<p>In recent automobiles, because of the increase in the number and complexity of control systems, the number of electronic control units (ECUs) is also increasing. Given the limited space available within an automobile, downsizing of such ECUs is thus important. However, reducing the size of an ECU results in an increased thermal density within it, so efficient heat dissipation is crucial. For the autonomous driving ECUs and advanced driver-assistance system ECUs, improving the heat dissipation of ECUs has become a more critical issue since the plural heat-generating components like the recognition microcomputer, control microcomputer and memory are mounted in those ECUs. On the other hand, it is necessary to provide a gap between the heat-generating components and the housing from the viewpoint of component solder joint reliability for the thermal deformation caused by the thermal expansion coefficient mismatch between the component, PCB and housing. However those gaps cause the large thermal resistance between the heat-generating component and the housing. Reducing this thermal resistance is one of the important viewpoints in ECUs thermal management. One solution is to fill the gap with a thermal interface material (TIM). Now, we focused on the metal foam as a filler installed in those TIMs. Since the metal foam is not a powder, it does not scatter inside the ECU. This means that the metal foam does not cause a short circuit. Also, the metal foam has higher thermal conductivity than the conventional ceramics filler used inside ECU, and low modulus of elasticity. In previous study, we proposed and prototyped the bran new composite thermal interface component (TIC), which is mounted between heat generating component such as microcomputer and ECU housing. A prototyped composite TIC was made of copper metal foam with the pore diameter of 0.52mm and porosity of 85%, and the conventional TIMs of 2.3 W/(m·K), 3.5 W/(m·K), and 5.1 W/(m·K). The thermal conductivity of the prototyped composite TICs were measured using the steady-state method. The experimental value was higher than the theoretical value predicted by Boomsma’s model. Those result suggested that there was room for improvement in the theoretical model examined in the previous study. In this study, we will report the results on the improving the theoretical models for the composite TICs thermal conductivity prediction by examining another theoretical models and some parameters.</p>

Thermal Conductivity Prediction Model for Composite Thermal Interface Materials Using Copper Metal Foam

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2021/volume/85505

ASME 2021 International Electronic Packaging Technical Conference and Exhibition (InterPACK2021)

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