Improving the power cycling performance of IGBT modules by plating the emitter contact

• Reliability improvement of power modules in terms of power cycling performance.
• Investigation of electroless and electro-plating as a tool to improve reliability of power modules.
• Description of a novel method to manufacture Cu-clad-Al joints, which profits from the benefits of both materials.
• Experimental cycling and evaluating of wire and ribbon-bond layouts.
• Improvement of the cycling capability of power modules by a factor of 4.

In terms of power cycling reliability one of the most critical joints of a typical power module is the emitter contact. A typical emitter contact of the IGBTs or diodes consists of a front metallization and bond wires connecting the chips to the emitter lead. In this study, a novel method was implemented to the entire emitter contact to support and reinforce the mechanical as well as electrical durability and reliability. These modules were characterized in terms of the power cycling performance. The emitter contact of the standard wire bonded as well as heavy ribbon bonded HiPak modules were reinforced by Cu electroplating. The two groups of modules were subjected to power cycling tests. The results of the cycling tests proved the method as effective and the power cycling performance was improved up to 4 times compared to the standard wire bonded modules. This study describes a novel method for designing high-reliability emitter contacts for IGBT modules with improved power cycling performance.