US 7,321,496 B2
Flexible substrate, multilayer flexible substrate and process for producing the same
Yoshihisa Yamashita, Kyoto (Japan); Toshio Fujii, Neyagawa (Japan); Seiichi Nakatani, Hirakata (Japan); Takashi Ichiryu, Moriguchi (Japan); Satoru Tomekawa, Yokohama (Japan); and Hiroki Yabe, Moriguchi (Japan)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan)
Filed on Mar. 15, 2005, as Appl. No. 11/79,316.
Claims priority of application No. P2004-079847 (JP), filed on Mar. 19, 2004.
Prior Publication US 2005/0205294 A1, Sep. 22, 2005
Int. Cl. H05K 1/11 (2006.01); H05K 1/14 (2006.01)
U.S. Cl. 361—793  [361/766; 361/795; 361/803; 174/260] 15 Claims
OG exemplary drawing
 
1. A flexible substrate comprising:
a film;
a first insulating resin layer on a front surface of said film, and a second insulating resin layer on a rear surface of said film, with said front surface and said rear surface facing in opposite directions;
a front-sided wiring pattern embedded in said first insulating resin layer such that an exposed surface of said front-sided wiring pattern is flush with an outer surface of said first insulating resin layer, and a rear-sided wiring pattern embedded in said second insulating resin layer such that an exposed surface of said rear-sided wiring pattern is flush with an outer surface of said second insulating resin layer; and
a via between said front-sided wiring pattern and said rear-sided wiring pattern, said via electrically interconnecting said front-sided wiring pattern and said rear-sided wiring pattern,
wherein said first insulating resin layer and said second insulating resin layer are each thicker than said film;
wherein a ratio of a thickness of said first insulating resin layer to a thickness of said film is within a range of from 1.2 to 6, and a ratio of a thickness of said second insulating resin layer to a thickness of said film is within a range of from 1.2 to 6, and
further comprising: at least one of a passive element and an active element, along with wiring connected thereto, on at least one of said front face and said rear face of said film, with said wiring and said via being electrically connected to each other.