JPH05138794A - Laminate and its manufacture - Google Patents

Abstract

PURPOSE:To improve electric properties and drill workability by placing the hollow spherical glass powder having specified specific gravity and average particle diameter in the resin with which the base material of a surface layer is impregnated of the laminate formed under heating and pressurizing after the sheetlike base materials impregnated with thermosetting resin have been laminated. CONSTITUTION:A laminate is formed under heating and pressurizing, after sheetlike base material impregnated with thermosetting resin has been laminated. Then, the hollow spherical glass powder having the specific gravity of 0.8-2 and the average particle diameter of at most 30mum is placed in the resin with which the base material of a surface layer is impregnated. In order to produce said laminate, the prepreg obtained by impregnating the sheetlike base material with thermosetting resin varnish and by drying it, is placed inside of the laminate. On one hand, the prepreg obtained by impregnating said base material with the thermosetting resin compounded with the hollow spherical glass powder having said properties, is placed on the surface of the laminate. Then, the laminate is completed by heating and pressurizing. consequently, while the occurrence of void is suppressed and electric properties are prevented from being lowered, its drill workability is improved.

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 and a method for producing the laminated board.

[0002]

2. Description of the Related Art For use as a substrate of a printed wiring board, a predetermined number of prepregs obtained by impregnating a glass fiber woven fabric base material with a thermosetting material such as epoxy resin or polyimide and drying are stacked and heated. Press formed laminates are manufactured. The dielectric constant of these laminated plates is 4.9 to 5.
Since it is as large as 1, the electrostatic capacitance of the printed wiring board using this as a substrate is large, which is unsuitable as a printed wiring board that handles high frequencies. Therefore, as a substrate for a printed wiring board used in a high frequency range, a laminated plate is used in which a glass fiber woven fabric base material is impregnated with a thermoplastic resin having a low dielectric constant and dried, and prepregs are stacked and heat-pressed. ing. However, this laminated plate has a very complicated manufacturing process, has poor dimensional stability in the soldering process, and is expensive.

On the other hand, there has been proposed a laminated plate having a dielectric constant reduced by filling a hollow glass powder in a thermosetting resin (JP-A-56-49256, JP-A-56-56).
49257, and JP-A-2-133436).
This laminated plate is produced by heat-press molding a prepreg obtained by impregnating and drying a resin varnish mixed with hollow glass powder into a base material such as a glass fiber woven cloth, but the specific gravity of the hollow glass powder is small. However, the hollow glass powder mixed in the resin varnish floats and cannot be uniformly applied to the substrate. Further, the average particle diameter of the hollow glass powder is as large as 60 μm or more,
During the heat and pressure molding, the hollow glass powder is easily broken by the molding pressure, and voids are easily generated in the laminated plate. When such a laminated board is used as a substrate of a printed wiring board, the insulation characteristics between the through-holes are significantly deteriorated, which is not practical. Further, since the hollow glass powder is contained, the drill workability is deteriorated.

[0004]

DISCLOSURE OF THE INVENTION The problem to be solved by the present invention is to prevent voids from being generated and prevent deterioration of electrical characteristics in a laminated plate having a low dielectric constant by containing hollow spherical glass powder. In addition to improving drilling workability.

[0005]

In order to solve the above-mentioned problems, the laminated plate according to the present invention is one in which sheet-like base materials impregnated with a thermosetting resin are laminated and heat-pressed,
The specific gravity of the thermosetting resin impregnated into the base material of the surface layer is 0.8 to
In No. 2, hollow spherical glass powder having an average particle diameter of 30 μm or less was present. In addition, a method for producing this laminated plate is such that a prepreg obtained by impregnating and drying a thermosetting resin varnish in a sheet-shaped substrate is placed inside, and a hollow spherical glass having a specific gravity of 0.8 to 2 and an average particle diameter of 30 μm or less. Place the prepreg obtained by impregnating and drying the powder-blended thermosetting resin varnish on the surface,
It is characterized by being heated and pressed.

[0006]

Since a high frequency signal is transmitted on the circuit surface of the printed wiring board, the dielectric constant of the insulating layer in contact with the circuit may be reduced. The hollow spherical glass powder contains a gas such as air or nitrogen having a low dielectric constant, and the laminated plate according to the present invention in which it is present in the thermosetting resin on the surface has excellent dielectric properties and high frequency. It is suitable as a substrate for printed wiring boards that handle signals. And since the hollow spherical glass powder is only present in the resin on the surface, the laminated plate has excellent drilling workability. Further, the hollow spherical glass powder having a limited specific gravity and particle diameter as described above has a large wall thickness and a pressure resistance of 500 Kg / cm ² or more, and sufficiently withstands the pressure at the time of heat and pressure molding and retains its shape. Since the particle size is small, the smoothness of the surface of the laminated plate is not deteriorated, and the hollow spherical glass powder is not easily broken even when drilling. This means that the plating solution is less soaked in and the insulation resistance between the through-hole holes can be made sufficiently large. Furthermore, by limiting the specific gravity as described above, it becomes close to the specific gravity of the resin varnish, and it is possible to uniformly disperse the hollow spherical glass powder in the resin varnish,
It is possible to obtain a laminated plate with a small variation in dielectric properties, and it is also possible to make the dielectric properties sufficiently small.

[0007]

EXAMPLES The thermosetting resin used in the laminate according to the present invention is not particularly limited, and may be polyimide resin, phenol resin, cyanate resin, cyanate ester resin, epoxy resin, unsaturated polyester resin, or the like. In order to provide flame resistance, a halogen-containing organic compound, a flame-retardant aid such as antimony oxide, etc. may be added, and other fillers, colorants, etc. may be added. As the sheet-shaped substrate, glass fiber woven cloth, glass fiber nonwoven cloth, amide fiber woven cloth, amide fiber nonwoven cloth,
Polyester fiber woven fabric, polyester fiber non-woven fabric, Teflon non-woven fabric and the like, and mixed paper-woven fabrics and mixed woven fabrics thereof are not particularly limited. A metal foil may be integrated on the surface of the laminated plate, but the metal foil is a copper foil, an aluminum foil, a nickel foil, or the like, and the kind and thickness of the metal foil are not particularly limited as long as the metal foil has good conductivity. If necessary, a metal foil with an adhesive can be used. As the adhesive, a general-purpose adhesive for metal foil such as phenol-based, epoxy-based, butyral-based, polyester-based, polyurethane-based and mixtures thereof can be used. The compounding amount of the hollow spherical glass powder is 10 to 100 parts by weight of the resin solid content of the resin varnish in consideration of sufficient dielectric properties, wear of a jig during machining such as a drill, viscosity of the resin varnish, and the like. It is preferably set in the range of 200 parts by weight.

Example Ep-1001 (Epoxy resin made by Yuka Shell, epoxy equivalent: 480) 3 parts by weight of dicyandiamide and 0.2 parts by weight of 2-ethyl 4-methylimidazole as a catalyst were added to 100 parts by weight of resin varnish. Was prepared. A glass fiber woven fabric (basis weight: 215 g) was impregnated with this varnish and dried to obtain a prepreg (a) to be used on the inside having a resin amount of 50% by weight. 100 parts by weight of hollow spherical glass powder having a specific gravity of 1.1 and an average particle diameter of 10 μm was mixed with the above resin varnish,
A glass fiber woven fabric (basis weight: 215 g) was impregnated with this varnish and dried to obtain a prepreg (b) having a resin amount of 50% by weight. Two prepregs (b) are placed on each side of four prepregs (a), and copper foils (thickness 18 μm) are placed on the top and bottom of the prepregs (a) at a temperature of 170 ° C. and a pressure of 40 Kg / cm ² .
It was heated and pressed for 0 minutes to obtain a copper-clad laminate having a plate thickness of 1.6 mm. The characteristics of the obtained copper-clad laminate are shown in Table 1.

Conventional Examples 1 and 2 A copper-clad laminate (Conventional Example 1) formed by using eight prepregs (a) used in the Examples and 8 prepregs (b).
Table 1 shows the characteristics of the copper-clad laminate (conventional example 2) formed by using one sheet.

[0010]

[Table 1]

Measurement method Dielectric constant / dielectric loss tangent: Measured according to JIS-C-6481 Soldering heat resistance: Floating on solder bath at 260 ° C, measuring time until blistering Insulation resistance: Pressure cooker (121 ° C) Measured according to JIS-C-6481 after processing for 6 hours

[0012]

As is apparent from Table 1, the laminated plate according to the present invention has a small dielectric constant and is suitable for use in a high frequency range. Further, it has excellent drilling workability and suppresses the generation of voids, and therefore has good moisture resistance.

Claims (2)

[Claims] 1. A laminated sheet produced by laminating sheet-like base materials impregnated with a thermosetting resin and molding under heat and pressure, in a resin impregnated into the base material of the surface layer, with an average particle diameter of 0.8 to 2 30 μm
A laminated plate characterized by the presence of the following hollow spherical glass powder. 2. A prepreg obtained by impregnating a sheet-shaped base material with a thermosetting resin varnish and drying the prepreg is placed inside, and a specific gravity of 0.8 to 2 is obtained.
A method for producing a laminated sheet, comprising placing a prepreg obtained by impregnating and drying a thermosetting resin varnish containing a hollow spherical glass powder having an average particle diameter of 30 μm or less, and heat-pressing the prepreg.