IGBT dice stress-tested for automotive powertrain certification

May 23, 2016 // By Graham Prophet
Mentor Graphics' MicReD Power Tester 600A has been configured to allow semiconductor companies and automotive equipment builders to apply long-term and realistic power/thermal cycling tests to the IGBTs typically used in electric and hybrid vehicle inverters and drives, in sufficient numbers to gain AEC qualification.

Mentor has for some time produced a series of test chassis for evaluating power semiconductors. The product line is based around modelling of the thermal structure of power switch dice (and packaged parts, and modules), plus their wire-bond terminations, and package layer structure, in Mentor's FloTherm CFD simulation tool. FloTherm can model devices in detail, or in a 'compact' format. The testers subject devices to power cycling, and thermal cycling, to accelerate the ageing they will encounter in service. Failure modes can include such effects as wire-bonds becoming brittle and fracturing, or part of semiconductor chips and their packaging delaminating. With a detailed thermal model of the device, it is possible to identify the specific point in its thermal path where a degradation has occurred, from electrical measurements.

In this most recent variant of the MicReD, Mentor has built a unit adapted to the voltage levels that prevail in automotive applications; and that can test many more dice in parallel: gaining AEC certification involves testing at least 77 individual examples. A further refinement is that the models used to simulate the devices can be 'tuned' with feedback from the test process, for significantly greater accuracy.


The MicReD Power Tester 600A offering allows EV/HEV development and reliability engineers to test power electronics (such as insulated gate bipolar transistors – IGBTs, MOSFETs, transistors, and chargers) for mission-critical thermal reliability and lifecycle performance. Asked if the company is yet seeing requests for test configurations for silicon carbide transistors, a spokesman said that there was some early interest, and he anticipated no barriers to testing those devices when called for.


The tester provides comprehensive diagnostics for thermal reliability, and a simple reliability testing process for lifecycle estimation. Device set-up is easy and power cycles are fully automated. The T3Ster “structure function” feature inside the Power Tester yields non-destructive “failure-in-progress” data for each IGBT. All diagnostic information is recorded during testing, from current,