Jacob

HASL has a very good solderable surface. The coplanarity problem can be reduced by using new, horizontal plating equipment. We made trials approx. 3 years ago where were able to produce 50 boards with pitch 0.3 mm QFP's as well as BGA's without problems. Well, 50 boards are no reference for mass production. However, I believe it's possible. One point that has to be looked at with these plating process is the fact  that the solder layer on the copper is quite thin ( I don't have the numbers in mind ). This means that growth of intermetallics might become a problem when storing the PCB's over a long period. On the other hand we used some of our test boards, left over from the project, to play around and they could be hand soldered without a problem ( not the 0.3 mm of course ). 
But maybe the cold climate in Switzerland slows down the growth of intermetallics. 

Have a nice weekend

Guenter

Guenter Grossmann
Swiss Federal Institute for Materials Testing and Research EMPA
Centre for Reliability
8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :      xx41 1823 4054
mail:     [log in to unmask]

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