JPS61278537A - Production of prepreg for printed wiring board - Google Patents

Abstract

PURPOSE:To obtain the titled prepreg excellent in drillability and copper foil peeling strength, by impregnating a base with a varnish comprising a specified epoxy resin, a polyphenol, cure accelerator and a guanidine derivative and drying it. CONSTITUTION:A varnish is obtained by dissolving 100pts.wt. epoxy resin (A) containing 1-100wt% silicone-modified epoxy resin obtained by reacting 100pts. wt. bisphenol A epoxy resin with 40-80pts.wt. tetrabromobisphenol A and 0.1-30pts.wt. methoxy group-containing silicone intermediate at 100-200 deg.C in the presence of 0.001-0.05pt.wt. catalyst, a polyphenol (B) in an amount to provide 0.5-1.5 equivalent of the phenolic hydroxyl groups per equivalent of the epoxy groups, 0.05-1.0pt.wt. cure accelerator (C) (e.g., imidazole compound with a masked imino group) and 0.1-2pts.wt. guanidine derivative (D) in a solvent. A base (e.g., glass cloth) is impregnated with this varnish and dried at 80-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing prepreg for printed wiring boards.

[Conventional technology]

As the density of printed wiring boards increases, the number of layers and through holes become smaller, and materials for printed wiring boards with good drillability are required. In terms of drillability, the occurrence of smear significantly impairs through-hole reliability by interfering with conduction between the inner layer circuit steel and the through-hole plating copper. In order to remove smear, printed wiring board manufacturers carry out a smear removal process, but there are safety precautions as concentrated sulfuric acid, hydrofluoric acid, etc. are used, and the inner wall of the through hole becomes gold-plated, reducing reliability. It can also be a cause. The cause of smear is said to be that the resin softened by the frictional heat during drilling attaches to the cross section of the inner layer circuit copper. Although softening of the resin can be prevented by using a cured resin with a high Tgcl), the hardness of the resin also increases, causing various problems. One way to reduce the occurrence of smear is to reduce the frictional heat generated during drilling. That is, the low j of the resin
l&! This is a method of suppressing the generation of frictional heat and preventing softening of the resin.

[Problem that the invention seeks to solve]

The present invention relates to a method for producing prepreg for paulownia wiring boards, which aims to improve the drill workability of epoxy-dicyandiamide-based multilayer materials, the storage stability of epoxy-polyphenol-based materials, and the copper foil peeling strength.

[Means for solving problems]

The method for producing a prepreg for printed wiring boards of the present invention includes: (a) containing 1 to 100 wt 1% of a silicone-modified epoxy resin obtained by reacting a bisphenol Am epoxy resin, tetrabromobisphenol A, and a methoxy group-containing silicone intermediate; It is characterized by impregnating a base material such as glass cloth or glass nonwoven fabric with a phenol containing an epoxy resin, (b) a polyfunctional phenol, (C) a curing accelerator, and (d) a guanidine derivative as essential components, and then drying it. - The present invention will be explained in detail below.

(The epoxy resin as a component contains 1 to 100% by weight of a silicone-modified epoxy resin obtained by reacting a bisphenol A type epoxy resin, tetrabromobisphenol A, and a methoxy group-containing silicone intermediate as an essential component.

As the bisphenol A type epoxy resin, one having few hydroxyl groups is preferable, and one having a hydroxyl value of 0 to α08 is preferable. If the hydroxyl value is higher than that, the obtained silicone-modified epoxy resin will have a high molecular weight and will give a non-uniform cured product. The hydroxyl value is the reciprocal of the hydroxyl equivalent multiplied by 100t, and the hydroxyl equivalent was measured by the acetyl chloride method.

Tetrabromobisphenol A is used to impart flame retardancy to epoxy resins, and the amount of bisphenol A
40 to 80 for 10xt part of type epoxy AT resin! Parts by weight are preferred. If the amount is less than 40 parts by weight, sufficient flame retardancy cannot be obtained, and if it is more than 80 parts by weight, the silicone-modified epoxy resin will have a high molecular weight.

The methoxy group-containing silicone intermediate is or a condensation polymer thereof, and has a methoxy group equivalent of 50 to 30.
0 is used. If the methoxy group equivalent is larger than this, the silicone-modified epoxy resin will have a high molecular weight,
Gives an unevenly cured product. If it is smaller than this, the reaction will not proceed sufficiently due to steric hindrance, and unreacted methoxy groups will remain, resulting in a moisture resistance of 1. Heat resistance decreases. The silicone intermediate is used in an amount of α1 to 50 parts by weight per 100 parts of bisphenol A epoxy resin, but if the amount is less than this, there is no effect on drilling workability, and if the amount is more than this, unreacted methoxy groups remain.

When these compounds are reacted, tertiary amines, quaternary ammonium salts, imidazole, alkali metal hydroxides, halogenated phosphonium salts, sulfonium salts, tertiary phosphines, organic titanate compounds, organic zirconium compounds are used as catalysts. etc. may also be used. Examples of tertiary amines include benzyldimethylamine, triethanolamine, and pyridine. Examples of quaternary ammonium salts include benzyltrimethylammonium hydroxide, benzyltrimethylammonium chloride, tetramethylammonium bromide, tetramethylammonium chloride, tetraethelammonium bromide, tetraethelammonium chloride, and N-cetylpyridinium chloride.

Imidazole includes 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimi-4"
Sol, 1-cyanoethyl-2-7 enylimidazole, and the like. Examples of alkali metal hydroxides include IJium hydroxide, potassium hydroxide, and lithium hydroxide. Examples of INQ genated phosphonium salts include ethyltriphenylphosphonium bromide, tetra72nylphosphonium chloride, tetrabutylphosphonium chloride, and methyltriphenylphosphonium iodide. Examples of sulfonium salts include triphenylsulfonium chloride, benzyldimethylsulfonyl chloride, and dimethylpropylsulfonium bromide. Examples of the tertiary phosphine include triphenylphosphine and tributylphosphine. Examples of organic titanate compounds include tetrapropyl titanate, tetrabutyl titanate, inglobil triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, inglobil tolyl (dioctyl pyrophosphate) titanate, tetraisoprobil bis (dioctyl phosphite) titanate, and tetra Octyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyldimethyl-1-butyl) bis(di-tridecyl) phos-21 ito titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) Examples include ethylene titanate, tetraisopropyl titanate, tetraoctyl titanate, and tetrastearyl titanate. Examples of organic zirconium compounds include zirconium acetate, tetrakis(acetylacetonate)zirconium, di-normal globoxyacetylacetonyl-stearyloxyzirconium, stearylzirconium,
Zirconium acetylacetone, hydroxyzirconium tolyl (acetylacetonate), etc.

The catalyst of Kokura is bisphenol A type epoxy resin 100
Use α001 to 005M parts per part by weight, but if it is less than that, there will be no catalytic effect, and if it is longer than that, it will become an impurity in the resin and affect the electrical properties of the cured product! #Give wo.

The temperature for the synthesis reaction of silicone-modified epoxy resin is 10
0 to 200°C is preferred. When the temperature is lower than 100°C, the reaction is slow and takes 10 hours or more. When the temperature is higher than 200°C, the catalytic effect is lost and tetrabromobisphenol A begins to decompose.

The synthesis reaction time may be any number of hours, but is preferably 2 to 5 hours. The end point of the reaction is confirmed by measuring the epoxy equivalent by the cetyltrimethylammonium bromide-perchloric acid method.

If the measured epoxy equivalent is between 90% and 110% of the theoretically calculated value, it is considered as the end point. If it is less than 90%, there will be a large amount of unreacted substances and curing will be slow, and if it exceeds 110%, there will be a large amount of high molecular weight substances and the appearance of the prepreg will be poor, which is not preferable.

During the synthesis reaction, inert gas substitution may or may not be performed.

Methanol, which is a reaction by-product, is removed from the system by distillation, and if necessary, by vacuum distillation.

The silicone-modified epoxy resin obtained as described above is used in an amount of 1 to 100% by weight. If it is less than 1% by weight, no improvement in drilling workability will be observed.

There is no particular restriction on the type of epoxy resin used as a component other than the silicone-modified epoxy resin. For example, bisphenol A type epoxy resin, bispheno-A
-F m epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin There are many kinds of Φ resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, incyanurate type epoxy resin, resorcin type epoxy resin, and their halides and hydrogenated substances, and several types can be used together. . Furthermore, there are no restrictions on the method or temperature for mixing these epoxy resins.

The polyfunctional phenol (b) may be of any type as long as it can be polymerized with the epoxy resin, such as bisphenol A, bisphenol F, polyvinylphenol, or novolacs such as phenol, cresol, alkylphenol catechol, bisphenol A, and bisphenol F. These include resins and halides of these phenolic resins. Several types of these phenol resins can also be used in combination. The blending amount is preferably in the range of CL5 to 1.5 equivalents of phenol hydroxyl group to epoxy group from the viewpoint of drill workability.

As the curing accelerator (C), imidazole compounds, organic phosphorus compounds, 5th-class amines, quaternary ammonium salts, etc. are used, but imidazole with imino groups masked with acrylonitrile, incyanate, melamine acrylate, etc. By using the compound, it is possible to obtain prepregs that have storage stability that is more than twice that of conventional products.

The imidazole compounds used here include imidazole, 2-:r:tylimidazole, 2-ethyl-4
-methylimidazole, 2-phenylimidazole,
2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecyl imidazole, 4,
5-diphenylimidazole, 2-methylimidacillin, 2-7enylimidazoline, 2-undecylimidacilline, 2-heptadecylimidacilline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-
As a masking agent, phenyl-4-methylimidazole, 2-ethylimidacilline, 2-isopropylimidacilline, 2,4-dimethylimidacyline, 2-phenyl-4-methylimidacyline, etc. , acrylonitrile, phenylene diisocyanate.

Examples include toluene diisocyanate, naphthalene diisocyanate, hequinamethelene diisocyanate, methylene bisphenyl incyanate, and melamine acrylate.

Several types of these curing accelerators may be used in combination, and the blending amount is preferably α01 to 5 parts by weight per 100 parts by weight of the epoxy resin. If it is less than 101 parts by weight, the accelerating effect will be small, and if it is more than 5 parts by weight, drilling workability will be reduced.

The guanidine derivative (d) is necessary to improve the peel strength of the copper foil. Examples of guanidine derivatives include dicyandiamide, dicyandiamide-aniline adduct, dicyandiamide-methylaniline adduct, dicyandiamide-diaminodiphenylmethane adduct, dicyandiamide-dichlorodiaminodiphenylmethane adduct, dicyandiamide-diaminodiphenyl ether adduct, aminoguanidine hydrochloride, and hydrochloric acid. Guanidine, guanidine nitrate, guanidine carbonate, guanidine phosphate, guanidine sulfate, guanidine salts such as aminoguanidine bicarbonate, acetylguanidine, diacetylguanidine, propionylguanidine, dibropionylguanidine, cyanoacetylguanidine, guanidine succinate, diethyl cyano Acetylguanidine, dicyancyamidine, N-oxymethyl-N'
-cyanoguanidine, acetylguanylurea, N, N'
Examples include 7 dicarboethoxyguanidine, riQQ guanidine, and bromoguanidine, and several of these can be used in combination. The blending amount is 100 Ift of epoxy resin.
Part y vs. shite [11~1.01! jtf[: It is preferable to do so. If the amount is less than this, the copper foil peeling strength will decrease, and if it is more than this, the drilling performance and storage stability will decrease.

Solvents used in varnish production include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, etc. Some of these may be used as a mixture.

However, the above (a), (b), (e), and (d) are essential components, and it is also possible to mix other compounds.

After incorporating the varnish obtained by blending each of the above components into a base material such as a glass nonwoven fabric, it is heated at 80 to 200°C in a drying oven.
Dry within a range of 100 to obtain a prepreg for printed wiring boards. Prepreg is heated and pressed to produce printed wiring boards and metal-clad laminates.

〔Example〕

Examples of the present invention will be described below.

The epoxy resin used in the present invention was synthesized as follows.

Epoxy J1175 bisphenol A type epoxy resin 4000 g, tetrabromobisphenol A207
0g1 KR9218 (product name: Shin-Etsu Chemical Co., Ltd., silicone intermediate with methoxy group equivalent weight 210) 400 g
, tetrabutyl titanate (L5 g) were mixed and stirred and kept at a temperature of 150° C. for 4 hours, during which volatile components in the system were removed under reduced pressure. Silicone-modified epoxy resin A having an epoxy equivalent of 576 was obtained.

Bisphenol A epoxy 11 with epoxy equivalent weight 190
Fat 4000g, Tetrabromobisphenol A2860
g, 540 g of KR213 (9 product name: manufactured by Shin-Etsu Chemical Co., Ltd., silicone intermediate with methoxy group equivalent weight 157), 540 g of pyridine, stirred and kept at a temperature of 120° C. for 2 hours. During that time, volatile components in the system were removed under reduced pressure. Epoxy equivalent weight 565
A silicone-modified epoxy resin B was obtained.

Epoxy-1190 bisphenol A epoxy resin 4000 g, tetrabromobispheno-eA
2290g, KR2j7C Product name: Shin-Etsu Chemical Co., Ltd.
Silicone intermediate with methoxy group equivalent weight 265) 2 0
0 g, TetrazoΩvir 2-methylimidazole 1. O
gy&: The mixture was mixed and stirred, and the temperature was kept at 160°C for 1 hour. During that time, the volatile components in the system were removed under reduced pressure. Epoxy equivalent 55
8 silicone-modified Eboshiki 11Wct-i7'c.

Bisphenol A type epoxy resin with epoxy equivalent weight 175 4000 g, tetrabromobisphenol A2
070g, Tetramethylammonyl chloride α25
gt-mix with stirring and maintain the temperature at 160°C for 2 hours. During that time, volatile components in the system were removed under reduced pressure. Epoxy equivalent 550
An epoxy resin of 90 or more was obtained, and a varnish was prepared using the epoxy resin according to the formulation shown in Table 1.

The varnishes of Examples 1 to 5 and Comparative Examples 1 and 2 (11
Next, a prepreg was obtained by impregnating a glass cloth with a thickness of 100 mL and drying it at 160°C for 10 minutes.

Using 15 sheets of the above prepreg and 6 sheets of O copper foil with a thickness of 55 μm, a 6-layer printed wiring board was fabricated by heat-pressing molding at 170°C for 60 minutes, and the results showed drilling workability, copper foil peeling strength, and soldering heat resistance. , the storage stability of prepreg was tested. The drill workability test was conducted by rotating a 6-layer printed wiring board at a rotation speed of 60 kr.
p.m.

Feed speed 50m/min, general frame 1. Holes were drilled to f 20 Q Q hits using 2 sheets of Q mm 1 stacked, and the incidence of stain 1 was measured.

The characteristics test results are shown in Table 2.

The measurement was performed according to JIS C-6481.

1) Smear occurrence rate evaluation method Through-hole plating was applied to a drilled 6-layer wiring board, and the cut surface of the through-hole part was examined using a microscope for 5000 hours.
its, 20 holes IF3 near 10000 hits
The connection portion between the J#lI steel and the through-hole plated steel was observed, and the smear occurrence rate was evaluated. The smear occurrence rate was determined by calculating the ratio of the height of the smear to the connection height for each connection location, and averaging the ratio.

2) @Foil peeling strength measurement method A line with a width of 10mIII is formed on the outer layer steel foil, and the peeling strength in the 90° direction of the line is measured at 50m+e/
Measurements were made at a peeling speed of min.

3) Inner layer steel peel strength measurement method Copper oxide treatment was applied to the shiny surface of the inner layer steel foil, and the peel strength between the copper oxide treated surface and the prepreg layer was measured under the same conditions as in 2).

4) Solder heat resistance After dipping in solder at 260° C. for 20 seconds, the appearance was visually evaluated, and those without blisters were rated OK, and those with blisters were rated NG.

5) Prepreg Gel Time The gel time at 160°C of the prepreg immediately after coating was taken as the initial value, and the gel time at 160°C of the prepreg after being stored for 60 days at a temperature of 20°C and a humidity of 40% was measured.

As shown in Table 2, Examples 1 to 5 had a lower relative pestmia incidence rate than Comparative Example 1.2.

Further, since Examples 1 to 5 use a guanidine derivative and masked imidazole, the copper foil peeling strength and storage stability are better than that of Comparative Example IK.

〔Effect of the invention〕

The prepreg for printed heald boards of the present invention has improved drill workability for multiple wiring boards, copper foil peeling strength, and storage stability of the prepreg compared to the prior art.

Claims (1)

[Scope of Claims] 1. (a) An epoxy resin containing 1 to 100% by weight of a silicone-modified epoxy resin obtained by reacting a bisphenol A type epoxy resin, tetrabromobisphenol A, and a methoxy group-containing silicone intermediate, (b 1. A method for producing a prepreg for a printed wiring board, which comprises impregnating a base material with a varnish containing as essential components a) polyfunctional phenol, (c) a curing accelerator, and (d) a guanidine derivative, and then drying the varnish. 2. The printed wiring board according to claim 1, wherein the curing accelerator is an imidazole compound whose imino group is masked, and the blending amount is 0.05 to 1.0 parts by weight per 100 parts by weight of the epoxy resin. A method for manufacturing prepreg for use. 3. Claim 1, wherein the amount of the guanidine derivative is 0.1 to 2 parts by weight per 100 parts by weight of the epoxy resin.
2. A method for producing a printed wiring board prepreg according to item 1 or 2.