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Improved Design Life and Environmentally Aware Manufacture of Electronics Assemblies by Lead-Free Soldering


Objectives and content

The technical limits of tin-lead solder, in particular its relatively low thermo-mechanical fatigue strength, are now being reached in many applications as component sizes and operating temperatures are constantly increasing. The consequence is impaired design-life and functionality of these assemblies and of all the products which contain them.
There are two environmental concerns with soldering technology: - currently there is no recycling capability for the lead content of the solder which therefore is dumped into land-fill (from where it leaches into groundwater) or is incinerated in central facilities (to condense over the neighbourhood).

- the current fluxing technology is based on VOC (volatile organic compounds) carriers and solvents, all of which are vented to atmosphere in the soldering operation. Both these aspects are, or will be, the subject of legislative control within Europe and the EU's key export markets. The objectives of this project are to develop soldering processes to the point of production readiness for:
- reflow and wave soldering with :
. novel lead-free high strength solders pastes
. lead-free board and component metallisations
. substantially VOC-free flux media
- repair/rework with a novel lead-free high strength flux-cored wire - enhanced functionality and service life in electronic assemblies. Achievable targets for the high strength solder technology are a 30-50% increase service life and an 80% reducton in field failures.
This improvement will stimulate the recycling and reuse of electronics assemblies in electronics products.

The research approach is to develop and characterise in parallel improved solders (based on known tin-based alloys), fluxes and board & component metallisations and to iterate and optimise these in the real soldering situation both in terms of the quality of the soldered joints, the defect level of the soldering process and the reliability of the solder joints under accelerated ageing conditions (tasks 1 and 2). The optimised materials and processes will be assessed, characterised and validated in large scale trials (tasks 3 and 4) and complete process specifications will be produced. At all points in the project, the environmental impact of the materials and processes used will be assessed and minimised and recyclability will be promoted.


GEC-Marconi Materials Technology Ltd
Elstree Way
WD6 1RX Borehamwood
United Kingdom

Participants (5)

Multicore Solders Ltd
United Kingdom

HP2 4RQ Hemel Hempstead
Nederlandse Philips Bedrijven BV
5600 MD Eindhoven
Siemens AG
13629 Berlin
University College Cork
Prospect Row
30 Cork
Witmetaal BV
1410 AA Naarden