MACFEST: Benchmarking a New Solderable PCB Finish

Thomas Jones, Heriot Watt University | 04-05-2017

New, innovative manufacturing procedures have been developed by the recently completed project, Manufacturing Advanced Coating for Future Electronics SysTems (MACFEST), which has been funded by several partners and the government’s Innovate UK. The objective of the project was to harness the potential of ionic liquid technology, to be used as a substitute for dangerous and costly processing chemistries applied in printed circuit board manufacture.

The specific process under consideration for ionic liquids was the electroless nickel/ immersion palladium/immersion gold (ENIPIG) plating finish. ENIPIG is recognised as a universal finish, as it allows a circuit designer to cater for the competing needs of wire bonding and surface mount soldering, which are often both required for high-density circuit designs. The chemistries currently applied within the ENIPIG process employ the use of complex multistage processes with high material costs and with dangerous chemical formulations. These costly processing factors can be overcome by the substitution of novel ionic liquids, developed by the University of Leicester (UoL), within the ENIPIG process.

Merlin Circuit Technology has worked closely with UoL and Bob Willis, a recognized global expert in microelectronics testing and training, to benchmark the performance of the ionic liquid-ENIPIG coatings developed in the project. Tests were performed on the finish, where an evaluation of the solderability was made. Solderability provides a measure of the ease with which a solder joint can be made between materials and includes a review of the wetting of the solder to the board surface.

Solderability is a vital parameter defining the success of component assembly onto a PCB, where poor quality could result in a manufacturing or an in-service failure. A PCB test board was provided by Willis to evaluate the quality of the new ionic liquid-ENIPIG finish for the 2016 Swedish Electronics Exhibition (SEE) in Stockholm. 

To read the full version of this article, which appeared in the March 2017 issue of The PCB Magazine, click here.