Reflow solder flux residue and humidity interaction: investigation using real PCBA component designs

Abstract

This paper investigates the climatic reliability of realistic PCBA component geometries soldered using reflow process, from the perspective of the interaction between component design parameters, reflow residue and humidity. The study was carried out using electrochemical characterization, electron microscopy, and X-ray imaging. Custom-designed PCBA test cards with dummy components have been exposed to harsh climate after reflow soldering. A methodology of combining Leakage current and electrochemical impedance measurements has been used to characterize PCBA performance. Changes in flux morphology and any associated negative effects as a function of humidity interaction have been connected to component connector design parameters, to achieve a holistic understanding of flux system-component suitability and humidity interaction.