatic hydrocarbon ring is at least one of a naphthalene type epoxy resin and an anthracene type epoxy resin.   The laminated structure for a printed wiring board according to any one of claims 1 to 5, wherein the film thickness of the second cured coating film is thinner than the film thickness of the first cured coating film.   Irradiating the laminated structure for printed wiring board according to any one of claims 1 to 6 with an ultraviolet laser to remove the first cured coating film and the second cured coating film, A method of manufacturing a printed wiring board, comprising forming a via hole reaching a substrate.

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