Thick Printed Copper as Highly Reliable Substrate Technology for Power Electronics

Up to now Direct Bonded Copper (DBC) is the standard substrate technology for most power electronics applications. This paper presents Thick Printed Copper (TPC) as an alternative technology for applications with highest reliability requirements in power electronics and high brightness LEDs with a high freedom in design. The drawbacks of DBC are the relatively low reliability under thermo-mechanical stress, a low spatial resolution and a low freedom of design in regards of layer thickness. The outstanding high reliability of Thick Printed Copper is demonstrated in this paper by passive thermal shock tests in direct comparison to DBC. In the second part, the high spatial resolution possible with copper paste technology is described. Furthermore, the work shows that TPC can be applied to a wide range of relevant ceramic substrate materials including alumina, aluminum nitride and zirconia toughened alumina. Finally, a detailed review is given discussing the different copper layer to substrate bonding mechanisms, which prevent void formation and are responsible for the excellent thermo-mechanical reliability.