Against a first resin film formed on a first metal film are pressed bumps on a second metal film so that the bumps are embedded into the first resin film. Either one of the first metal film or the second metal film or both is (are) patterned while the bumps are in contact with the first metal film, and...http://www.google.com.tw/patents/US6737588?utm_source=gb-gplus-share專利 US6737588 - Processes for manufacturing flexible wiring boards and the resulting flexible wiring board
