Category | Thermal Management

Thermal Modeling of Power Module Cooling Systems

Posted on 24 July 2020

              The extensive heat build-up in power modules caused by forward, switching, and blocking losses has to be dissipated by means of heatsinks. These heatsinks provide an expanded surface for convection and radiation, spreading the heat flow as well as reducing the intensity of transient thermal processes. Due to [...]

Modeling of Temperature Dependence of Power Semiconductor I-V Curves

Posted on 10 April 2020

              The I-V curve is the most important parameter of power semiconductors (PSD), since power semiconductor output capacity and efficiency depends upon it to a great extent. Many publications are devoted to the analysis of the physical phenomena determining I-V curves of power semiconductor devices (e.g. the monographies [1, [...]

Thermal Paste Application

Posted on 18 March 2020

              Designated use of thermal interface material (TIM) When in operation, power modules produce losses which increase the module temperature and impair module efficiency and/or functionality. To dissipate the heat that builds up in power modules, the power modules are mounted onto heat sinks. The heat is then dissipated [...]

Evaluation of Temperature Curves Regarding Power Module Lifetime

Posted on 01 February 2020

              All internal connections of power modules are subject to aging caused by temperature fluctuations. The fatigue of material as well as wear and tear is caused by thermal stress due to the different expansion coefficients of the connected materials. Module lifetime or respectively, the number of possible temperature [...]

Water Cooling of Power Modules

Posted on 30 January 2020

              Water cooling in power modules can be used for very high power inverters (MW range) as well as for low-power devices which already have a water cycle for operating reasons (e.g. car drives, galvanic installations, inductive heating). In most cases, the admission temperature of the coolant values is [...]

Forced Air Cooling of Power Modules

Posted on 21 January 2020

              In contrast to natural air cooling, forced air cooling can reduce the thermal heatsink resistance to 1/5...1/15. Figure 1 compares the Zth(s-a) characteristics of natural and forced air cooling up to the final Rth(s-a) value using the example of a SEMIKRON P16 heatsink in different lengths. Figure 1. [...]

Thermal stacking of Power Modules

Posted on 14 January 2020

              When thermally stacking several heatsinks, in particular in combination with larger power electronics assemblies, the reduction in coolant flow rate resulting from the increased pressure drop and pre-heating of the coolant for the "backward" units has to be considered in the calculations. Figure 1. a) Individual cooling; b) [...]

Failure Mechanisms During Power Cycling

Posted on 10 January 2020

  The thermo-mechanical stress between materials with different thermal expansion coefficients (CTE) leads to aging of connections when they are exposed to temperature changes. Which of the mechanisms will eventually cause component failure depends on the load and cooling conditions. The further the connection is away from the chip, the longer it takes to heat [...]

Power Module Junction Temperature Calculation

Posted on 08 January 2020

  Examples of power module junction temperature calculations for various operating conditions are given below. The following calculations make use of thermal equivalent circuit diagrams, a method that can be used in certain situations to simplify junction temperature calculations. For more complex situations, other calculation techniques must be employed.     Junction temperature during stationary [...]

Thermal Equivalent Circuit Diagrams for Junction Temperature Calculations

Posted on 03 January 2020

              The calculation of junction temperatures is based on simplified thermal equivalent circuit diagrams (Figure 1)  in which three dimensional structures are mapped to one dimensional models. This will inevitably result in errors, since thermal connections between different components inside one housing or on one heatsink are dependent on [...]