For decades soldering has been the technology of choice in die bonding. However, due to worldwide health protection regulations, the most common solder alloys, which contain lead, have been banned. Furthermore, standard solders cannot fulfil the reliability requirements of future power electronic devices. New interconnection technologies have to be developed. One of them is pressure sintering (p=30..50 MPa) of silver flakes below 300 °C. It forms a strong, highly electrically and thermally conductive bond. In order to lower the level of pressure, silver nanoparticles can be used. Shear tests have shown that even 5 s of sintering, a temperature of 225 °C, or a pressure as low as 2 MPa is sufficient to generate bonds comparable to solder and high pressure sinter joints if the remaining parameters (p, t and T, respectively) are set correctly. However, strength is only a necessary criterion as aging comes into play. Therefore, reliability tests using thermal cycling and pow er cycling were run. These returned superior reliability of the sintered samples. 160 million of the power cycles between +45 and +175 °C run in this work can be extrapolated using a Coffin-Manson model. Solder joints failed at about 40,000 cycles. ©2010 IEEE

Increasing the temperature in power electronic applications usually causes a decreasing lifetime and reliability. This study shows that packaging materials and technologies like silver sintering or gold germanium solders can easily deal with temperatures above 150°C. Furthermore the power cycling capability at increased temperatures can be much better than at room temperature. Active power cycling tests with 240 devices offered more cycles to failure at 120°C cooling temperature than at 40°C. The three tested sample groups consisted of silicon carbide diodes which were soldered (gold germanium/ tin lead) or silver sinter to copper-ceramic-substrates (DBCs). The reason behind this effect is the decreasing of Youngs modulus, yield strength and ultimate strain over temperature. The materials are getting much more ductile and robust against load cycling at higher temperatures. The three mentioned material properties were measured by nano-indentation and tensile tests up to 200°C. In summary, packaging materials and their properties should be adopted to the intended application and its requirements, starting with a temperature-dependent analysis

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A ball bonding process was simulated over a high-voltage isolation structure. The removal of an inter-dielectric metal crack-stop layer was investigated through 3D simulation. Material properties for the bonded gold ball were obtained using nanoindentation and atomic force microscopy with a methodology from the work of Ma et al. This yielded both elastic and plastic material parameters. The methodology was then evaluated by using the parameters in a nanoindentation simulation. Although the topography simulated only roughly agreed with measurement, the simulated and measured indenter curves closely overlapped. The parameters were then used in the bonding simulation. The deformation of the bond ball was also measured so that the equivalent deformation could be simulated. This was achieved following the incorporation of both ultrasonic motion and softening in the simulation. Two bonding process geometries were then set up: one with the crack-stop layer present and the other without. Both were simulated and the output was applied within a failure theory to evaluate the risk to the isolation oxide