When faced with these uncertain challenges I like to include the individuals
who will be working with the assembly. It often gives insight into other
areas of concern, and helps make the decision less concerning and makes for
less finger crossing. I would ask the assy house who has to deal with your
decision what they would like to see, and I also often ask for ideas from
one of our "value add" pcb manufacturers. They see alot more diverse
challenges than I do and they are the ones who will have to manufacture, and
deal with the separation issues if you need to make changes later. Good
luck, Lenny Carter ERG, Inc. www.ergpower.com
----- Original Message -----
From: "Carl VanWormer" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, December 08, 2009 10:08 AM
Subject: [TN] Looking for guidance on V-Score requirements
Background:
We have a couple of small (2"x2" and 2"x3") boards that arrive as pallets
(x6 and x4) for surface mount assembly (pictures available upon request).
Since some components are placed too close to the edges for the "pizza
cutter" separation machine, the assembly house is separating the boards by
hand. Since the v-scores run the lengths of the boards, I worry that there
is too much twisting force applied to the board, risking fracturing of some
of the components. I am considering asking the board fabrication house to
route most of the board edges, leaving the v-scores for only a small length
at the PCB corners, maybe 1/4" or so. I don't want to reduce the stiffness
of the pallet too much, making the board difficult to run through the
assembly process. My hope is to simulate the routing and "mouse-bites" type
pallet, without having to deal with the ragged protrusions of the left-over
"mouse-bite" broken edges.
Question:
Are there guidelines on the limits of structural material required to keep a
board stiff enough to avoid irritating my assembly house?
Extra credit question:
Is there something else I should be doing?
Thanks,
Carl
Carl Van Wormer, P.E.
Senior Hardware Engineer
Cipher Systems
1800 NW 169th Place, Suite B-100
Beaverton, OR 97006
Cipher Systems (503) 617-7447
Direct Line (503) 425-5163
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