The experiments were performed with a 31mm × 31mm × 7mm simulated module mounted on the floor of a parallel plate channel. The base wall is made of a 1mm thick copper plate. The conductive thermal resistance through the interface support, Rc, is thereby changed in three steps, namely, 0.02 K/W, 0.31K/W and 210K/W. Thermal conductance (UBB) of the board and convective thermal conductance (UA) from the module were derived, and the effect of Rc on UBB was investigated. It is found that the temperature of the module (TM) and the convective heat transfer ratio (QA/Q) depend on the thermal resistance of the connection layer The change of interface thermal resistance helps to elucidate the relative significance of heat transfer paths through the connection layer, the board, and from the board surface to the air.