Utilizing the SEMIKRON technology portfolio, MiniSKiiP boosts reliability and power density and is now finding its way into new markets such as medium-voltage inverters. In the area of motor drives, MiniSKiiP has become the Power Density Master.
This is achieved by optimizing the thermal resistance layer between chip and heatsink. Using the unique SEMIKRON packaging technologies, the output current capability and, consequently, the power density is increased by more than 30% while using the same physical chipset and power module size.
At approx. 50%, the Thermal Interface Material (TIM or thermal grease) accounts for the biggest proportion of the thermal resistance from chip to heatsink (Rth(j-s)), which is why it makes sense to focus on improving that layer first.
The main task of the TIM is the thermal interconnection of two surfaces by smoothing out the module base and the heatsink roughness with a minimum of layer thickness. Why does one paste perform better than another and why is it superior to a thermal pad? The answer is in the composition of the TIM, with the two main components the thermally conductive filling material (particles), and the matrix carrier material being responsible for the wettability.
For the thermal resistance of the bulk part of the thermal interface material layer (Rth,bulk), the filling degree is the most important factor, while the thermal conductivity of the individual particles has less impact. The filling degree describes the volume of conductive material inside a compound. However, the thermal resistance of the contact layers close to the metal surfaces (Rth,contact) is mainly defined by the particle size and the size distribution of these particles.
Therefore, for an optimum overall thermal resistance Rth, TIM, the filling degree, particle size, particle size distribution and, of lesser importance, the thermal conductivity of the particles has to be optimized. SEMIKRON’s High Performance Thermal Paste (HPTP) does precisely this.