A New Ultra-Thin High Voltage Power Supply Using FPC with Low Expansion Coefficient

Abstract

We have developed a maintenance-free ultra-thin high withstand-voltage power source with a polarity inversion function for mounting on industrial equipment. To realize such a power source, we have developed a new process using Sn-3.0Ag-0.5Cu solder for joining low expansion coefficient flexible printed circuits (FPC) and the bare chips of switching devices. In this new joining process, we investigated the effects on the solder joining capability of highly volatile flux and of surface cleanliness with Sn-3.0Ag-0.5Cu solder on the FPC. We also developed a highly reliable solder joining process for fine and narrow gaps between the FPC and the bare chips. Based on this process, we experimentally manufactured an ultra-thin power source, and confirmed its high-withstand characteristics and its high-reliability.