Multi-layer wiring board and method of manufacturing the same

A method of manufacturing a multi-layer wiring board, the multi-layer wiring board including:

• a plurality of multi-layer wiring units each having a plurality of printed wiring boards stacked therein via an adhesive layer, the printed wiring board having a wiring layer formed on an insulating base therein and having flexibility, and the wiring layers being connected to each other via a via that penetrates in a stacking direction;
• and a cable unit connecting between the plurality of multi-layer wiring units and having flexibility, the method comprising the steps of:
• forming the plurality of printed wiring boards each having the wiring layer formed on the insulating base therein;
• forming the adhesive layer on an opposite side to the wiring layer of the insulating base of a certain printed wiring board of the plurality of printed wiring boards;
• forming the via in a certain place of the certain printed wiring board;
• and aligning the plurality of printed wiring boards and performing stacking and thermal compression bonding so as to form:
• the plurality of multi-layer wiring units each having the plurality of printed wiring boards stacked therein via the adhesive layer and in each of which the wiring layers are connected to each other via the via that penetrates in the stacking direction;
• and the cable unit configured having a lower insulating base, the wiring layer formed on the lower insulating base and an upper insulating base disposed above the lower insulating base via the adhesive layer, the lower insulating base and the wiring layer correspond to one-layer of the printed wiring board, and the lower and upper insulating bases and the wiring layer being led out from the multi-layer wiring units, wherein the upper insulating base includes the wiring layer formed on an upper surface of the upper insulating base in the multi-layer wiring units;
• and wherein the cable unit includes therein an empty space where the adhesive layer has been removed, the empty space being provided between those of the insulating bases adjacent in the stacking direction that do not have the wiring layer formed therebetween.