FLEXIBLE CIRCUIT BOARD, METHOD FOR MAKING THE SAME, FLEXIBLE MULTI-LAYER WIRING CIRCUIT BOARD, AND METHOD FOR MAKING THE SAME

摘要

There is provided a flexible circuit board 22 that, when deposited on another flexible circuit board 40, causes no gap to occur between wiring films 4a, 4a, of the flexible circuit board 40. Moreover, a plurality of flexible circuit boards are deposited on one another to provide a flexible multi-layer wiring circuit board having no gaps between the flexible circuit boards and having less bowing. In the flexible circuit board 22, the thickness of a bonding layer 16, 16a, on the opposed side of a bowing metallic member 2, of an inter-layer insulating film 10 where which bumps 6 are formed is greater than the thickness of a bonding layer on the side of metallic member 2. When the flexible circuit board 22 is deposited on the other flexible circuit board 40 to form a flexible multi-layer wiring circuit board 50, the bonding layer 16, 16a can be filled between the wiring films 4a, 4a, so that the flexible multi-layer wiring circuit board 50 has no gaps and a less bowing.