TY - GEN A1 - Wunderle, Bernhard A1 - May, Daniel A1 - Heilmann, Jens A1 - Arnold, Jörg A1 - Hirscheider, Josef A1 - Lee, Yi A1 - Bauer, Jörg A1 - Schacht, Ralph A1 - Abo Ras, Mohamad T1 - Accelerated Pump Out Testing for Thermal Greases T2 - 20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) N2 - Thermal greases allow a low stress bond at low bond line thicknesses (BLT) at medium thermal conductivities and simple application, all of which make it an alternative to solders, thermal adhesives or pads. It is widely used in power and microprocessor applications, most of which involve large areas to be used for heat transfer. However, for years thermal overload failure of power modules and chips has been a pressing problem due to pump-out of thermal grease as a die or module thermal interface material (TIM): Most thermal greases are Bingham fluids and thus not solids, so they can be squeezed out from in between the gap, driven by thermo-mechanical action of the adjacent layers as e.g. DCB substrate or silicon chip with the heat sink. Today, thermal greases have to be qualified in lengthy stress tests in a product relevant environment which consumes substantial resources as often a system test is required. Therefore, a fast test is necessary which accelerates testing and thus allows a fast screening of commercial greases on one hand, and guidelines for material development on the other. For that purpose this paper addresses this topic in a combined simulative and experimental way, where at the same time a novel test procedure is proposed for accelerated grease pump-out testing (GPOT) in the framework of a completely new approach, combining loading with in-situ failure analytical techniques and decoupling thermal from mechanical loading. This allows for the first time a realistic loading of greases during accelerated testing with testing times below one hour. The method is demonstrated on various commercial and custom greases, varying their composition and structure, and benchmarked against industry standard thermal cycling tests. Further, two fundamental failure mechanisms have been identified being at work simultaneously, notably fluid transport (which constitutes actually a pump-in phenomenon) and air entrapment. We were able to identify key properties of the materials and loading variables, on which their intensity depends. KW - Thermal Grease, Pump out Y1 - 2019 SN - 978-1-5386-8040-7 SN - 978-1-5386-8039-1 SN - 978-1-5386-8041-4 U6 - https://doi.org/10.1109/EuroSimE.2019.8724540 PB - IEEE ER - TY - GEN A1 - Nourbakhsh, Amirhasan A1 - Adelmann, Christoph A1 - Song, Yi A1 - Lee, Chang Seung A1 - Asselberghs, Inge A1 - Huyghebaert, Cedric A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Elshocht, Sven van A1 - Heyns, Marc A1 - Kong, Jing A1 - Palacios, Tomás A1 - De Gendt, Stefan T1 - Graphene oxide monolayers as atomically thin seeding layers for atomic layer deposition of metal oxides T2 - Nanoscale N2 - Graphene oxide (GO) was explored as an atomically-thin transferable seed layer for the atomic layer deposition (ALD) of dielectric materials on any substrate of choice. This approach does not require specific chemical groups on the target surface to initiate ALD. This establishes GO as a unique interface which enables the growth of dielectric materials on a wide range of substrate materials and opens up numerous prospects for applications. In this work, a mild oxygen plasma treatment was used to oxidize graphene monolayers with well-controlled and tunable density of epoxide functional groups. This was confirmed by synchrotron-radiation photoelectron spectroscopy. In addition, density functional theory calculations were carried out on representative epoxidized graphene monolayer models to correlate the capacitive properties of GO with its electronic structure. Capacitance–voltage measurements showed that the capacitive behavior of Al2O3/GO depends on the oxidation level of GO. Finally, GO was successfully used as an ALD seed layer for the deposition of Al2O3 on chemically inert single layer graphene, resulting in high performance top-gated field-effect transistors. KW - Graphene Oxide KW - seed layer KW - atomic layer deposition KW - oxygen plasma treatment KW - photoelectron spectroscopy KW - density functional theory KW - capacitance-voltage Y1 - 2015 U6 - https://doi.org/10.1039/C5NR01128K SN - 2040-3364 SN - 2040-3372 VL - 2015 IS - 7 SP - 10781 EP - 10789 ER -