The Effect Of Design Parameters On PTH Barrel Fill In High Complexity Assembly
Authors: Jinda Songninluck, Juthathip Fangkangwanwong, Teng Hoon Ng, John McMahon Company: Celestica Inc. Date Published: 10/16/2011
Abstract: Plated through hole barrel fill continues to be an issue in lead-free soldering, especially for high complexity thick printed circuit boards (PCB). Many experimenters have identified that inadequate hole fill can be improved by optimized preheat profiles, increasing pot temperatures, and the use of more aggressive fluxes. However, increased process temperatures are limited by the thermal tolerances of the laminate and components. Even Pb-free compliant laminates cannot withstand extended exposures to liquid solder and flux chemistries, limiting the assemblers ability to raise preheat temperatures. The application of more aggressive fluxes with high solid contents often leads to undesirable residues which can affect Automated Optical Inspection (AOI), pin probability at downstream testing and a host of other problems associated with reduced cleanliness. This work explores the effects of physical product design on through hole solder fill. The focus is on investigation of design factors affecting barrel fill of high complexity thick boards (>0.120 inches, >10 layers) populated with high thermal mass components. Assembly processes, test methods, analysis and selected results are discussed.
Lead-Free, Wave Soldering, Design for Manufacturability