A flow-soldering process has been implemented for producing electronic circuit boards used in lighting fixtures by using lead-free solder to eliminate hazardous lead from the product. While examining the lead-free soldering conditions, which tend to make the melting point higher and wetting properties worse than conventional solder, the conditions required in components, flux and equipment were identified. Also, pitting and voids that saliently appear in lead-free solder were studied and it was confirmed that the resulting condition would deliver reliability equivalent to or better than conventional lead-based eutectic solder. In addition, by paying attention to the transition of solder composition as an alloy and tracing the composition change by the number of units produced, a composition control standard was examined and provisionary values of solder composition have been established.
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