JPS5939545A - Manufacture of flexible circuit material - 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 The present invention relates to a method for manufacturing flexible circuit materials. More specifically, the present invention relates to a method of firmly adhering metal foil to a polyimide film and obtaining a flexible circuit material with good heat resistance.

In recent years, with the development of the electronic industry, there has been an increasing demand for simplified mounting methods, miniaturization, high reliability, and high performance of various electronic devices, and various flexible circuit materials have been proposed in response to these demands.

As insulating substrates for flexible circuit materials, thermoplastic resins with high flexibility are generally used, such as polyester films, polyethylene films, polyvinyl chloride films, polyimide films, polyamide-imide films, and the like. In particular, polyimide film 1 has excellent mechanical properties, heat resistance, and dimensional stability, and its use in bonding with metal foil is useful for wiring components of devices that require heat resistance and precision. It is suitable as a material for In addition, flexible circuit materials using polyimide film as a substrate have the advantage of being able to be soldered at temperatures higher than the processing temperature of eutectic solder (260°C), and also have excellent mold releasability from other materials. It has the following characteristics. However, this advantage of having good mold releasability has the disadvantage that it has poor surface activity and is difficult to adhere to metal foil. Therefore, in order to improve the adhesion of this polyimide film, the film surface is mechanically roughened or treated with an alkaline solution to improve the adhesion of the surface. Attempts have been made to bond the material with foil, but no practically satisfactory results have been obtained.

On the other hand, flexible circuit materials are required to have heat resistance that can withstand the soldering process. Therefore, heat-resistant adhesives such as polyimide resin, polybenzimidazole resin, maleimide adhesive, epoxy adhesive, or phenol adhesive are used alone. Adhesives have the disadvantage of poor adhesion to polyimide films.

The present invention aims to solve the above-mentioned drawbacks and provide a flexible circuit material that firmly adheres polyimide film and metal foil and has good heat resistance. , a method for producing a flexible circuit material, characterized in that an adhesive with good adhesiveness is placed on the polyimide film side and an adhesive with good heat resistance is placed on the metal foil side to bond them together.

Adhesives with good adhesion properties include those with a peel strength of around 350 P/cm or more, such as polyester adhesives, rubber adhesives, and nylon adhesives. Agents etc. can be used.

As an adhesive with good heat resistance, for example, 2
Any material that does not peel off or swell from the polyimide film substrate when held at a temperature of 60°C for 10 seconds or more may be used. For example, the above-mentioned polyimide resin, polybenzimidazole resin, maleimide adhesive, epoxy adhesive An adhesive, phenol butyral resin, or the like can be used.

The drawings show enlarged cross-sectional views of the flexible circuit material according to the present invention, where 1 is a polyimide film, 2 is an adhesive with good adhesion, 3 is an adhesive with good heat resistance, and 4 is a copper foil.

The entire adhesive layer has a thickness of, for example, about 20 to 30 μm, and a heat-resistant adhesive 3 is applied thereon to a thickness of 90 to 50 times the total thickness of the adhesive. 3, the polyimide film 1 and the copper foil 4 are bonded together.

In addition, for the above bonding, apply an adhesive with good adhesiveness to the polyimide film, apply an adhesive with good heat resistance to the copper foil, laminate both adhesive sides together, and attach the copper foil to the polyimide film. may be joined together.

The flexible circuit material according to the present invention uses an adhesive with good heat resistance on the copper foil side, so it has enough heat resistance to withstand the soldering process, and uses an adhesive with good adhesiveness on the polyimide film side. Since the bonding with the peripheral adhesive is also done closely, the bonding strength between the polyimide film and the copper camphor is also excellent.

Examples and comparative examples are shown below.

Example 1 A polyvarnish = 5-chill adhesive was applied to a thickness of 5 to 8 μm on a polyimide film having a thickness of 5 μm, and then a phenol butyral resin adhesive was applied to a thickness of 15 to 18 μm on top of this. A copper foil was attached to the polyimide film and the copper foil was bonded to the polyimide film.

Comparative Example 1 Only a polyester adhesive was applied to the same polyimide film as in Example 1, and a copper foil was attached thereto to join the polyimide film and the copper foil.

Comparative Example 2 Only a 7-functional butyral resin adhesive was applied to the same polyimide film as in Example 1, and a copper foil was attached thereto to join the polyimide film and the copper foil.

Example 2 One layer of rubber adhesive was applied to a 5 μm thick polyimide film.
After applying a cloth to a thickness of 0 μm, a phenol butyral resin adhesive was applied to a thickness of 4 μm, and a copper foil was attached to this to bond the 6-copper foil to the polyimide film.

Comparative Example 3 The same polyimide film as in Example 2 was coated with only a rubber adhesive, and a copper foil was pasted thereon to bond the copper foil to the polyimide film.

The peel strength and soldering heat resistance of the flexible circuit materials obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were examined, and the results are shown in Table 1.

According to Table 1, Examples 1 and 2 exhibited solder heat resistance that withstood the processing temperature (approximately 260°C), and at the same time had high peel strength. Comparative Examples 1 to 3 are inferior in either tear strength or solder heat resistance. Therefore, according to the method of the present invention, it is possible to provide a flexible circuit material that has excellent heat resistance, which is required for a flexible circuit material, and has good adhesiveness between a polyimide film and a metal foil.

[Brief explanation of drawings]

The figure shows an enlarged cross-sectional view of a flexible circuit material according to the invention. ■...Polyimide film, 2...Adhesive with good adhesion, 3...
Adhesive with good heat resistance, 4...Copper foil. Commissioner of the Patent Office Kazuo Wakasugi 1. Indication of the case: 1982 Patent Application No. 151176 2. Name of the invention: Process for manufacturing flexible circuit materials 3. Relationship with the person making the amendment: Patent applicant address 4. Person: 107 Address: 7th Floor, New Akasaka Building, 3-2-3 Akasaka, Minato-ku, Tokyo Telephone: (586) 0108 Ken 0109 Name: (6006) Patent Attorney Takashi Okuyama Contents of male amendment (1) “Inventor” in the application 's address'r'Kf-i,'
I am corrected by saying "Ki4hana". (2) [Certificate file] of ``address of inventor other than above'' in the application.
is corrected to "¥4k". (3) "Polyethylene film" was deleted from lines 5 and 6 of page 2 of the specification. 232-

Claims (1)

[Claims] The feature is that the polyimide film and metal foil are bonded by placing an adhesive with good adhesive properties on the polyimide film side and an adhesive with good heat resistance on the metal foil side between the polyimide film and the metal foil. A method for manufacturing a flexible circuit material.