Selection of process parameters for mass plating of discrete electronic components

The miniaturisation of electronic components coupled with requirements for high temperature lead-free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLVs) with nickel and tin layers have been explored. The tooling selected was a 'rotary flow-thru' plater which achieved high volume plating with <0.5% rejects. The anode selection proved critical and Nickel S rounds only were suitable with the chosen parameters. A very tight plating distribution with nickel thickness average 2.2 mm (±0.28 mm) and tin thickness average 3.5 μm (±0.31 mm) was achievable in production size quantities. An evaluation of product by examining solder fillet heights and tombstoning in mass board mounting trials concluded that the nickel tin finish is effective for high speed soldering applications.