JP3047593B2 - Method for producing prepreg for printed wiring board and copper-clad laminate containing metal core using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a delamination or the glass transition point due to thermal shock (hereinafter referred to as Tg) process for producing the material and a printed wiring board prepreg of the printed wiring board and which is excellent in heat resistance such as The present invention relates to a copper-clad laminate containing a metal core using the same .

[0002]

2. Description of the Related Art With the increase in density of printed wiring boards, various characteristics are required for laminates or copper-clad laminates used as this material. In particular, since the number of layers is increased and the diameter of the through hole is reduced, a laminate having good drill workability is required.

[0003] Smear is one of the defects generated during drilling. When the smear occurs, conduction between the inner layer circuit and the through-hole plated copper is hindered, and the reliability of the through-hole is significantly impaired. In order to remove the smear, it must be treated with concentrated sulfuric acid, hydrofluoric acid, or the like, which is a safety problem and also causes the inner wall of the through-hole to be roughened, thereby reducing reliability.

The cause of the smear is that the resin softened by frictional heat during drilling adheres to the copper cross section of the inner layer circuit by the drill. Dicyandiamide, which has been conventionally used as a curing agent for epoxy-glass cloth prepreg, has poor compatibility with resins and often remains unreacted.
Therefore, at a temperature of 250 ° C. or higher, the cured resin softens with decomposition. In order to prevent such softening of the resin, a curing agent which is sufficiently compatible with the epoxy resin and has high reactivity is required. Also, epoxy resins that have heat resistance and good reactivity are required.

In order to satisfy these requirements, an epoxy resin containing a diglycidyl etherified product of bisphenol A or bisphenol F and formaldehyde and a method using a polycondensate of bisphenol A and formaldehyde as a curing agent have been proposed. Yes ( Japanese Patent Laid-Open No. 60-
No. 260627 ).

[0006]

THE INVENTION Problems to be Solved] JP was the 60-
The method disclosed in Japanese Patent No. 260627 improves the drilling processability, which is a drawback of the conventional epoxy resin-dicyandiamide system, the heat discoloration property, the storage stability, which is the drawback of the epoxy resin-polyphenol system, and also has excellent heat resistance. It is a method of providing a material.

[0007] Recently, there has been an increasing demand for laminated plates with metal cores for use in multichip modules. However, in a metal-filled laminated plate obtained by laminating a prepreg manufactured by the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-260627 together with a metal core, a hole in the metal core is formed by drilling or subsequent soldering. Cracks are apt to occur in the resin in which the resin is filled, which causes a significant reduction in reliability.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above-mentioned cracks, and as a result, by adding a glass filler to the varnish , the resin filled in the hole of the metal core was filled. It has been found that there is a remarkable effect on preventing cracks from occurring.

That is, the present invention relates to (a) an epoxy resin which contains a polycondensate of bisphenol A or bisphenol F and formaldehyde and has a maximum molecular weight of 10,000 or less and a glycidyl etherified product of 1 to 100% by weight;
(B) a polycondensate of bisphenol A or bisphenol F with formaldehyde having a maximum molecular weight of 10.0
A printed wiring, characterized by impregnating a glass cloth or glass nonwoven fabric with a varnish containing a polycondensate of not more than 00, (c) a curing accelerator, (d) a glass filler, and (e) a solvent as essential components, and drying. This is a method for producing a prepreg for a plate.

In the present invention, the measurement of the maximum molecular weight of the epoxy resin and the curing agent was carried out, for example, by a molecular weight distribution measurement using known polystyrene in pattern analysis by high performance liquid chromatography.

The epoxy resin (a) is a glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F and formaldehyde as an essential component, and has a maximum molecular weight of 10,000 and other epoxy resins. No problem.

However, with regard to the glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F and formaldehyde, the effect expected in the present invention cannot be obtained if there are many components having a molecular weight of 10,000 or more. When there are many components having a molecular weight of 10,000 or more, the surface tension of the varnish becomes high, the permeability deteriorates when impregnating the glass cloth or the glass nonwoven fabric, and the surface is liable to be coated during the drying process.

There is no particular limitation on the type of epoxy resin used as a component other than the above, but in order to suppress the occurrence of uneven coating of the prepreg, the molecular weight must be 10,000.
It is desirable to use: Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, alicyclic epoxy resin, glycidyl ester epoxy resin, and glycidylamine. Type epoxy resin, hydantoin type epoxy resin, isocyanate type epoxy resin, and halides and hydrogenated products thereof, and some of them may be used in combination.

The method and temperature for mixing these epoxy resins are not limited. If required flame retarded the produced prepreg, in addition to the bisphenol A or of polycondensates of glycidyl ethers of bisphenol F with formaldehyde which is an essential component, it is necessary to halide .

The prepreg thus produced must be flame-retardant, and the glycidyl etherified product of a polycondensate of bisphenol A or bisphenol F with formaldehyde, which is an essential component of the epoxy resin (a), is prepared using an epoxy resin 100. When the content is more than 80 parts by weight, sufficient flame retardancy cannot be obtained only with the halogenated epoxy resin. It is desirable to incorporate the compounds referred to.

However, in order to maintain the properties as a prepreg for a printed wiring board, the amount of the flame retardant other than the halogenated epoxy resin should be minimized, and at most 100 parts by weight of the epoxy resin. It is desirable that the amount be 30 parts by weight or less.

Further, when a normal phenol resin is used as a curing agent for the epoxy resin, there is a problem of heat discoloration of the cured product. However, in the present invention, a polycondensate of bisphenol A and formaldehyde is used. No problem.

With respect to the molecular weight of the polycondensate of bisphenol A and formaldehyde in (b), the molecular weight is 1 as in the case of the glycidyl etherified product of bisphenol A or bisphenol F and formaldehyde.
Those having a molecular weight of 000 or less, preferably 8,000 or less are used. Further, a bisphenol A monomer may be contained. The amount is not limited, but is preferably 1 to 100 parts by weight based on 100 parts by weight of the epoxy resin. Further, a phenol novolak resin may be used in combination as long as the effects of the present invention are not impaired.

As the curing accelerator (c), an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt or the like is used. These imidazole compounds include imidazole, 2-ethylimidazole,
-Ethyl-4-methylimidazole, 2-phenylimidazole , 4 -undecylimidazole, 2-ethyl-
4-methylimidazole , 2 -undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-phenyl Imidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2
- isopropyl imidazole, 2,4-dimethylimidazole, 2-phenyl-4 - methylimidazole, 2-imidazoline, 2-isopropyl imidazoline,
Examples include 2,4 dimethyl imidazoline and 2-phenyl-4 methyl imidazoline. Some of these curing accelerators may be used in combination, and the amount is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the epoxy resin. 0.
If the amount is less than 01 parts by weight, the curing is small, and if it is more than 5 parts by weight, there is no storage stability.

As the glass filler (d), those having an average particle diameter of 10 μm or less, which are generally used as a filler, are used.

As the solvent (e), acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether (methyl cellosolve), cellosolve acetate, N, N
-Dimethylformamide, N, N-dimethylacetamide, methanol, ethanol and the like, and any of these may be used in combination.

The above (a), (b), (c), (d),
After impregnation varnish obtained by blending the (e) a glass cloth or glass nonwoven fabric, and Drying in a drying oven, no uneven coating, to obtain a good appearance for printed wiring board Puripufuregu. Further, by using a varnish cooled and heated to room temperature after heating and stirring at 50 to 70 ° C., preferably 50 to 60 ° C. for 1 hour or more before impregnating the glass cloth or nonwoven fabric, the appearance of the prepreg can be further improved. It will be good.

A prepreg is laminated, a metal core such as an aluminum plate is sandwiched between the prepregs if necessary, and then a copper foil is laminated on one or both sides thereof and heated and pressed to produce a copper-clad laminate. Further, the prepregs are superposed, heated and pressed to form a circuit board on a laminated board, thereby producing a printed wiring board.

[0024]

【Example】

Example 1 Bisphenol A novolak type epoxy resin, adjusted to a maximum molecular weight of 8,000, 100 parts by weight, bisphenol A
Novolak resin, adjusted to a maximum molecular weight of 8,000, 30 parts by weight, tetrabromobisphenol A, 45 parts by weight, 2
-Undecyl imidazole, 0.30 parts by weight, glass filler (average particle size: 3 µm), 20 parts by weight, ethylene glycol monomethyl ether (methyl cellosolve), 30
By weight, methyl ethyl ketone and 50 parts by weight were mixed to form a varnish. This varnish was aged at 60 ° C. for 1 hour, and then impregnated in a glass cloth having a thickness of 0.1 mm.
Dried for minutes to prepare a prepreg.

Example 2 Bisphenol A novolak type epoxy resin, adjusted to a maximum molecular weight of 8,000, 100 parts by weight, bisphenol A
Novolak resin, adjusted to a maximum molecular weight of 8,000, 30 parts by weight, tetrabromobisphenol A, 45 parts by weight, 2
A varnish was prepared by mixing 0.30 parts by weight of undecyl imidazole, 30 parts by weight of a glass filler (average particle size: 3 μm), 30 parts by weight of ethylene glycol monomethyl ether (methyl cellosolve), and 50 parts by weight of methyl ethyl ketone. After aging this varnish at 60 ° C. for 1 hour,
Impregnate and impregnate 0.1 mm thick glass cloth,
Dried for minutes to prepare a prepreg.

Example 3 Bisphenol A novolak type epoxy resin, adjusted to a maximum molecular weight of 8,000, 100 parts by weight, bisphenol A
Novolak resin, adjusted to a maximum molecular weight of 8,000, 30 parts by weight, tetrabromobisphenol A, 45 parts by weight, 2
A varnish was prepared by mixing 0.30 parts by weight of undecyl imidazole, 30 parts by weight of a glass filler (average particle size: 3 μm), 30 parts by weight of cellosolve acetate, and 50 parts by weight of methyl ethyl ketone. The varnish was aged at 60 ° C. for 1 hour, then impregnated in a glass cloth having a thickness of 0.1 mm, and dried at 150 ° C. for 5 minutes to obtain a prepreg.

Comparative Example 1 Bisphenol A novolak type epoxy resin, adjusted to a maximum molecular weight of 8,000 to 10,000, 100 parts by weight, bisphenol A novolak resin, a maximum molecular weight of 8,000
30 parts by weight, 10,000 parts by weight, tetrabromobisphenol A, 45 parts by weight, 0.30 parts by weight of 2-undecylimidazole, 30 parts by weight of ethylene glycol monomethyl ether (methyl cellosolve), 50 parts by weight of methyl ethyl ketone To make a varnish. The varnish was aged at 60 ° C. for 1 hour, then impregnated in a glass cloth having a thickness of 0.1 mm, and dried at 150 ° C. for 5 minutes to obtain a prepreg.

Comparative Example 2 Bisphenol A novolak type epoxy resin, adjusted to a maximum molecular weight of 8,000 to 10,000, 100 parts by weight, bisphenol A novolak resin, a maximum molecular weight of 8,000
A varnish was prepared by mixing 10,000 to 30,000 parts by weight, tetrabromobisphenol A, 45 parts by weight, imidazole, 0.30 parts by weight, cellosolve acetate, 30 parts by weight, methyl ethyl ketone, and 50 parts by weight. The varnish was aged at 60 ° C. for 1 hour, then impregnated in a glass cloth having a thickness of 0.1 mm, and dried at 150 for 5 minutes to obtain a prepreg.

Using the prepregs obtained in Examples 1 to 3 and Comparative Examples 1 and 2, a 0.5 mm-thick aluminum plate drilled with a 2.0 mm diameter drill (100 holes) was sandwiched.
An 18 μm-thick copper foil was placed on both sides and heated and pressed at 175 ° C. for 90 minutes to obtain an aluminum core-containing double-sided copper-clad laminate.

The aluminum core-containing double-sided copper-clad laminate was concentrically drilled at the center of the hole in the aluminum core with a drill having a diameter of 1.0 mm. This through-hole is plated by electrolytic plating, cut into samples of a predetermined size, dipped in a solder bath at 260 ° C. for 10 seconds and 20 seconds, and cracks generated in the through-holes are removed for every sample. Observed from horizontal and vertical directions.

Further, eight prepregs were stacked, a copper foil having a thickness of 18 μm was placed on the surface, and heated and pressed at 175 ° C. for 90 minutes.
A double-sided copper-clad laminate was used. The appearance, glass transition temperature (Tg), and solder heat resistance after the moisture absorption treatment of this double-sided copper-clad laminate were evaluated. The evaluation results are shown in Tables 1 and 2. Table 1 shows the occurrence of cracks in the aluminum core-containing double-sided copper-clad laminate, and Table 2 shows the evaluation results of the double-sided copper-clad laminate.

As shown here, it can be seen that the addition of the glass filler to the varnish significantly reduces the occurrence of cracks after drilling and solder dip.
In addition, it can be seen that the double-sided copper-clad laminate obtained from this prepreg has no change in appearance, no decrease in Tg, and no deterioration in heat resistance.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

The laminate obtained by using the prepreg for a printed wiring board obtained according to the present invention has excellent heat resistance, and the copper-clad laminate containing a metal core is obtained by the prior art. In comparison with the above, in the hole filling portion of the metal core, the occurrence of cracks during drilling and after soldering is significantly reduced.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 63/02 C08L 63/02 H05K 1/03 610 H05K 1/03 610G (56) References JP-A-60-260627 (JP, A) JP-A-1-150543 (JP, A) JP-A-2-39930 (JP, A) JP-A-63-77195 (JP, A) JP-A-61-12874 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) C08J 5/24 B32B 15/08 C08G 59/18 C08K 7/20 C08L 61/12 C08L 63/02

Claims (5)

(57) [Claims] 1. An epoxy resin containing (a) a polycondensate of bisphenol A or bisphenol F and formaldehyde and having a maximum molecular weight of 10,000 or less, and (b) bisphenol A or bisphenol F and formaldehyde. A varnish containing, as essential components, a polycondensate having a maximum molecular weight of 10,000 or less, a (c) curing accelerator, (d) a glass filler and a (e) solvent as a glass cloth or glass nonwoven fabric A method for producing a prepreg for a printed wiring board, wherein the prepreg is impregnated and dried. 2. The method for producing a prepreg for a printed wiring board according to claim 1, wherein the glass filler has an average particle size of 10 μm or less. 3. The method for producing a prepreg for a printed wiring board according to claim 1, wherein the compounding amount of the glass filler is 1 to 30% by weight based on the resin solid content of the varnish. 4. After mixing the essential components, at a temperature of 50 to 60.degree.
Claim 1, 2 or 3 manufacturing method of printing wiring board prepreg according impregnating time aged varnish glass cloth or glass nonwoven fabric. 5. The method according to claim 1, wherein:
Sandwich the metal core between the printed circuit board prepregs
In one or both sides, layer copper foil and heat and press mold
The resulting copper-clad laminate with a metal core.