Answer Happy

A rectangular board with dimensions of length, L = 20cm,
breadth, B = 10cm, and thickness, t = 0.5cm and the board has has
100 microprocessors that are each giving out heat at the rate of
0.05W. The circuit board material has thermal conductivity k
= 40 W/m-K. All the heat from the microprocessors is
conducted through the circuit board and dissipated to
the surrounding air at 40oC. The heat
transfer coefficient, h = 40 W/m2·K.
A heat sink is attached to the back of the board (the side
exposed to ambient temperature) using a layer of adhesive epoxy
0.03cm thick and thermal conductivity k_epoxy = 2 W/m·K. The
heat sink is made of an aluminum base plate ( base area is
the same as the circuit board) with 900 cylindrical pin fins.
Thermal conductivity of aluminum, k_sink = 240 W/m·K. The base
plate of the heat sink is 0.3cm thick. Each fin has diameter
0.2cm and length L_fin = 2.0cm.
1) Find the thermal resistance of the circuit board
in
2) Find the convective thermal resistance at the back surface of
the circuit board
3) Find the total thermal resistance of the circuit
board
4) Find the temperature at the back surface (cooler face) of the
circuit board in
5) Find the temperature at the front surface (warmer surface) of
the circuit board
6) Find the fin efficiency using the corrected length
concept
7) Find the total (convective and conductive) thermal resistance
(in oC/W) of the circuit board with the epoxy adhesive and heat
sink
8) Find the temperature in C of the front surface (warmer surface)
of the circuit board