5. You are asked to design a heat sink, like the one shown below, for power electronic applications. To prevent electrical coupling and stray capacitance between chip and heat sink, the heat sink must be a good electrical insulator with a resistivity of pe > 1019 Q.cm. But to drain heat away from the chip as fast as possible, it must also have the highest possible thermal conductivity (). All dimensions are constrained by other aspects of the design. List the function, constraints, objective, and free variables for this heat sink. Substrate Connecting pins Chips Heat sink Cooling fins 6. By looking at the thermal conductivity vs. electrical resistivity chart given below, which material or materials would be your choice for the heat sink application in Q5? Thermal conductivity, (W/m.K) 1000 Metals T-Conductivity - Resistivity Boron Silicon SIC Cu alloys carbide Al alloys Tungsten carbide Al nitride 100 10 10 Zn alloys W alloys Mg alloys Steels Lead alloys Stainless steels Ti alloys Technical ceramics 0.1- 0.01 MFA, 04 Line of =C/pe CFRP Stone Concrete Composites Leather Natural materials Cork 1 104 108 Wood Al2O3 SigN4 Glasses Polymers and Soda glass Glass ceramic elastomers Silica glass PET PA. PE GFRP PP Butyl rubber PMMA Neoprene Rigid polymer foams Foams Flexible polymer foams 1012 1016 1020 1024 Electrical resistivity, pe (-2.cm) 1028