IRC/TTE MELF resistor failures

The program I'm working on is having endcap metallization/resistive element failures. These are on MELFs manufactured by IRC/TTE (MCHP). A sister program is having the same issues. They pulled a couple of date codes and did visual examination and 60% of the resistors had endcap metallization flaking. I did a search of the archives and their was another post from 2003 with the same issue (IRC CHP). Anyone else having this problem now? The big question is what could cause this? Simple answer is contaminated surface preventing adhesion. Funny thing is, the metal glaze operation moved in 2012 from one location to another, and the problem followed. So process related. Any brilliant insight would be greatly appreciated.

reply »