An integrated circuit, with dimensions 3 cm times 3 cm, dissipates q = 5 W of heat to
surrounding air at T infin = 25 degrees C. The heat transfer coefficient is h = 20 W/m2 middot K.
Calculate the surface temperature of the circuit if no fins are present. Based on the result of your
answer, is it accurate to assume that convection is the sole heat transfer mechanism from the
circuit? To enhance heat removal from the circuit, rectangular fins of length L = 2 cm, thickness
t = 0.1 cm, and width w = 3 cm are attached to the surface. The fins are made from aluminum (k
= 200 W/m middot K). If the maximum allowable surface temperature of the circuit is TB = 75
degrees C, calculate the required number of fins on the surface.
Solution
1)ha(t-ts)=5
t=302.77C
some of the heat transfer may also be due to radiation
2)m=sqrt(hp/kac)
m=14.37
heat transfer through a fin=sqrt(hpkac)(t-ts)tanhml
l=l+k=2.0483m
heat transfer through each fin is approx 4.3
so we need to keep 1.15 or 2 fins