JPH0356583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate, and its purpose is to provide a laminate that has excellent mechanical strength and exhibits small dimensional changes during temperature and humidity treatments. Conventionally, in the industrial field, glass cloth base materials, paper-based epoxy resin or phenolic resin laminates, and copper-clad laminates have been used for printed wiring boards for consumer electronic devices and insulating boards for electronic components. . In recent years, demands for smaller and lighter electronic devices have required higher density, finer, and multilayer circuits for printed wiring boards, and there has been a trend toward thinner laminates. However, in the case of paper-based laminates and copper-clad laminates, the X, Y, and Z axes (=horizontal,
It lacks dimensional stability in the longitudinal and thickness directions, and is prone to warping and twisting.In addition, when the plate thickness is thinned, the mechanical strength decreases, and warping and twisting become larger during processing and final assembly processes. There was a drawback that became a major problem for automation. In order to solve these problems, we have modified the resin used in various ways, pre-treated the base paper, or changed its composition, dispersed inorganic powders in the base paper or resin, etc. The problem is being dealt with by using laminates. However, no material has been found that satisfies all of the dimensional stability, mechanical strength, lightness (specific gravity), low-temperature punching workability, cost, etc. of a laminate. In view of these points, the present inventors have earnestly pursued the effect of improving dimensional stability by compositing the base paper base material used, and have found that dimensional stability can be greatly improved by compositing between specific fibers. . The present invention provides a laminate in which the base material is impregnated with a thermosetting resin for laminates and dried prepreg is heated and laminated, and the amount of glass fiber as the base material is 3 to 3.
It is a thermosetting resin laminate with good dimensional stability characterized by using cellulose fiber base paper with a density of 0.3 to 0.6 g/cm ³ mixed with 20% by weight. It is a filament-like fiber with a fiber diameter of 6 to 13 μm and a length of 3 to 20 mm. It is also a one-sided or double-sided copper glass made by pasting copper foil on the surface of a laminate. The stretched thermosetting resin laminate is characterized in that a prepreg using at least one glass fiber-mixed cellulose fiber base paper is arranged in the layer directly below the copper foil. That is, it is characterized by using, for example, mixed paper made from cotton linter pulp as a raw material and made by uniformly dispersing and defibrating specific glass fibers in the process of making linter base paper for laminate boards. In this case, there is no need for a special binder, and the glass fibers are moderately mixed in the gaps between the base paper fiber micelles, which makes it strong and creates a rigid network structure, making it possible to suppress dimensional changes to a significantly smaller level than with unmixed base paper. I found that. As a result of various studies, for this purpose, it is most preferable to use a mixed paper containing cellulose fibers, such as cellulose fiber pulp called linter paper or kraft paper, in which the glass fiber content is in the range of 3 to 20% by weight. It became clear. If it is less than 3%, the improvement effect on the dimensional stability of glass fiber is insufficient;
At 20% or more, a reinforcing effect on mechanical strength is observed, but there is also a tendency for dimensional stability to warp and decrease. That is, when the heating yield of the laminate is 20% or more, it becomes almost constant, but the amount of heating expansion in the thickness direction (Z direction) becomes large, which is not preferable. This is thought to be because the glass fibers in the mixed paper are thoroughly decomposed and mixed, so the internal stress during lamination molding becomes large, especially in the thickness direction. Moreover, when the amount of glass fiber increases to 20% or more, the rigidity, hardness, and specific gravity become large, and the punching process of the laminate board also deteriorates. Next, the selection of glass fibers to be mixed is an important factor in terms of electric properties, dimensional stability, strength, processability, productivity of base paper, and economic efficiency, as well as the mixing ratio, and from the viewpoint of mixing with cellulose fibers. E-glass fibers with a fiber diameter of 6 to 13 μm and a fiber length of 3 to 20 mm are suitable. It is not necessarily necessary to use a material treated with a silane coupling agent. This objective can be achieved by incorporating a silane coupling agent when impregnating the resin varnish. Density as a base paper is an important factor for impregnation with resin varnish, but by mixing glass fiber, a low-density base paper with good impregnation properties can be obtained, with a density in the range of 0.3 to 0.6 g/ ^cm3 . is appropriate. Of course, an inorganic substance such as antimony trioxide can be added to impart heat resistance to this mixed paper. Furthermore, the most important thing is that when manufacturing this mixed paper, the amount of glass fiber in the range of 3 to 20% by weight can be produced using a conventional base paper machine without any special equipment modification, making it economical. This is a major driving force behind the practical application of the present invention. The thermosetting resin used in the present invention is, for example, a resin in which phenols and formaldehyde are reacted, and if necessary, alkylphenols,
Phenol resin modified with drying oil and xylene resin, or one or more mixed resins such as bisphenol epoxy resin, novolac epoxy resin, and alicyclic epoxy resin, and amine curing agent or other curing agent. Epoxy resin made of a mixture of Before impregnating these thermosetting resin varnishes, prepare varnishes that have good affinity for the base material.
It is also possible to treat the resin with a dinuclear low molecular weight phenol resin or methylolated melamine resin. The laminates obtained by impregnating, drying, and heating laminated molding using the above-mentioned base paper and these resins according to conventional methods have excellent mechanical strength, and are resistant to dimensional changes, warping, and twisting due to temperature and humidity treatments. It was possible to obtain a plate that has the necessary strength even with a small thickness and has good low-temperature punching workability. In addition, because the heat shrinkage rate not only in the XY direction but also in the Z direction is extremely small, conventional paper-based laminates are manufactured using double-sided copper-clad laminates or laminates as starting materials, which have had problems with through-hole connection reliability. Application to double-sided circuit boards is now possible, and highly reliable paper-based through-hole circuit boards can now be obtained. One-sided or double-sided copper-clad laminates can be obtained by overlapping copper foil during lamination molding, but by placing at least one prepreg using glass fiber mixed paper in the layer directly below the copper foil, the copper foil and the substrate can be obtained. Warping and twisting due to temperature and humidity treatment during the processing process caused by the difference in thermal expansion coefficient between the board and heat shrinkage of the board, especially during the soldering process where components are mounted and connected on the printed wiring board. It has a very large suppressing effect. Of course, a copper-clad laminate formed using mixed paper for all layers has good properties, but this is accompanied by a decrease in low-temperature punching properties, making it particularly suitable for thin plates. As described above, by carrying out the method of the present invention, a laminate or copper-clad laminate can be obtained that exhibits little dimensional change due to temperature and humidity treatment, has little warping or twisting, and has high mechanical strength. This also makes it possible to make the material thinner, which is preferable from the standpoint of resource conservation. The present invention will be specifically explained below using Examples. Example 1 Linter base paper with a different mixing ratio of glass fibers was impregnated with a phenolic resin varnish modified with tung oil and a silane coupling agent to obtain a prepreg, which was then laminated and molded to form a 1.6 mm thick laminate with a resin content of 50%. I got it. The dimensional change rate and bending strength of these laminates due to heating and humidity treatment are shown in Table 1.

【table】

[Table] Example 2 Using linter base paper with a different mixing ratio of glass fibers, a prepreg was obtained by impregnating a varnish containing a phenol resin modified with tung oil and a silane coupling agent, and then laminated and molded to obtain a prepreg with a resin content of 45%. Laminated plates of various thicknesses were obtained. Table 2 shows the results of comparing the bending strength, punchability, and warpage characteristics of these laminates.

[Table] Example 3 Using kraft paper with a glass fiber mixing ratio of 10%, a prepreg was obtained by impregnating it with a varnish made of phenol resin or epoxy resin mixed with a silane coupling agent, and then layered with copper foil and laminated. death,
A copper-clad laminate with a thickness of 1.2 mm and a resin content of 40% was obtained.
The properties were compared with a board with a thickness of 1.6 mm obtained using conventional kraft base paper, and the results shown in Table 3 were obtained.

【table】

[Table] mm
Warpage characteristics: 320(Y) x 420(X) After pattern creation, various treatments were performed and measured using the horizontal method.
Example 4 Using linter base paper with a glass fiber mixing ratio of 10%, it was impregnated with a varnish containing an epoxy resin and a silane coupling agent to obtain a prepreg, which was then laminated and molded into a board with a thickness of 1.6 mm with a resin content of 50%. A laminate was obtained. Furthermore, an adhesive for additive processes consisting of nitrile rubber and phenol resin was applied to the lower surfaces and dried and cured to obtain a substrate for additive processes. Using this, we created a copper through-hole plating circuit board using a semi-additive process, and conducted a through-hole connection reliability test. The results are shown in Table 4.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A laminate formed by heating and laminating prepregs impregnated with a thermosetting resin and dried as a base material, with a density of 0.3 to 20% by weight, in which glass fiber is mixed in an amount of 3 to 20% by weight as the base material. A thermosetting resin laminate with good dimensional stability, characterized by using 0.6 g/cm ³ of cellulose fiber base paper. 2. Good dimensional stability according to claim 1, wherein the glass fibers to be mixed are E-glass for electrical use, and are in the form of opened filaments with a fiber diameter of 6 to 13 μm and a length of 3 to 20 mm. thermosetting resin laminate. 3. A thermosetting resin laminate with good dimensional stability according to claim 1, wherein the cellulose fiber base paper is linter paper made from linter pulp. 4 In a single-sided or double-sided copper-clad laminate made by heating and laminating prepregs impregnated with a thermosetting resin and dried, the layer directly below the copper foil contains 3 to 20% by weight of glass fiber as the base material. Mixed paper density 0.3
A thermosetting resin laminate with good dimensional stability, characterized in that at least one sheet of prepreg using cellulose fiber base paper of ~0.6 g/cm ³ is arranged and used. 5. Good dimensional stability according to claim 4, wherein the glass fibers to be mixed are E-glass for electrical use, and are in the form of opened filaments with a fiber diameter of 6 to 13 μm and a length of 3 to 20 mm. thermosetting resin laminate. 6. A thermosetting resin laminate with good dimensional stability according to claim 4, wherein the cellulose fiber base paper is linter paper made from linter pulp.