03. Electronics Packaging and Thermal Management

A prototype ultra-thin vapor chamber (UTVC)/plate-fin heatsink module is fabricated to cool the GaN chips on a block up-converter (BUC) for satellite communication usage. The UTVC has a dimension of 120  120  1 mm3. This novel module consists of a high-power UTVC with composite wick in combination with a plate-fin heatsink and a 120  120 mm2 impinging axial fan. In place of the pin-fin heatsink, the copper plate-fin heatsink, having a fin thickness of 0.8 mm, a length of 140 mm, a spacing of 2.7 mm, and a height of 30 mm, and coupled with a downward-blowing fan, induces lower pressure drop and lower fan-blowing power. The performance tests were conducted with three stages. The first is to ensure the attained maximum heat flux to exceed the highest heat flux of 140 W/cm2 of the GaN chips, using an oxygenless-copper heating rod with a top area of 10  10 mm2. Then, the maximum heat transfer rate was measured, using a 30  30 mm2 oxygenless copper heater and a cold plate, to be 497.7 W. The third is to show that the UTVC/plate-fin heatsink module displays a case temperature of 62.7 ℃ at 260.4 W dissipation. Instead, the case temperature of the current pin-fin heatsink at 261.5 W dissipation was calculated to be about 87.5 ℃, 24.8 ℃ higher than using the present thermal module. Also, the present UTVC/plate-fin heatsink module consumed only 1/9 of the pin-fin heatsink module.

Dr.

Chih-Chao Hsu