Packaging technologies of direct-cooled power module

A power module, which includes an insulating plate soldered to a heatsink, is called a direct-cooled power module. There are several packaging technologies to improve a direct-cooled power module in terms of not only reduction of thermal resistance but also elongation of lifetime. Among those approaches, this paper describes optimization of heatsink thickness and prevention of ratchet deformation. The calculation results show that a thicker heatsink is better to avoid liquid leakage although thicker heatsink provides shorter solder-lifetime. A heatsink with Vickers hardness of greater than 60 MPa is expected to prevent ratchet deformation under the condition of thermal cycling between -40oC and 125oC. and hardness is verified as an effective approach to produce reliable direct-cooled power modules.