Advanced micro air-cooling systems for high density packaging

Future 3D electronics packaging systems will require micro cooling systems that can be integrated and permit the continued use of air as a coolant. To achieve this, new types of silicon micro heat exchangers were made using an anisotropic etching process. Various heat exchanger configurations and sizes were made using sandwich and stacking techniques. They can be used either as a heat exchanger for direct cooling with compressed air or as a heat pipe and thermosyphon for indirect cooling with fan-blown air. The performance characteristics of the various cooling systems are stated. The micro-heat-pipe can be used for power loss densities of up to 3 W/cm², the direct air cooling up to 15 W/cm² and the thermosyphon up to 25 W/cm². Cooling performances are achieved that are otherwise only possible with liquid cooling. The practical application of the micro cooling system is demonstrated using the example of the Pentium processor. With a power loss of 15 W, the micro cooling system is able to limit the increase in operating temperature to 15 K. The volume of the micro heat exchanger is 2.5 cm³ and therefore considerably smaller than that of standard heat sinks