Computer simulation of the reliability of wire bonds and ribbon bonds in power electronics modules

Abstract

Aluminium wires are widely used in power electronics modules to connect power semiconductor devices and other parts of the module electrically. Recently, other interconnect techniques have been proposed such as ribbon bond to improve the reliability, performance and reduce costs of power modules. The reliability of ribbon bond technique for an IGBT power module under power cycling is compared with that of conventional wire bond in this study using electro-thermal nonlinear Finite Element Analysis. The results showed that a single ribbon of 2000μm x 200μm will replace three wire bonds of 400μm in diameter to achieve a similar module temperature distribution under same power load. Using the equivalent plastic strain increment per cycle, it is seen that the ribbon bond is more reliable than the wire bonds. The impact of neglecting joule heat in the wire/ribbon bonds during power cycling simulation has also been investigated.

An analysis of the reliability and design optimization of aluminium ribbon bonds in power electronics modules using computer simulation method

“…Design optimization of ribbon bond considering power cycling has not been carried out. In an earlier work by the authors of this paper, the thermo-mechanical behaviors of ribbon bonds under simplified power cycling loading conditions were analyzed and compared with those of conventional wire bonds, and it was concluded that ribbon bonds are more reliable than wire bonds under the given conditions [5]. In the present work, a more realistic loading conditions are used in the thermal mechanical simulation.…”

“…The effect of wire bond failure results in changes in either contact resistance value or internal distribution of current leading to increased temperature above the safe operating area (SOA) of the power device. Some ribbon bond thermo-mechanical behaviour studies in the literature for different applications and their limitations has been presented in [5].…”

“…However, recently, their use in the IGBT power electronic module such as in Toyota Prius 2010 model [4] has been gaining attention. The advantages of ribbon over conventional round wire has been discussed in [5] and references therein. One of the reasons ribbon is gaining attention is because a single ribbon usually has a lower electrical resistivity than a single wire of the same length.…”