Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1995-02-22
1997-04-15
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528125, 528128, 528170, 528172, 528173, 528185, 528188, 528220, 528229, 528350, 4284111, 428456, 4284735, 428901, 264258, 4273722, 4273831, 427384, C08G 7310
Patent
active
056210680
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to thermoplastic polyimide polymer, thermoplastic polyimide film, polyimide laminate, and a method of manufacturing the polyimide laminate. More particularly, the invention relates to thermoplastic polyimide polymer featuring distinguished thermal resistant property, solid adhesion under low temperature, and low hygroscopic degree; thermoplastic polyimide film which is produced from this thermoplastic polyimide polymer and applicable to the formation of adhesive film and base film or cover-lay film for producing flexible printed circuit boards (FPC); polyimide laminate which consists of a laminate of layers of the above identified thermoplastic polyimide film and nonthermoplastic polyimide film and is usable for bilateral adhesive sheets, flexible copper coated laminated boards, or cover-lay film; and the invention also relates to the method of manufacturing the polyimide laminate.
BACKGROUND ART
Recently, as a result of rapidly promoted functional capacity and down-sizing of a variety of electronic apparatuses, there is a growing demand for further reduction of the size and weight of electronic parts built therein. In particular, there is a sharply growing demand for flexible printed circuit boards (hereinafter merely referred to as FPC) for mounting a variety of electronic parts against conventional rigid printed circuit boards.
Basically, any of conventional flexible printed circuit boards has such a structure in which "cover-lay film" is coated on the surface of circuit patterns formed on a soft and thin base film. At present, in order to satisfy essential characteristics such as mechanical characteristic, electrical characteristic, chemical resistant property, thermal resistant property, and resistance to environmental condition normally being required for the base film and the cover-lay film, polyimide film has been used most extensively.
Sequential processes for manufacturing such a conventional flexible printed circuit board comprise the following: Initially, a flexible copper-coated laminate (FCCL) is formed by laminating a base polyimide film and a copper foil. Next, a resist pattern is formed on the produced conductor via a screen printing process or a photo-resist process, and then a circuit pattern is formed by executing an etching process. Finally, a cover-lay film is laminated on the surface of circuits of the film having the circuit pattern formed therein. When executing the above sequential processes, either acrylic adhesive agent or epoxy adhesive agent is mainly used for laminating :the base film with copper foil or laminating the cover-lay film on the surface of the built-in circuits.
Nevertheless, any of these conventional adhesive agents proved to be poor in the thermal resistant property and yet contains high rate of hygroscopicity. In consequence, physical properties of the produced flexible printed circuit boards such as the thermal resistant property and dimensional stability are dependent on the physical properties of the used adhesive agent, thus preventing the polyimide film being used for the cover-lay film and the base film from fully exerting own distinct performance characteristic in many cases. In association with the promotion of multiplied layers of flexible printed circuit boards in recent years, there is a growing demand for bi-lateral adhesive sheets having both surfaces of the base film coated with adhesive agent. However, since either acrylic adhesive agent or epoxy adhesive agent is also used for producing such a bilateral adhesive sheet, like the above case, polyimide film cannot fully exert own distinct performance characteristic.
In order to laminate a cover-lay film on the surface of the built in circuits in the course of manufacturing a flexible printed circuit board, it is a conventional practice to execute those sequential processes including an initial step to adhere either of the above adhesive agents onto the surface of a polyimide film, a next step to process a cover-lay film having one-side surfac
Danno Kazuhisa
Furutani Hiroyuki
Ida Junya
Nagano Hirosaku
Okamoto Yoshifumi
Hampton-Hightower P.
Kanegafuchi Kagaku Kogyo & Kabushiki Kaisha
Seidleck James J.
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