4. Soles

The base plate is located between the metallized ceramic substrate and the heat sink (Figure 1 ). It is soldered to the lower metallization of the substrate, then assembled to the cooling system. It provides mechanical support for the assembly. It must also have good mechanical properties (CTE close to the assembly components, good rigidity and low mass, etc.) and thermal properties (good thermal conductivity, etc.). The typical thickness of a soleplate is a few millimeters. To ensure good thermal contact between the base plate and the heatsink after the soldering stage, we recommend using a base plate with domed and flat surfaces facing the heatsink and substrate respectively (figure