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Thermo-mechanical impact of laser-induced solder ball attach process on ball grid arrays

Current trends in electronics packaging are driven by the demands imposed by the ever increasing high-volume consumer electronics market. The consequence of this, along with the introduction of the European Union legislations that banned the use of lead (Pb) and other hazardous materials in electrical and electronic products, is that high reliability equipment manufacturers have their component selection choices almost entirely limited to lead-free packaged commercial-of-the-shelf (COTS) components. The widespread adoption of lead-free electronic components into complex electronic systems designed for the Aerospace, Defence and High Performance (ADHP) industry must be judiciously planned in order to preserve the industry's reliability expectations. One area of concern for BGAs is thermo-mechanically induced premature (intermittent) electronic faults. One strategy to eliminate that risk is to replace the Pb-free solder balls with the baseline tin-lead solder alloy. Post-manufacturing processes that can be used to remove (deballing) and then deposit back (reballing) BGA solder balls are increasingly put in practice. The discussion in this paper focuses on the modelbased approach for assessing the thermo-mechanical responses of BGAs subjected to laser reballing. The findings of this work are that laser assisted BGA re-balling is a safe process with very localised thermal effects that present very small or no risk of thermally induced damage in relation to the discussed failure modes.