UK : PhD Studentship Lead-Free Interconnections for Very Low Temperature Electronic Systems

Loughborough University - Wolfson School of Mechanical and Manufacturing Engineering

Ref: DPW291009

Space, aviation and maritime environments present particularly low temperature harsh operating conditions for electronics under which solder joints have to survive, and provide long term operational integrity. At the same time the majority of the electronics industry has moved to the use of high tin content, lead-free solder alloys. A potential issue in the use of such alloys for prolonged periods of low temperature is so called "tin pest", a phase transformation from β-Sn to α-Sn accompanied by a 26% volume expansion that causes loss of structural strength. Other factors in the transformation are known to be stress, presence of a seed and composition of the alloy. However an understanding of the basic mechanisms of the phenomenon, that would allow a realistic assessment of likely failure rates of lead free solder joints due to tin pest, is lacking.

This study aims at contributing to the required understanding through a systematic investigation of the phenomenon under representative conditions encountered in harsh environments. The research programme is likely to involve:

• Experimental exploration of long term aging of lead-free, high tin solders, matching the accelerated aging protocols to harsh environments;
• High resolution electron microscopy (HREM) characterisation of the interphase boundary, and of the ordered and disordered regions;
• Modelling of the thermodynamic driving forces for phase separation in the tin system.
• Analysis of the effects on the transformation of the microstructure and morphology of the system.

A PhD Studentship supported by the Innovative electronics Manufacturing Research Centre (IeMRC) and NPL is available to support the research. Subject to satisfactory progression, the Studentship will cover fees at the UK/EU student rate for three years, and in addition will pay a stipend of around £13,290 per annum. For high quality candidates from outside the EU top-up funding to cover the higher rate of student fees may be available. Applicants should have, or be about to gain, a first or upper second-class degree or MSc in a materials, physics, engineering or chemistry - related subject.

To express an interest or for more details please contact:

Dr Patrick Webb

Wolfson School of Mechanical and Manufacturing Engineering

Loughborough University,

Loughborough, Leicestershire

LE11 3TU, United Kingdom

tel:+44 (0)1509 227678

e-mail: D.P.Webb@lboro.ac.uk

For an application pack and details of admissions requirements please contact:

Ms J R Mason, Research Administrator, e-mail: J.R.Mason@lboro.ac.uk.

PLEASE QUOTE REF: DPW291009 ON APPLICATION FORM AND ENQUIRY.

The closing date for applications is: Friday 20^th November 2009