Diagnostics of a Future Blow Hole Issue Before Assembly

Abstract

Incorrect production of PTHs (Plated Through Holes) lead to problems during PCBA (Printed Circuit Board Assembly), specifically during soldering and caused blow hole issues. A novel method for identification of incorrectly produced PTHs is suggested in this work. Samples with questionable quality of plated through holes were received for analysis and various micro-sections and optical observations were performed. As the issue is a statistical problem, a thorough diagnostic of a single cross-section – an approach used commonly nowadays is nearly worthless as the fault is often a single weak point located anywhere within a 3D area of a plated barrel or within a significant number of such barrels. A method based on the optical observation of analyzed samples immersed in a viscous liquid in a vacuum chamber was successfully implemented.