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Quantification of cracked area in thermal path of high-powermulti-chip modules using transient thermal impedance measurement

Eleffendi, Mohd. Amir; Yang, Li; Agyakwa, Pearl; Johnson, C. Mark


Mohd. Amir Eleffendi

Li Yang

Anne Mclaren Research Fellow

C. Mark Johnson


Transient thermal impedancemeasurement is commonly used to characterize the dynamic behaviour of the heat flowpath in power semiconductor packages. This can be used to derive a “structure function”which is a graphical representation of the internal structure of the thermal stack. Changes in the structure function can thus be used as a non-destructive testing tool for detecting and locating defects in the thermal path. This paper evaluates the use of the structure function for testing the integrity of the thermal path in high powermulti-chipmodules. A 1.2 kV/200 A IGBT module is subjected to power cycling with a constant current. The structure function is used to estimate the level of disruption at the interface between the substrate and the baseplate/case. Comparison with estimations of cracked area obtained by scanning acoustic microscopy (SAM) imaging shows excellent agreement, demonstrating that the structure function can be used as a quantitative tool for estimating the level of degradation. Metallurgical cross-sectioning confirms that the degradation is due to fatigue cracking of the substrate mount-down solder.


Eleffendi, M. A., Yang, L., Agyakwa, P., & Johnson, C. M. (2016). Quantification of cracked area in thermal path of high-powermulti-chip modules using transient thermal impedance measurement. Microelectronics Reliability, 59,

Journal Article Type Article
Acceptance Date Jan 9, 2016
Online Publication Date Jan 25, 2016
Publication Date Apr 1, 2016
Deposit Date Apr 19, 2016
Publicly Available Date Apr 19, 2016
Journal Microelectronics Reliability
Print ISSN 0026-2714
Electronic ISSN 0026-2714
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 59
Keywords Structure function, Reliability, Power modules, Solder fatigue
Public URL
Publisher URL


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