Design of the Contact Metallizations for Gold-Tin Eutectic Solder-A Thermodynamic-Kinetic Analysis

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2016-09-30
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Date

2016

Department

Sähkötekniikan ja automaation laitos
Department of Electrical Engineering and Automation

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Mcode

Degree programme

Language

en

Pages

pp. 59 + app. 73

Series

Aalto University publication series DOCTORAL DISSERTATIONS, 176/2016

Abstract

This dissertation focuses on the design of reliable interconnections using Au-20wt.%Sn solder with the assistance of thermodynamic calculations. In this work, three commonly encountered contact metallizations, namely Ni, Cu, and Pt, have been selected. In order to assess the reliability of the Au-20wt.%Sn|X (X=Ni, Cu and Pt) interconnections from the metallurgical viewpoint, firstly, the phase diagrams of the Au-Sn-X ternary systems have been thermodynamically established with the Calphad method. Secondly, the diffusion couple method was employed to study the interfacial reactions experimentally. The microstructures of the as-soldered and subsequently aged Au-20wt.%Sn|X interconnections were characterized by means of scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (EDX) and scanning transmission electron microscopy with EDX. The observed interfacial reaction phenomena have been rationalized by combining the experimental results with the thermodynamic considerations. Emphasis has also been placed on collecting the mechanical properties of the IMCs formed at the solder/Cu and Ni interfaces since these values are essential for evaluating the reliability of the interconnections.  The results in this dissertation show that Au-20wt.%Sn|Pt was more thermally stable than Au-20wt.%Sn|Ni and Au-20wt.%Sn|Cu when these as-soldered reaction couples were subsequently aged at 150 °C for a long-term. When a short bonding time is employed, Pt contact metallization is superior to the Ni and Cu contact metallizations for the Au-20wt.%Sn solder.

Description

Supervising professor

Paulasto-Kröckel, Mervi, Associate Prof., Aalto University, Department of Electrical Engineering and Automation, Finland

Thesis advisor

Vuorinen, Vesa, Dr., Aalto University, Department of Electrical Engineering and Automation, Finland

Keywords

contact metallization (Ni, Cu, Pt), Au-20wt.%Sn solder, Calphad, microstructural characterization, interfacial reaction, mechanical properties

Other note

Parts

  • [Publication 1]: Dong Hongqun, Vuorinen Vesa, Laurila Tomi, Paulasto-Kröckel Mervi. 2013. Thermodynamic reassessment of Au–Ni–Sn ternary system. Elsevier, Calphad, 43, 61-70. ISSN: 0364-5916.
    DOI: 10.1016/j.calphad.2013.10.001 View at publisher
  • [Publication 2]: Dong Hongqun, Vuorinen Vesa, Tao Xiaoma, Laurila Tomi, Paulasto- Kröckel Mervi. 2014. Thermodynamic reassessment of Au-Cu-Sn ternary system. Elsevier. Journal of Alloys and Compounds, 588 (5), 449-460. ISSN:0925-8388.
    DOI: 10.1016/j.jallcom.2013.11.041 View at publisher
  • [Publication 3]: Dong Hongqun, Vuorinen Vesa, Liu Xuwen, Laurila Tomi, Li Jue, Paulasto- Kröckel Mervi. 2016. Microstructural Evolution and Mechanical Properties of Au-20wt.% Sn| Ni Interconnection. Springer. Journal of Electronic Materials, 45(1), 566-575. ISSN: 0361-5235.
    DOI: 10.1007/s11664-015-4152-3 View at publisher
  • [Publication 4]: Dong Hongqun, Vuorinen Vesa, Laurila Tomi, Paulasto-Kröckel Mervi. 2016. Microstructural Evolution and Mechanical Properties in (AuSn)eut-Cu interconnections. Springer. Journal of Electronic Materials, 45(10), 5478–5486. ISSN: 0361- 5235.
    DOI: 10.1007/s11664-016-4733-9 View at publisher
  • [Publication 5]: Dong Hongqun, Vuorinen Vesa, Broas Mikael, Paulasto-Kröckel Mervi. 2016. Thermodynamic Reassessment of the Au-Pt-Sn System and Microstructural evolution of the (AuSn)eut-Pt Interconnection. Journal of Alloys and Compounds, 688, 388-398. ISSN: 0925-8388.
    DOI: 10.1016/j.jallcom.2016.07.129 View at publisher

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https://urn.fi/URN:ISBN:978-952-60-6995-1

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[diss] Sähkötekniikan korkeakoulu / ELEC