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Advanced Thermal Management for High Power Applications
Materials Tech |
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Authored By:Gregor Langer, Markus Leitgeb Austria Technologie & Systemtechnik AG,Leoben, Austria Johann Nicolics, Michael Unger Institute of Sensor & Actuator Systems, Vienna University of Technology, Vienna Austria Hans Hoschopf Tridonic Jennersdorf GmbH, Jennersdorf, Austria Franz P. Wenzl Institute for Surface Technologies and Photonics, Weiz, Austria SummaryWith increasing power loss of electrical components, thermal performance of an assembled device becomes one of the most important quality factors in electronic packaging. Due to the rapid advances in semiconductor technology, particularly in the regime of high-power components, the temperature dependence of the long-term reliability is a critical parameter and has to be considered with highest possible care during the design phase. Two main drivers in the electronics industry are miniaturization and reliability. Whereas there is a continuous improvement concerning miniaturization of conductor tracks (lines / spaces have been reduced continuously over the past years), miniaturization of the circuit carrier itself, however, has mostly been limited to decreased layer-counts and base material thicknesses. This can lead to significant component temperature and therewith to accelerated system degradation. Enhancement of the system reliability is directly connected to an efficient thermal management on the PCB-level. There are several approaches, which can be used to address this issue: Optimization of the board-design, use of base materials with advanced thermal performance and use of innovative buildup concepts. The aim of this paper is to give a short overview about standard thermal solutions like thick copper, thermal vias, plugged vias or metal core based PCBs. Furthermore, attention will be turned on the development of copper filled thermal vias in thin board constructions. In another approach advanced thermal management solutions will be presented on the board level, exploring different buildup concepts (e.g. cavities). Advantages of cavity solutions in the board will be shown, which not only decrease the thermal path leading from the high power component through the board to the heat sink, but also have an impact concerning the mechanical miniaturization of the entire system (reduction of z-axis). Such buildups serve as packaging solution and show an increase in mechanical and thermal reliability. Moreover, thermal simulations will be conducted and presented in this paper in order to reduce production efforts and to offer optimized designs and board buildups. ConclusionsSeveral different concepts for thermal management solutions on printed circuit boards for high power applications were shown in this paper. Benefits of state-of-the-art concepts, like Insulated Metal Substrates and open or plugged thermal vias were illustrated by comparing the thermal performance of high-power LED modules built-up with different concepts. In particular the plugged thermal vias and the Insulated Metal Substrates as they allow to realize short heat conduction paths turned out be interesting thermal management solutions. Beside these well-established variants also some new concepts have been presented. Cavity boards (boards with local depth reduction) show thermal advantages due to a reduced thermal path along the z-axis through the board. Thermal simulations of cavity boards attached with high power light emitting devices show excellent cooling performance. In comparison with the simulation results of state of the art concepts, the cavity board approach shows by far the lowest thermal resistance of the board system and guarantees therefore also the lowest junction temperature for the attached high power component. The realization of test vehicles of these concepts is planned, to verify the simulation data by thermal measurements on these test boards. Furthermore also the thermal advantages of copper-filled thermal vias in chip carrier boards have been presented. First results of thermal simulations have been shown and discussed. Further simulations and measurements on test vehicles are going on, and the results of these thermal investigations are also planned to be published in the near future. Initially Published in the IPC Proceedings |
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