Tin‐lead Composition—Its Control and Effect on Solderability

Alloys deposited from plating solutions vary in composition with changes in solution constituents and processing parameters. With the increasing demand on miniaturisation and quality of subsequent solder joints made to plated tin‐lead alloys, it is important to ensure stable deposit composition and also to know to what extent changes in operating conditions will affect the composition. This paper examines the major causes of changes in composition of deposits plated from solutions based on fluoboric acid and organic sulphonic acid. The methods available for measuring the deposit composition are also discussed.