JP2013076004A - Thermosetting resin composition for laser beam machining, cured product, and printed wiring board - Google Patents

Abstract

The present invention provides a thermosetting resin composition for laser processing which is excellent in laser processability and can provide a cured product having good adhesion, solvent resistance and heat resistance.
It comprises (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring, (B) a crosslinkable polyimide resin, (C) a thermosetting catalyst, and (D) an inorganic filler. It is a thermosetting resin composition for laser processing. The (B) crosslinkable polyimide resin preferably contains at least one of a carboxyl group and a phenolic hydroxyl group. Moreover, the blending ratio of the epoxy resin having the (A) polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is from (A) :( B) = 9: 1 to 1: A ratio of up to 9 is preferred.
[Selection] Figure 1

Description

  The present invention relates to a thermosetting resin composition for laser processing and a printed wiring board, and more specifically, laser processing capable of obtaining a cured product having excellent laser processability and good adhesion, solvent resistance, and heat resistance. The present invention relates to a thermosetting resin composition, a cured product of the resin composition, and a printed wiring board using the same.

  Generally, in a printed wiring board, a solder resist is used for the purpose of protecting circuit wiring and preventing solder from adhering to unnecessary parts when soldering when mounting electronic components. In this solder resist, a resin composition is printed on a copper-clad laminate for a printed wiring board, and is cured by heating to form a resin insulating layer.

  When forming a via hole reaching the conduction part of a narrow-pitch circuit wiring, a thermosetting resin composition is printed on the entire surface of the printed wiring board, heat-cured to form a resin insulating layer, and then the resin insulating layer is formed by laser processing. There is a method of forming a via hole by penetrating through. For example, Patent Document 1 discloses a thermosetting resin composition for laser processing capable of obtaining a resin insulating layer having an appropriate desmear property. Patent Document 2 discloses a method for producing a multilayer printed wiring board, wherein a resin substrate containing a pigment is used as a substrate, and the substrate is irradiated with laser light to form through holes. ing.

  In order to form a fine via hole by laser processing, an ultraviolet laser such as a third harmonic laser or excimer laser whose YAG or YVO4 crystal is a medium is preferably used.

  However, in the formation of via holes by ultraviolet laser, the performance of scraping and penetrating the resin insulating layer is poor, and therefore, there is a problem that a large number of times of laser irradiation is required for the via holes and it takes a long time for laser processing.

  The solution is to increase the ultraviolet light absorbability of the resin insulation layer, improve the scraping performance of the resin insulation layer, and to perform ultraviolet laser processing in a short time. A method of adding an absorbent has been studied.

JP 2010-180355 A JP 2003-101244 A

  Among the methods for improving laser processability, the method of blending a pigment does not dissolve in the resin but disperses as particles and causes reflection and scattering, so the ultraviolet light absorption of the resin does not improve as expected. Sometimes. On the other hand, many of the ultraviolet absorbers have a problem of causing volatilization and bleed out due to heat at the time of heat curing when forming a cured product.

  Also, for thermosetting resins with high ultraviolet light absorption, laser processing of the resin insulation layer is possible, but the familiarity between the resin and the inorganic filler is poor, and the printability of the composition is poor. However, even if the resin insulation layer could be formed, there were problems such as poor adhesion to the substrate and poor solvent resistance and heat resistance of the resin insulation layer. .

  Accordingly, an object of the present invention is to provide a thermosetting resin composition for laser processing, which is excellent in laser processability, and capable of obtaining a cured product having good adhesion, solvent resistance and heat resistance, and a cured product thereof. It is in providing the used printed wiring board.

  As a result of intensive studies to solve the above problems, the present inventors have (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring, (B) a crosslinkable polyimide resin, (C) a thermosetting catalyst, and (D ) By finding a thermosetting resin composition containing an inorganic filler, the inventors have found that the above problems can be solved, and have completed the present invention.

  That is, the thermosetting resin composition for laser processing of the present invention comprises (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring, (B) a crosslinkable polyimide resin, (C) a thermosetting catalyst, and (D ) An inorganic filler.

  In the thermosetting resin composition for laser processing of the present invention, the (B) crosslinkable polyimide resin preferably contains at least one of a carboxyl group and a phenolic hydroxyl group.

  In the thermosetting resin composition for laser processing of the present invention, the blending ratio of the (A) epoxy resin having a polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is (A ) :( B) = A ratio of 9: 1 to 1: 9 is preferred.

  Moreover, the thermosetting resin composition for laser processing of the present invention is such that the total amount of the (A) epoxy resin having a polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is for laser processing. It is preferable that it is 40-80 mass parts with respect to 100 mass parts of thermosetting resin compositions.

  In the thermosetting resin composition for laser processing of the present invention, the (A) epoxy resin having a polycyclic aromatic hydrocarbon ring is at least one of a naphthalene type epoxy resin and an anthracene type epoxy resin. Is preferred.

  The cured product of the present invention is obtained by curing any one of the above-described thermosetting resin compositions for laser processing.

  The printed wiring board of the present invention is characterized by comprising the above cured product.

  In the printed wiring board of the present invention, it is preferable that a via hole penetrating the resin insulating layer made of the cured product is formed by an ultraviolet laser.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the thermosetting resin composition for laser processing which is excellent in laser workability and can obtain the hardened | cured material which has favorable adhesiveness, solvent resistance, and heat resistance.

It is a schematic cross section which shows the via hole formation process by the laser processing of the printed wiring board provided with the resin insulating layer which consists of a hardened | cured material of the thermosetting resin composition for laser processing of this invention.

Hereinafter, the present invention will be described in detail.
The thermosetting resin composition for laser processing of the present invention comprises (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring, (B) a crosslinkable polyimide resin, (C) a thermosetting catalyst, and (D) inorganic filling. It contains an agent.

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

  Specific examples of the epoxy resin having the (A) 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 Corporation); 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.

  The (B) crosslinkable polyimide resin contains a cyclic imide bond in the resin skeleton, has a high absorbency in the ultraviolet region, and has a reactive functional group, so that it can be cured by heating. It is a resin. Further, it is preferably soluble in an organic solvent. Examples of the reactive functional group include functional groups having active hydrogen such as amino group, carboxyl group, and hydroxyl group. Examples of the hydroxyl group having active hydrogen include a phenolic hydroxyl group.

  (B) Specific examples of the crosslinkable polyimide resin include V-8005 (manufactured by DIC), GPI-NT, GPI-HT (manufactured by Gunei Chemical Industry Co., Ltd.) and the like. These may be used individually by 1 type and may be used in combination of 2 or more types.

  In addition, as long as it is contained in the definition of the said (B) crosslinkable polyimide resin, the polyimide resin other than having described in the specific example can also be used. On the other hand, examples that cannot be used include a polyamic acid resin solution that is a polyimide precursor and an alicyclic polyimide resin.

  Since the (A) epoxy resin having a polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin have high ultraviolet light absorbability, the thermosetting resin composition for laser processing of the present invention. Has good processability with an ultraviolet laser, and laser processing can be performed in a short time.

  (A) Epoxy resin having a polycyclic aromatic hydrocarbon ring and (B) Epoxy resin having a polycyclic aromatic hydrocarbon ring by heating from 150 ° C. to 230 ° C. in the presence of a crosslinkable polyimide resin. An epoxy group in the resin and the reactive functional group in the (B) crosslinkable polyimide resin undergo a curing reaction to form a crosslinked structure, whereby a resin insulating layer having adhesion, solvent resistance, and heat resistance can be formed.

  The blending ratio of the epoxy resin having the (A) polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is (A) :( B) = 9: 1 to 1: 9 in mass ratio. The ratio is preferably 5: 5. When the blending ratio exceeds 9: 1 ((A) an excess amount of epoxy resin having a polycyclic aromatic hydrocarbon ring or a single use), the heat-cured resin insulation layer becomes hard and brittle, which is one of circuit wiring materials. It may be inferior to the adhesion to copper foil. On the other hand, when the blending ratio exceeds 1: 9 ((B) excessive amount of crosslinkable polyimide resin or used alone), the resin insulating layer may have insufficient thermosetting properties and may have poor chemical resistance.

  The blending amount of (A) the epoxy resin having a polycyclic aromatic hydrocarbon ring and (B) the crosslinkable polyimide resin in the whole composition is (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring and ( B) The total amount of the crosslinkable polyimide resin is preferably 40 parts by mass to 80 parts by mass with respect to 100 parts by mass of the thermosetting resin composition for laser processing. When the blending amount is less than 40 parts by mass, the resin amount in the entire composition is low, the fluidity of the composition becomes too high, and the printability may deteriorate. 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.

  The (A) epoxy resin having a polycyclic aromatic hydrocarbon ring and (B) the crosslinkable polyimide resin constituting the thermosetting resin composition used in the present invention are preferably liquid, but at room temperature. Since it may exist as a solid or crystalline solid, 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 the solvent for the resin composition. 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, propylene Glycol ethers such as 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 butyl ether acetate, methyl lactate, ethyl lactate, lactic acid Esters such as til; Amides such as γ-butyrolactone, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol; Aliphatic hydrocarbons such as octane and decane; petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha are mentioned, particularly γ-butyrolactone, N-methyl-2-pyrrolidone, N, N Amides such as dimethylformamide and N, N-dimethylacetamide are preferable because of their good solubility.
These solvents may be used alone or in combination of two or more.

  The (C) thermosetting catalyst is used to further improve the thermosetting characteristics of the 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, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, and methylnadic anhydride Use acid anhydrides, etc. Rukoto can. More specifically, as imidazole compounds, 1B2PZ, 2E4MZ, 2MZ-A, 2MZ-OK, 2PHZ, 2P4MHZ and the like (all manufactured by Shikoku Kasei Kogyo Co., Ltd.); U-CAT3502T (all manufactured by San Apro); bicyclic amidine compounds and salts thereof include DBU, DBN, U-CATSA102, U-CAT5002 (all manufactured by San Apro), and the like. These may be used singly or in combination of two or more.

  The blending amount of the (C) thermosetting catalyst is sufficient at a normal blending ratio. For example, (A) an epoxy resin having a polycyclic aromatic hydrocarbon ring and (B) a crosslinkable polyimide which are thermosetting components. 0.1 to 10 parts by mass is preferable with respect to 100 parts by mass of the total amount of resin. If the amount is less than 0.1 parts by mass, the reaction may not be promoted. If the amount exceeds 10 parts by mass, the storage stability of the composition may be significantly reduced.

  The (D) inorganic filler is used for suppressing the curing shrinkage of the resin insulating layer and improving the 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.

  The average particle size of the (D) inorganic filler is preferably 5 μm or less. The blending ratio is preferably 75% by mass or less, more preferably 0.1 to 60% by mass based on the total solid content of the composition (the amount obtained by removing the solvent from the entire composition). When the blending ratio of the inorganic filler exceeds 75% by mass, the viscosity of the composition becomes high, the applicability may be lowered, and the resin insulating layer may become brittle.

  Moreover, the thermosetting resin composition for laser processing of the present invention contains an epoxy resin other than the solvent-soluble epoxy resin having a high ultraviolet light absorption (A) polycyclic aromatic hydrocarbon ring. Also good. In particular, a known and commonly used polyfunctional epoxy resin having at least two epoxy groups in one molecule can be used. Examples of the epoxy resin include bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, Biphenyl type epoxy resin, catechol type epoxy resin, epoxy resin having dicyclopentadiene skeleton, epoxy resin having triphenylmethane skeleton, Xylok type epoxy resin, amino epoxy resin, CTBN modified epoxy resin, phosphorus containing epoxy resin, containing bromine atom Epoxy resin, epoxy resin of condensate of phenols and aromatic aldehyde having phenolic hydroxyl group, diglycidyl ether of propylene glycol or polypropylene glycol Polytetramethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4′-diglycidyl ether, 1,6-hexanediol diglycidyl ether , Ethylene glycol or propylene glycol diglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, triglycidyltris (2-hydroxyethyl) isocyanurate, and the like. Epoxy resins other than these components (A) may be used alone or in combination of two or more.

  The thermosetting resin composition for laser processing of the present invention can further contain known and commonly used additives such as a colorant, a thickener, an antifoaming agent, a leveling agent, and an adhesion imparting agent.

  The colorant is used to improve the concealment of the resin insulating layer as imitation of circuit wiring or prevention of theft. Either a pigment or a dye may be used, and for example, a colorant such as phthalocyanine blue, phthalocyanine green, disazo yellow, titanium oxide, or carbon black can be used.

  Even if pigments with high UV light absorption are used, they do not dissolve in the resin and are dispersed as particles, causing reflection and scattering, so the UV light absorption of the resin insulation layer does not increase so much, and UV laser processing Therefore, the component (A) and the component (B) are necessary. Although it is possible to increase the ultraviolet light absorbency of the resin insulation layer to some extent by adding a large amount of pigment, in that case, it may be difficult to control physical properties such as coating strength due to poor compatibility with the resin is there.

  Further, even if a dye having a high ultraviolet light absorption property is used, the dye is discolored by heat at the time of heat curing and the ultraviolet light absorption property is lowered. Therefore, the component (A) and the component (B) are also necessary.

  Next, a method for forming a resin insulating layer using the thermosetting resin composition for laser processing of the present invention and penetrating the resin insulating layer by ultraviolet laser processing to form a via hole will be described.

  After the substrate is subjected to pretreatment such as buffling and chemical polishing, a thermosetting resin composition adjusted with an organic solvent to a viscosity suitable for the coating method is applied so that the dry film thickness is from 10 μm to 30 μm. . Next, the organic solvent contained in the composition is volatilized and dried at a temperature of 40 ° C. to 100 ° C. Furthermore, the resin insulating layer can be formed by heating and curing at a temperature of 150 to 230 ° C. for 30 to 120 minutes (see FIG. 1A).

  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. 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 / polyphenylene ether, polyphenylene oxide / cyanate ester Can be used.

  Examples of the coating 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 coating film by coating and drying on a carrier film, winding up as a film to form a dry film, and laminating on a substrate. In addition, 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 form a via hole, and the circuit wiring is exposed (see FIG. 1B).

The ultraviolet laser is a laser having an oscillation wavelength in the ultraviolet region (which indicates a wavelength of 200 nm to 400 nm). In the present invention, an excimer laser (308 nm) using a combination of HCl gas and Xe gas, YLF crystal is the medium. Nd: YAG third harmonic laser (351 nm), Nd: YAG third harmonic laser (355 nm) with YAG crystal as medium, Nd: YVO ₄ third harmonic laser (355 nm) with YVO ₄ crystal as medium It is preferable that

  The ultraviolet laser irradiation method includes pulse irradiation and continuous irradiation, but pulse irradiation is preferable because there is less damage such as thermal expansion and cracks in the resin insulating layer around the via hole.

  The irradiation energy of the ultraviolet laser is shown as irradiation energy [μJ / pulse] per pulse, and in the present invention, 0.5 μJ / pulse to 50 μJ / pulse is preferable, and more preferably 1 μJ / pulse to 10 μJ. / Pulse. The pulse width at that time is 1 microsecond or less. If it is less than 0.5 μJ / pulse, the resin insulating layer is hardly scraped off, and it becomes difficult to form a via hole, which is not preferable. On the other hand, if it exceeds 50 μJ / pulse, the resin insulating layer around the via hole may be damaged such as cracks.

  The irradiation with the ultraviolet laser needs to be performed until a via hole can be formed. Further, at the same irradiation energy, it is proportional to the film thickness of the resin insulating layer. The number of times of laser irradiation is preferably 1 to 100 times, more preferably 10 to 50 times. If the number of times of irradiation is too large, laser processing takes a long time, which may lead to a decrease in productivity.

  The via hole shape formed by the ultraviolet laser is expressed by the ratio of the via hole diameter D on the surface of the resin insulating layer and the via hole diameter d on the surface of the circuit wiring (bottom of the via hole), that is, the formula (d / D) × 100 [%]. In the present invention, it is preferably 50% or more, more preferably 70% or more. If it is less than 50%, the surface of the circuit wiring (bottom of the via hole) is too thin, the solder does not adhere to the circuit wiring portion, and there is a problem that conduction cannot be obtained.

  Further, the via hole diameter formed by the ultraviolet laser is preferably 10 μm to 70 μm, more preferably 20 μm to 45 μm in the via hole diameter D on the surface of the resin insulating layer. By using the ultraviolet laser and the composition of the present invention, for example, a carbon dioxide laser used for general purposes and a printed wiring board corresponding to narrow pitch circuit wiring which cannot be used by the 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 desmear treatment after forming a resin insulating layer using a thermosetting resin composition and forming a via hole with a laser.

  After the printed wiring board manufactured in this way is subjected to gold plating on the circuit wiring or preflux treatment, electronic components such as semiconductor chips to be mounted are mounted by bonding with gold bumps or solder bumps. .

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Unless otherwise noted, all are based on mass.

(Preparation of thermosetting resin composition for laser processing)
The components described in Table 1 and Table 2 are blended, premixed with a stirrer, kneaded using a three-roll mill, and heat for laser processing in Examples 1 to 10 and Comparative Examples 1 to 5 A curable resin composition was prepared. In addition, the unit of the numerical value of Table 1 is a mass part.

(Preparation of sample for evaluation)
The thermosetting resin compositions for laser processing of Examples 1 to 10 and Comparative Examples 1 to 5 prepared in this way were applied onto a copper-clad laminate that had been buffed and polished at 80 ° C. in a hot air circulating drying oven. After drying for 30 minutes, the test pieces including the resin insulating layers of Examples 1 to 10 and Comparative Examples 1 to 5 were prepared by heat curing at 230 ° C. for 1 hour. The thickness of the cured coating film, that is, the resin insulating layer was 20 μm. Each test piece was subjected to the following adhesion test, solvent resistance test, heat resistance test and laser workability test.

(Performance evaluation)
(Adhesion test)
In accordance with JIS K5600-5-6: 1999, a cross-cut was made on the resin insulation layer of the test piece, a cellophane tape was applied to the cured product, and a peeling test was performed to peel it off. The state of peeling was visually observed and evaluated according to the following criteria.
○: No peeling Δ: Peeling on a part of the resin insulation layer ×: Peeling on most of the resin insulation layer The results are shown in Tables 3 and 4 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 on part of the resin insulation layer ×: Peeling on most of the resin insulation layer The results are shown in Tables 3 and 4 below.

(Heat resistance test)
The test piece was immersed in a solder bath at 260 ° C. (solution composition: Sn-3.0Ag-0.5Cu solder (tin 96.5%, silver 3.0%, copper 0.5%)) for 10 seconds. After repeating 3 times, the same peeling test as the adhesion test was performed, and then the state of peeling of the resin insulating layer was visually observed and evaluated according to the following criteria.
○: No peeling Δ: Peeling on a part of the resin insulation layer ×: Peeling on most of the resin insulation layer The results are shown in Tables 3 and 4 below.

(Laser workability test)
Via holes were formed using an ultraviolet laser (Nd: YVO ₄ third harmonic laser, wavelength: 355 nm) to expose circuit wiring. The shape of the via hole was measured using a laser microscope. The number of times of irradiation required for the ratio [formula (d / D) × 100 [%]] of the via hole diameter D on the surface of the resin insulating layer and the via hole diameter d on the surface of the circuit wiring (via hole bottom surface) to exceed 70% is as follows: Evaluation based on the criteria. The laser irradiation conditions were set so that only the resin insulating layer was processed and the circuit (conducting portion) was not damaged.
○: 40 times or less Δ: More than 40 times and 100 times or less ×: More than 100 times The results are shown in Table 3 and Table 4 below.

※１：YX-8800（三菱化学社製）を不揮発分３０％になるようにジメチルアセトアミドで溶かしたワニス
※２：HP-4032（ＤＩＣ社製）を不揮発分５０％になるようにジメチルアセトアミドで溶かしたワニス
※３：E828（三菱化学社製）
※４：V-8005（ＤＩＣ社製）を不揮発分１５％になるようにジメチルアセトアミドで溶かしたワニス
※５：1B2PZ（四国化成工業社製）
※６：BYK-310（ビックケミー社製）
※７：TINUVIN234（ＢＡＳＦジャパン社製）

* 1: Varnish prepared by dissolving YX-8800 (Mitsubishi Chemical Corporation) with dimethylacetamide to a non-volatile content of 30% * 2: HP-4032 (DIC) with dimethylacetamide to have a non-volatile content of 50% Melted varnish * 3: E828 (Mitsubishi Chemical Corporation)
* 4: Varnish prepared by dissolving V-8005 (manufactured by DIC) with dimethylacetamide to a non-volatile content of 15% * 5: 1B2PZ (manufactured by Shikoku Kasei Kogyo Co., Ltd.)
* 6: BYK-310 (by Big Chemie)
* 7: TINUVIN234 (BASF Japan)

As is clear from the results shown in Tables 3 and 4, Comparative Examples 1 and 2 having no component (B) and Comparative Example 3 having no component (A) have laser processability, but have adhesion. Or the solvent resistance was poor. Further, Comparative Examples 4 and 5 having neither component (A) nor component (B) were inferior in laser processability. In Comparative Example 5, a benzotriazole ultraviolet absorber was blended, but the laser processability was not sufficient.
On the other hand, the resin insulating layer comprising the thermosetting resin composition for laser processing of the present invention is excellent in adhesion to the substrate, solvent resistance and heat resistance, and is excellent in laser processability.
Therefore, it can be seen that, particularly as a thermosetting solder resist for laser processing of a printed wiring board, it can have characteristics equal to or higher than those of conventional ones.

  The present invention can be used as a thermosetting solder resist for laser processing of a printed wiring board corresponding to a narrow pitch circuit wiring for mounting.

1. 1. Resin insulation layer Substrate (copper-clad laminate)
2a. Conductor layer (circuit wiring)
2b. 2. Insulating layer Via hole4. Laser light

Claims (8)

  (A) An epoxy resin having a polycyclic aromatic hydrocarbon ring, (B) a crosslinkable polyimide resin, (C) a thermosetting catalyst, and (D) an inorganic filler, for laser processing Thermosetting resin composition.   The thermosetting resin composition for laser processing according to claim 1, wherein the (B) crosslinkable polyimide resin contains at least one of a carboxyl group and a phenolic hydroxyl group.   The mixing ratio of the epoxy resin having the (A) polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is (A) :( B) = 9: 1 to 1: 9 in mass ratio. The thermosetting resin composition for laser processing according to claim 1 or 2, wherein   The total amount of the (A) epoxy resin having a polycyclic aromatic hydrocarbon ring and the (B) crosslinkable polyimide resin is 40 to 80 parts by mass with respect to 100 parts by mass of the thermosetting resin composition for laser processing. It is a mass part, The thermosetting resin composition for laser processing as described in any one of Claim 1 to 3.   The thermosetting resin for laser processing according to any one of claims 1 to 4, wherein the epoxy resin (A) having a polycyclic aromatic hydrocarbon ring is a naphthalene type epoxy resin and / or an anthracene type epoxy resin. Composition.   Hardened | cured material formed by hardening | curing the thermosetting resin composition for laser processing as described in any one of Claim 1-5.   A printed wiring board comprising the cured product according to claim 6.   The printed wiring board according to claim 7, wherein a via hole penetrating the resin insulating layer made of the cured product is formed by an ultraviolet laser.

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