Effects of fin geometry on boiling heat transfer from silicon chips with micro-pin-fins immersed in FC-72

摘要

Experiments were performed to study the effects of the height and thickness of square micro-pin-fin on boiling heat transfer from silicon chips immersed in a pool of degassed or gas-dissolved FC-72. Six kinds of micro-pin-fins with the dimensions of 30 x 60, 30 x 120, 30 x 200, 50 x 60, 50 x 200 and 50 x 270 μm~2 (thickness, t x height, h) were fabricated on the surface of a square silicon chip with the dimensions of 10 x 10 x 0.5 mm~3 by using the dry etching technique. The fin pitch was twice the fin thickness. The experiments were conducted at the liquid subcooling, ΔT_(sub), of 0, 3, 25 and 45 K under the atmospheric condition. The results were compared with previous results for a smooth chip and three chips with enhanced heat transfer surfaces. The micro-pin-finned chips showed a considerable heat transfer enhancement in the nucleate boiling region and increase in the critical heat flux, q_(CHF), as compared to the smooth chip. The wall temperature at the CHF point was always less than the maximum allowable temperature for LSI chips (= 85℃). For a fixed value of t, q_(CHF) increased monotonically with increasing h. The increase was more significant for larger t. The q_(CHF) increased almost linearly with increasing Δ_T(sub). The maximum value of allowable heat flux (= 84.5 W/cm~2), 4.2 times as large as that for the smooth chip, was obtained by the chip with h = 270 μm and t = 50 μm at ΔT_(sub) = 45 K.