Cu- Sintering on Organic and Inorganic Substrates for Power Modules

Silver and Copper sintering technology, currently still with pressurized sintering pastes up to 2, 10 and 20 MPa, has been evaluated on organic and inorganic laminates as an approach for alternative high temperature die-attach. In the paper will be given an overview, to add the technology solutions for powerful sintering interconnects. That means for different technical, material and metallurgical solutions any descriptions will be provided for reliable and efficient high temperature resistant interconnects. There is an increasing demand for high-power electronic systems from various industrial sectors including e.g. automotive, grid, power infrastructure and aerospace. The sinter-bonding reactions and mechanical strength of Cu-sintered joints with Ag- and Cu-surface finished SiC chip and inorganic DCB and organic substrates were evaluated during the sintering process. From the observations made via cross-sectional SEM and C-SAM, it was confirmed that relatively stable sintered microstructures and dense Cu-sintered layers were formed in bonding pressure conditions. At higher temperatures, high thermal conductivity and high thermal stability interconnect materials are crucial in the manufacture of power devices for product reliability and efficiency. As an example, die-attach materials connect devices to their package to provide heat dissipation paths, which is a key component to ensure the entire system works efficiently and reliably. As a result of good bonding, significant plastic flow and ductile fracture of the sheared copper joint could be observed by scanning electron microscopy (SEM). SEM also showed that the fracture of the sheared silver joint was a cohesive failure (stable interfaces). In this paper, we addressed the reliability gaps in this area by characterizing the evolution of porosity and microstructures of the pressure-assisted nano-Cu joints on Cu and Ag, direct bond copper (DBC) and bare Cu organic substrates during their high-temperature storage in air at 200 °C corresponding to the T j max development in the next years.