Abstract

Electric and hybrid electric vehicles (EVs and HEVs) are creating an increasing demand for power modules. They are also demanding lots from the modules, such as the ability to switch high voltages at high frequencies into loads that draw hundreds of Amps. Increase the power density is nowadays priority and main goal for all the manufacturers including: batteries, fuel cells, inverters, motors, power supply units etc. Increase power density require the use of modern materials (including the transaction from Si standard Chips to SiC or GaN). New methods are emerging to boost performances, increase production efficiency, reduce defects and enormously contain the cost. Pressure assisted bonding method show more reliable join, higher lifetime and are considered first choice for SiC and also Si main powertrain inverter die attach (lower electrical resistivity ~2 µΩcm and higher thermal conductivity >250 W/m∘K)

Also the complexity of power module design is increasing: Semiconductor industries and SATs are producing advance package including different components. Clips, Sensors, copper foils, power contacts should also be pressure sintered avoiding re-melting problems. High performance package architecture, like 3D structures (DSC), are becoming more and more popular; this request more than one sintering process on the same module assembling layers after layers (frames, Spacers and second DBC on top DSC, other elements. On the other hand of the supply chain Tier1 and OEMs are also using pressure sintering at second level: large area pressure sintering of the package on the cooler can provide better thermal performances and increase the joint lifetime.

Compared with soldering or other standard methods Ag or Cu pressure sintering shows outstanding results on all the previous application; new higher characterization parameters are necessary to deeply check the wright functioning of the mechanical joint.   Higher repeatability methods capable to assure best bonding condition, no die lost and no cosmetic defect are worldwide production priority. The AMX Automatrix Patented Micro Punch System is nowadays considered the most advanced method to guarantee less waste of components and to assure to the entire package best performances, longer lifetime and outstanding reliability.