I recently posted a bit of a bad OSP board with the conclusion that it was only worthy of scrap. Over on the CIRCUITS ASSEMBLY blog, Mike commented that if the board was expensive enough, he’d rework it and make it usable. He gave a pretty detailed description of the process he’d use, too. And he’s absolutely right. A picture of the full BGA land pattern is below. You can see just how many pads were messed up and how random the pattern seems to be.
While not everything can be fixed, a lot of things can. It all depends on the cost of remaking vs. reworking, the time to remake vs. the time to rework and what you need ultimately in reliability. In the prototype world, we do a lot of work to just make messy things work simply because of the time constraints.
Most of things would never be done in a production environment these days, but sometimes they are. Not that long ago, judicious use of mod wires was commonplace on shipping PCB assemblies.
Here’s an example of something yucky that we made work.
We’ve also cleaned tarnish off of silver boards and done a bunch of other things to recover from difficult challenges. As always, when we do do something like this, you’re really in test-pilot mode.
Duane Benson
Rolly polly fish heads
Eat them up, yum.
Funny. If it happend to be gold plated to begin with, you’d be using the board. “Oh! But the costs!” Well now you have a crappy OSP board that will either be scrapped, examined, analyzed, etc. and possibly be rework to make it “acceptable” again. Gosh that gold plating seems pretty cheap now…
ENIG! ENIG! ENIG!.
OSP is gone, and most houses don’t even do it anymore.
If you ask for it they probably will have to send it out.
Black pad is a thing of the past. ENIG get used to it.
We do both OSP and ENIG…
Mitch… for most players in the US.. ENIG is same or slightly cheaper than OSP!
reason: volume
so.. most have to pay extra for OSP!..
In fact I have been quoted cheaper for ENIG than nearly any other ROHS compatible surface, including “ROHS compliant HASL” finishes.
of course , there are always exceptions…and things are constantly changing.
However….. OSP is far from gone…
We ship completed PCB assemblies to a very large customer.
They are so large, they can influence large percentage of the total market!
They are trying move their assemblies back to OSP..
reasons:
– latest versions of OSP are rated for shelf life of 1 year (or longer).. much better than in the past.
– in the long term .. has chances of better consistency (no plating complexity/control issues)
and potential to be cheaper ( less complex processing, no nickel, no gold)
– Their engineering is viewing OSP as more reliable!
( I have been given conflicting reports on this issue from other sources, mainly concerning the effect on plating of holes).
In the long run.. I wouldn’t rule out OSP.
OSP, ENIG…. I don’t really care .. so long as it is done correctly.
John: “OSP, ENIG…. I don’t really care .. so long as it is done correctly.”
Ditto that John! Do it correctly, and I’ll come back. Do it bad, and I won’t pick up your calls for new work…