Public defence: Stéphane Léonard Kuziora

Stéphane Léonard Kuziora will defend his PhD degree in Applied Micro- and Nanosystems. His dissertation explores Advancing metallurgical bonding for microelectronics, through low-temperature metal joining, high temperature resistant bonds, and the investigation of cavitation-induced voiding..

25 Mar

Practical information

  • Date: 25 March 2025
  • Time: 10.15 - 13.15
  • Location: Vestfold, Auditorium A1-36 and Zoom
  • Download calendar file

    • Link to digital participation (Zoom)

     

    Programme

    10.15 Trial lecutre: "CALPHAD construction and assessment of phase diagrams for alloy solidification and soldering”

    12.15 Public defence: Advancing metallurgical bonding for microelectronics, through low-temperature metal joining, high temperature resistant bonds, and the investigation of cavitation-induced voiding

    Supervisors

    • Main supervisor: Professor Knut Eilif Aasmundtveit, Universitetet i Sørøst-Norge
    • Co-supervisor: Associate Professor Hoang-Vu Nguyen, Universitetet i Sørøst-Norge

     

     

Any questions?

Stéphane Léonard Kuziora is defending his dissertation for the degree philosophiae doctor (PhD) at the University of South-Eastern Norway.

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Disputas Stéphane Léonard Kuziora

The doctoral work has been carried out for the PhD degree in Applied Micro- and Nanosystems at the Faculty of Technology, Natural Sciences and Maritime Sciences. 

You are invited to follow the trial lecture and the public defence.

Summary

Stéphane Léonard Kuziora presents his PhD research on metallurgical solid-liquid interdiffusion (SLID) bonding at the University of Southeastern Norway (USN). His academic journey began with a degree in chemical engineering from Lakehead University in Canada, followed by a master’s in micro and nano technology at USN before embarking on his PhD studies.


His PhD introduces a promising low temperature bonding system, presenting the first micrographs and description of the Ag-(In-Bi) SLID system, while demonstrating bonding at 150 °C with Ag substrates and an In-Bi foil of 78.5 at%In. The bonds can then be re-heated without melting, having a theoretical temperature stability up to ⁓480–570°C. This can enable the unique bonding of piezo-electric materials (PEM) at temperatures lower than their Curie temperature, eliminating the need for costly magnetic re-poling. Additionally, the technique supports metal-polymer composite materials and interconnection joining for temperature-sensitive electronic systems. The technique is also ideal for advancing computing density through 3-D stacking and fine interconnection pitch at the micrometer length.  


A phenomenon unique to the Ag-(In-Bi) SLID system was discovered and termed, “Bi precipitation” where pockets of Bi were formed behind the original bonding surfaces. Unlike similar occurrences in other SLID systems, experimental evidence with solid-state bonding of the Ag-(In-Bi) system showed the Bi pockets are formed through a dissolution mechanism. This bonding also demonstrated an even lower bonding temperature of 65 °C, being theoretically stable to ⁓166 °C.


Investigation into the high temperature resistant bonds found in the Ni-Sn SLID system revealed unique cavitation-induced voiding. Thermodynamic modelling confirmed that intermetallic growth within enclosed liquid Sn pockets generates sufficient pressure to initiate cavitation, a previously unexplored consideration in metallurgical bonding. The work presents a first approach and focused discussion to cavitation-induced voiding and may be utilized to enhance the reliability of SLID bonds by reduced voiding.