Stock material or miscellaneous articles – Composite – Of polyimide
Reexamination Certificate
2002-10-11
2004-10-26
Hightower, P. Hampton (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyimide
C428S411100, C428S458000, C428S216000, C528S125000, C528S128000, C528S170000, C528S172000, C528S173000, C528S183000, C528S187000, C528S220000, C528S229000, C528S350000, C528S353000
Reexamination Certificate
active
06808818
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fusible polyimide, a fusible polyimide film, a composite polyimide film having a fusible surface, and a metal film/composite polyimide film laminate, and a metal film/composite polyimide film/metal 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, and therefore are widely employed in a variety of technical fields. For instance, an aromatic polyimide film is favorably employed in the form of a continuous aromatic polyimide film/metal film laminate structure 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.
The aromatic polyimide film/metal film laminate can be produced by bonding a 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.
For obviating the above-mentioned problem, a variety of bonding methods have been proposed. For instance, an aromatic polyimide film/metal film laminate sheet is manufactured by producing a copper metal film on an aromatic polyimide film by electro-plating. Otherwise, an aromatic polyamide solution (i.e., a solution of a precursor of an aromatic polyimide resin) is coated on a copper film, dried, and heated for producing an aromatic polyimide film on the copper film.
An aromatic polyimide film/metal film composite sheet also can be produced using a thermoplastic polyimide resin.
U.S. Pat. No. 4,543,295 describes that a metal film/aromatic polyimide film laminate in which the metal film is bonded to the polyimide film at a high bonding strength is prepared by combining, by heating under pressure, a metal film and a composite aromatic polyimide film composed of a highly heat resistant substrate film and a thermoplastic thin polyimide layer bonded to the substrate film at a high bonding strength.
Each of Japanese Patent Publication No. 7-102648 and Japanese Patent Provisional Publication No. 10-138,318 describes a composite polyimide film produced by a co-extrusion method.
SUMMARY OF THE INVENTION
It is an object of the invention to provide fusible aromatic polyimide which can be bonded to a metal film, particularly, a stainless steel film and a copper film, with a high strength and which can be easily etched by a chemical etching method (or wet etching method).
The invention resides in fusible polyimide showing a fusion endothermic peak in a differential scanning calorimeter (DCS), preferably at a temperature of 340-380° C., which has a recurring unit of the formula (1):
in which Ar
1
is a mixture of residues of tetracarboxylic dianhydrides comprising 12-25 mol. % of a residue of pyromellitic dianhydride, 5-15 mol. % of a residue of 3,3′4,4′-benzophenonetetracarboxylic dianhydride, and a remaining mol. % of a residue of 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and Ar
2
is an aromatic diamine residue comprising 1,3-bis (4-aminophenoxy)benzene.
The invention also resides in a fusible polyimide film showing a fusion endothermic peak in a differential scanning calorimeter, preferably at a temperature of 340-380° C., which comprises aromatic polyimide having a recurring unit of the aforementioned formula (1).
The invention further resides in a composite polyimide film comprising a polyimide substrate sheet and a fusible polyimide film united to the substrate sheet, in which the fusible polyimide film shows a fusion endothermic peak in a differential scanning calorimeter, preferably at a temperature of 340-380° C., and comprises aromatic polyimide having a recurring unit of the formula (1).
The invention further resides in a metal/composite polyimide film laminate comprising the above-mentioned composite polyimide film and a metal film combined to the composite polyimide film via the fusible polyimide film.
The invention furthermore resides in a metal/composite polyimide film/metal laminate comprising a first metal film having a thickness of 3 to 35 &mgr;m, a composite polyimide film having a thickness of 7 to 150 &mgr;m, and a second metal film having a thickness of 30 to 200 &mgr;m, in which the composite polyimide film comprises a polyimide substrate sheet and a fusible polyimide film united to the substrate sheet, in which the fusible polyimide film shows a fusion endothermic peak in a differential scanning calorimeter and comprises aromatic polyimide having a recurring unit of the aforementioned formula (1).
The invention furthermore resides in a metal film/composite polyimide film/metal film laminate in which each metal film independently is a copper film or a stainless steal film, comprising a first metal film having a thickness of 3 to 35 &mgr;m, a composite polyimide film having a thickness of 7 to 150 &mgr;m, and a second metal film having a thickness of 3 to 200 &mgr;m, in which the composite polyimide film comprises a polyimide substrate sheet and a fusible polyimide film united to each surface of the substrate sheet, in which the fusible polyimide film shows a fusion endothermic peak in a differential scanning calorimeter, the composite polyimide film shows a modulus in tension in the range of 400 to 1,000 kgf/mm
2
at 25° C. in machine direction and traverse direction, the composite polyimide film shows a chemical etchable rate of 2.0 &mgr;m/min. or more, and both of the metal films are bonded to the composite polyimide film at 90° peel strength of 0.8 kgf/cm or more.
The chemical etchable rate is determined by the following procedure:
A specimen (i.e., laminate of a metal film/polyimide film/metal film, thickness: 20 &mgr;m) is immersed in an etching solution (composition: 36 wt. % of potassium hydroxide, 37 wt. % of monoethanol amine, and 27 wt. % of water) heated to 80° C. Thereafter, a period of time required for completely dissolving the polyimide film in the etching solution is measured.
REFERENCES:
patent: 4795798 (1989-01-01), Tamai et al.
patent: 4923968 (1990-05-01), Kunimune et al.
patent: 5171828 (1992-12-01), Meterko et al.
patent: 5298331 (1994-03-01), Kanakarajan et al.
patent: 5300619 (1994-04-01), Okada et al.
patent: 5306741 (1994-04-01), Chen et al.
patent: 5338826 (1994-08-01), St. Clair et al.
patent: 5418066 (1995-05-01), Chen et al.
patent: 6133408 (2000-10-01), Chiu et al.
patent: 6143399 (2000-11-01), Kohno et al.
patent: 6605366 (2003-08-01), Yamaguchi et al.
Ozawa Hideki
Yamamoto Shigeru
Hampton Hightower P.
Reed Smith LLP
Ube Industries Ltd.
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