lead free pcb plating?

Our preference has been ENIG. We find that we achieve higher quality (visually) soldering for through hole and surface mount parts, with less handling issues than when we use white-tin, or immersion tin.

We are about to do a test on some boards that have lead-free HASL. I'm hoping that the results will be good, as a number of my customers are edging away from ENIG due to the costs.

cheers ..rob

reply »

There is no good choice.

Board Finishes: Industrial/Battelle Class 3 Environment [Reliability Knowledge Gaps: For use of Pb-free solders in High Reliability Applications, J Smetana, iNEMI Availability of SnPb-Compatible BGAs Workshop, March 1, 2007, Alcatel-Lucent]: * ENIG, OSP, and immersion silver ALL are subject to corrosion in Battelle Class 3 environments (creep corrosion and/or fiber assisted electrochemical migration, blistering/peeling of conductive corrosion products, etc.) * Only SnPb HASL and immersion tin survive this environment ** SnPb HASL is not Pb-free ** Immersion tin has poor solderability performance in Pb-free assembly (and whisker concerns) * SnCu HASL - has not been tested for this issue but� Greatly undesirable (we don't want this!) ** Additional severe thermal shock to PWB ** Same issues with non-flat pads as SnPb HASL ** Extremely limited availability ** Tin whisker risk - worse than immersion tin ** Cu dissolution ** Process control at fabricator ** Etc. NO PATH FORWARD at this Time!

reply »

>immersion ...easily changes color..

See that's the GREAT thing about immersion coatings. If they change color, they probably will not solder well. Try that with other coatings.

reply »