JPH05136559A - Laminated board for high-frequency printed circuit use - Google Patents

Abstract

PURPOSE:To obtain a metal foil-clad laminated board having low high-frequency loss in a high-frequency region. CONSTITUTION:Laminated board for high-frequency printed circuit use is formed by laminating insulating base materials of a dielectric dissipation factor of 0.01 or lower on the surface of metal foil which has a mean roughness of 2mum or smaller along the center line and the largest height of 8mum or lower. In this laminated board for high-frequency printed circuit use, the insulating base materials of a dielectric constant of 4 or lower are obtained by using a resin, such as a fluorine resin or a polyolefin resin, and the insulating base materials of a dielectric constant of 7 or higher can be obtained by using the above resin in combination with low-dielectric dissipation factor and high-dielectric powder, such as barium titanate ceramic. It is desirable that the thickness of the metal foil is 35mum or thinner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil-clad laminate used for forming a high frequency printed circuit board.

[0002]

2. Description of the Related Art Recently, frequencies used in various fields of electronics industry and communication industry gradually shift to high frequency regions,
From the frequently used kilohertz and megahertz to the gigahertz range. As a substrate material for a printed wiring board used in accordance with such a technical trend, a glass-based epoxy resin-based laminated board using a polyolefin-based or fluorine-based resin has come to be used. These are disclosed in JP-A-60-239228, JP-A-1-138238 and JP-A-1-138239. However, as the metal foil integrated with the insulating base material, only the copper foil used in the ordinary glass cloth base material epoxy resin system is diverted, and the surface texture of the copper foil used is The surface of the copper foil is roughened to improve the adhesion between the prepreg and the copper foil, and the center line average roughness (Ra) is 3μ.
The maximum height (Rt) is about 10 to 15 μm. Since the roughening of the copper foil surface causes a large high frequency loss, improvement is required.

[0003]

In the high frequency region,
An object of the present invention is to provide a metal foil-clad laminate having less high frequency loss.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is characterized by a center line average roughness (Ra) of 2 μm or less and a maximum height (Rt) of 8 μm or less. A high frequency printed circuit laminate is obtained by laminating an insulating base material having a dielectric loss tangent of 0.01 or less on the surface of a metal foil having a surface texture.

The high frequency printed circuit laminate of the present invention comprises:
It is composed of a laminated plate formed by laminating a metal foil on the surface of an insulating base material, or a multilayer laminated plate formed by combining a plurality of the laminated plates.

As the insulating base material having a dielectric loss tangent of 0.01 or less, the resin is generally a fluorine-based resin or a polyolefin-based resin, and the base material is generally a glass cloth, a glass non-woven fabric, a glass mat or the like made of glass fibers. However, the material is not particularly limited, and a cloth, non-woven cloth, mat, or the like of organic fiber or a composite material thereof may be used. The one having a smaller dielectric loss tangent is preferable.

With the above structure, an insulating base material having a low dielectric loss tangent and a dielectric constant of 4 or less can be obtained.
Depending on the application such as downsizing of the device, a large dielectric constant of 7 or more is required. As a method for increasing the dielectric constant, it is preferable to contain a powder of high dielectric material, and use of barium titanate-based ceramics or the like is suitable for obtaining an insulating substrate having a low dielectric loss tangent and a high dielectric constant.

As the metal foil to be laminated on the surface of the insulating base material, metal foils such as copper, nickel, aluminum and stainless steel are preferable, and copper foil is particularly preferable in view of good electric conductivity. In this case, either electrolytic copper foil or rolled copper foil may be used without any particular limitation. Further, a metal foil in which a circuit is formed on these metal foils can also be used. In any of these cases, the thickness of the metal foil used is preferably 35 μm or less, and the thinner it is, the better the high frequency printed circuit processing accuracy becomes.
When the center line average roughness (Ra) and the maximum height (Rt) of the metal foil are small and the adhesiveness is likely to be deteriorated, it is preferable to apply a coupling agent suitable for the resin to the copper foil surface. desirable.

[0009]

In the high frequency printed circuit, the high frequency current has a skin effect and the current concentrates on the surface of the base material side where the electric field concentrates, so that the roughening of the metal foil becomes a resistance component for the high frequency signal. It is not preferable because it causes a conductor loss as a transmission line. According to the present invention, since the resistance of the metal foil is reduced, the resistance component is reduced, and a laminated board for a high frequency printed circuit having a small conductor loss as a transmission line can be obtained.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) MIL standard # melt-impregnated with fluororesin (Daikin Industries, Ltd., PTFE) having a dielectric loss tangent of 0.0002 to 0.0003
Centerline average roughness (Ra) on the outside of 10 pieces of 108 glass cloth
Of 1 .mu.m and maximum height (Rt) of 5 .mu.m having a matte surface texture of 35 .mu.m of copper foil are overlaid and laminated to obtain a laminate for high frequency printed circuit. (Example 2) PPO resin having a dielectric loss tangent of 0.001 to 0.002 (GE
The center line average roughness (Ra) is 1μ on the outside of four MIL standard # 2116 glass cloths, which are melt-impregnated with the brand name Noryl)
m, the maximum height (Rt) was 8 μm, and this surface of a copper foil of 18 μm having a matte surface texture was stacked and laminated to obtain a laminate for a high frequency printed circuit. (Example 3) Fluorine resin with a dielectric loss tangent of 0.0002 to 0.0003 (PTFE, manufactured by Daikin Industries, Ltd.) containing 50% by weight of barium titanate, was melt-impregnated, and the center was placed on the outside of 10 glass cloths of MIL standard # 108. A matte surface having a line average roughness (Ra) of 1 μm and a maximum height (Rt) of 5 μm 3
This surface of copper foil of 5 μm was placed on top of each other and laminated to obtain a laminate for high frequency printed circuits. Comparative Example 1 The centerline average roughness (Ra) is 3 μm and the maximum height (Rt) is 1 on the outside of the resin-impregnated glass cloth of Example 1.
A 35 μm copper foil having a matte surface texture of 0 μm was superposed on this surface and laminated to obtain a laminate for a high frequency printed circuit. Comparative Example 2 The center line average roughness (Ra) is 1 μm and the maximum height (Rt) is 1 on the outside of the resin-impregnated glass cloth of Example 2.
A 35 μm copper foil having a matte surface texture of 2 μm was superposed on the surface and laminated to obtain a laminate for a high frequency printed circuit.

[0011] was obtained in the above, a circuit formed on the surface of copper foil using a laminating plate for a high-frequency printed circuit, the resonance frequency characteristics Q in 10GH _Z, were measured dielectric constant based on JIS-C6481. The results are shown in Table 1.

From Table 1, in the printed circuit board of the embodiment, the Q value is almost proportional to the reciprocal of the dielectric loss tangent as compared with that of the comparative example. It was confirmed that the loss was small and that a printed circuit board having a high dielectric constant was obtained in Example 3 as compared with Example 1.

[0013]

[Table 1]

[0014]

According to the present invention, in the high frequency range,
A metal foil-clad laminate for high-frequency printed wiring boards with low high-frequency loss is obtained.

Claims (4)

[Claims] 1. A center line average roughness (Ra) of 2 μm or less,
A laminate for a high frequency printed circuit, characterized in that a metal foil having a surface texture with a maximum height (Rt) of 8 μm or less is laminated with an insulating base material having a dielectric loss tangent of 0.01 or less. 2. The laminate for a high frequency printed circuit according to claim 1, wherein the metal foil according to claim 1 has a thickness of 35 μm or less. 3. The laminate for a high frequency printed circuit according to claim 1 or 2, wherein the insulating base material according to claim 1 contains a fluorine-based resin or a polyolefin-based resin and a reinforcing material. 4. The high frequency print according to claim 1, wherein the insulating base material according to claim 1 contains a fluorine-based resin or a polyolefin-based resin, a reinforcing material, and a fine particle dielectric having a high dielectric constant and a low dielectric loss tangent. Circuit laminates.