Diagnostics of a Future Blow Hole Issue Before Assembly

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.