JPH03155933A - Laminate - Google Patents

Abstract

PURPOSE:To obtain sufficient stability at the time of the exposure to a solder bath by enhancing close adhesiveness and eliminating the release of a film at the time of high temp. by forming a membrane based on copper having specific peel strength to the single surface or both surfaces of a heat-resistant plastic film. CONSTITUTION:In forming a membrane based on copper to a heat-resistant plastic film, a membrane of nickel, chromium or oxide thereof is preliminarily formed to the plastic film in thickness of 500Angstrom or less to set the substantial peel strength of the copper membrane formed thereon to 0.5kg/cm or more. As the thickness of the preliminarily formed membrane of nickel, chromium or oxide thereof increases, the peel strength of the copper membrane can be enhanced but, on the other band, the characteristics of the copper membrane are damaged and, therefore, the thickness of the membrane is pref. set to 500Angstrom or less. Further, when the membrane is excessively thin, peel strength is insufficient and the release phenomenon of the copper membrane becomes easy to generate and, therefore, the thickness thereof is set to 50Angstrom or more.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a transparent and heat-resistant plastic film laminated with metal. More specifically, the present invention relates to a laminate in which nickel, chromium, or an oxide film thereof is formed in advance, and copper is formed thereon.

[Background technology]

Thin metal films formed on heat-resistant plastic films such as polyethylene terephthalate and polyimide are widely used in applications such as flexible circuit boards that take advantage of their excellent mechanical, electrical, and thermal properties. . For example, copper laminates with polyimide as a substrate are more commonly used because of their good heat resistance.

However, polyimide film is colored and has poor transparency, so it cannot be used in fields that require light transparency.Also, when polyethylene terephthalate film is used, it has poor transparency. Although this is sufficient, there was a problem in terms of heat resistance.

On the other hand, polyether ether getone, polyether sulfone, etc. have been developed as plastic films with excellent transparency and heat resistance of 180°C or higher, and the potential of this type of metal laminate has been expected. ,
The adhesive strength with the copper thin film was extremely low, and even if a film could be formed, it would not be usable because it would easily peel off during processing or when exposed to a solder bath.

[Problem to be solved by the invention]

The present invention aims to solve these problems of the prior art, and in particular, a transparent and heat-resistant plastic film J,
1. The purpose is to form a metal thin film containing copper as a self-contained material, and to create a metal laminate whose adhesion strength does not cause peeling even in a solder bath and has a peel strength of 0.5 kg/cm or more. That is.

[Disclosure of the Invention] The present invention has the following configuration to achieve the above object. That is, it is a heat-resistant plastic film laminate characterized by having a thin film mainly made of copper with a peel strength of 0.5 kg/cm or more formed on one or both sides, and preferably a plastic film mainly made of copper. When forming a thin film (hereinafter referred to as copper thin film), 500
A laminate characterized in that by forming a thin film of nickel or chromium or their oxides with a thickness of Å or less, the actual peel strength of the copper thin film formed thereon is 0.5 kg/cm or more. be.

In the present invention, the thin film of nickel or chromium or their oxides and the thin copper film can be formed by various methods such as vacuum evaporation, sputtering, and ion blasting. Further, although both may be formed continuously or each may be formed independently, continuous film formation is more efficient and preferable.

Formation of the oxide thin film is achieved by making the atmosphere slightly oxygen. It is preferable that the thickness of the copper film is sufficient to exhibit its function, and any method can be selected, but forming a thin film with a thickness of 5 μm or more using only the vacuum evaporation method or sputtering method has a high productivity. This is difficult in practice due to poor quality, and when a film thickness of 5 μm or more is required, it is desirable to use methods such as electroplating in combination. Note that it is of course possible to use the electroplating method in combination even if the thickness is 5 μm or less. The thickness of the copper gJ film is about 500 to 100 μm, preferably lltm to
It is about 100 μm.

The thicker the nickel, chromium, or oxide thin film formed in advance, the higher the peel strength of the copper thin film, but on the other hand it impairs the properties of the copper thin film, so it is preferably 500 Å or less. . If it is too thin, the peel strength will not be sufficient and the copper thin film will likely peel off. Therefore, the thickness of the thin film layer of nickel or chromium or their oxides should be between 5 and 5
00 people is desirable. More preferably, the number is 50 to 200 people.

Plastic films as base materials used in the present invention include polyethylene naphthalate, polyetheretherketone, polyethersulfone, and polysulfone.

Further, a copolymer or a mixture thereof may be used.

[Example 1] Polyethylene naphthalene 1 with a thickness of 50 μm to 100 μm
・A 200-layer thick layer of chromium was formed on each film of polyetherethergetone, polyethersulfone, and polysulfone using a sputtering method, and then 5,000 layers of copper was layered on top of the film using a sputtering method, followed by electroplating. The peel strength was measured for a copper film having a thickness of 3 μm. All laminated films have a peel strength of IK g/cm or higher, and their adhesion does not peel off even when exposed to high temperatures of 180°C or higher.
It was sufficient.

[Example 2] On 100 μm polyetheretherketone and hypopolyethersulfone, 50 layers of Ni-Nkel were formed by sputtering, and then 3,000 layers of copper were continuously layered, and then copper was further layered by electroplating. Peel strength was measured for the film with a thickness of 5 μm. The peel strength of these is 1
．． They were 2Kg/cm and 0.9Kg/cm.

[Example 3] A partial oxide film of Ninkel was formed on 100 μm polyetheretherketone and polyethersulfone by 50 people using a reactive sputtering method, and then 3000 people used a sputtering method to stack the same, and then electroplated. The peel strength was measured for a film in which the copper thickness was 5 μm using the method. Their peel strength was 1.3Kg/cm and 1.2Kg/cm.

[Comparative example]

50 and 100 μm thick polyethylene terephthalate and polyether sulfone were directly coated with 3000 copper by vacuum evaporation, and then 3 μm thick copper was deposited by electroplating.
The peel strength of the film was measured. The peel strength of all samples was completely less than 0.5 kg/cm, and when polyethylene terephthalate was used as the base material, a peeling phenomenon was already observed at a high temperature of 150°C.

〔Effect of the invention〕

According to the present invention, a copper thin film with a peel strength of 0.5 Kg/cm or more could be formed on a heat-resistant transparent plastic film. Note that the film laminate on which the metal film containing copper as the main component obtained in this way is formed can be patterned in any desired manner by performing an etching process.

What is noteworthy is that in this case, especially when a polyimide film is used, the etched surface becomes transparent, resulting in a surprisingly new phenomenon that is significantly different from conventional polyimide-copper laminates. We would like to particularly emphasize that the present inventors have found the following. Therefore, optical applications can be expected even when used as a flexible circuit board. At the same time, high peel strength was obtained, resulting in improved adhesion, no peeling of the film at high temperatures, and sufficient stability even when exposed to a solder bath.

Claims (1)

[Scope of Claims] 1) A heat-resistant plastic film laminate characterized in that a thin film mainly composed of copper with a peel strength of 0.5 kg/cm or more is formed on one or both sides. 2) The laminate according to claim 1, wherein a nickel, chromium, or oxide thin film layer of 500 Å or less is previously formed on the surface of the film when forming the copper thin film. 3) The laminate according to claim 1, wherein the plastic film is a transparent and heat-resistant plastic film selected from polyethylene naphthalate, polyether ether ketone, polyether sulfone, and polysulfone.