ÿþ<html><head> <title>Investigation on Mechanism of Creep Corrosion of Immersion Silver Finished Printed Circuit Board by Clay Tests</title></head> <body bgcolor="#ffffff"> <center> <em>55th Annual IEEE Holm Conference, Vancouver, British Columbia, Canada, pp. 321-330, September 14-16, 2009</em><br> <h2><strong>Investigation on Mechanism of Creep Corrosion of Immersion Silver Finished Printed Circuit Board by Clay Tests</strong></h2> <p><br> <strong>Yilin Zhou</strong><br> Research Lab of Electric Contacts, Automation School<br> Beijing University of Posts and Telecommunications<br> Beijing, 100876, P. R. China<br> </p> <p><strong>Michael Pecht</strong><br> CALCE Electronic Products and Systems Center<br> University of Maryland <br> College Park, MD 20742, USA<br> </p> <p><br> </p> </center> <b>Abstract:</b> <p>This paper studies the creep corrosion of immersion silver (ImAg) finished printed circuit board (PCB) under high sulfur environments. Clays containing sulfur were heated with water to simulate high sulfur environment and to drive creep corrosion on ImAg finished pads. Except the silver sulfide film formed on ImAg finish, creep corrosion began by growth of dendrites on pad edges, which was caused by galvanic corrosion. Copper sulfide and silver sulfide were the main components of creep corrosion products. The different coverage extent of ImAg finish on pad edges caused different reaction speed, the morphology and the creep distance of corrosion products, and different content of copper sulfide and silver sulfide in corrosion products. The impact of creep corrosion products on surface insulation resistance (SIR) was measured. Weibull distribution with two parameters was used to analyze the length of dendrites and to quantitatively evaluate the corrosion resistance of ImAg finish. The methods to improve the reliability of ImAg finished PCB was also discussed in the paper.</p> <p><strong>Keywords:</strong> immersion silver, creep corrosion, sulfur, surface insulation resistance, Weibull distribution</p> <p><a href="../../fulltext/2009/Holm Paper_13_3.pdf">Complete article</a><a href="../../fulltext/2009/Fusion_Prognostics_Method.pdf"></a><a href="../../fulltext/2009/JIJR1528.pdf"></a> is available to CALCE Consortium Members.</p> <p><font size="-2"><font color="red">&copy; IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.</font></font></p> <hr><br> <center> [<a href="http://www.calce.umd.edu">Home Page</a>] [<a href="../../">Articles Page</a>] </center> <center> <font size="-1">Copyright &copy; 2009 by CALCE and the University of Maryland, All Rights Reserved </font> </center> </body></html>