Flexible printed wiring board
AssigneeIbiden Co., Ltd.
InventorsKiyotaka Tsukada, Terumasa Ninomaru, Masaki Kizaki
Life of this patent
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Abstract
A flexible printed wiring board includes a first conductor layer in the element mounting part adjacent to the top surface of the wiring board; a second conductor layer in the element mounting part adjacent to the bottom surface of the wiring board; and a third conductor layer between the first conductor layer and the second conductor layer, wherein the first and third conductor layers extend through and beyond the bending part, and the second conductor layer is absent in the bending part.
Claims20
A flexible printed wiring board having an element mounting part configured to mount circuit elements on both top and bottom surfaces thereof and a bending part that is to be bent around a bending axis that extends substantially in parallel with the wiring board, the top surface of the wiring board being defined as a surface that comes to the outermost side when the bending part is bent around the bending axis, the bottom surface of the wiring board being defined as a surface that comes to the innermost side when the bending part is bent around the bending axis, the flexible printed wiring board comprising:
- a first conductor layer in the element mounting part adjacent to the top surface of the wiring board;
- a second conductor layer in the element mounting part adjacent to the bottom surface of the wiring board;
- and
- a third conductor layer between the first conductor layer and the second conductor layer,
- wherein the first and third conductor layers extend through and beyond the bending part, and the second conductor layer is absent in the bending part.
A flexible printed wiring board having three parts of 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.
A flexible wiring board for mounting circuit elements on both surfaces on one end, the other end of the flexible wiring board being configured to be folded over against said one end and configured to be mounted on an external host board to enable high-density low profile mounting of the circuit elements on the external host board, the flexible wiring board having a three-layered conductor structure on said one end so that the circuit elements can be mounted on both surfaces and having a two-layered conductor structure in a fold-over portion at which the flexible wiring board is to be folded over, the two layered conductor structure being configured to provide for improved crack resistance at the fold-over portion.
A method for manufacturing a flexible printed wiring board having an element mounting part configured to mount circuit elements on both top and bottom surfaces thereof and a bending part that is to be bent around a bending axis that extends substantially in parallel with the wiring board, the top surface of the wiring board being defined as a surface that comes to the outermost side when the bending part is bent around the bending axis, the bottom surface of the wiring board being defined as a surface that comes to the innermost side when the bending part is bent around the bending axis, the method comprising the steps of:
- forming a first conductor layer in the element mounting part adjacent to the top surface of the wiring board;
- forming a second conductor layer in the element mounting part adjacent to the bottom surface of the wiring board;
- and
- forming a third conductor layer between the first conductor layer and the second conductor layer,
- wherein the first and third conductor layers extend through and beyond the bending part, and the second conductor layer is absent in the bending part.
Dependencies are inferred from the claim text.