Stock material or miscellaneous articles – Composite – Of polyimide
Reexamination Certificate
2000-02-03
2002-08-27
Hampton-Hightower, P. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyimide
C428S411100, C428S457000, C428S458000, C428S221000, C528S170000, C528S353000
Reexamination Certificate
active
06440576
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a metal-plated aromatic polyimide film in which the plated metal is fixed to the surface of the aromatic polyimide film with high bonding strength.
BACKGROUND OF THE INVENTION
An aromatic polyimide film shows high heat resistance as well as good electric characteristics, and are widely employed as material for producing various electronic devices. The aromatic polyimide film, however, has such a disadvantageous feature as poor adhesive property to an adhesive which is ordinarily employed for constituting electronic devices. Further, a metal film deposited on the aromatic polyimide film by sputtering shows poor adhesion to the polyimide film and is easily peeled off from the polyimide film. Therefore, studies for improving the poor adhesive property of an aromatic polyimide film have been made and reported.
U.S. Pat. No. 5,218,034 describes a polyimide film having improved adhesion and thermal durability containing from 0.02 to 1% by weight of tin based on the weight of the film.
U.S. Pat. No. 5,543,222 describes a vacuum metallized polyimide film comprising an aromatic polyimide layer containing a hydrocarbyl tin compound in oxidation state (II) or (IV) as an additive and metal plated layer bonded integrally with high bonding strength or high adhesion via a vacuum deposited metal layer without the use of an adhesive.
U.S. Pat. No. 5,272,194 describes a strengthened polyimide film having improved adhesion when bonded to a metal foil via a heat-resistant adhesive, containing from 0.02 to 1% by weight, based on the weight of the film, of an organo-metallic compound wherein the metal is tin, bismuth or antimony.
U.S. Pat. No. 5,227,244 describes a polyimide film having improved adhesion which is prepared by coating the surface of a partially cured or partially dried polyamide acid film with an organic solvent solution of a metal salt and heating the coated film to convert the polyamide acid to polyimide and dry the film. The metal salt is a salt of Sn, Zn, Cu, Fe, Co, Mn, or Pd. Thus treated surface can be combined with a copper metal foil via an acrylic resin adhesive.
Japanese Patent Provisional Publications 59-86634 and H2-134241 both describe that a polyimide film can be improved in its adhesion by plasma discharge processing.
Japanese Patent Provisional Publication H1-214840 describes a process for preparing a polyimide resin pattern which comprises the steps of forming a film of an aluminum alcoholate or a chelated aluminum compound on a film of polyimide or its precursor, coating a photoresist on the aluminum-compound layer, imagewise exposing the photoresist coat to light, and etching the light-exposed photoresist.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a metal-plated aromatic polyimide film in which a metal film is plated on the polyimide film with high strength bonding.
It is another object of the invention to provide a metal-plated aromatic polyimide film in which a metal film is plated on the polyimide film with high strength bonding which is produced easily in industry.
The present invention resides in metal-plated aromatic polyimide film comprising an aromatic polyimide resin film, a surface layer of which contains a palladium metal or a palladium compound dispersed therein, and a metal layer which is chemically plated on the surface layer of the polyimide resin film.
It is preferred that the metal-plated aromatic polyimide film of the invention further contains an aluminum metal or an aluminum compound in the surface layer of the aromatic polyimide resin film.
On the chemically plated metal-plated aromatic polyimide film of the invention, an electrolytically plated metal layer is easily formed.
The palladium metal- or palladium compound-containing surface layer of the polyimide film of the metal-plated aromatic polyimide film of the invention is preferably formed by placing a palladium compound on a self-supporting film of an aromatic polyimide precursor and heating the self-supporting film having the palladium compound thereon to a temperature such as 420° C. or higher, at which the polyimide precursor is converted into its corresponding aromatic polyimide.
The palladium metal- or palladium compound-containing surface layer of the polyimide film is also favorably formed by coating or spraying a solution of a palladium compound on a self-supporting film of an aromatic polyimide precursor and heating the self-supporting film having the palladium compound thereon to a temperature such as 420° C. or higher, at which the polyimide precursor is converted into its corresponding aromatic polyimide.
The palladium metal- or palladium compound-containing surface layer of the polyimide film is also favorably formed by extruding an aromatic polyimide precursor solution containing no palladium compound and an aromatic polyimide precursor solution containing a palladium compound simultaneously from a die and placing one extruded precursor solution on the other precursor solution to give a combined precursor solution film, and heating the precursor solution film to a temperature such as 420° C. or higher, at which the polyimide precursor is converted into its corresponding aromatic polyimide.
DETAILED DESCRIPTION OF THE INVENTION
In the metal-plated aromatic polyimide film of the invention, the plated metal film can be placed on one side or both sides of the polyimide film.
The polyimide film of the invention which has a surface layer containing a palladium metal or a palladium compound comprises a resin matrix of aromatic polyimide resin. The aromatic polyimide resin is preferably composed of an aromatic tetracarboxylic acid residue and an aromatic diamine residue. The aromatic tetracarboxylic acid residue is preferably derived from an aromatic tetracarboxylic dianhydride, and the aromatic diamine residue is preferably derived from an aromatic diamine. A small portion of the aromatic tetracarboxylic acid residue can be replaced with an aliphatic tetracarboxylic acid residue, and a small portion of the aromatic diamine residue can be replaced with an aliphatic diamine. The polyimide resin can contain an aminodicarboxylic acid residue such as 4-aminophthalic acid residue, 4-amino-5-methylphthalic acid residue, or 4-(3,3′dimethyl-4-anilino)phthalic acid residue, in addition to the aromatic tetracarboxylic acid residue and the aromatic diamine residue.
Examples of preferred aromatic tetracarboxylic acid dianhydrides include 3,3′,4,4′-biphenyltetracarboxylic dianhydride(s-BPDA), 2,3,3′,4′-biphenyltetracarboxylic dianhydride(a-BPDA), pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and bis(3,4-dicarboxyphenyl)ether dianhydride (i.e., oxydiphthalic dianhydride).
Examples of the aromatic diamines include p-phenylene diamine and 4,4′-diaminodiphenyl ether. A portion of the aromatic diamine can be replaced with an aromatic diamine having plural benzene rings and a flexible structure such as 4,4′-diaminodiphenyl sulfide, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenyl)diphenyl ether, 4,4′-bis(4-aminophenyl)diphenylsulfone, 4,4′-bis(4-aminophenyl)diphenylsulfide, 4,4′-bis(4-aminophenyl)diphenylmethane, 4,4′-bis(4-aminophenoxy)diphenyl ether, 4,4′-bis(4-aminophenoxy)diphenylsulfone, 4,4′-bis(4-aminophenoxy)diphenylsulfide, 4,4′-bis(4-aminophenoxy)diphenylmethane, 2,2-bis[4-(aminophenoxy)phenyl]propane, or 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, an aliphatic diamine such as 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminodecane, or 1,12-diaminododecane, and other aromatic diamines such as xylylenediamine..
The aromatic polyimide resin preferably has a low linear expansion coefficient such as that in the range of 10×10
−6
to 25×10
−6
cm/cm/° C., in the temperature range of 50 to 250°
Shimokawa Hiroto
Takagi Jun
Yamamoto Tomohiko
Hampton-Hightower P.
Reed Smith LLP
Ube Industries Ltd.
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