Embedding of Power Semiconductors for Innovative Packages and Modules

摘要

The spectrum of conventional power electronics packaging reaches from SMD packages for power chips to large power modules. In most of these packages the power semiconductors are connected by bond wires, resulting in large resistances and parasitic inductances. Power chip packages have to carry semiconductors with increasing current densities. Conventional wire bonds are limiting their performance. Today's power modules are based on DCB (Direct Copper bonded) ceramic substrates. IGBT switches are mounted onto the ceramic and their top side contacts are connected by thick Al wires. This allows one wiring layer only and makes an integration of driver chips very difficult. Additionally, bond wires result in a high stray inductance which limits the switching frequency. Especially for the use of ultra-fast switching semiconductors, like SiC and GaN, it is very difficult to realize low inductive packages. A new approach for embedded power modules will be presented, which can cover different application fields, ranging from 50 W over 500 W to 50kW power modules for different applications like single chip packages, over power control units for pedelec (Pedal Electric Cycle), to inverter modules for automotive applications. This approach will focus on a power core base structure for with embedded semiconductors, which is then connected to a high power PCB. The connection to the embedded die is realized by a direct copper connection only. The technology principle will be described in detail. The embedding of chips offers a solution for many of the problems in power chip packages and power modules. While chip embedding was an academic exercise a decade ago, it is now an industrial solution [1]. A huge advantage of packaging using PCB technology is the cost-effective processing on large panel. Furthermore embedded packages and modules allow either double-side cooling or 3D assembly of components like capacitors, gate drivers or controllers.