Consider a power transistor encapsulated in an aluminumcase that is attached at its base to a square aluminumplate of thermal conductivity k= 240W/m.K, thicknessL= 6mm, and width W= 20mm. The case is joined to theplate by screws that maintain a contact pressure of 1bar, and the back surface of the plate transfers heatby natural convection and radiation to ambient air andlarge surroundings at T∞ =Tsur -25°C. The surface has anemissivity of ε=0.9, and the convection coefficient ish=4 W/m².K. The case is completely enclosed such thatheat transfer may be assumed to occur exclusivelythrough the base plate.a) If the air-filled aluminum-to-aluminum interface ischaracterized by an area of A₁=2×10-4 m² and contactresistance of R+c= 1.375 K/W, what is the maximumallowable power dissipation if the surface temperatureof the case, Ts,c, is not to exceed 85°C?S,C'TransistorcaseTs. PelecS,C'EnclosureWIsurBase plate, (k,ε)Interface, AcAirTh801b) How much should the h be toenhance power dissipation to 1 Watt?

Answered: Consider a power transistor…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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