Title: Accelerated aging and thermal-mechanical fatigue modelling of Cu-plated through holes with partial solder filling

Authors: Donald F. Susan, Alice C. Kilgo, Michael K. Neilsen, Paul T. Vianco

Addresses: Sandia National Laboratories, P.O. Box 5800, Mailstop 0886, Albuquerque, NM 87185, USA. ' Sandia National Laboratories, P.O. Box 5800, Mailstop 0886, Albuquerque, NM 87185, USA. ' Sandia National Laboratories, P.O. Box 5800, Mailstop 0847, Albuquerque, NM 87185, USA. ' Sandia National Laboratories, P.O. Box 5800, Mailstop 0889, Albuquerque, NM 87185, USA

Abstract: The reliability of connector-to-board solder joints was investigated by accelerated aging experiments and finite element analysis (FEA), with a strain-based criterion for fatigue failure of Cu vias. The accelerated aging temperature cycle was –55°C to +125°C. The pin/through hole solder joints were examined by metallography after test intervals up to 1000 thermal cycles. Partial solder filling of the joints was observed and attributed to Au contamination of the solder and thin solder gaps between the connector pins and Cu-plated vias. All fatigue cracks observed in the vias after thermal cycling were associated with partial solder filling of the joints. The effects of partial solder fill on failure location were confirmed by FEA and acceptable agreement was found between the predicted cycles to failure and the experimentally observed onset of via cracking. The model and experimental results were used to predict component lifetimes for milder thermal-cycle conditions typically found in service.

Keywords: joint reliability; metallography; copper vias; electroplated; solder joints; Au; finite element analysis; FEA; thermal cycle; cracking; aging; thermal-mechanical fatigue; modelling; through holes; partial solder filling; solder joint failure.

DOI: 10.1504/IJMSI.2008.018904

International Journal of Materials and Structural Integrity, 2008 Vol.2 No.1/2, pp.138 - 163

Available online: 21 Jun 2008 *

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