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Now showing 1 - 2 of 2
  • Publication
    Thermal Investigation of GaAs Microwave Power Transistors
    (IMAPS, 2004) ;
    Mayer, Markus 
    Mündlein, Martin 
    Nicolics, Johann 
    The lower thermal conductivity of gallium arsenide (GaAs) compared to silicon (Si) requires a careful thermal design for optimizing device performance and reliability. In this paper a recently developed thermal simulation tool (TRESCOM II) is applied for investigating the thermal behavior of a heterojunction GaAs power field effect transistor (FET). Main features of the simulation tool are an easy model creation procedure and an efficient numerical solver. Moreover, the tool allows to consider temperature dependent material properties and temperature dependent boundary conditions. The investigation of the thermal behavior of the power transistor has two goals. First goal is to establish the temperature distribution within the active layer of the FET to allow predictions of thermal-electrical interactions. A deeper insight into thermal-electrical interaction will lead to better equivalent circuit models used in electrical circuit design. Due to the fact that reliability of the component is mainly determined by thermal load and induced thermomechanical stress, second goal of this work is to investigate the influence of chip thickness and die bonding variations on the thermal behavior. Thermal response on different power levels is investigated and the influence of chip thickness tolerances and die bonding on the thermal performance of the device is discussed.
  • Publication
    Highly Accelerated Mechanical Lifetime Testing for Wire Bonds in Power Electronics
    (IMAPS, 2022-06) ;
    Khatibi, Golta 
    This article presents various experimental studies on fatigue evaluation of wire bond interconnects and interfaces in electronic devices using an accelerated mechanical fatigue testing system. This dedicated experimental setup is designed to induce fatigue failure in the weak sites of the wire bond by reproducing the thermomechanical failure modes occurring during operation. An exceptional highly test acceleration is achieved by increasing the mechanical testing frequency into the kHz regimen enabling the determination of lifetime curves in a very short time. A com parison of this method to conventional testing methods such as power cycling, a shear testing exploits the potential of customized accelerated mechanical testing. Exemplary studies on the degra dation and fatigue failure of heavy Al wire bonds typically used in power electronics and novel Cu wire bonds are presented and advantages and some restrictions of the proposed method are discussed.