SMTA International Conference Proceedings


Mitigation of Resistor Silver Sulfide Corrosion Through Design and SMT Process Optimization

Authors: Biao Cai, Marie Cole, Jing Zhang, Hongqing Zhang, Bae Byung Kwon, Jang In Seok, Ryu Jang Hwan, DongChul Gack
Company: IBM Corporation and SK Hynix
Date Published: 9/28/2014   Conference: SMTA International


Abstract: ABSTRACT Thick film resistors are used extensively in Dual In-line Memory Module (DIMM) applications. The silver in the construction of a conventional thick film resistor is sensitive to an environment high in sulfur bearing gaseous contamination. The growth of silver sulfide, resulting from silver corrosion, can cause an increase in resistance and eventually an electrical open of the resistor. The analysis of DIMMs that have been returned from the field due to electrical failure has revealed silver sulfide corrosion of thick film resistors to be a culprit in various geographic locations. For systems (server or storage) without DIMM redundancy, this DIMM failure mode could result in a system crash.

The mitigation of silver sulfide corrosion offered by the resistor industry is an Anti Sulfuric Resistor (ASR) with either a structure alteration to seal the ingress path from sulfur bearing gases or the use of a noble metal. This paper will focus on another potential solution – a reverse type resistor. The reverse type of resistor was introduced on DIMMs around 2010 to reduce DIMM electrical failures resulting from resistor mechanical damage. With proper design and surface mount technology (SMT) engineering, the solder can effectively minimize the ingress of the sulfur bearing gases and enhance the life expectancy of DIMMs with the reverse type of resistor in a sulfur rich environment.

This paper will provide information on the reverse format configuration and flowers of sulfur test data to demonstrate improved sulfur corrosion resistance.

Key Words: 

corrosion, resistor, flowers of sulfur



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