JP2568347B2 - Copper clad laminate for printed circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-clad laminate for a printed circuit using an epoxy resin impregnated prepreg containing a large amount of an inorganic filler.

[0002]

2. Description of the Related Art In recent years, a copper-clad laminate for a printed circuit has a structure in which a glass non-woven fabric is used as an intermediate layer base material and a glass woven fabric is used as a surface layer base material. , Composite laminates) have been used in large quantities. Laminates made by impregnating only glass woven fabric with epoxy resin have excellent mechanical strength, dimensional stability, moisture resistance, heat resistance, and high reliability of through-hole plating, so computers, communication equipment, electronic exchanges, etc. Is widely used in industrial electronic devices. However, since only a glass woven fabric is used as a base material, punching cannot be performed in a drilling step, which is one of the processing steps of a printed circuit board, and drilling is a reality.

[0003] On the other hand, composite laminates are economically less expensive than glass woven substrate laminates and are superior in that they can be punched. It was evaluated that the reliability of the through-hole plating was lower than that of the glass woven fabric substrate laminate. For this reason, the weight ratio of the epoxy resin, which is an organic substance, and the glass woven cloth, which is an inorganic substance, is about 40:60 in the configuration of the glass woven fabric base epoxy laminate. In this case, it is considered that the epoxy resin mainly improves various electric performances, and the glass woven fabric improves mechanical performance such as bending strength and dimensional stability.

[0004] By the way, a general composite laminate has a smaller total amount of an inorganic base material, a glass woven fabric and a glass nonwoven fabric which contribute to mechanical performance than a glass woven laminate. Since the ratio of the organic substance to the inorganic substance was about 60:40, and the ratio was reversed to that of the glass woven laminate, it was evaluated that the dimensional stability and the reliability of through-hole plating were low. On the other hand, a method of impregnating a glass nonwoven fabric containing an inorganic filler with an epoxy resin in order to increase the ratio of inorganic substances is known (Japanese Patent Laid-Open No. 50-136377). Since the resin impregnating property is poor, the resulting composite laminate does not have sufficient water absorption and strength, and the adhesion of through-hole plating is not sufficiently improved.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have studied to improve these disadvantages while taking advantage of the excellent characteristics of the composite laminate. By adding a large amount of an inorganic filler to the resin varnish, the ratio of the inorganic substance was increased, and a novel composite laminate was obtained which could not be obtained by the conventional one.

[0006]

According to the present invention, the surface layer is made of woven epoxy resin glass, the intermediate layer is made of non-woven epoxy resin glass, and copper foil is laminated on one or both of the surface layers. In the copper-clad laminate integrated by heating and pressing, the intermediate layer contains 100 to 200 parts by weight of the inorganic filler based on 100 parts by weight of the epoxy resin of the intermediate layer, and the inorganic filler contains A copper-clad laminate for printed circuits, characterized by containing fine-particle silica.

As the inorganic filler used in the present invention, clay, talc, mica, silica powder, alumina, aluminum hydroxide, glass powder, titanium white, wollastonite, antimony trioxide and the like are used. As a preferred inorganic filler, a mixed powder of silica and / or alumina and aluminum hydroxide is used. Silica and alumina are effective in improving the heat resistance of the laminate, and aluminum hydroxide is effective in improving the heat resistance.

In order to uniformly disperse the inorganic filler in the epoxy resin without causing so-called self-standing, it is preferable that the filler has an average particle size of 5 to 10 μm and a maximum particle size of 40 μm or less. When the maximum particle size is larger than 40 μm or the average particle size is larger than 10 μm, the distribution of the inorganic filler in the glass nonwoven fabric of the laminate is due to the filtering action by the nonwoven fabric when the epoxy resin containing the inorganic filler is impregnated into the glass nonwoven fabric. Tend to be non-uniform. On the other hand, when the average particle diameter of the particles of the inorganic filler is smaller than 5μ, the fine particles of the inorganic filler are likely to be in this state as solidified,
Again, the distribution of the inorganic filler tends to be non-uniform. The amount of the inorganic filler is 10 per 100 parts by weight of the epoxy resin.
If the amount is less than 0 parts by weight, the compounding effect of the inorganic filler is small,
If the amount is more than 200 parts by weight, the impregnating property of the resin varnish into the glass nonwoven fabric is reduced.

Next, by adding ultrafine silica having an average particle size of 10 nm to 40 nm as a part of the inorganic filler, sedimentation of the inorganic filler in the epoxy resin varnish is prevented, and the glass nonwoven fabric is impregnated. It is effective to make the distribution of the inorganic filler uniform when it is made. Specific examples of such ultrafine silica include "Carplex" manufactured by Shionogi & Co., Ltd. and "AEROSIL" manufactured by Nippon Aerosil Co., Ltd. This amount is effective in the range of 0.5 to 15% by weight of the whole inorganic filler. If the amount is less than 0.5% by weight based on the total amount of the inorganic filler, the effect is almost negligible. It is particularly effective in the range of 2 to 10% by weight. In particular, when the ratio of the inorganic filler to 100 parts by weight of the epoxy resin is 150 parts by weight or more, if the amount of the solvent in the epoxy resin varnish is increased to reduce the viscosity, the inorganic filler is likely to settle, but This can be prevented by the presence of silica.

[0010]

The present invention will be described below with reference to examples. Formulations are by weight. Example 1 The composition of the epoxy resin varnish is as follows. (1) 100 parts of brominated epoxy resin (manufactured by Yuka Shell, EP-1046) (2) 4 parts of dicyandiamide (3) 0.15 part of 2-ethyl 4-methylimidazole (4) 36 parts of methyl cellosolve (5) 60 parts of acetone The above materials were mixed to produce a uniform varnish. Next, the varnish is made of a glass woven fabric (WE-18KBZ-2, manufactured by Nitto Bo).
Impregnated and dried so that the resin content becomes 42-45%,
A glass woven prepreg was obtained. Subsequently, an inorganic filler having the following composition was added to the epoxy resin varnish based on 100 parts of the resin component, and the mixture was stirred and mixed to prepare an inorganic filler-containing varnish. (1) 30 parts of silica (Crystallite VX-3, manufactured by Tatsumori) (2) 70 parts of aluminum hydroxide (manufactured by Showa Light Metal, Hijilite H-42) (3) Ultrafine powdered silica (manufactured by Shionogi Pharmaceutical, Carplex) 5 parts) The following inorganic filler-containing varnish was impregnated and dried in a glass nonwoven fabric (EP-4075, manufactured by Japan Vilene Co., Ltd.) so that the content of the resin and the inorganic filler was 90% by weight to obtain a glass nonwoven prepreg. . Next, the glass nonwoven fabric prepreg was used as an intermediate layer, and the glass woven fabric prepreg was disposed on the surface layer.
Laminate molding was performed at 90 ° C. and a pressure of 60 kg / cm ³ for 90 minutes to obtain a 1.6 mm-thick copper-clad laminate.

[Example 2] In Example 1, the mixing ratio of the inorganic filler to be added to the epoxy resin varnish was 100 parts by weight of the resin in the varnish. (1) 5 parts of silica (2) Aluminum hydroxide A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1 except that 95 parts (3) 5 parts of ultrafine powdered silica were used.

Comparative Example 1 A glass woven prepreg was obtained in the same manner as in the example. Subsequently, the epoxy resin varnish used in the examples was applied to a glass nonwoven fabric with a resin content of 70 to 75.
It was impregnated and dried to obtain a glass non-woven fabric prepreg so as to have a weight percent. Thereafter, a copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in the example. [Comparative Example 2] In Example 1, the mixing ratio of the inorganic filler to be added to the epoxy resin varnish was 100 parts by weight of the resin component in the varnish. (1) Silica 20 parts (2) Aluminum hydroxide 45 parts ( 3) 3.5 parts of ultrafine powdered silica, impregnated so that the content of resin and inorganic filler was 85% by weight, and dried to obtain a glass nonwoven fabric prepreg.
Thereafter, a copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1.

Comparative Example 3 In Example 1, the mixing ratio of the inorganic filler to be added to the epoxy resin varnish was 100 parts by weight of the resin in the varnish, (1) 70 parts of silica (2) aluminum hydroxide 170 parts (3) 10 parts of ultrafine silica powder, but the amount of the inorganic filler was too large to be sufficiently mixed. When mixing with increasing amount of solvent,
When impregnating the glass non-woven fabric, the inorganic filler did not impregnate the inside of the glass non-woven fabric, and a prepreg could not be obtained. Comparative Example 4 A woven glass prepreg was obtained in the same manner as in Example 1. Subsequently, the glass nonwoven fabric is made to contain an inorganic filler composed of aluminum hydroxide and silica (weight ratio 7: 3) in an amount three times that of the glass nonwoven fabric, and the epoxy resin varnish has a resin content of 45% by weight. And dried to obtain a glass nonwoven prepreg. Hereinafter, Example 1
1.6 mm thick copper-clad laminate was obtained in the same manner as described above. In Examples 1 and 2 and Comparative Examples 1, 2, and 4, the properties of the obtained copper-clad laminates are as shown in Tables 1 and 2. The measurement method is JIS except for heat resistance, shrinkage and punching property.
C6481.

[0014]

[Table 1]

[0015] The (1) initial dimensions and L _0, after removing the copper foils by etching, the size after heat treatment 0.99 ° C. 30 minutes and L _1, was calculated by the following equation. Heat shrinkage (%) = [(L ₀ −L ₁ ) / L ₀ ] × 100 (Note 2) After the copper foil is removed by etching, the thickness at room temperature is set to L _0, and heating is performed from room temperature to 240 ° C. 24
The thickness at 0 ℃ and L _1, was calculated by the following equation. Expansion coefficient (%) = [(L ₁ −L ₀ ) / L ₀ ] × 100

[0016]

[Table 2]

The method of measuring the adhesion of through-hole plating is as follows (see FIG. 1). A through hole (2) having a predetermined diameter is provided in the copper clad laminate (1) by drilling, and after performing through hole plating (3), the copper foil on the surface is removed. Next, a 0.6 mmφ nickel silver wire (4) is fixed in the through hole with solder (5). The nickel-white wire (4) is drawn in the direction A, and the drawing strength is measured.

[0018]

As described above, since the present invention has a constitution containing a large amount of an inorganic filler, a conventional product (comparative example) is used.
It can be seen that the adhesion of the through-hole plating is superior to that of the above, and the reliability of the through-hole plating is improved. In addition to the above, in general characteristics, the water absorption ratio, the shrinkage ratio, and the like are improved, and the electric characteristics are almost the same or higher. The mixing ratio of the inorganic filler to 100 parts by weight of the epoxy resin was
It was confirmed that the adhesion of through-hole plating was excellent as in the case of Example 1 and Example 2 even when the content was 200 parts by weight.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a method for measuring the adhesion of through-hole plating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copper-clad laminate 2 Through-hole 3 Through-hole plating 4 Western wire 5 Solder

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-136377 (JP, A) JP-A-60-7796 (JP, A) JP-A-56-59837 (JP, A) 195117 (JP, A)

Claims (1)

(57) [Claims] The surface layer is made of a woven epoxy resin glass fabric, the intermediate layer is made of an epoxy resin glass nonwoven fabric, and copper foil is laminated on one or both of the surface layer surfaces, and these are integrated by heating and pressing. In the copper clad laminate, the intermediate layer contains 100 to 200 parts by weight of the inorganic filler based on 100 parts by weight of the epoxy resin of the intermediate layer, and the inorganic filler has an average particle size of 10 nm to 40 nm. A copper-clad laminate for printed circuits, characterized by containing ultrafine silica.