Research Repository

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Comparison of thermal and reliability performance between a SiC MOSFET module with embedded decoupling capacitors and commercial Si IGBT power modules (2018)
Conference Proceeding
Yang, L., Agyakwa, P., Corfield, M., Johnson, M., Harris, A., Packwood, M., & Paciura, K. (2018). Comparison of thermal and reliability performance between a SiC MOSFET module with embedded decoupling capacitors and commercial Si IGBT power modules

This paper characterizes thermal and reliability performance of a SiC MOSFET power module with embedded decoupling capacitors and without anti-parallel diodes. Active and passive temperature cycling, supported by transient thermal impedance character... Read More

Time-efficient sintering processes to attach power devices using nanosilver dry film (2017)
Journal Article
Dai, J., Li, J., Agyakwa, P., & Johnson, C. M. (2017). Time-efficient sintering processes to attach power devices using nanosilver dry film. Journal of Microelectronics and Electronic Packaging, 14(4), doi:10.4071/imaps.521776. ISSN 1551-4897

Pressure-assisted sintering processes to attach power devices using wet nanosilver pastes with time scales of minutes to a few hours have been widely reported. This paper presents our work on time-efficient sintering, using nanosilver dry film and an... Read More

Damage evolution in Al wire bonds subjected to a junction temperature fluctuation of 30 K (2016)
Journal Article
Agyakwa, P., Yang, L., Arjmand, E., Evans, P., Corfield, M., & Johnson, C. M. (in press). Damage evolution in Al wire bonds subjected to a junction temperature fluctuation of 30 K. Journal of Electronic Materials, doi:10.1007/s11664-016-4519-0. ISSN 0361-5235

Ultrasonically bonded heavy Al wires subjected to a small junction temperature fluctuation under power cycling from 40°C to 70°C were investigated using a non-destructive three-dimensional (3-D) x-ray tomography evaluation approach. The occurrence of... Read More

Predicting lifetime of thick Al wire bonds using signals obtained from ultrasonic generator (2016)
Journal Article
Arjmand, E., Agyakwa, P., Corfield, M., Li, J., & Johnson, C. M. (2016). Predicting lifetime of thick Al wire bonds using signals obtained from ultrasonic generator. IEEE Transactions on Components, Packaging, and Manufacturing Technology, 6(5), doi:10.1109/TCPMT.2016.2543001. ISSN 2156-3985

Routine monitoring of the wire bonding process requires real-time evaluation and control of wire bond quality. In this paper, we present a nondestructive technique for detecting bond quality by the application of a semisupervised classification algor... Read More

A thermal cycling reliability study of ultrasonically bonded copper wires (2016)
Journal Article
Arjmand, E., Agyakwa, P. A., Corfield, M. R., Li, J., Mouawad, B., & Mark Johnson, C. (2016). A thermal cycling reliability study of ultrasonically bonded copper wires. Microelectronics Reliability, 59, doi:10.1016/j.microrel.2016.01.009. ISSN 0026-2714

In this work we report on a reliability investigation regarding heavy copper wires ultrasonically bonded onto active braze copper substrates. The results obtained from both a non-destructive approach using 3D X-ray tomography and shear tests showed n... Read More

Quantification of cracked area in thermal path of high-powermulti-chip modules using transient thermal impedance measurement (2016)
Journal Article
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, doi:10.1016/j.microrel.2016.01.002. ISSN 0026-2714

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 s... Read More

Response to comments on “A numerical method to determine interdiffusion coefficients of Cu6Sn5 and Cu3Sn intermetallic compounds” (2015)
Journal Article
Li, J., Agyakwa, P. A., & Johnson, C. M. (2016). Response to comments on “A numerical method to determine interdiffusion coefficients of Cu6Sn5 and Cu3Sn intermetallic compounds”. Intermetallics, 69, doi:10.1016/j.intermet.2015.10.016. ISSN 0966-9795

Comments have recently been made by Yuan et al. [1] to deny one statement in our paper [2], Eq. (21) in Wagner's paper [3] can be used to accurately calculate the integrated interdiffusion coefficient for an incremental diffusion couple only under th... Read More

Quantitative microstructure characterization of Ag nanoparticle sintered joints for power die attachment (2014)
Journal Article
Wang, Y., Li, J., Agyakwa, P., Johnson, C. M., & Li, S. (in press). Quantitative microstructure characterization of Ag nanoparticle sintered joints for power die attachment. Molecular Crystals and Liquid Crystals, 604(1), doi:10.1080/15421406.2014.967647. ISSN 1542-1406

The samples of sintered Ag joints for power die attachments were prepared using paste of Ag nanoparticles at 240 °C and 5 MPa for 3 to 17 minutes. Their microstructural features were quantitatively characterized with scanning elec-tronic microscopy,... Read More

Interdiffusion coefficients of binary multiphase systems with consideration of variation in Molar volumes (2014)
Journal Article
Li, J., Agyakwa, P., & Johnson, C. M. (2014). Interdiffusion coefficients of binary multiphase systems with consideration of variation in Molar volumes. ISSN 0975-0444

This communication introduces a modification to the Wagner method to reveal and correct considerable systematic errors existing in the previously established analytical methods used to calculate the interdiffusion coefficients of binary multiphase sy... Read More

A non-destructive study of crack development during thermal cycling of Al wire bonds using x-ray computed tomography (2014)
Conference Proceeding
Agyakwa, P., Yang, L., Corfield, M., & Johnson, C. M. (2014). A non-destructive study of crack development during thermal cycling of Al wire bonds using x-ray computed tomography

This paper concerns the non-destructive visualisation of the evolution of damage within ultrasonically bonded alumini-um wires using three dimensional x-ray computed tomography. We demonstrate the potential to observe the progressive accumulation of... Read More

Physics-of-failure lifetime prediction models for wire bond interconnects in power electronic modules (2013)
Journal Article
Yang, L., Agyakwa, P. A., & Johnson, C. M. (2013). Physics-of-failure lifetime prediction models for wire bond interconnects in power electronic modules. IEEE Transactions on Device and Materials Reliability, 13(1), doi:10.1109/TDMR.2012.2235836. ISSN 1530-4388

This paper presents a review of the commonly adopted physics-of-failure-based life prediction models for wire bond interconnects in power electronic modules. In the discussed models, lifetime is generally accounted for by loading temperature extreme... Read More

Packaging/assembling technologies for a high performance SiC-based planar power module
Conference Proceeding
Li, J., Agyakwa, P., Evans, P., Johnson, C. M., Zhao, Y., Wu, Y., & Evans, K. (in press). Packaging/assembling technologies for a high performance SiC-based planar power module

This work is to investigate the relevant packaging / assembling technologies for developing a SiC-based planar power module which is aimed to meet the requirements such as operating temperature of -60 °C to 200 °C, SiC devices connected to 540 V DC b... Read More