Claudio Maria Villa

Thermal transient modeling and experimental validation in the European project PROFIT

Results of the European project PROFIT on thermal transient measurement and modeling of IC packages are presented. All together 16 different packages from the three semiconductor manufacturers Infineon, Philips and ST Microelectronics were measured in four dual cold plate (DCP) environments as defined in the preceding DELPHI and SEED projects. Solutions to measure TO-type and fine pitch packages in the DCP, especially for the critical DCP-4 boundary condition were demonstrated, as well as reduction of interface resistance and increased reproducibility by using Woods alloy as an interface material. The measurements were simulated using the commercial software packages ANSYS/spl reg/, FLOTHERM/spl reg/ or MARC/spl reg/. The agreement between simulated and measured thermal impedance is quite good (<15%) from steady state (t=1000s) to transients with t<0.1s, i.e. 4 orders of magnitude. In a few cases, this level of accuracy was kept even over 7 orders of magnitude. Increasing relative inaccuracy with shorter transients corresponds to small absolute errors in temperature. So for practical pulse temperature prediction, the accuracy should already be sufficient, for extraction of geometrical and material parameters, it is probably not.A major objective of the European project PROFIT is to generate boundary condition independent (BCI) dynamic compact thermal models (DCTM) of semiconductor products. Extending the methods for steady BCI-CTM developed in preceding projects DELPHI and SEED to the transient domain, a detailed numerical model of the component is needed, which is validated against four dual cold plate (DCP) experiments extracting heat along the main heat flow paths from a package. The validated detailed model is then used for numerical experiments in many environments represented by external BC. Results are used to optimize resistors and capacitors of a small network forming the DCTM. This work is focused on the first part of developing validated detailed dynamic models by comparison of modeling and measurements. Results of the European project PROFIT on thermal transient measurement and modeling of integrated circuit packages are presented. All together sixteen different packages from the three Semiconductor Manufacturers Infineon, Philips, and ST Microelectronics were measured in four DCP environments as defined in the preceding DELPHI and SEED projects. Solutions to measure TO-type and fine pitch packages in the DCP, especially for the critical DCP-4 boundary condition were demonstrated, as well as reduction of interface resistance and increased reproducibility by using Woods alloy as an interface material. The measurements were simulated using the commercial software packages ANSYS, FLOTHERM, or MARC. The agreement between simulated and measured thermal impedance is 15% or better from steady state (t=1000 s) to transients with t>0.1, i.e., four orders of magnitude. In a few cases, this level of accuracy was kept even over seven orders of magnitude. Increasing relative inaccuracy with shorter transients corresponds to small absolute errors in temperature. So practical pulse temperature prediction will usually be correct within a few degrees. Extraction of geometrical and material parameters will need further improvement.

From Power SO to E-Pad packages: a thermal bargain?

Facing the demand of low cost solutions for medium power applications from various segments of the electronics market, a full thermal study comparing existing power SMD package families and new e-pad structures is performed. Different body sizes and pin counts are considered. The study consists of thermal modeling analysis carried on using FLOTHERMreg. Thermal simulation results with different PCB configurations are presented. The thermal dissipation mechanism for those packages through the metal bottom case to the PCB is described. The copper exposed area dimension soldered onto the PCB is identified as the dominating factor controlling the total package thermal resistance. Consequently the limits of applicability of new small body e-pad packages versus the old style power SMDs are finally defined