Steve is right and your placement engineer is difficult .
With mirror double sides , if you have a crossed out panel,
just train your fab folks (specs) they blacken fiducials of rejects;
vision will therefore skip it and there is no problemo at all .

You need only one program with this system for both sides;
but 'm sure Steve will give you details

paul

-----Original Message-----
From: Martin Christie [mailto:[log in to unmask]]
Sent: Tuesday, 1 February 2000 19:44
To: [log in to unmask]
Subject: [TN] Double-sided reflow with uBGA


Steve,

I'm interested in the top/bottom/top/bottom place and reflow that you
described. One of our placement engineers has said we wouldn't be able to do
it unless the board supplier could guarantee that we wouldn't get any bad
boards on the panel. What he's saying is that we would have to program the
machine so the top/bottom was essentially one board and that if one of these
boards was bad from the board vendor we would end up placing components on
it (we have Panasert MV100, MV150 and MVIIF chipshooters).

I've used Universal and Yamaha machines before and have always had the
option to program "top" as sub-routine 1 and "bottom" as sub-routine 2 and
then put them into one program i.e. goto xy1 call up subroutine 1, goto xy2
call-up subroutine 2 etc. I hope this makes sense. I've used this approach
before for placing onto 2 completely different types of board on 1 panel but
never for the top/bottom/top/bottom scenario that you describe. It just
seems such a good idea.

I've never used Panasert's before so I don't know whether they are capable
of having a program calling up 2 different sub-routines. What placement
machines do you use and have you had similar difficulties?

Also, I'd like to hear if anyone else out there know's whether the
Panasert's are capable of being programmed as I described.

Regards,
Martin Christie

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