抄録
Continuing trend of higher packaging density and the increasing device heat dissipation rate of electronic control unit (ECU) for automobiles requires the further advancement of ECU cooling technology. One of the major heat transfer paths from the ECU to the ambient is the contact between the ECU enclosure and the metal chassis where the ECU is attached to the body of the vehicle. Bolted attachment however cause surface deformation of the ECU enclosure that deteriorate the heat transfer capability. Although the deformation-caused surface waviness is apparently responsible for the increase of thermal contact resistance (TCR), vast majority of the conventional TCR works have focused only on the effect of surface roughness, including the pioneering works done by the Japanese researchers, Tachibana and Sanokawa. Their Tachibana-Sanokawa Equation of TCR considers various surface roughness parameters, it however cannot handle the waviness. This work mainly focuses on the effect of the strain caused by the bolted joint and the resulting or designed waviness on the TCR. Elasticity analysis of bolt-jointed two test plate specimens shows the deformation characteristics. Then, the pressure distribution between the ECU enclosure and metal surfaces is visualized in order to confirm the effect of designed waviness on ECU enclosure surface. Thermal experiment is then conducted to quantitatively show the significance of the designed waviness. The results discussed in the present work is expected to have impact not only to the ECU cooling but to the wide range of industrial application.
