Overview Thermal management (electronics)

1 overview

1.1 thermal resistance of devices
1.2 thermal time constants
1.3 thermal interface material

overview
thermal resistance of devices

this quoted thermal resistance junction case of semiconductor device. units °c/w. example, heatsink rated @ 10 °c/w 10 °c hotter surrounding air when dissipates 1 watt of heat. thus, heatsink low °c/w value more efficient heatsink high °c/w value. given 2 semiconductor devices in same package, lower junction ambient resistance (rθj-c) indicates more efficient device. however, when comparing 2 devices different die-free package thermal resistances (ex. directfet mt vs wirebond 5x6mm pqfn), junction ambient or junction case resistance values may not correlate directly comparative efficiencies. different semiconductor packages may have different die orientations, different copper(or other metal) mass surrounding die, different die attach mechanics, , different molding thickness, of yield different junction case or junction ambient resistance values, , obscure overall efficiency numbers.

thermal time constants

a heatsink s thermal mass can considered capacitor (storing heat instead of charge) , thermal resistance electrical resistance (giving measure of how fast stored heat can dissipated). together, these 2 components form thermal rc circuit associated time constant given product of r , c. quantity can used calculate dynamic heat dissipation capability of device, in analogous way electrical case.

thermal interface material

a thermal interface material or mastic (aka tim) used fill gaps between thermal transfer surfaces, such between microprocessors , heatsinks, in order increase thermal transfer efficiency.

it has higher thermal conductivity value in z-direction xy-direction.