- Approximately 10 Discrete Electrical Components Can Be Placed On A Single Integrated Circuit Chip With Electrical He 1 (250.31 KiB) Viewed 39 times
Approximately 10% discrete electrical components can be placed on a single integrated circuit (chip), with electrical heat dissipation as high as 30,000 W/m2. The chip, which is very thin, is exposed to a dielectric liquid at its outer surface, with ho = 1000 W/m²K and T20,0 = 20 C, and is joined to a circuit board at its inner surface. The thermal contact resistance between the chip and the board is 10-4 m²K/W, and the board thickness and thermal conductivity are Lo = 5 mm and kn = 1 W/mK, respectively. The other surface of the board is exposed to ambient air for which hi = 40 W/m²K and Too,i = 20 C. Coolant Topho Chip 9T Thermal contact resistance, RC -Board, ko Air Tojsh (a) Sketch the equivalent thermal circuit corresponding to steady-state conditions. In variable form, label appropriate resistances, temperatures, and heat fluxes. (b) Under steady-state conditions for which the chip heat dissipation is qe = 30,000 W/m², what is the chip temperature? (c) The maximum allowable heat flux, qc,m, is determined by the constraint that the chip temperature must not exceed 85 C. Determine qe,m for the foregoing conditions. If air is used in lieu of the dielectric liquid, the convection coefficient is reduced by approximately an order of magnitude. What is the value of qc,m for ho = 100 W/m²K With air cooling, can significant improvements be realized by using an aluminum oxide circuit board and/or by using a conductive paste at the chip/board interface for which R4,c = 10-5 m²K/W? =