JP2555819B2 - Composite laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board suitable as a substrate for a printed wiring board used in a high frequency range.

[0002]

2. Description of the Related Art A composite laminated board in which an epoxy resin-impregnated intermediate layer substrate is a glass non-woven fabric or a paper substrate and a surface layer substrate is a glass woven fabric is used as a substrate for a printed wiring board. The composite laminated plate has a great advantage in workability as compared with the laminated plate of the glass woven fabric base material, and is therefore widely used not only in the consumer equipment field but also in the industrial equipment field. However, a laminated board using these epoxy resins has a large dielectric constant of 4.5 to 5.1, so that the electrostatic capacitance of the printed wiring board becomes large and it is not practical in the field where a high frequency is used. Therefore, as a substrate for a printed wiring board used in a high frequency region, a glass woven fabric substrate impregnated with a low dielectric constant thermoplastic resin, or a substrate using a low dielectric constant Teflon substrate has been proposed. There is. However, all of these have extremely complicated manufacturing processes, are difficult to process, and are expensive. On the other hand, a laminate having a dielectric constant lowered by filling a hollow glass powder in a thermosetting resin has been proposed (JP-A-56-49256, JP-A-56-49257, JP-A-2-). 133436). Hollow glass powder is used by dispersing it in the resin varnish that impregnates the base material in the manufacturing process of the laminated plate, but due to its small specific gravity, the hollow glass powder floats when mixed with the varnish used in ordinary laminated plate manufacturing. Therefore, it cannot be uniformly applied to the substrate. Also, the average particle diameter of the hollow glass powder is 60 μm.
Since it is large than the above, it is easily destroyed by pressure when forming a laminated plate, and it is also destroyed by drilling the laminated plate,
Through-hole reliability is extremely poor when used as a substrate for a printed wiring board. There is also a problem that the smoothness of the surface is significantly deteriorated due to the large particle size of the hollow glass powder.

[0003]

The problem to be solved by the present invention is to be handled in the same manner as an ordinary composite laminated board, suitable for laminated board manufacturing and circuit processing steps, and excellent in dielectric properties, moisture resistance characteristics and heat resistance characteristics. It is to provide a laminated board.

[0004]

In order to achieve the above object, in the composite laminate of the present invention,
Hollow glass powder having a specific gravity of 0.8 to 2 and an average particle diameter of 30 μm or less is contained in the epoxy resin impregnated in the intermediate layer glass nonwoven fabric. Then, the epoxy resin with which the glass woven fabric of the surface layer is impregnated contains the phenol-added polybutadiene. The chemical composition of the glass fibers that make up the glass woven fabric is preferably D-glass.

[0005]

Since a high-frequency signal is transmitted on the circuit surface of the printed wiring board, it is affected by the insulating layer directly below the circuit. In the composite laminated plate in which the insulating layer is composed of two kinds of layers (epoxy resin-impregnated glass woven fabric and epoxy resin-impregnated glass nonwoven fabric), it is necessary to reduce the dielectric constant of both layers. In the laminated plate according to the present invention, the intermediate layer contains hollow glass powder to form a gas layer (air or nitrogen) to reduce the dielectric constant, while the surface layer contains polybutadiene having a low dielectric constant. The overall structure is to improve the dielectric characteristics. Hollow glass powder is used by mixing it with the epoxy resin varnish that impregnates the glass nonwoven fabric.
By setting the specific gravity to 0.8 to 2, the varnish can be uniformly dispersed, and as a result, the hollow glass powder can be uniformly dispersed in the intermediate layer of the laminated plate to reduce variations in dielectric properties. If the specific gravity of the hollow glass powder is small or large, the hollow glass powder floats or sinks in the varnish, resulting in non-uniform dispersion and large variations in the dielectric constant. Further, when the specific gravity of the hollow glass powder exceeds 2, the dielectric constant of the hollow glass powder itself becomes large and the original meaning is lost. If the average particle diameter of the hollow glass powder exceeds 30 μm, the hollow glass powder is destroyed by the pressure during the molding of the laminated plate, and also when the laminated plate is drilled, the hollow glass powder is destroyed and A chip occurs and it cannot be put to practical use.

[0006]

EXAMPLE The amount of hollow glass powder blended is preferably set in the range of 10 to 200 parts by weight per 100 parts by weight of the resin solid content of the resin varnish. If it is too small, sufficient improvement in dielectric properties cannot be expected, and if it is too large, the viscosity of the resin varnish becomes high, and the workability of prepreg manufacturing becomes poor, and the drilling workability of the laminated plate also becomes poor.

The phenol-added butadiene (co) polymer contained in the epoxy resin of the surface layer is a butadiene homopolymer or a butadiene copolymer obtained by copolymerizing butadiene and a vinyl monomer such as styrene or a diolefin such as isoprene. The combined product is sulfuric acid, perchloric acid, aluminum chloride, boron trifluoride, boron trifluoride / ether complex,
It is produced by reacting with phenols using boron trifluoride / phenol complex as a catalyst. The addition amount of the phenols is preferably adjusted so that the hydroxyl group contained in 100 g of the resulting addition polymer is 0.1 to 1 mol. The phenol-added butadiene (co) polymer cross-links with the epoxy resin, but when the amount of the hydroxyl group is small, the cross-linking density of the cured epoxy resin becomes small and the heat resistance is lowered. On the other hand, when the amount of the hydroxyl group is large, the fluidity of the composition is deteriorated and molding becomes difficult. The phenols used here are selected from monohydric phenols, polyhydric phenols, and alkyl-substituted products thereof.

The glass woven cloth is usually made of E-glass, but the use of D-glass makes the dielectric properties better and the coefficient of thermal expansion smaller. Table 1 shows the composition of E-glass and D-glass (Wt
%) Is shown.

[0009]

[Table 1]

Example 1 A varnish of an epoxy resin (curing agent is phenol novolac resin) varnish containing 50 parts by weight of hollow spherical glass powder (specific gravity 1.2, average particle size 25 μ) with respect to 100 parts by weight of resin solid content is used. A glass non-woven fabric (70 g) was impregnated and dried to obtain a prepreg (a) having a resin adhesion amount of 90% by weight. Also, an epoxy resin varnish containing phenol-added polybutadiene as a curing agent was impregnated into a 0.2 mm-thick glass woven cloth, which was plain-woven with single yarn made of D-glass filament strands having a diameter of 9 μm, and dried to deposit the resin. 43% by weight of prepreg (b) was obtained. Then, one prepreg (b) is superposed on each surface of the three prepregs (a), and a copper foil having a thickness of 0.018 mm is arranged on each of the upper and lower surfaces, and the pressure is 50 kg / cm ² Then, it was heated and pressed at a temperature of 165 ° C. for 90 minutes to obtain a copper-clad laminate having a thickness of 1.6 mm.

Example 2 A glass woven cloth having a thickness of 0.2 mm obtained by plain-weaving a single yarn made of a strand of E-glass filament having a diameter of 9 μm was used in place of the glass woven cloth of Example 1, and the other examples were used. A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in 1.

Comparative Example 1 Epoxy resin (curing agent is phenol novolac resin) varnish containing 50 parts by weight of aluminum hydroxide (specific gravity 2.4) based on 100 parts by weight of resin solid content, basis weight 70 g
Was impregnated into the glass non-woven fabric and dried to obtain a prepreg (a ′) having a resin adhesion amount of 92% by weight. Further, a glass woven cloth having a thickness of 0.2 mm obtained by plain weaving a single yarn made of a strand of E-glass filament having a diameter of 9 μ was impregnated with an epoxy resin having a curing agent of dicyandiamide and dried to obtain a resin adhesion amount of 4
3% by weight of prepreg (b ') was obtained. Then, prepreg (b ') is formed on both surfaces of which three prepregs (a') are stacked.
Each of them is overlaid and a copper foil with a thickness of 0.018 mm is placed on each of the upper and lower surfaces, and this is heated and pressed for 90 minutes at a pressure of 50 kg / cm ² and a temperature of 165 ° C. to form a thickness of 1.6 mm. To obtain a copper-clad laminate.

COMPARATIVE EXAMPLE 2 One prepreg (b ') was superposed on both surfaces of three prepregs (a) used in Example 1, and the same procedure as in Example 1 was followed. A copper-clad laminate was obtained.

Comparative Example 3 One prepreg (b) was superposed on each surface of the three prepregs (a ') used in Comparative Example 1, and the same procedure as in Example 1 was followed. A copper-clad laminate was obtained.

Table 2 shows the test results obtained by measuring the water absorption rate, dielectric constant, dielectric loss tangent, and solder heat resistance of the above laminated plate according to JIS-C-6481.

[0016]

[Table 2]

[0017]

As is apparent from Table 2, the composite laminate according to the present invention has excellent heat resistance and a low water absorption rate.
In particular, it has excellent dielectric properties. Therefore, it has great utility value as a substrate of a printed wiring board used in the field of handling high frequency signals.

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Claims (2)

(57) [Claims] 1. A composite laminate having an epoxy resin-impregnated intermediate layer substrate made of glass nonwoven fabric and a surface layer substrate made of glass woven fabric, wherein the specific gravity of the intermediate layer resin is 0.8 to 2
And a hollow glass powder having an average particle diameter of 30 μm or less, and a resin for the surface layer containing phenol-added polybutadiene. 2. The composite laminate according to claim 1, wherein the surface woven glass fabric has a chemical composition of D-glass.