IGBT-Modules: Design for reliability

In several IGBT applications, power cycling capability of the modules determines the lifetime of the device under given conditions. Modern power modules are manufactured in typical structures; in focus are standard modules with Al
₂
O
₃
ceramics. Weak points regarding the module lifetime are the substrate solder joint, the chip solder and the bond wires. Typical failure mechanisms of these interconnection layers are shown. Thermo-mechanical simulations are used to find the deformations and the points of maximal strain and stress. Aging mechanisms are not independent. Based on a large number of power cycling results, an equation for power cycling lifetime was derived and published at the CIPS 08 conference. The presentation will discuss some application examples and the estimated lifetime using the CIPS 08 model.