Technetters,

        This debate, I believe, is an old one.  We manufacture our own
PCBs but our main business is contract manufacture.

        Most of our PCBs are tin lead fused.  The only time we
subcontract HASL is if the PCB has a large ground plane on the solder
side which could wrinkle and take in solder during wave soldering.

        By carefully monitoring the amount of tin/lead being plated it
is possible to achieve a very flat solderable finish this way, it is
equally possible to get a simiolar finish with HASL.

        However, many companies using HASL seem to be getting very
sloppy and I have seen some boards which have a finish as bad as a
single sided roller tinned PCB.

        Due to problems in using HASL for fine pitch etc. I think this
debate needs to move on and that greater discussion on immersion tin and
organic finishes would be more beneficial.

        We are currently looking at an "Omikron" as a finish and it is
showing excelent shelf life and good solderability.  We are still in the
early stages but if this is successful then we will skip HASL and go
straight to this or a similar finish.

        One final point, fused tin/lead is much cheaper that HASL and if
it gives good results why not consider it.  It has the added benefit
that all copper is covered with tin/lead so the PCB has better
environmental protection.


        Neil

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