Abstract: The principles described herein relate to methods for soldering electrode terminals, pins or lead-frames of commercial electric components for high temperature reliability. In one embodiment, prior to soldering the electric components, a pre-plated solder layer is removed from the lead frame or pins, and nickel and/or gold films are formed with electroless plating. The removal of the pre-plated solder layer avoids excess pre-plated Sn with high-Pb solder that lowers the melting point to between 180° C. and 220° C. and weakens solder joints. The nickel layer formed with an electroless plating acts as a barrier to the interdiffusion of tin from solder with copper of the lead frame material, which may otherwise occur at high temperatures. Interdiffusion forms an intermetallic compound layer of copper and tin and degrades solder joint strength. The novel soldering processes improve high temperature reliability of solder joints and extend electronics life-time.

Abstract: The principles described herein relate to methods for soldering electrode terminals, pins or lead-frames of commercial electric components for high temperature reliability. In one embodiment, prior to soldering the electric components, a pre-plated solder layer is removed from the lead frame or pins, and nickel and/or gold films are formed with electroless plating. The removal of the pre-plated solder layer avoids excess pre-plated Sn with high-Pb solder that lowers the melting point to between 180° C. and 220° C. and weakens solder joints. The nickel layer formed with an electroless plating acts as a barrier to the interdiffusion of tin from solder with copper of the lead frame material, which may otherwise occur at high temperatures. Interdiffusion forms an intermetallic compound layer of copper and tin and degrades solder joint strength. The novel soldering processes improve high temperature reliability of solder joints and extend electronics life-time.