Charlotte Gillot

System on Wafer: A New Silicon Concept in SiP

System integration is clearly a driving force for innovation in packaging. The need for miniaturization has led to new architectures that combine disparate technologies and materials. Today several different approaches have been developed. These include technologies like system in package. In this way, a new concept for heterogeneous integration is currently being developed at CEA-LETI and is called system on wafer (SoW). This concept is based on a chip to wafer approach. Every component is achieved by using wafer-level technologies, and the final system is performed by single component mounting on a silicon substrate. The main strength of this approach is to use silicon as a substrate for components and for basic support. To perform the SoW, a generic technological toolbox is needed. This includes every standard packaging technology such as flip chip, signal rerouting, and passive component integration as well as new advanced technologies such as microelectromechanical systems packaging, advanced interconnections, energy source integration, integrated cooling, or silicon through vias. In this paper, the SoW concept will be presented and the generic toolbox for SoW achievement will be described.

Double-sided cooling for high power IGBT modules using flip chip technology

A new technique for the packaging of IGBT modules has been developed. The components are sandwiched between two DBC (direct bond copper) substrates with aluminum nitride. Wire bonds are replaced with flip chip solder bumps, which allows to cool components on both sides. Microchannel heat sinks are directly integrated in the package to decrease the thermal resistance of the module. Thus, a very compact module with high thermal performance is obtained. A prototype with two IGBTs (insulated gate bipolar transistor) and four diodes associated in parallel was realised and tested. In this paper, the innovative packaging technique is described, and results of thermal tests are presented.

A new packaging technique for power multichip modules

A new packaging technique for power multichip modules has been developed. The components are sandwiched between two DBC (direct bond copper) substrates with aluminum nitride. This innovative technique allows to replace wire bond with flip chip and to cool the module on both sides. Thus, electrical, thermal and reliability performance can be improved.

Integrated single and two-phase micro heat sinks under IGBT chips

Experiments have been performed to assess the feasibility of single and two-phase micro heat exchangers applied to the cooling of IGBT power components. After a brief recall of the principal characteristics of such heat exchangers, prototypes that have been built and tested are described. Experimental measurements are then compared to the predictions of the thermal and hydraulic performances with water and the inert fluorocarbon liquid (FC72) as coolant fluids.