Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Advanced mixed-mode bending test: A rapid, inexpensive and accurate method for fracture-mechanical interface characterisation
    ( 2012)
    Wunderle, B.
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    Schulz, M.
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    Keller, J.
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    May, D.
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    Maus, I.
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    Pape, H.
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    Michel, B.
    This paper presents a comprehensive method for obtaining urgently required critical interface delamination data of material pairings used in electronic packaging. The objective is to thereby enable rapid, inexpensive and accurate lifetime prediction for that failure mode. A new testing method is presented which allows maximum mode-angle range and enhanced throughput testing under multiple loading conditions, the coverage of which is usually a rather lengthy and resource-demanding procedure. The approach is specimen-centred in the sense that the accent is put on test-specimens which are easily manufacturable industrially, rather than having to adapt them to a special testing machine. The concept is also scalable, i.e. it has potential to work also for smaller samples cut from real devices. We show the first version of a newly developed test-stand and discuss the obtained results for copper-molding compound interfaces in the light of the current state of the art used for delamination testing in electronic packaging.
  • Publication
    Automated test system for in-situ testing of reliability and aging behaviour of thermal interface materials
    ( 2011)
    AboRas, M.
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    Haug, R.
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    Schacht, R.
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    Monory-Plantier, C.
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    May, D.
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    Wunderle, B.
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    Winkler, T.
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    Michel, B.
    Thermal interface materials (TIMs) are widely needed to improve thermal contacts for facilitation heat transfer in electronic packaging, such as that associated with the flow of heat from microprocessor to a heat spreader or a heat sink in a computer. Due to thermal mismatch between these components mechanical strain occur which cause pump-out, cracks or delamination of TIM. In order to qualify the reliability and aging of TIMs, traditional power cycle test is commonly used to detect potential thermal failures. This traditional power cycle test is a time consuming process due to its long heating and cooling time. Therefore a new automated test system for in-situ reliability testing of TIMs is developed and will be presented in this paper. The new test system is designed to be able to analyze the aging and reliability behavior of most common TIMs. The TIMs can be measured in-situ and under real conditions as they are used in real applications.
  • Publication
    In-situ measurement of various thin bond-line-thickness thermal interface materials with correlation to structural features
    ( 2008)
    Wunderle, B.
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    Kleff, J.
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    Mrossko, R.
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    Abo Ras, M.
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    May, D.
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    Schacht, R.
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    Oppermann, H.
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    Keller, J.
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    Michel, B.
    Thermal characterisation of thermal interfaces becomes even tougher a challenge at low bond line thicknesses and higher thermal conductivities of the interface materials as more accurate measurement techniques are required. As in parallel the quest for high conductivity adhesives and greases is ongoing, a correlation between thermal bulk or interface properties and structure is in high demand. We have developed test-stands for various classes of thermal interface materials. These permit characterisation for materials with thin bond line thickness and high thermal conductivity still using steady state techniques. The methods are benchmarked for greases, adhesives and sintered silver. For the latter, the technology development is described. Then, structural features such as particle density and porosity are examined. It will be the aim to compare and correlate them to thermal resistance. Part of the work has been accomplished within the running EU. Project "Nanopack".
  • Publication
    Non-destructive failure analysis and modeling of encapsulated miniature SMD ceramic chip capacitors under thermal and mechanical loading
    ( 2007)
    Wunderle, B.
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    Braun, T.
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    May, D.
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    Mazloum, A.
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    Bouazza, M.
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    Walter, H.
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    Wittier, O.
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    Schacht, R.
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    Becker, K.-F.
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    Schneider-Ramelow, M.
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    Michel, B.
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    Reichl, H.
    The use of multi-layer ceramic chip capacitors as integrated passive in e. g. system in package applications needs methods to examine and predict their reliability. Therefore, a nondestructive failure analytical technique is described to detect cracks in the ceramic and the metallic layers within encapsulated 0402 SMD capacitors. After choosing from techniques to reproducibly generate cracks, it is shown that an in-situ capacitance measurement is a convenient method to detect these failures unambiguously. Finite Element simulations support the experimental results. A reliability estimate for capacitor integrity under given loading conditions is given.