Improved Printed Circuit Board Reliability Through Quantitative Control of Cleaning Processes
Authors: E.J. Kidd, Brooke Campbell, R. Giles Dillingham, Ph.D. Company: BTG Labs Date Published: 9/22/2019
Abstract: PCB manufacturing incorporates various cleaning processes that can negatively or positively impact laminate and coating adhesion throughout fabrication. These include aqueous/solvent cleaning, chemical etching, and plasma cleaning. Validating the surface chemical composition and properties of printed circuit boards (PCB’s) is crucial for controlling these processes and achieving high reliability in end product performance. Current methods such as ion chromatography provide some information pertaining to surface conductivity and electrical performance but do not correlate to organic contaminants and laminate or coating adhesion. This presentation discusses surface chemistries of PCB’s exposed to process contaminants. The relative ability of solvent cleaning and atmospheric pressure plasma cleaning to remove contaminants and create wire bondable surfaces are compared by X-ray photoelectron spectroscopy (XPS) and surface energy measurements via contact angle techniques. Contact angle methods were found to be convenient and practical for real time process monitoring in manufacturing.