Investigation on Evaluation Methods of Creep Corrosion on Immersion Silver Finished Printed Circuit Boards
This paper discusses failure issues of immersion silver (ImAg) finished printed circuit boards (PCBs) under high-sulfur environments with a focus on creep corrosion. The simulation approach was studied by adapting clays containing sulfur as the source to drive creep corrosion on ImAg finished PCBs. Based on electrical chemistry theory and simulation tests, it was found that the creep corrosion products grew with dendrite shape. The coverage extent of ImAg finish on pads was dependent on the relative location of the pad edges and the solder mask, which caused the different creep distance and the different content of CuS and Ag2S in corrosion products. Weibull distribution with two parameters was used to analyze the length of creep corrosion products, and the creep corrosion resistance of ImAg finished PCBs under high-sulfur environments was quantitatively evaluated by the mean length. Simulation tests showed that the corrosion products could not creep any longer only by increasing the corrosion time, but the creep of corrosion products could be aggravated by heating the clays and increasing relative humidity for many times, which was proper to simulate the harsh industrial environments. Increasing the thickness of ImAg finish and separating the solder mask from the pads could reduce the mean length and the occurrence probability of the creep corrosion products to improve the reliability of ImAg finished PCBs.
immersion silver creep corrosion sulfur evaluation
Zhou Yilin Michael Pecht
Research Lab of Electric Contacts, Automation School, Internal Box 71,Beijing University of Posts an CALCE Electronic Products and Systems Center, Room 1103, Building 089,University of Maryland, Colleg
国际会议
温州
英文
73-79
2009-10-18（万方平台首次上网日期，不代表论文的发表时间）