Barry, Hi. We design our circuits in house for subcontract manufacture
externally. We begin by learning who our CMS will use for board fab, then
find out what their panel sizes are. We design the circuit itself to try to
maximize the material usage in the panel and consider any thieving or
fabrication requirements that may be unusual. Both of our CMS vendors have
furnished us with their DFM criteria for placement and preferred
panelization detail. These specifications are different for each. This
means we design specific circuits / panels for each CMS and subsequent
fabricator. On rare occasion when we shift product from one to the other,
we usually have to redesign or edit our panel. By doing it this way, we're
able to integrate the concerns of the CMS, fab house, and circuit engineer
and are able to generate our artwork files in full panel format for fab and
assembly floor processing.
To do this you've got to be very close with your assembly house, be willing
to change at their request and occasionally, have to fight tooth and nail
with the design engineer over component placement issues. Prior to going
out for the first prototype, even if it's only a breadboard, we review the
board and panel for manufacturability. If it doesn't meet the requirements,
it gets kicked back or, if the engineer can argue the placement from a
performance standpoint, it can go out. We've saved countless thousands of
dollars on wasted prototypes with this method alone. It also gives a fab
vendor an opportunity to check out the panel in his process. Our proto and
production houses are often different, but it at least it lets us know if
there's any significant problems. Doing your prototypes in panel form also
gives you assurance that any scoring, routing, or overhanging parts issues
aren't going to bite you later. We had to learn that lesson the hard way.
If you're not controlling the entire process in house right now, then you've
probably got a culture to change as well. If your EMS provider doesn't have
panelization design specs to give you, then you need to take control of that
process as well. Good Luck.
Bob Croslin
Nielsen Media Research
-----Original Message-----
From: Barry Gallegos [mailto:[log in to unmask]]
Sent: Monday, January 06, 2003 12:54 PM
To: [log in to unmask]
Subject: [TN] Board Penalizations.
Happy New Years T-netters.
I am researching Board Penalizations in an effort to standardize our
processes.
I am curious as to how the rest of the industry handles this. We have been
told that most manufacturers do not submit board penalization specs. for the
board house to follow.
Is this true.
We are trying to create a Spec. to issue to our board house's and would be
very interested in any guidance or input that the Tech. community would be
willing to provide.
Thank you.
Barry.
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