Passivation Integrity Test on Transistors

Gideon Analytical Laboratories performed failure analysis on several IXYSIGBT IXGH32N60B transistors, encased in TO-247 packages. These transistors are 60 amp 600V 2.3 Rds 200W. The concern was that the devices were not functioning as 600V but topped out at 480V in the application. After failure analysis was performed on the transistors, the company requested that Gideon Analytical Laboratories administer passivation integrity tests on the two good IXYSIGBT IXGH32N60B transistors.

The transistors were prepared for passivation integrity testing. The termination rings were between the guard ring and the gate ring. The central part of the device where the gate and emitter region meet had little effect in the passivation integrity test. There was a particular area of concern on the device. After the passivation integrity test, some of the posts were missing the metal but most of the metal was still intact. The emitter area was excellent. However, Gideon Analytical Laboratories concluded that metal under the glassivation near the edges is vulnerable to attack by the etchant while the emitter appears very good in comparison. The lower voltage was the not a manufacturing problem but the installation site was insulated and the ambient temperature rose by 30 C. Several of these failed due to junction temperatures in excess of the manufacturer’s limit.

Gideon Analytical Laboratories has been operating for over 20 years, and during that time, has helped dozens of electronics companies solve hundreds of problems. Whether it is failures in manufacturing, application, or design, Gideon Analytical Laboratories is in business to help companies get to the root cause. Failure analysis provided by Gideon Analytical Laboratories can help companies achieve peace of mind with the knowledge that their products are reliable.

IXYS transistor

IXYS transistor

Area of concern before test

Area of concern before test

Emitter and Gate labeled

Emitter and Gate labeled

Metal etched away

Metal etched away

Posts before test

Posts before test

Some posts missing metal after test

Some posts missing metal after test

Termination rings

Termination rings