Estimated reading time: 15 minutes

SMART Group Seminar: Harsh Environments & Electronics

“The great thing about lead is that it works! It’s worked for a long time, and it’s cheap,” said Boyle. He commented that the market would have to change, and the way the electronics manufacturing industry looked at the market would have to change as well. The aims of the High-Lead Solder Replacement Program were to find suitable replacements in terms of electrical, thermal and mechanical performance, to develop products in compliance with RoHS and ELV standards, and ideally to produce drop-in alternatives to existing paste, wire and preforms. Additionally, recognising the changing needs in automotive and IGBT applications, to improve upon high-lead solder especially with regard to power and thermal cycling performance. The programme was taking a multi-faceted approach, looking at different solutions for sub-segments of the market, in respect of application, cost and performance.

Boyle summarised work to date on organic-based, metallurgic-based, and combination organic-metallurgic techniques including high silver-content organic die attach, epoxy-solder paste based on tin-antimony alloys, transient liquid phase sintering, and low-pressure or no-pressure silver sintering. Developments were ongoing, but his opinion was that no single drop-in solution would emerge and that different methodologies would be required for individual market segments, which might involve radical changes to production processes. Boyle reminded the group, “We’ve got five years left..”

“A changing environment” was the scenario for David Greenman, non-executive director at HumiSeal Europe, to make then and now comparisons. In the past, electronic assemblies had been based on relatively simple design rules with wide spaces between conductors, and had generally been expected to work in relatively controlled environments. Worst case, they might be required to withstand thermal cycling, damp heat, electro migration, mould growth, and salt mist. Modern day electronics, with ever-increasing packing density and decreasing conductor spacings, were expected to work in all environments: Examples of additional stress factors included thermal shock and thermal cycling to high temperatures, cyclic damp heat, mechanical shock and vibration, corrosive liquids, salt spray fog, and tin whiskers.

Page 5 of 7

• < Previous Page
• Next Page >