Chip Resistor Failure Analysis
SEM Lab, Inc. has seen the same type of resistor failures repeatedly since ~ 1997 when we were founded. The trigger appears to be the local environment where the resistors are deployed, for example …
- A computer module in a tractor.
- Fireworks display controller. Boards coated with ~ 0.300 inches of Dow Corning “tough gel”.
- A display at an outdoor drive-up kiosk.
- Many other previous analysis efforts where the source of sulfur is unexplained.
The problem, sulfur pollution and corrosion of silver, is illustrated in the figure below and explained thoroughly in references  & . The resistors increase in value and eventually fail open.
Chip Resistors Corrosion
 Craig Hillman, Joelle Arnold, Seth Binfield, Jeremy Seppi, “Silver And Sulfur: Case Studies, Physics, And Possible Solutions”, DfR Solutions, College Park, MD, USA, 2007, email – firstname.lastname@example.org, http://www.dfrsolutions.com/uploads/publications/2007_10_silver_and_sulfur.pdf. link
 Marie Cole et al, “Harsh Environment Impact On Resistor Reliability”, SMTA International 2010 Conference Proceedings, http://researcher.ibm.com/researcher/files/us-kleinl/Resistor_Harsh_Environ_final_SMTAI2010.pdf.