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NPL's SSTC Summer Meeting Concentrates on Lead-free Solder Reliability
August 31, 2004 |Estimated reading time: 1 minute
Teddington, UK — National Physical Laboratory's (NPL) summer Soldering Science & Technology Club meeting was held on July 15, 2004, with 10 papers covering aspects relating to lead-free reliability.
The venue was the new lecture theatre at NPL in Teddington, UK.
James Vincent from Bookham Technology chaired the day, then welcomed the delegates and introduced the first speaker, Alan Brewin (NPL), who presented an overview on the WEEE and RoHS legislation and then concentrated on supply chain issues. Nick Jolly from DTI was in the audience and was able to clarify some audience concerns and offer the very latest status on the legislation.
Ian Wilding from Henkel presented "Issues Concerned with Wave Soldering," including bath erosion, process parameters, solder balling, fillet lifting and the relative costs of selected alloys.
Bob Willis (EPS) continued on lead-free fillet lifting, which occurs during reflow, wave and selective soldering, and used graphics and video clips to illustrate the problems.
Strain measurement techniques as applied to solder joints was covered by Salih Gungor from The Open University. He concluded that understanding failure mechanisms in solder joints is crucial for improving thermomechanical reliability of electronic packaging and whole-field optical methods are powerful tools to identify and study critical areas in electronic packaging.
Steve Ridout — Greenwich University outlined university research in predicting damage in thermal-cycled solder joints. The university validates their models with experiments at NPL. Among Ridout's conclusions were that new models are required for lead-free solder and for a resistor component, strain is a better damage indicator than creep strain energy.
The afternoon session highlighted some of these projects presented by NPL staff:
- Milos Dusek — "Pad Design for Reliability"
- Martin Wickham — "Understanding the Effect of Solder Joint Composition as Industry Transitions to Lead-free with a Range of Component Finishes"
- Zing Lou — "Effect of Alloy and Component Temperature on Solderability Testing"
- Martin Wickham — "Impact on Service Environment on Reliability of ICA and ACA"
- "Impedance Measurement of Flux Residues" — Alan Brewin
More than 40 delegates attended the exhibition, and visit a tabletop exhibition.