Patent ID: 7312401
Filing Date: 2007-12-25
Classification: H01L,H01R,H05K

Abstract:
1. A flexible printed wiring board having three parts including an element mounting part, a folding part, and a board mounting part, which are laterally disposed in that order, the element mounting part being configured to mount circuit elements on both top and bottom surfaces of the wiring board, the board mounting part being configured such that the top surface of the board mounting part can be mounted on an external circuit board, the flexible printed wiring board being configured to be folded over at the folding part around a virtual folding line that extends substantially in parallel with the wiring board such that the top surface of the wiring board faces an exterior when the flexible printed wiring board is bent, the flexible printed wiring board comprising: a bottom conductor pattern in the element mounting part, the bottom conductor pattern being configured to mount a first circuit element on the bottom surface of the wiring board through a first plurality of pads that are directly in contact with the bottom conductor pattern, the bottom conductor pattern being absent in the folding part: a lower insulating layer on the bottom conductor pattern in all of said three parts, the lower insulating layer having a first plurality of via holes in the element mounting part: a middle conductor pattern on the lower insulating layer in all of said three parts, portions of the middle conductor pattern being electrically in contact with portions of the bottom conductor pattern via said first plurality of via holes: an upper insulating layer on the middle conductor pattern in all of said three parts, the upper insulating layer having a second plurality of via holes in the element mounting part; and a top conductor pattern on the upper insulating layer in all of said three parts, the top conductor pattern in the element mounting part being configured to mount a second circuit element on the top surface of the wiring board through a second plurality of pads that are directly in contact with the top conductor pattern, the top conductor pattern in the board mounting part being configured to mount the flexible printed wiring board to an external circuit board through a plurality of pads that are directly in contact with the top conductor pattern, portions of the top conductor pattern being electrically in contact with portions of the middle conductor pattern via said second plurality of via holes, wherein the top conductor pattern includes a plurality of signal lines in the folding part that extends in parallel with each other in a direction that forms an angle of about 30° to about 90° with respect to the direction of the virtual folding line, wherein the middle conductor pattern includes a ground pattern configured to impart a ground potential, and the ground pattern has a solid pattern that covers substantially an entire area over which said plurality of signal lines are disposed in the folding part, wherein the upper and lower insulating layers are made of a fiber-reinforced resin having warps and wefis, and each have a thickness of about 25 μm to about 65 μm, and the warps or the wefts of said fiber-reinforced plastic extend in a direction that forms an angle of about 0° to about 60° with respect to the direction of the virtual folding line.