The impending introduction of environmental legislation aimed atreducing the quantity of heavy metals disposed of into landfill siteshas caused many organisations to look at their choice of interconnectmedia. A response to this challenge has been the recent activity to finddrop-in replacements for tin/lead solders which do not contain lead.Switching from a well characterised and mature interconnection medium,such as the tin-lead and tin-lead-silver alloys, includes a number ofpotential risks if the proposed alternatives are not sufficientlyunderstood. Candidate materials will have to satisfy a number ofdemands, such as those relating to reliability and manufacturingcompatibility. Reliability demands include fatigue resistance,predictable failure modes, toughness, understanding of themicrostructure evolution over time and satisfactory in-serviceenvironmental performance (temperature, vibration and humidity).Manufacturing demands include a reasonable liquidus temperature andpercentage heat above liquidus to achieve satisfactory wetting,compatibility with current production equipment and product materialsand a reasonable shelf life. This paper presents some of the results ofan ongoing series of manufacturability trials at Loughborough which areassessing the solderability of various component termination finishesand styles with two candidate lead free solders under a number ofdifferent test regimes, these being representative of proposedmanufacturing conditions (temperature and atmosphere inert)
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