Patent ID: 6362433
Filing Date: 2002-03-26
Classification: H05K

Abstract:
A flexible printed circuit board comprising:a conductor pattern corresponding to a predetermined circuit; a first polyimide-resin layer formed on a first surface of said conductor pattern for supporting said conductor pattern; and a second polyimide-resin layer formed on a second surface of said conductor pattern for covering and protecting the predetermined circuit, wherein a difference between a coefficient of linear thermal expansion of said first polyimide-resin layer and a coefficient of linear thermal expansion of said second polyimide-resin layer is 3Ã—10âˆ’6/K or less, and wherein at least one of said first polyimide-resin layer and said second polyimide-resin layer has a triple-layered structure formed by laminating a polyimide-resin layer adjacent to said conductor pattern, an intermediate polyimide-resin layer and an outer polyimide resin layer successively, wherein a coefficient of linear thermal expansion of the polyimide resin layer adjacent to said conductor pattern and a coefficient of linear thermal expansion of the outer polyimide resin layer are larger than a coefficient of linear thermal expansion of the intermediate polyimide resin layer.