Patent ID: 8240031

Claim:
A method of joining a semiconductor device/chip to a printed wiring board through a multilayer flexible substrate, the steps comprising: a) providing a semiconductor device having a first set of pads disposed on one surface thereof, said pads having predetermined small dimensions and a fine pitch; b) providing a printed wiring board having a first and a second surface, with a site on said first surface thereof for attaching a semiconductor device through a multilayer flexible substrate, the site having a second set of pads on said first surface of said printed wiring board with dimensions and spacing substantially greater than those of said first set of pads; c) providing a multilayer flexible substrate having a first surface with a first set of substrate pads having dimensions and spacing corresponding to said first set of pads on said semiconductor device, and a second surface with a second set of substrate pads having dimensions and spacing corresponding to said second set of pads on said first surface of said printed wiring board, the first set of substrate pads of said semiconductor device being in electrical communication, through the flexible substrate, with said second set of substrate pads on said first surface of said printed wiring board; d) joining the semiconductor device pads to said first set of substrate pads on said multilayer flexible substrate to obtain a flexible chip-on-a-carrier; and e) joining said second surface of said flexible chip-on-a-carrier to the site on said first side of said printed wiring board.