Glutaric acid as a flux substitute for soldering on ceramic substrates

Abstract

This article deals with using glutaric acid as a flux substitute for soldering on ceramic substrates with conductive patterns created by thick printed copper technology (TPC). The main goal of the research was to create high quality connections by soldering on ceramic substrates, together with elimination of conventional flux from the process. Conventional flux brings additional expenses because of its difficult cleaning after the soldering process. Necessity of connecting large surface chips is becoming increasingly relevant due the rising demand for power electronics, but brings out several challenges, especially on ceramic substrates. Further in the article is discussed soldering process optimization, its enhancement by using formic acid vapours for additional wetting. X-ray analysis for voids and shear test for determining mechanical resistance were also performed. Results shows that using the glutaric acid as a flux substitute yield joints of similar quality on comparison to conventional flux, with high shear strength and low amount and size of the voids.