JPH0476783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Prior Art] The present invention relates to a method for manufacturing an insulating metal foil for circuits. As a substrate material conventionally used for flexible printed circuits, a material made by bonding copper foil to a polyimide film or a polyester film is generally used. However, after bonding the film material to a conductive metal foil, such as a copper foil, using an adhesive, these substrate materials require a long period of time to fully cure the adhesive and satisfy the required characteristics. (6-10 hours)
Post cure is required.

As an alternative to these laminating methods, the present inventors have proposed a method of manufacturing an insulating metal foil for circuits by forming an insulating layer on one side of a metal foil by electrodeposition. According to this method, one side of the metal foil can be coated with any desired thickness, and the time-consuming post-curing required in conventional lamination methods is not required, so production efficiency is significantly improved.

However, in the method of forming insulation by electrodeposition, the film is baked in the baking process, so
Residual stress generated by the crosslinking reaction of the film during baking is present in the film after baking, so when the circuit is written and etched, the metal is removed and the remaining film shrinks slightly, creating a dense pattern. In this case, there was a drawback that the dimensions did not match. In particular, when the thickness of the metal foil was 150 μm or less, especially 100 μm or less, the shrinkage of the film was large.

[Summary of the invention]

The present invention was made for the purpose of improving the conventional drawbacks in dimensional stability in methods for manufacturing single-sided insulated metal foils by electrodeposition.

That is, this is a method of making an insulated metal foil for a circuit by bonding a metal foil to the insulating surface of a single-sided insulated metal foil that is insulated by electrodeposition on one side of the metal foil.

According to the present invention, there is no poor dimensional stability due to shrinkage that was conventionally seen during etching or soldering, and it has characteristics equivalent to polyimide type flexible printed circuits made by lamination.
And by pasting metal foil on the back side,
This improves thermal conductivity.

The metal foil used in the present invention includes highly conductive metals such as copper, aluminum, and nickel, especially rolled or electrolytic copper, as well as anodized aluminum,
Foils of iron, Zn-plated iron, or other materials with excellent thermal conductivity are used. The thickness of the foil is preferably 150 μm or less, particularly 10 to 100 μm. In addition,
At least one of the two layers of metal foil in the present invention is a highly conductive metal foil for forming a circuit.

In that case, it may be electrodeposited on a highly conductive metal foil or a thermally conductive metal foil, and then the thermally conductive metal foil or the thermally conductive metal foil may be laminated on the electrodeposited insulating layer.

The effects of the present invention will be described below in Examples and Comparative Examples.

Comparative example 1 V551, an acrylic anionic electrodeposited varnish
-20 (manufactured by Ryoden Kasei), width 250mm thickness 50μ
Continuously (line speed 3.0 m/min) using the copper foil as an anode on a rolled copper foil with masking tape pasted on one side of the copper foil.
After electrodeposition, immersion in dimethylformamide and temperature
The film was passed through a baking oven at 200°C to obtain a single-sided insulated metal foil (thickness: 50μ).

After screen-printing a circuit on the single-sided insulating metal foil obtained as above with a circuit width and inter-circuit length of 1 mm, etching and measuring the length between the circuits, it was found that the circuit interval had shrunk by 0.05 mm. Ta.

Example 1 A single-sided insulated metal foil obtained in the same manner as Comparative Example 1 was cut into pieces of 500 mm in length and 250 mm in width, and aluminum foil of the same size with a thickness of 100 μm was coated with Pyralax adhesive (Du
(manufactured by Pont), pressure 40Kg/cm ² temperature x time
Heat pressing was performed at 190°C for 10 minutes to obtain an insulating metal foil for copper-clad circuits with aluminum foil attached.

When this was formed into a circuit with the same dimensions as Comparative Example 1 and the inter-circuit dimensions were measured, no dimensional change was observed.

Example 2 Electrodeposition was performed on one side of galvanized iron foil with a thickness of 100 μm using the same varnish as in Example 1 under the same conditions.
A 50 μm single-sided insulated metal foil was obtained. This width is 250mm,
After cutting into a length of 500 mm, the insulating layer and copper foil were bonded together under the same conditions as in Example 1 using Pyralax (Du Pont) as an adhesive. At the same time, etching was performed after circuit formation, but there was no dimensional change before and after etching.

Claims (1)

[Claims] 1. A method for manufacturing an insulating metal foil for circuits, which is obtained by bonding a metal foil to the insulating surface of a single-sided insulated metal foil that is insulated by electrodeposition on one side of the metal foil.