PWB Surface Finishes for COB

When implementing chip-on-board (COB), the surface finish on the printed wiring board needs to be chosen with several key considerations in mind. The choice of bonding technology dominates the selection of finishes. Wire bonding, tape automated bonding and flip chip assembly all have their own special requirements for effective assembly. The considerations must also examine the presence of intermetallics in the solder joints. These issues are discussed along with several advanced techniques for applying solder coating and organic solderability preservatives on bare copper PWBs.