Failure Analysis of Glass Encapsulated Zener Diodes

Failure Analysis Lab examines performs a failure analysis on surface mount glass encapsulated Zener diodes. These diodes were in an appliance control board, and they are surface mounted to the underside a printed circuit board. The entire board is encapsulated in rigid polyurethane. There was a significant yield loss due to cracking of the glass encapsulation around the active assembly. Glass failure analysis determined that the failure origin was at the end of the diode where the glass is in contact with the metal end contact. Examination of  new diodes by glass experts found that the glass was cracked in the same location on new diodes. Thus, the failures were initiated before these diodes were assembled onto the printed circuit board.

Glass Expert Performs Failure Analy on Low E Windows

California failure analysis lab was asked to determine why windows in an expensive hilltop home failed. The windows in question were Lo- E windows that were tinted to absorb infra-red light. At this location two south facing, side-by-side windows cracked. The window expert at Read Consulting was asked to perform a glass failure analysis to determine the root cause of the failure. For this failure analysis the site of the origin was cut from the window and  the failure origin was examined using a low power optical microscope. Both windows failed in an identical manner. Thermal expansion of the center of the Low-E window put the ground glass window edges in tension.A damage site from either the window sizing or window seaming processes was activated by the thermally generated stresses and cracked these windows. Please refer to the photographs above.