JPS6112732A - Preparation of prepreg for printed circuit board - Google Patents

Abstract

PURPOSE:To obtain the titled prepreg reducing occurrence of smears during drill processing, having small warpage, by blending an epoxy resin with a polyhydric phenol, a curing promotor, a polyethylene glycol, and a solvent to give varnish, impregnating it to glass cloth, etc., drying cloth, etc. CONSTITUTION:(A) An epoxy resin (e.g., halogenated bisphenol A type epoxy resin) is blended with (B) a polyhydric phenol (e.g., phenolic novolak resin) in an amount to give 0.5-2 equivalents phenolic hydroxyl groups based on epoxy group, (C) 0.05-1pt.wt. based on 100pts.wt. component A of a curing promotor (e.g., 2-methylimidazole), (D) 0.2-20pts.wt. based on 100pts.wt. component A of polyethylene glycol having 200-10,000 average molecular weight, and (E) a solvent (e.g., acetone) to give varnish, which is impregnated into glass cloth or nonwoven fabric of glass, and dried in a drying furnace at 80-200 deg.C, to give the aimed prepreg.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to epoxy glass cloth, which is a material for printed wiring boards;
The present invention relates to a method for producing an epoxy-glass nonwoven fabric prepreg.

(Prior Art) 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 the reliability of through-holes by interfering with the conduction between the inner layer circuit copper and the through-hole plating copper. In order to remove smear, a smear removal process is performed on printed wiring board manufacturers, but it uses concentrated sulfuric acid, hydrofluoric acid, etc., which poses safety issues, and also causes the inner walls of through holes to become rough, reducing reliability. It also becomes. Polyimide material is known as a material for printed wiring boards that causes less smearing, but it is expensive and the cured resin is hard, so it is not likely to become more widespread than K. In addition, polyimide material has high hardness, and problems such as drill breakage and drill wear occur when drilling small diameter holes of α6φ pieces or less.

It is said that the cause of smear is 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 resin with a high Tg, the hardness of the resin usually increases, causing various problems.

Another problem in manufacturing printed wiring boards is warping. If a wiring board warps, it becomes difficult to insert it into an etching machine, etc., and there are also problems with printing resist ink.

Also, problems often arise when mounting parts.

(Problems to be Solved by the Invention) The present invention uses epoxy glass, which is a material for printed wiring boards, for the purpose of reducing the occurrence of smear during drilling and reducing the warping of printed wiring boards. The present invention relates to a method for producing cloth prepreg and epoxy-glass nonwoven fabric prepreg.

(Means for Solving the Problems) The present invention provides a varnish containing (a) an epoxy resin, (b) a polyfunctional phenol, (C) a curing accelerator, (d) a polyethylene glycol, and (e) a solvent, a glass cloth, Alternatively, a prepreg for printed wiring boards is produced by impregnating a glass nonwoven fabric and then drying it.

The epoxy resin (a) may be any polyfunctional one, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolak epoxy Resins, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, and the like. There are halides, hydrogenated substances, etc., and several types can be used in combination.

The polyfunctional phenol (b) may be of any type as long as it can be polymerized with an epoxy resin, such as bisphenol A, halogenated bisphenol A, phenol novolac resin, cresol novolac resin, tert-
Examples include butylphenol novolak resin, nonylphenol novolak resin, bisphenol A novolak resin, bisphenol F novolak resin, and their halogenated products. Several types of these polyfunctional phenols can also be used in combination. It is preferable that the amount of phenolic hydroxyl group is in the range of 0.5 to 2.0 equivalents to the epoxy group. If it is not within this range, sufficient crosslinking density cannot be obtained.

As the curing accelerator (c), tertiary amines, quaternary ammonium salts, imidazole compounds, alkali metal hydroxides, phosphonium halides, sulfonium salts, tertiary phosphines, etc. are used. Examples of tertiary amines include benzyldimethylamine, α-methylbenzyldimethylamine, 2-(dimethylaminemethyl)phenol,
．． 4.6-) Lis(dimethylaminomethyl)phenol, pyridine, triethanolamine, etc. Imidazole compounds include 2-methylimidazole, 2-
Ethylimidazole, 2-ethyl-4-methylimidazole, 2-7 enylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2
-Heptadecylimidazole, 4,5-diphenylimidazole, 2-methylimidacillin, 2-ethyl-4-
Methylimidacillin, 2-phenylimidacillin, 2
-Undecylimidacilline, 2-heptadecylimidacilline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidacilline, 2-ingrobylimidazoline, 2 , 4-dimethylimidacyline, 2-phenyl-4-methylimidacyline, and compounds in which the hydrogen of the secondary amine of these imidazoles is replaced with a cyanethyl group, and the product name Curazole 2E4M manufactured by Shikoku Kasei ■.
Z-CNS, *knee 7zol Cu Z-CNS, *x
7zor 2PZ-CNS, key 7zor/l/C, IZ
-AZ INE, Ky7zo #2MZ-AZINE, etc. are used. Examples of quaternary ammonium salts include benzyltrimethylammonium hydroxide, benzyltrimethylammonium chloride, tetramethylammonium bromide, tetramethylammonium bromide, tetraethylammonium bromide, tetraethylammonium chloride, and N-cetylpyridinium chloride.

Alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and potassium hydroxide. Examples of the halogenated phosphonium salts include ethyltriphenylphosphonium furomite, tetraphenylphosphonium chloride, tetrabutylphosphonium bromide, and methyltriphenylphosphonium iodide.

Examples of sulfonium salts include triphenylsulfonyl sulfonium tetrahydride, benzyldimethylsulfonium chloride, and dimethylpropylsulfonium bromide.

Examples of tertiary phosphine include triphenylphosphine and tributylphosphine.

Several types of these curing accelerators can also be used in combination. The blending amount is preferably α01 to 5 parts by weight per 1001 parts by weight of the epoxy resin.

The average molecular weight of the polyethylene glycol (d) is 200
~io, ooo, preferably 400-6,00
0, and those having various average molecular weights within this range may be used in combination. If the average molecular value is smaller than 200, the heat resistance of the cured product will be poor, and if it is larger than 10.000, the solubility in epoxy resins and solvents will be poor. The blending amount is 1 part epoxy resin
The amount is 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight. If the amount is less than 0.2 parts by weight, the effect of reducing smear occurrence rate and improving warpage will not be obtained, and if it is more than 20 parts by weight, hygroscopicity, solvent resistance, discoloration by heating in air, etc. will deteriorate. . As for the blending method, the epoxy resin may be directly dissolved in the epoxy resin, or it may be dissolved in a solvent and then mixed with the epoxy resin. In this case, the temperature is arbitrary.

The solvent for (e) is acetone, methyl ethyl ketone,
Toluene, xylene, methyl in butyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N,
Examples include N-dimethylformamide, N,N-dimethylacetamide, methanol, and ethanol, and several types of these may be used in combination.

The pheno obtained by blending the above (a), (b), (c), (Φ, (e)) is impregnated into glass cloth or glass nonwoven fabric, and dried in a drying oven at a temperature of 80 to 200 ° C. A prepreg for a printed wiring board is obtained.The prepreg is heated and pressed to be used for manufacturing a printed wiring board or a metal-clad laminate.

In addition, when the obtained prepreg for printed wiring board requires flame retardation, the above (a), (b), (c), (Φ, (
In addition to the compound e), it is necessary to include halogenated Epoquin resin, tetodipromopisphenol A, decabromodiphenyl ether, antimony trioxide, and natho-2-phenylphosphine, which are generally referred to as flame retardants. In order to maintain the properties as a prepreg for printed wiring boards, the amount of flame retardants other than halogenated epoxy resins should be kept to the minimum necessary amount, which is at most 30 parts by weight or less per 100 important parts of the epoxy resin. This is desirable.

〔Example〕

Example 1 Brominated bisphenol A type epoxy resin (epoxy equivalent: 530) 80 parts by weight Phenol novolac type epoxy resin (epoxy equivalent: 20G) 20 parts by weight Phenol novolak tree strength 60 parts by weight 2-ethyl-4
- Methylimidazole 0.6 parts by weight Polyethylene glycol (average molecular weight 4000) 5 parts by weight Acetone 90 parts by weight A varnish was produced by blending the above six types of compounds, and this varnish was impregnated into a glass cloth with a thickness of 110. A prepreg was obtained by drying at °C for 5 minutes.

Example 2 Example 1 was prepared by blending 2 parts by weight of polyethylene glycol (average molecular weight 1000) instead of the Sfi parts of polyethylene glycol (average molecular weight 4000) in Example 1.
Prepreg was obtained in the same manner as above.

Example 3 Brominated bisphenol A epoxy resin (epoxy equivalent: 530) 80 parts by weight Bisphenol A novolak epoxy resin (epoxy equivalent: 205)
203j parts bisphenol A novolak resin 3ash
s1-cyanoethyl-2-2 enylimidazole
0.5 parts by weight Polyethylene glycol (average molecular weight 4000) 5 parts by weight Methyl ethyl ketone 90 parts by weight A varnish was produced by blending the above 6 types of compounds, and a 1 mm thick glass cloth was impregnated with this varnish and heated at 130°C. A prepreg was obtained by drying for 5 minutes.

Example 4 A prepreg was obtained in the same manner as in Example 3 except that 0.5 parts by weight of 1-cyanoethyl-2-7 enylimidazole in Example 3 was replaced by 83i parts of tetrabutylphosphonium bromide.

Comparative Example 1 A prepreg was obtained in the same manner as in Example 1, except that the polyethylene glycol (average molecular weight 4000) in Example 1 was not blended.

Comparative Example 2 A prepreg was obtained in the same manner as in Example 2 without blending the polyethylene glycol (average molecular weight 4000) in Example 6.

Table 1 shows the varnish formulations and drying conditions of Examples and Comparative Examples.

Prepreg 15 obtained in Examples 1 to 4 and Comparative Examples 1 and 2 above
A six-layer printed wiring board was manufactured by heat-forming at 170° C. for 60 minutes using six sheets of 35μ copper foil, and drilled. Drilling conditions are rotation speed 60.000rph, feed rate 3
．． 000 mrn/min, a hole diameter of 1.0φmm, and a stack of 2 sheets to a maximum of 12,000 bits.

Table 2 shows the results of the drill workability test of the 6-layer printed wiring board and the results of other characteristic tests.

As shown in Table 2, all six-layer wiring boards manufactured using prepreg containing polyethylene glycol had a smear rate less than half that of the comparative example, and the same was true for the amount of warpage. I can say that. When polyethylene glycol is used, the Tg is slightly lower and the Percoll hardness is almost the same, so it is thought that drill breakage and drill wear will be reduced even when a small diameter drill of 0.6φmm or less is used.

As for the curing accelerator, it can be seen that the imidazole compound used in Example 3 gives better results than the organic phosphorus compound used in Example 4.

〔Effect of the invention〕

Printed wiring boards using prepregs obtained from the In invention have less smear generation during drilling and less warpage.

Claims (1)

[Claims] 1. (a) epoxy resin, (b) polyfunctional phenol, (
c) curing accelerator, (d) polyethylene glycol and (
e) A method for producing a prepreg for printed wiring boards, which comprises impregnating glass cloth or glass nonwoven fabric with a varnish containing a solvent and then drying the impregnated glass cloth or glass nonwoven fabric. 2. The average molecular weight of polyethylene glycol is 200-1
0,000, and the blending amount is 0.2 to 20 parts by weight per 100 parts by weight of the epoxy resin. 3. Claim 1 or 2, characterized in that the curing accelerator is an imidazole compound, 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 producing prepreg for printed wiring boards.