Influence of various micro channels integrated in LTCC multilayer module on the thermal resistance

Abstract

This paper presents novel application of using micro channels integrated in LTCC (Low Temperature Co-fired Ceramics) structure as new solution for cooling in power electronics. The aim of this paper is detailed investigation of the thermal resistance, flow analysis and distribution of coolant inside LTCC substrates with internal micro channels. Three different LTCC multilayer structures with integrated micro channel and thermal vias were designed, simulated, fabricated and measured. It was applied various micro channel widths and various quantities of thermal vias under the power chip for improving cooling affect. The impact of the volume flow of liquid coolant, structures of multilayer substrate and thermal vias on thermal resistance of substrate was simulated by using the simulation software Mentor Graphic FloEFD™. The fluidic channel was integrated in the third layer from the top of 6 layers substrate. Thermal vias were embedded inside substrate and channel excluding the top dielectric layer. This cooling concept improves homogeneity and effectivity of heat transfer between the power chips and the coolant. The coolant is pumped through channel for cooling down the 2 tested chips. Principle of thermal resistance measuring was on investigation of the impact of the first chips' thermal load on the second chip. The heat transfer is characterized by the decrease of maximum working temperature, thermal resistance of substrate, temperature distribution, fluid pressure and flow velocity. The main advantage of presented cooling concept is effective and homogenous cooling of critical components.