LEAD-FREE WAVE SOLDERING FOR PROCESS AND PRODUCT DESIGN IMPROVEMENT IN SnCu ALLOYS
Authors: Juthathip Fangkangwanwong, Mongkhol Phuhattsuan, and Teng Hoon Ng Company: Celestica Co., Ltd. Date Published: 10/24/2010
Abstract: An optimization of lead-free wave soldering process for thick PCBs with thermal challenges, using a selected SnCu alloy is being demonstrated. Special designed test vehicle was created for the study of factors influencing pin-through-hole barrel fill. Variation on the design complexity of the printed circuit assemblies i.e. finished hole size, Cu pad to Cu pad spacing, number of ground layers, and ground connection design with and without thermal relief were included in the test vehicle. Designs of experiments were carried out to determine the optimum process condition and study the interaction significance of contact time, preheat temperature, solder pot temperature, board surface finish, no. of nozzle opening, and type of wave nozzle. Quantitative measurements of the percent pin-through-hole barrel fill by 5DX X-ray are explored. The final results target not only to provide practical product design guidelines for improving solder joint hole filling but also additional process optimization guidance on factors critical lead-free pin-through-hole components wave soldering.