Heat Transfer

Fins and Heat Sinks 167

is 30 W/m

2

°C. This heat sink will be used to cool a 40 mm × 40 mm

package. Calculate total thermal resistance of this heat sink for this

package. Neglect caloric thermal resistance.

Note: Cross section area and perimeter of a diamond with diagonals

D

1

and D

2

are

ADD

c

=

12

2/

and

PDD=+2

1

2

2

2

,

respectively.

10 mm

2 mm

Fin cross

section

100 mm

100 mm

5 mm

50 mm

7.14 Consider the copper pin n heat sink shown below. Its base dimen-

sions are 100 mm × 100 mm × 5 mm and has 100 ns with square

cross sections. The ns are 50 mm long and 2 mm × 2 mm cross sec-

tion. Air with a velocity of 2 m/s blows into this heat sink. Therma