Stock material or miscellaneous articles – Composite – Of polyimide
Reexamination Certificate
2001-03-27
2003-04-01
Hampton-Hightower, P. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyimide
C428S458000, C428S216000
Reexamination Certificate
active
06541122
ABSTRACT:
This application claims Paris Convention priority of two Japanese Patent Application Nos. 2000-088278 filed Mar. 28, 2000 and 2000-088279 filed Mar. 28, 2000.
FIELD OF THE INVENTION
The present invention relates to a roll of a web comprising metal film/aromatic polyimide composite film laminate.
BACKGROUND OF THE INVENTION
Aromatic polyimide films show good high temperature resistance, good chemical properties, high electrical insulating property, and high mechanical strength. Therefore, the aromatic polyimide film is widely employed in various technical fields. For instance, an aromatic polyimide film is favorably employed in the form of a continuous metal film/aromatic polyimide film composite web for manufacturing a flexible printed circuit board (FPC), a carrier tape for tape-automated-bonding (TAB), and a tape of lead-on-chip (LOC) structure.
A metal film/aromatic polyimide film composite sheet can be produced by bonding an aromatic polyimide film to a metal film using a conventional adhesive such as an epoxy resin. However, due to low heat-resistance of the conventional adhesive, the produced composite sheet cannot show satisfactory high heat-resistance.
A metal film/aromatic polyimide film composite sheet also can be produced using a thermoplastic polyimide resin.
U.S. Pat. No. 4,543,295 describes a polyimide laminate which is produced by applying a pressure onto a laminated sheet composed of an aromatic polyimide film, a polyimide adhesive, and a metal film in vacuo.
From the viewpoint of industrial production, it is advantageous that the metal film/aromatic polyimide composite sheet is produced in the form of a continuous web by combining a continuous aromatic polyimide film with a continuous metal film using no adhesive. The continuous aromatic polyimide film web is generally produced by heating a continuous aromatic polyamide acid solution film to a high temperature, and the continuous film web is then wound on a core to give a roll of continuous film web. The continuous metal film/aromatic polyimide film web is generally produced by combining the continuous aromatic polyimide film web (which is drawn from the roll) and a continuous metal film web by means of, for instance, a combination of heating rolls.
As a result of the studies made by the present inventors, however, it has been noted that thus produced continuous metal film/aromatic polyimide film web shows poor thermal dimensional stability in the longitudinal direction (i.e., machine direction, MD) when it is cut to give sheets of predetermined dimensions and subjected to the conventional processing such as etching and heat treatment. The poor thermal dimensional stability is disadvantageous, particularly, for the use of the metal film/polyimide film composite sheet in the preparation of electronic parts.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a metal film/aromatic polyimide film composite sheet having a high thermal dimensional stability.
As a result of the studies made by the present inventors, it has been discovered that the thermal dimensional stability of a metal film/aromatic polyimide film composite sheet obtained by cutting a continuous metal film/aromatic polyimide film composite web is enhanced by obtaining a roll of a continuous metal film/aromatic polyimide film composite web having a low heat shrinkage ratio in the longitudinal direction.
Accordingly, the present invention resides in a roll of an aromatic polyimide composite web comprising a non-thermoplastic aromatic polyimide base film and a thermoplastic aromatic polyimide cover film laminated on the base film, in which the polyimide composite web shows a heat shrinkage ratio of less than 0.1% at 300° C., in each of a longitudinal direction (or a machine direction: MD) and a width direction (or a traverse direction: TD).
The above-mentioned roll of an aromatic polyimide composite web can be favorably produced by a method which comprises heating a roll of an aromatic polyimide composite web comprising a non-thermoplastic aromatic polyimide base film and a thermoplastic aromatic polyimide cover film laminated on the base film, the polyimide composite web showing a heat shrinkage ratio of more than 0.1% at 300° C. in a longitudinal direction, at a temperature in the range between 150° C. and a glass transition temperature of the thermoplastic aromatic polyimide cover film, for a period of at least one minute.
The invention further resides in a roll of a web comprising an aromatic polyimide composite film and a metal film fixed to the composite film in which the polyimide composite film comprises a non-thermoplastic aromatic polyimide base film and a thermoplastic aromatic polyimide cover film laminated on the base film, the polyimide composite film showing a heat shrinkage ratio of less than 0.1% at 300° C.
The above-mentioned roll of a metal film/aromatic polyimide composite film web can be favorably produced by a method which comprises heating a roll of a web comprising an aromatic polyimide composite film and a metal film fixed to the composite film in which the polyimide composite film comprises a non-thermoplastic aromatic polyimide base film and a thermoplastic aromatic polyimide cover film laminated on the base film, the polyimide composite film showing a heat shrinkage ratio of more than 0.1% at 300° C. in a longitudinal direction, at a temperature in the range between 150° C. and a glass transition temperature of the thermoplastic aromatic polyimide cover film, for a period of at least one minute.
DETAILED DESCRIPTION OF THE INVENTION
The aromatic polyimide composite web of the invention comprises a non-thermoplastic aromatic polyimide base film and a thermoplastic aromatic polyimide cover film laminated on the base film. The thermoplastic polyimide cover film is preferably placed on each surface side of the non-thermoplastic aromatic polyimide base film. The web preferably has a width of 40 cm or larger.
On the thermoplastic aromatic polyimide cover film of the composite film, a metal film is fixed. If the composite film has a thermoplastic aromatic polyimide cover film on each surface side, a metal film is preferably fixed onto each cover film.
Examples of the metal films include copper films, stainless steel films, aluminum films, gold films, and metal alloy films. The metal film generally has a thickness of not larger than 70 &mgr;m, preferably 3 to 35 &mgr;m. The metal film preferably has a surface roughness (Rz) of 7 &mgr;m or less, more specifically 0.5 to 5 &mgr;m.
The aromatic polyimide composite film has a thermoplastic surface at least on the side to be brought into contact with the metal film.
The composite film preferably has a thickness of 7 to 125 &mgr;m, specifically 7 to 50 &mgr;m, and a linear expansion coefficient (in the MD-direction as well as in the TD direction) of not higher than 30×10
−6
cm/cm/°C., particularly 10×10
−6
to 25×10
−6
cm/cm/°C., in the temperature range of 50 to 200° C. A modules of tensile elasticity (in the MD direction, according to ASTM-D882) preferably is not less than 300 kg/mm
2
.
The thermoplastic aromatic polyimide is preferably produced from the following combination of an aromatic tetracarboxylic dianhydride and an aromatic diamine compound:
(1) 2,3,3′,4′-biphenyltetracarboxylic dianhydride and 1,3-bis(4-aminophenoxybenzene);
(2) a combination of 2,3,3′,4′-biphenyltetracarboxylic dianhydride and 4,4′-oxydiphthalic dianhydride and 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane; or
(3) a combination of pyromellitic dianhydride and 4,4′-oxydiphthalic dianhydride and 1,3-bis(4-aminophenoxybenzene).
The thermoplastic polyimide film (or layer) can be prepared from a dope solution containing an aromatic polyamide acid in an organic solvent, which is produced from one of the combinations of the aromatic tetracarboxylic dianhydride(s) and diamine compound(s) by a reaction in an organic solvent at a temperature of 100° C. or lower, particularly at a temperature of 20 to 60° C.
Alternatively, the t
Hosoma Toshinori
Kato Katsumi
Yamamoto Tomohiko
Hampton-Hightower P.
Reed Smith LLP
Ube Industries Ltd.
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