JPH07221444A - Manufacture of insulation substrate with metallic thin layer - Google Patents

Abstract

PURPOSE:To acquire a manufacturing method of an insulation substrate with a metallic thin layer which enables manufacture of a high density wiring board by realizing a one-piece structure by interposing an organic bonding layer whose thickness after heating and compression is specific between a glass fabric and a metallic thin layer. CONSTITUTION:A 1mum-thick copper layer 2 and a 100A-thick chromium layer 3 are successively formed in one side of a polyimide film 1 by using an electron beam vapor deposition device. Epoxy adhesive 4 is applied to the chromium layer 3 to attain a thickness of 35mum and dried. It is then heated and compressed with a glass fabric epoxy prepreg with an organic adhesive layer 4 not less than 5mum inside. Thereafter, a polyimide film is peeled off between the polyimide film 1 and the copper layer 2. In the acquired insulation substrate with a metallic thin film, a wiring board is manufactured by performing circuit working by resist pattern formation-pattern plating-resist pattern removal-quick etching after resist formation surface treatment is performed for a copper foil, for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an insulating substrate with a thin metal layer used for manufacturing a high density wiring board.

[0002]

2. Description of the Related Art Copper-clad laminates used in the manufacture of wiring boards include prepregs obtained by electrolytically depositing copper foil on a stainless steel rotating drum and a paper or glass base material impregnated with a thermosetting resin. There is a stack of and. In this case, the main thickness of the copper foil is 18 μm, 35 μm, and 50 μm. As a method for manufacturing a wiring board using the above copper-clad laminate, there are an etched foil method and a semi-additive method in which the copper-clad laminate is etched to perform circuit processing. The etched foil method has a problem of side etching, and it is difficult to form high-density wiring. It depends on the thickness of the underlying metal layer (copper foil) for fine and high-density wiring in the semi-additive method. That is, the thinner the underlying metal layer to be etched, the higher the etching accuracy.

Therefore, when forming high-density wiring, 5
Although it is based on a copper-clad laminate using a thin copper foil of ~ 9 μm, it is an aluminum foil (a thickness of about 50
When mechanically or chemically removing (μm), the aluminum foil does not have mechanical strength, so the aluminum foil may break during peeling, or a large amount of hydrogen gas may be generated when etching away with an etching solution. There is. Other methods for forming a thin base metal layer include electroless plating, vacuum deposition,
There is a sputtering method and the like. The electroless plating method requires a step of treating the surface of the insulating substrate by a physical or chemical method to make the surface hydrophilic and rough, and also has a low adhesive force between the generated metal layer and the substrate.

For this reason, a method has been proposed in which electroless plating is applied to the roughened surface of the copper-clad laminate to which the copper foil is etched to improve the adhesive strength. However, the roughened surface is used in the exposure step during resist pattern formation. However, since the exposure light is diffusely reflected at a position where a resist pattern should not be exposed, a large amount of undeveloped residue occurs. Vacuum deposition methods such as vacuum evaporation and sputtering are stable on smooth substrates.
A metal layer having a thickness of 1 μm or less can be formed, but when a glass cloth-epoxy laminated board or glass cloth-polyimide laminated board is used as the substrate, the water content adsorbed on the glass cloth and the solvent remaining in the resin layer Therefore, under high vacuum required for vapor deposition, sputtering, etc., water and solvent are gasified, and peeling or voids occur at the glass cloth-resin interface.

For these reasons, a method has been proposed in which a vapor deposition or sputtering process is performed in a separate process to form a thin metal layer and then laminated with an organic base material for wiring boards (Japanese Patent Laid-Open No. 53-1140).
74, JP-A-57-72851, JP-A-57-87359, and JP-A-57-142355).

[0006]

However, even in these methods, when the thickness of the metal thin layer is 3 μm or less, the metal corresponding to the intersection of the glass fibers forming the glass cloth of the base material during thermocompression bonding is used. The problem is that the thin layers are damaged.
In this case, increasing the thickness of the thin metal layer reduces damage to the thin metal layer, but using the semi-additive method reduces the wiring width.
In order to stably form ultra-high-density wiring of about 20 to 50 μm, it is essential that the underlying metal be as thin as 3 μm or less. The present invention provides a method for producing an insulating substrate with a thin metal layer, which enables production of a high-density wiring board.

[0007]

According to the present invention, a thin metal layer is formed on a temporary substrate, and the temporary substrate and an insulating base material for a wiring board in which a glass cloth is impregnated with a thermosetting resin are used. In the method for producing an insulating substrate with a thin metal layer, in which the layers are laminated so as to face the insulating base material for the wiring board, integrated by thermocompression bonding, and the temporary substrate is removed, It is a method of manufacturing an insulating substrate with a thin metal layer that is integrated through an organic adhesive layer having a thickness of 5 μm or more after thermocompression bonding.

An embodiment of the present invention will be described with reference to FIG. 1A to 1D are cross-sectional views for explaining the manufacturing process of the present invention. Ube Industries Co., Ltd. polyimide film (trade name UPILEX) 1 on one side using an electron beam vapor deposition device (Japan Vacuum Technology Co., Ltd. EBV-6DA type) thickness of 1μm
The copper layer 2 and the chromium layer 3 having a thickness of 100 A were continuously formed (FIG. 1 (a)). The conditions are shown in the following table.

[0009]

[Table] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Condition Condition Item Unit Unit Copper chrome ━━━━━━━━━━━━ ━━━━━━━━━━━━━━━ Accelerating voltage kV 10 8 Pressure Torr 1 × 10 ^-5 7 × 10 ^-6 Substrate temperature ℃ RT RT Deposition rate A / sec 200 5 ━━━━ ━━━━━━━━━━━━━━━━━━━━━━━

Next, an epoxy adhesive 4 was applied on the chrome layer 3 of this film to a thickness of 35 μm and dried at 80 ° C. for 15 minutes (FIG. 1 (b)). Next, with the adhesive 4 inside, glass epoxy epoxy prepreg (manufactured by Hitachi Chemical Co., Ltd., trade name GEA-67N) was thermocompression bonded at 170 ° C and 40 kgf / cm2 for 40 minutes (Fig. 1 (c)). . Then, the polyimide film was peeled off between the polyimide film 1 and the copper layer 2 (FIG. 1 (d)). As a result of cross-section observation, the adhesive layer thickness is 18μ
Since it was m, no damage to the copper thin layer, which had been a problem in the past, was observed. In this case, the average center roughness of the thin copper layer surface is
It is 0.1 μm.

As the temporary substrate, a film-shaped, plate-shaped or roll-shaped one made of polymer, metal or the like is used. The thin metal layer is not limited to one formed on the entire surface of the temporary substrate, but may be one having a predetermined wiring pattern. The thickness is preferably 5 μm or less,
More preferably, it is 3 μm or less. The thinner the thickness, the more convenient it is to manufacture a high-density wiring board. For thermocompression bonding between the temporary substrate and the insulating base material for the wiring board, the pressure is 10 to 70 kgf / cm, the temperature is 100 to
200 ° C is preferred. The adhesive layer does not include a glass cloth base material and may be provided separately from the wiring board insulating base material.
Further, the resin content impregnated into the glass base material may be increased so that the resin layer on the surface of the glass base material serves as an adhesive layer. The thickness of the adhesive layer should be 5 μm or more after thermocompression bonding. If it is less than 5 μm, damage to the thin metal layer cannot be prevented. The insulating substrate with a thin metal layer obtained by the present invention is a wiring board obtained by subjecting a copper foil to a resist forming surface treatment and then performing resist pattern formation → pattern plating → resist pattern removal → circuit processing by quick etching. To manufacture.

[0012]

According to the present invention, the damage to the thin metal layer at the time of transferring the thin metal layer, which has been a problem in the past, is drastically reduced, and the fine circuit pattern forming process can be stabilized.

[Brief description of drawings]

1A to 1D are cross-sectional views illustrating a manufacturing process of the present invention.

[Explanation of symbols]

 1. Polyimide film 2. Copper layer 3. Chrome layer 4. Adhesive layer 5. Glass cloth substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 17/04 A H05K 3/00 R 3/20 A 7511-4E // B29K 101: 10 B29L 31 : 34

Claims (1)

[Claims] 1. A thin metal layer is formed on a temporary substrate, and
The temporary substrate and the insulating base material for wiring board in which the glass base material is impregnated with the thermosetting resin are superposed so that the thin metal layer of the temporary substrate faces the insulating base material, and integrated by thermocompression bonding (C ) Removing the temporary substrate In the method of manufacturing an insulating substrate with a thin metal layer, the glass cloth and the thin metal layer should be integrated with an organic adhesive layer having a thickness of 5 μm or more after thermocompression bonding. And a method for manufacturing an insulating substrate with a thin metal layer.