抄録
An improved method for connecting flexible printed circuits and indium tin oxide (ITO) electrodes is proposed in this paper. The adhesives used were composed of a thermosetting resin and a thermoplastic resin. The test sample consisted of a polyimide base flexible printed circuit, (FPC). Non-conductive film (NCF) was pre-laminated on an ITO-glass and the test sample was then thermally bonded to the glass. The contact resistance between the ITO-glass and FPC was measured by a 4-probe method. A Cu wiring on the FPC was chemically etched, followed by selective electroless Ni–P deposition using hydrazine and sodium hypophosphite as reducing agents; Au film was then plated onto it. Since this method does not create extraneous deposition, it is one of the most promising candidates for future fine connection manufacturing processes. With lines and spaces of 75 μm and 75 μm, insulation resistance of 1 × 108 Ω remained constant at 60 °C, 90 %RH, 30 V for 60 hours. Various FPCs with different line and space combinations have been investigated by the same method. The lines and spaces of 15 μm and 25 μm, 20 μm and 20 μm, and 25 μm and 15 μm show contact resistance of 2.02 Ω, 1.26 Ω and 0.844 Ω, respectively. Therefore, this method is intrinsically suitable for fine pitch FPCs with high reliability.
