To provide an interlayer connecting sheet with a high connecting reliability and an excellent productivity, a method of manufacturing the interlayer connecting sheet, and a multilayer flexible printed wiring board (FPC) using the interlayer connecting sheet.
By using an interlayer connecting sheet 13 constituted by providing: an insulated adhesive sheet 1 having a through-hole 2 at a predetermined position; a copper system core member 6 in a core position, which is inserted in the through-hole 2 in order to obtain a conduction between FPCs and has a diameter smaller than that of the through-hole 2; and a copper system core conductor 5 whose front surface is covered with a solder alloy layer, a plurality of FPCs are stuck each other to manufacture multilayer FPCs. Since a front surface of the copper system core conductor 5 is made of a solder alloy, the solder alloy of the copper system core conductor 5 front surface is pressurized and deformed in case of laminating each wiring layer, and the copper system core conductor 5 can be certainly and electrically connected. Moreover, as the copper system core conductor 5 is inserted in through-hole 2 provided in the thickness direction, a cross section and an electric conductivity in a conductive area can be fully ensured, and the multilayer FPC with the high connecting reliability can be obtained.
YOSHINO TOYOICHI
MORIMOTO SHINJI
NAKAJIMA KOJI
Hiroki Naito
Daisuke Nagano
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