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Date: | Fri, 8 Oct 2004 18:12:25 -0500 |
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All -
I have a question related to surface mount component coplanarity.
Is there a set +/- "window of opportunity" that surface mount gull-wing
leads are allowed to fall within? Is this covered in a standard anywhere?
I looked into IPC-A-610 and J-Std - and I found information related to "toe
down" configuration but I did not see any information related to "toe up"
configuration.
I also referenced JESD22 Method B 108. Interesting guideline - using the
seating place method as a measure of determining coplanarity deviation. So,
if I am understanding this test method properly, the user (meaning the
manufacturer trying to build with the darn thing) defines the +/- window?
Background info:
Qualifying new board. One part on the board is a large transformer with
gull wing leads - 24 leads on either side of the component. We are
frequently seeing leads bent upwards (towards the heavens) and this is
obviously creating manufacturing frustrations. However, vendor is
indicating a +/- window of 4 mils - either side. Doesn't that seem large?
That would be a total of 8 mils of variation.....
So, I was just wondering if there was a criteria out there that we could
reference, to determine whether or not these parts are really acceptable.
Appreciate the help.
- D
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