JPH04115945A - Laminated sheet and manufacture thereof - Google Patents

Abstract

PURPOSE:To suppress the lowering of glass transition temp., rigidity at the time of heating and chemical resistance while attaining to lower the modulus of elasticity by compounding an inorg. filler coated with a thermosetting resin B having the modulus of elasticity lower than that of a thermoplastic resin A infiltrated in a glass nonwoven fabric with the thermosetting resin A. CONSTITUTION:The magnitude of the modulus of elasticity of a thermosetting resin B low in elasticity is determined by the relative comparison with the modulus of elasticity of a thermosetting resin A but, as the thermosetting resin B, for example, there are a tung oil modified phenol resin, a butyral modified phenol resin, a nitrile modified phenol resin, a vinylphenol modified epoxy resin, a nitrile phenol modified epoxy resin or a flexible epoxy resin. As an inorg. filler, there are aluminum hydroxide, alumina, magnesia or silica. In a laminated sheet, the resin B having the modulus of elasticity lower than that of the resin A has function relaxing the stress at the interface between the resin A and the inorg. filler and the modulus of the elasticity of the whole of the laminated sheet can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laminate suitable as a substrate for a printed wiring board on which surface mount devices (SMDs) are mounted, and a method for manufacturing the same.

Conventional technology As electronic and electrical equipment becomes more dense, highly integrated, and miniaturized, the parts that are mounted and soldered on printed wiring boards incorporated into these equipment have changed from insert-type discrete components to surface-mounted S.
MD has been increasing. The substrate for printed wiring boards is a laminate made by stacking sheet-like substrates impregnated with thermosetting resin and forming them under heat and pressure.As an SMD compatible substrate,
It is desirable to use a laminate with a low modulus of elasticity that can prevent cracks from forming in the solder joints of the SMD due to repeated heating and cooling cycles.

As a means to lower the elastic modulus of the laminate.

(1) A flexibility imparting agent is dispersed in a thermosetting resin.

(2) Reacting the thermosetting resin with a flexibility imparting agent.

etc. are being considered.

Problems to be Solved by the Invention In the above-mentioned conventional techniques, it is possible to lower the elastic modulus of the laminate and reduce the internal stress when the laminate expands and contracts in the plane direction during the cooling/heating cycle. The glass transition temperature of the constituent resin decreases, the rigidity during heating decreases, and the chemical resistance also deteriorates. Deterioration of these properties becomes an obstacle when processing the laminate as a substrate for a printed wiring board.

The problem to be solved by the present invention is to reduce the modulus of elasticity of a laminate using glass nonwoven fabric for part or all of the base material impregnated with resin, while improving the glass transition temperature, rigidity during heating, etc. The goal is to suppress the decline in chemical resistance.

Furthermore, it is also important to improve the heat resistance and moisture resistance of the laminate.

Means for Solving the Problems The laminate according to the present invention contains an inorganic filler coated with a thermosetting resin B having a lower elastic modulus than the resin A, in a thermosetting resin A impregnated into a glass nonwoven fabric. It is characterized by

The laminate may have a metal foil integrally attached to its surface.

The above-mentioned method for manufacturing laminates is particularly characterized in that the nonwoven glass fabric is coated with thermosetting resin B, which has a lower elastic modulus than resin A, in the varnish of thermosetting resin A that is impregnated into the glass nonwoven fabric, and resin B is completely The point is to mix in an inorganic filler that has been hardened. The surface of the inorganic filler is preferably treated with a silane coupling agent before being coated with resin B.

Function In the laminate according to the present invention, resin B, which has a lower elastic modulus than resin A, acts as a stress reliever at the interface between resin A and the inorganic filler, and can lower the elastic modulus of the entire laminate.

In a two-component system with a so-called sea-island structure (resin A is the sea part and resin B is the island part), where resin B is directly blended with resin A and dispersed in resin A, resins A and B have different freedoms. It has a different volume fraction and therefore has a different glass transition temperature, and its mechanical behavior becomes a composite of two components. However, in a system in which a hard inorganic filler is dispersed in the resin, such as the laminate according to the present invention, the mechanical properties such as the glass transition temperature are similar to those of the sea component resin A, and the glass transition It is assumed that there is no decrease in rigidity when heated.

Furthermore, if Resin B coated with an inorganic filler is completely cured and then added to Resin A varnish, Resin B will not dissolve into the varnish and will not participate in the crosslinking reaction of Resin A. , without impairing the original properties of resin A.

Further, by completely curing, there is no deterioration due to moisture absorption, and the storage stability of the resin B-coated inorganic filler is also good.

Example Next, embodiments according to the present invention will be described.

The magnitude of the elastic modulus of the low-elastic thermosetting resin B is determined by a relative comparison with the elastic modulus of the thermosetting resin A. Examples of the thermosetting resin B include tung oil-modified phenolic resin, These include butyral-modified phenol resin, nitrile-modified phenol resin, vinylphenol-modified epoxy resin, nitrile-phenol-modified epoxy resin, flexible epoxy resin, and the like.

Inorganic fillers include aluminum hydroxide, talc, alumina, magnesia, silica, and the like.

Example 1 A polyvinyl butyral modified phenol resin was prepared as resin B, and this was mixed with methyl ethyl ketone/toluene = 5
0150 to prepare a solution having a resin content of 2% by weight.

While stirring the aluminum hydroxide with a strainer, the above solution was added dropwise so that the resin content was 2% by weight based on the weight of the aluminum hydroxide. Thereafter, it was dried at 130° C. for 1 hour to obtain aluminum hydroxide whose surface was coated with a completely cured polyvinyl butyral modified phenol resin.

Then, glass nonwoven fabric (50g/m) was made with the following composition.
A resin varnish to be impregnated with was prepared.

(1) Brominated epoxy resin 100 parts by weight (2) Phenol novolak resin 20 parts by weight (3) Curing accelerator (2E4MZ) 0.1 part by weight (4) Aluminum hydroxide 90 parts by weight (5) Acetone
40 parts by weight of a glass nonwoven fabric base material was impregnated with the above resin varnish and dried to prepare prepreg I with a resin content of 88% by weight, while a glass woven fabric (205/m) was coated with the same resin varnish without the above aluminum hydroxide. A prepreg (2) with a resin content of 40% by weight was prepared by impregnation and drying.

Prepreg on both sides of 6 plies of prepreg I
A double-sided copper-clad laminate with a thickness of 1.6I was obtained by stacking one ply of the above and placing a 18 μm copper foil on the outermost surface, followed by heating and pressure molding.

Example 2 In Example 1, the polyvinyl butyral modified phenol resin content was 5% by weight based on the weight of aluminum hydroxide.
A double-sided copper-clad laminate was obtained in the same manner except that

Example 3 A double-sided mesh laminate was produced in the same manner as in Example 2, except that aluminum hydroxide was treated with aminosilane (used at 3% by weight based on the weight of aluminum hydroxide) and then coated with polyvinyl butyral-modified phenolic resin. I got it.

Example 4 A double-sided copper-clad laminate was obtained in the same manner as in Example 1, except that the polyvinyl butyral modified phenol resin content was 10% by weight based on the weight of aluminum hydroxide.

Example 5 A double-sided copper-clad laminate was obtained in the same manner as in Example 2, except that a flexible epoxy resin (dimer acid glycidyl ester) was used in place of the polyvinyl butyral-modified phenol resin.

Example 6 Both sides were copper-clad in the same manner as in Example 5, except that aluminum hydroxide was treated with epoxy silane (3% by weight based on the weight of aluminum hydroxide) and then coated with flexible epoxy resin. A laminate was obtained.

Conventional Example 1 In Example 1, except that aluminum hydroxide was not coated with polyvinyl butyral modified phenolic resin,
A double-sided copper-clad laminate was obtained in the same manner.

Conventional Example 2 In Conventional Example 1, the dimer acid-modified epoxy resin was
It was added in parts by weight to participate in the curing reaction.

Comparative Example 1 In Example 2, instead of coating aluminum hydroxide with polyvinyl butyral modified phenolic resin, the same amount of polyvinyl butyral modified phenolic resin was added to a brominated epoxy resin as a matrix resin with an average particle size of 20 μm.
A double-sided copper-clad laminate was obtained in the same manner, except that the particles were dispersed in a seabird structure with m (Max, 40 μm, Min, 5 μm).

Comparative Example 2 In Example 5, instead of coating aluminum hydroxide with a flexible epoxy resin, the same amount of flexible epoxy resin was added to a brominated epoxy resin as a matrix resin with an average particle size of 20 μm (Max, 40 μm). A double-sided copper-clad laminate was obtained in the same manner, except that the particles were dispersed in a seabird structure.

Table 1 shows the characteristics of the laminate on each side and the solder connection reliability when the laminate is processed into a printed wiring board and an SMD is mounted thereon.

Effects of the Invention As described above, the laminate according to the present invention has a low elastic modulus and has high solder connection reliability as an SMD compatible substrate, but there is no decrease in glass transition temperature or rigidity when heated. It also has good chemical resistance, so there will be no problems with its properties when processing it into printed wiring boards.

Furthermore, resin B will be uniformly dispersed in resin A as the inorganic filler is dispersed in resin A, and the particle size of the dispersion can be controlled simply by selecting the particle size of the inorganic filler. I can do it. Just by directly blending resin B with resin A, it is difficult to achieve uniform dispersion in the seabird structure.

By treating the surface of the inorganic filler with a silane coupling agent before coating the inorganic filler with resin B, the moisture resistance and heat resistance of the laminate can be further improved.

Claims (4)

[Claims] (1) In a laminate that is made by stacking and integrating base materials impregnated with a thermosetting resin, and in which part or all of the stacked base materials are made of nonwoven glass fabric, the nonwoven glass fabric is impregnated. Resin A in thermosetting resin A
A laminate comprising an inorganic filler coated with a thermosetting resin B having a lower modulus of elasticity. (2) The laminate according to claim 1, wherein a metal foil is integrated on at least one surface. (3) A method for manufacturing a laminate in which base materials impregnated with a thermosetting resin varnish are stacked and integrated by heating and pressure molding, in which a glass nonwoven fabric is used for part or all of the stacked base materials, It is characterized by blending into the varnish of thermosetting resin A that is impregnated into the glass nonwoven fabric, an inorganic filler coated with thermosetting resin B, which has a lower elastic modulus than resin A, and in which resin B is completely cured. A method for manufacturing a laminate. (4) The method for manufacturing a laminate according to claim 3, characterized in that before coating the inorganic filler with resin B, the surface of the inorganic filler is treated with a silane coupling agent.