JPH04198231A - Prepreg for printed wiring board and production of copper-clad laminate - Google Patents

Abstract

PURPOSE:To obtain the title prepreg improved in drillability, resistance to thermal discoloration, storage stability and heat resistance by impregnating a (non)woven glass cloth with a specified varnish and drying the cloth. CONSTITUTION:A varnish is obtained by mixing 100 pts.wt. epoxy resin containing 1-100wt.% glycidyl ether of a polycondensate (maximum molecular weight of 10000 or below) between bisphenol A or bisphenol F and formaldehyde with 1-100 pts.wt. polycondensate (maximum molecular weight of 1000 or below) between bisphenol A and formaldehyde, 0.01-5 pts.wt. cure accelerator and a solvent. The varnish is optionally aged by heating under agitation at 50-70 deg.C for at least 1hr and cooled to room temperature. A (non)woven glass cloth is impregnated with the cooled varnish and dried at 80-200 deg.C to obtain the title prepreg.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to printing, which is a material for printed wiring boards, which has excellent heat resistance such as delamination due to thermal shock and glass transition temperature (hereinafter abbreviated as Tg). The present invention relates to a prepreg for wiring boards and a method for manufacturing a copper-clad laminate using the prepreg.

[Prior Art] With the increasing density of printed wiring boards, the laminates or copper-clad laminates used as these materials are required to have various excellent properties. In particular, as the number of layers becomes higher and the diameter of through holes becomes smaller, prepregs for printed wiring boards and metal-clad laminates obtained using prepregs with good drillability are required.

Among drillability problems, smearing is caused by preventing conduction between the inner layer circuit copper and the through-hole plating copper.
Through-hole reliability is significantly impaired.

Printed wiring board manufacturers carry out smear removal treatment to remove smear, but it uses concentrated sulfuric acid, hydrofluoric acid, etc., which poses safety issues, and can also damage the inner walls of through-holes, reducing reliability. Become. The cause of smear is that the resin softened by the frictional heat during drilling adheres to the cross section of the inner layer circuit copper due to the drilling.

Dicyandiamide, which has been conventionally used as a curing agent for epoxy glass fabric prepregs, has poor compatibility with resins and often remains unreacted. Therefore, the resin cured product is 2
At temperatures above 50° C., the resin decomposes and softens. In order to prevent such softening of the cured product, a curing agent that is sufficiently compatible with the epoxy resin and has good reactivity is required. Further, the epoxy resin is also required to be heat resistant and have good reactivity.

As a device that satisfies these requirements, Japanese Patent Application Laid-open No. 63-366
As shown in Publication No. 21, there is a method using an epoxy resin containing a diglycidyl ether of a polycondensate of bisphenol A or bisphenol F and formaldehyde, and a polycondensate of bisphenol A and formaldehyde as a curing agent. .

[Problems to be Solved by the Invention] The method disclosed in JP-A-68-36621 solves the problem of drill workability, which is a drawback of conventional epoxy resin-dicyandiamide systems, and heat discoloration, which is a drawback of epoxy resin-polyphenol systems. Although storage stability is improved, uneven coating is likely to occur in the prepreg manufactured during the process of impregnating glass cloth with varnish and drying, and this uneven coating reduces formability during lamination. There was a problem that the heat resistance of the laminate also decreased.

The present invention has been made to solve the above problems.
The object of the present invention is to provide a method for manufacturing a prepreg for printed wiring boards that has excellent drill workability, heat discoloration properties, and storage stability as well as excellent heat resistance.

[Means for Solving the Problems] As a result of intensive studies on the occurrence of uneven coating described above, the present inventors have found that the main cause of uneven coating is the molecular weight 1 contained in the epoxy resin and curing agent used as raw materials.
We believe that this is due to ultra-high molecular weight substances of about 0,000 to 25,000, and by using an epoxy resin and curing agent that does not contain these ultra-high molecular weight substances and has a maximum molecular weight of 10.000 or less, uneven coating can occur. It is possible to obtain a prepreg with a good appearance and a laminate with good heat resistance without any varnish, and it has been discovered that the improvement can be further improved by aging the varnish, and based on this knowledge, the present invention has been completed. .

That is, the present invention comprises (a) an epoxy resin containing 1 to 100% by weight of a glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F and formaldehyde, (b) a polycondensate of bisphenol A and formaldehyde, (C ) A method for manufacturing a prepreg for a printed wiring board, which comprises impregnating a glass cloth or glass nonwoven fabric with a varnish containing a curing accelerator and (d) a solvent as essential components, and then drying the resulting prepreg, in which the bisphenol A or bisphenol F and formaldehyde are combined. This invention provides a method for producing a prepreg for a printed wiring board, characterized in that the maximum molecular weight of the glycidyl etherified product of the polycondensate and the polycondensate of bisphenol A or bisphenol F and formaldehyde is 10,00 or less. .

In the present invention, the maximum molecular weight of the epoxy resin and curing agent is measured using known polystyrene in pattern analysis by, for example, high performance liquid chromatography (TRIROTARVl, column manufactured by JASCO Corporation; gel column Hitachi Gelco 410 manufactured by Hitachi Chemical Co., Ltd.). This was carried out by molecular weight distribution measurement.

The epoxy resin (a) contains, as an essential component, 1 to 100% by weight, preferably 50 to 100% by weight, of a glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F and formaldehyde, and this glycidyl etherified product The molecular weight used is one having a molecular weight of 10,000 or less, preferably 8.000 or less.

If a varnish with a molecular weight exceeding 10,000 is used, the surface tension of the varnish will be high, and the permeability will deteriorate when impregnated into glass cloth or glass nonwoven fabric, making it likely that uneven coating will occur on the surface during the drying process. Become.

There are no restrictions on the type of epoxy resin used as a component other than the above, but in order to prevent uneven coating of the prepreg, it is desirable to use one with a molecular weight of 10,000 or less. Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, alicyclic epoxy resin, glycidyl ester epoxy resin, and glycidyl amine. Examples include epoxy resins, hydantoin epoxy resins, isocyanate epoxy resins, and their halides and hydrogenated products, and several types can be used in combination. Furthermore, there are no restrictions on the method or temperature for mixing these epoxy resins.

When flame retardation is required for the produced prepreg, a halide is required in addition to the glycidyl etherified product of the polycondensate of bisphenol A or bisphenol F and formaldehyde, which are essential components.

In addition, it is necessary to make the produced prepreg flame retardant, and in addition, the glycidyl etherified product of the polycondensate of bisphenol A or bisphenol F, which is an essential component of the epoxy resin (a), and formaldehyde is used as the epoxy resin 1.
If the halogenated epoxy resin contains 80 parts by weight or more of 00 parts by weight, sufficient flame retardance cannot be obtained with the halogenated epoxy resin alone, and generally refractory materials such as tetrabromobisphenol A1 decabromodiphenyl ether, antimony trioxide, and tetraphenylphosphine are used. It is preferable to include a compound called a refueling agent. In order to maintain the properties of prepreg for printed wiring boards, the amount of flame retardants other than halogenated epoxy resin should be kept to a minimum, and at most 30 parts by weight or less per 100 parts by weight of epoxy resin. It is desirable that there be.

In addition, when ordinary phenolic resin is used as a curing agent for epoxy resin, there is a problem of heat discoloration of the cured product.
In the present invention, there is no problem because a polycondensate of bisphenol A and formaldehyde is used.

Regarding the molecular weight of the polycondensate of bisphenol A and formaldehyde in (b), the molecular weight is 10,000 or less, preferably 8,000 or less, similar to the glycidyl etherified product of the polycondensate of bisphenol A or bisphenol F and formaldehyde. use something Moreover, bisphenol A monomer may be included. Although there is no restriction on the amount to be added, it is preferably 1 to 100 parts by weight per 100 parts by weight of the epoxy resin.

Furthermore, a phenol novolak resin may be used in combination within a range that does not impair the effects of the present invention.

As the curing accelerator (c), imidazole compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, etc. are used. These imidazole compounds include:
imidazole, 2-ethylimidazole, 2-ethyl-
4-methylimidazole, 2-phenylimidazole,
2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecyl imidazole, 4,
5-diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidacilline, 2-phenylimidazoline, 2-undecylimidacilline, 2-heptadecylimidacilline, 2-isopropylimidazole, 2,4 -dimethylimidazole, 2-phenyl-4-
Examples include methylimidazole, 2-ethylimidacilline, 2-isopropylimidacilline, 2,4-dimethylimidacillin, 2-phenyl-4-methylimidacillin.

Several types of these curing accelerators may be used in combination, and the blending amount is preferably 0.000 parts by weight per 100 parts by weight of the epoxy resin.
01 to 5 parts by weight. If it is less than 0.01 parts by weight, the effect will be small, and if it is more than 5 parts by weight, there will be no storage stability.

The solvent for (d) is acetone, methyl ethyl ketone,
Toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether (methyl cellosolve), acetic acid cellosolve, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, etc. They may be used in combination.

Moreover, the above (a), (b), (c), and (d) are essential components, and it is also possible to mix other compounds used in prepreg varnishes.

After impregnating glass cloth or glass nonwoven fabric with the varnish obtained by blending the above (a), (b), (c), and ((1)), dry it in a drying oven at a temperature of 80 to 200°C to prevent uneven coating. There is no
To obtain a prepreg for a printed wiring board with a good appearance.

In addition, before impregnating glass cloth or glass nonwoven fabric,
By using a varnish that has been aged by heating and stirring at 70° C., preferably 50 to 60° C., for 1 hour or more and then cooled to room temperature, the appearance of the prepreg becomes even better.

A copper-clad laminate can be manufactured by stacking prepregs, then stacking copper foil on one or both sides of the prepregs, and heating and press-molding the prepregs. Furthermore, a printed wiring board can be made by processing a circuit on a laminated board produced by stacking prepregs, heating and press-molding them.

[Example] Examples of the present invention will be described below.

Example 1 Ebicuron N-865 (bisphenol A novolac type epoxy resin, maximum molecular weight s, ooo ~ 10,000 adjusted product, Dainippon Ink ■
Product name) 100 parts by weight Bryophen LF346 (Bisphenol A novolac resin, maximum molecular weight s, o
oo ~ 10,000 adjusted product, product name manufactured by Dainippon Ink)
30 parts by weight Fireguard 2000 (tetrabromobisphenol A1 Teidai Kasei product name) 45 parts by weight Curazole CIIZ (imidazole, Shikoku Kasei Product name) 0.30 parts by weight Ethylene glycol monomethyl ether (methyl cellosolve) 30 parts by weight 50 parts by weight of methyl ethyl ketone 0.2 mm of this varnish
A thick glass cloth was impregnated and dried at 150° C. for 5 minutes to obtain a prepreg.

Example 2 Epicron N-865 (bisphenol A novolac type epoxy resin, maximum molecular weight adjusted product from 8,000 to 10,000, Dainippon Ink ■
Product name) 100 parts by weight Pryophen LF346 (Bisphenol A novolak resin, maximum molecular weight 8.0
00~10,000 adjustment product, product name manufactured by Dainippon Ink)
30 parts by weight Fire Guard 2000 (Tetrabromobisphenol A1 Teijin Kasei brand name) 45 parts by weight Cure Sol C! IZ (Imidazole, Shikoku Kasei Kogyo ■ Split product name) 0.30 parts by weight Ethylene glycol monomethyl ether (methyl cellosolve) 30 parts by weight Methyl ethyl ketone 50 parts by weight This varnish was heated to 60'C.
After aging for a period of time, a 0.2 mm thick glass cloth was impregnated and dried at 150° C. for 5 minutes to obtain a prepreg.

Example 3 Epicron N-865 (bisphenol A novolac type epoxy resin, maximum molecular weight s, ooo ~ 10,000 adjusted product, Dainippon Ink ■
Product name) 100 parts by weight Bryophen LF346 (Bisphenol A novolac resin, maximum molecular weight 8.0
00~10,000 adjustment product, product name manufactured by Dainippon Ink)
30 parts by weight Fireguard 2000 (tetrabromobisphenol A, trade name manufactured by Teijin Chemicals) 45 parts by weight Curazole CtiZ (imidazole, part name manufactured by Shikoku Kasei Corporation) 0.30 parts by weight Cellosolve acetate 30 parts by weight Methyl ethyl ketone 50 parts by weight A 0.2 mm thick glass cloth was impregnated with the varnish and dried at 150° C. for 5 minutes to obtain a prepreg.

Example 4 Epicron N-865 (Bisphenol A novolac type epoxy resin, maximum molecular weight N8,000-10,000i1, product name manufactured by Dainippon Ink) 100 parts by weight Bryophen LF346 (Bisphenol A novolac resin, maximum molecular weight 8 .0
00~10,000 adjustment product, product name manufactured by Dainippon Ink)
30 parts by weight Fireguard 2000 (tetrabromobisphenol A1 manufactured by Teijin Kasei ■ trade name) 47 parts by weight Curazole Cs 1Z (imidazole, manufactured by Shikoku Kasei ■ part name) 0.30 parts by weight Cellosolve acetate 30 parts by weight Methyl ethyl ketone 50 parts by weight After aging the varnish for 1 hour at 60'C. A 2 mm thick glass cloth was impregnated and dried at 150'C for 5 minutes to obtain a prepreg.

Comparative Example 1 Epicron N-865 (Bisphenol A novolac type epoxy resin 1, maximum molecular weight 25,000 adjusted product, product name manufactured by Dainippon Ink ■)
100 parts by weight Pryophen LF346 (bisphenol A novolac resin, maximum molecular weight 20.
000 adjusted product, product name manufactured by Dainippon Ink ■) 30 parts by weight Fireguard 2000 (tetrabromobisphenol A1 product name manufactured by Teijin Chemicals ■) 45 parts by weight Curazole CIIZ (imidazole, product name manufactured by Shikoku Kasei ■) 0.30 parts by weight 30 parts by weight of ethylene glycol monomethyl ether (methyl cellosolve) 50 parts by weight of methyl ethyl ketone A 0.2 mm thick glass cloth was impregnated with this varnish and dried at 150° C. for 5 minutes to obtain a prepreg.

Comparative Example 2 Epicron N-865 (Bisphenol A novolac type epoxy resin 1, maximum molecular weight 25,000 adjusted product, product name manufactured by Dainippon Ink ■)
100 parts by weight Pryophen LF346 (bisphenol A novolac resin, maximum molecular weight 20.
000 adjusted product, Dainippon Ink ■Product name) 30 parts by weight Fireguard 2000 (Tetrabromobisphenol A1 Teijin Kasei ■Product name) 45 parts by weight Curazole C, + Z (Imidazole, Shikoku Kasei ■Part name) 0 .30 parts by weight Ethylene glycol monomethyl ether (methyl cellosolve) 30 parts by weight Methyl ethyl ketone 50 parts by weight
After aging for 0. A 2 mm thick glass cloth was impregnated and dried at 1500C for 5 minutes to obtain a prepreg.

The prepregs obtained in Examples 1 to 4 and Comparative Examples 1 to 2 above were
The sheets were stacked, 18 μm copper foil was placed on the surface, and heated and pressed at 175° C. for 90 minutes to produce a double-sided copper-clad laminate.

In addition, 17 sheets were prepared using 15 sheets of prepreg and 6 sheets of 35μ copper foil.
The material was heated and pressed at 5° C. for 90 minutes to produce a 6-layer printed wiring board, which was then drilled. Drilling conditions are rotation speed 60. OOO
rpm, feed rate 2,400 mm/min, hole diameter φ1.
Omm, holes were drilled up to 10°000 with two stacked sheets.

Prepreg, double-sided copper-clad laminate and 6 obtained as above
Various properties of the layer printed wiring board are shown in Tables 1 to 3.

(Left space below) Table 1 shows the properties of the prepreg and laminate, Table 2 shows the properties of the double-sided copper-clad laminate, and Table 3 shows the properties of the 6-layer printed wiring board. As shown here, the maximum molecular weight is 10,00
It can be seen that when an epoxy resin of 0 or less is used, uneven coating of the prepreg is reduced compared to when an epoxy resin of 25,000 or less is used, and the appearance of the prepreg is improved by pre-aging the varnish. .

Moreover, as a result, the appearance of the copper-clad laminate also became good, and it can be seen that the solder heat resistance after moisture absorption treatment was improved.

Furthermore, Tg is 7 to 10°C higher. in this way,
The effects of limiting the molecular weight of epoxy resins and aging of varnishes are obvious.

In addition, when comparing the characteristics of 6-layer printed wiring boards, drill workability,
It can be seen that Examples 1 to 4 are equivalent to or higher than Comparative Examples 1 to 2 in terms of Tg, thermal discoloration property, and solder heat resistance after moisture absorption treatment.

[Effects of the invention] The prepreg for printed wiring boards obtained by the present invention has a much better appearance in terms of uneven coating than those obtained by the conventional technique, and as a result, by using it, heat resistance can be improved. A significantly superior copper-clad laminate and printed wiring board can be obtained.

Claims (3)

[Claims] 1. (a) an epoxy resin containing 1 to 100% by weight of a glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F and formaldehyde, (b) a polycondensate of bisphenol A and formaldehyde, (c) a curing accelerator, and ( d) A method for producing prepreg for printed wiring boards, which is produced by impregnating a glass cloth or glass nonwoven fabric with a varnish containing a solvent as an essential component and then drying the glycidyl polycondensate of bisphenol A or bisphenol F and formaldehyde. A method for producing a prepreg for a printed wiring board, characterized in that the maximum molecular weight of the etherified product and the polycondensate of bisphenol A or bisphenol F and formaldehyde is 10,000 or less. 2. 2. The method for producing a prepreg for a printed wiring board according to claim 1, wherein a glass cloth or a glass nonwoven fabric is impregnated with a varnish that has been aged at 50 to 60[deg.] C. for 1 to 2 hours after blending the essential components. 3. A method for producing a copper-clad laminate, which comprises stacking printed wiring board prepregs obtained by the production method according to claim 1 or 2, and then stacking copper foil on one or both sides of the prepregs, followed by heating and pressure forming.