JPS60248344A - Metallic foil lined laminated board for high frequency - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention belongs to the technical field related to materials for electronic devices, particularly materials for electronic devices scheduled for use in a high frequency region. It also belongs to the field of manufacturing technology for metal foil-clad laminates, such as copper-clad laminates.

[Background technology] X-band region (1
Electronic devices that operate at extremely high frequencies (0 GHz) require materials with particularly excellent properties. The excellent properties referred to here mean excellent dielectric constant, or in other words, low dielectric constant and low loss.

Furthermore, since the wavelength of radio waves has become significantly shorter, the characteristics are greatly influenced by local non-uniformity on the micron order, such as the mesh of glass cloth or unevenness on the surface of metal foil. For example, the bonding interface between the copper foil and the substrate of a conventional copper-clad laminate is provided with an unevenness of 4 microns or more in order to improve the adhesive strength. It is recognized that unevenness of such a scale increases dielectric loss by 50% or more compared to a perfectly clear surface. Therefore, in order to eliminate the influence of the bonding interface, a material with uniformity on such a scale is required.

Furthermore, in the above-mentioned fields, the entire board is treated as a circuit because radio waves are reflected inside the board. As a result, calculations of capacitance, reactance, etc. require thickness accuracy and dielectric properties with small variations.

Conventionally, laminates for the above-mentioned purposes have been made of materials mainly made of 4-fluorinated ethylene resin, crosslinked polyethylene resin, alumina ceramic, and the like.

However, the main purpose of using such materials is
The goal was to achieve low dielectric constant and low dielectric loss, and the uniformity of materials and products had not been studied for anything other than alumina ceramics.

On the other hand, in the case of alumina ceramic substrates, the method of obtaining a substrate with a smooth bonding interface is to polish the surface of the substrate well, apply lead in a lead bath, and then evaporate copper on top of it. A method of applying silver paste or the like to the surface is known.

[Object of the Invention] An object of the present invention is to provide a double-sided metal-clad laminate having a smooth bonding interface that could not be achieved with conventional resin-based materials.

DISCLOSURE OF THE INVENTION 1 The present invention provides a double-sided metal foil-clad laminate manufactured by using metal foil and bonding it to a resin-based substrate. The substrate used in this invention may be manufactured by following the so-called laminate manufacturing method in which a base material is impregnated with a resin composition and then laminated into a plurality of sheets, or by extruding the resin composition into a sheet. A manufacturing method in which the substrate is formed by molding may be adopted. Metal foil is bonded to the thus prepared substrate to form a laminate. There are no particular limitations on the technology for manufacturing such a laminate. For example, a conventional method for manufacturing so-called copper-clad laminates or a technique for compounding thermoplastic resins called lamination may be applied. Although the metal foil to which this invention is applied has a sufficiently broad concept that includes all metals used for forming electric circuits, the following description will be made using copper foil as an example. However, this does not mean that it is limited to copper foil. For example, aluminum foil and composite foil of copper foil and aluminum foil are also put into practical use.

Conventionally, when manufacturing copper-clad laminates, the copper foil to be bonded is an electrolytic copper foil that has been roughened on one side to form an uneven surface of 4μ or more. Use copper foil with a smooth surface. Therefore, rolled copper foil can also be used.

The copper foil used in this invention has a flat adhesive interface. There is no limitation on the smoothness, but it is desirable that the unevenness is 3 μm or less. It is desirable that the unevenness is preferably 2μ or less, more preferably 0.5μ or less.

In this invention, since the bonding interface between the substrate surface and the metal foil is smooth, an anchor effect for maintaining adhesion and adhesion cannot be expected at the bonding interface. Therefore, in order to obtain a strong bonding force, it is difficult to use a material for the base material unless it has some bonding force, such as chemical bonding force, with the copper foil. Materials that do not have any bonding strength are impenetrable. In this invention, any resin can be used as long as it has such a bonding strength. Of course, materials with excellent high frequency characteristics are preferred.

From the above viewpoint, examples of resins that can be used in the present invention are as follows. That is, polystyrene, polyethylene, high-density polyethylene, polyphenylene sulfide, polyphenylene oxide, polyphenylene sulfide, resins similar to these resins, or mixtures of the above resins are used.

The following will be explained based on examples.

Example 1 The following materials were used as base materials.

A. Adhesive resin composition Polyethylene resin 100 parts by weight Dicumyl peroxide 4 parts by weight The above composition was extruded at 120 to 130°C while thoroughly kneaded in an extruder to form a sheet with a thickness of 50μ. .

The polyethylene resin used was one in which the terminal groups of polyethylene were modified with maleic anhydride, glycidyl methacrylate, acrylic acid, or the like.

Examples of the above include Polycook M-600
Examples include TX (trademark, manufactured by Idemitsu Petrochemical Co., Ltd.), Atmar (trademark, manufactured by Mitsubishi Yuka Co., Ltd.), and Modisoku (trademark, manufactured by Mitsubishi Yuka Co., Ltd.).

B. Materials for base material High-density polyethylene 100 parts by weight Dicumyl peroxide 4 parts by weight Copper foil degreased with trichlene was laminated on the sheets of A and B above, and heated at 220°C1C11Q/c- for about 15 minutes. Tightened. As a result, the peel strength was 1.5 kg/cm.
A copper-clad laminate having an adhesive strength of .

Example 2 700μ of polyphenylene sulfide resin (manufactured by Phillips Beryllium, R-4, containing 40% glass fiber)
A copper clad laminate similar to that of Example 1 was obtained by laminating copper foils degreased with trichloride on the top and bottom, and pressing at 330° C. and a pressure of 110 kg/c+fl for about 15 minutes.

When experimenting with various irregularities on the adhesion interface of the copper foil of the copper-clad laminate in Example 1.2 above, it was found that when the circuit loss was measured using a smooth double-sided copper-clad laminate, the irregularities on the adhesive interface were If it is less than 0.5μ, the loss will be less than half that of using conventional roughened copper foil, and if it is less than 1μ
When there are the following irregularities, compared to a completely flat case (
Theoretical value) There was an increase in loss of about 13%, and when the unevenness was 2μ, the loss increased by about 30%. As a result of further experiments, 3μ
It has been found that if the loss is below, the loss remains at a practical level.

[Effects of the Invention] This invention is characterized in that it has a metal foil layer bonded to both sides of a laminate, and that the unevenness of the bonded interface is 3μ or less, so it is not necessary to use a metal foil layer that has a conventional rough surface. This has the effect of significantly reducing high frequency loss compared to a laminated plate using foil.

Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshikuro Takemitsu (and 2 others) Procedural amendment June 26, 1985 2. Name of invention Metal foil clad laminate for high frequency use 3. Related Patent Applicant Address: Marokin Daikushin 1048 Kanmei (583) Matsushita Electric Works Co., Ltd. Representative: Sadao Fujii 4, Agent Address: 1048-5 Kadoma, Kadoma City, Osaka Prefecture Amendment Order 84 Sun Voluntary Amendment "Increase in dielectric loss" on page 2, line 16 of the description of contents is corrected to "dielectric loss (loss due to surface resistance)."

"Reflection" in line 20 of the same page is corrected to "propagation."

Agent: Patent Attorney Toshimaru Takemitsu

Claims (3)

[Claims] (1) A metal foil-clad laminate for high frequency use, characterized in that it has metal foil layers bonded to both sides of a substrate, and the unevenness of the bonded interface is 3μ or less. (2) The metal foil-clad laminate for high frequencies according to claim 1, wherein each metal foil has a thickness of 18 to 35 μm, and the total thickness of the metal foil-clad laminate is 0.2 to 1 fi. (3) A metal foil-clad laminate for high frequency use according to claim 1 or 2, wherein the metal foil is copper foil.