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September 2005

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Subject:
From:
"Stadem, Richard" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard
Date:
Mon, 19 Sep 2005 12:53:03 -0500
Content-Type:
text/plain
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text/plain (88 lines)
Typically, the IPC standard or whatever standard is listed on the
assembly print would apply. If there are situations such as what you
describe where the design clearly needs an exemption, and there are no
form, fit, or function issues, a print note is added on the assembly
drawing to allow the longer lead protrusions via an Engineering Change
Notice that is signed off by the Design Engineer, Manufacturing
Engineer, Documentation Engineer, etc., and the Customer.
Within the industry the assembly print notes nearly always take priority
over all applicable industry and workmanship standards, even over any
conflicts caused by the assembly BOM. If there is not a noted exemption
on the assembly print, then the standards called out on the print apply
by default.
For example, every assembly drawing should have numbered notations such
as: "1. Assembly to fully conform to ANSI/J-STD-001, class three.  2.
All workmanship shall be per HIL-HDBK-454," etc. On the drawing there
should be a number inside of a box with an arrow pointing to one or more
of the holes with the exemption and the quantity. The corresponding
print note with the same number would state "Staked harness terminations
may exceed lead protrusion requirements in J-STD-001 for item Find
Number XX (the find number of the harness on the assembly Bill of
Materials), but may not protrude more than .155" from bottom surface of
assembly" or some such wording.
If your inspector or customer has noted that the leads are longer than
.098", then you need to cover this with an Engineering Change Order or
Notice or a completed and signed-off Non-conforming Material Notice that
will allow this condition until the assembly print is updated. In the
meantime, all product with this non-conformance needs to be quarantined
until you have some documentation that allows you to ship the
non-conforming product.
Industry standards cannot address every exemption that may occur.
Therefore notes on all of the assembly prints are required where there
are exemptions. This is so the inspector will not assume that because
some of the terminations are longer than .098" then it must be OK if
they all are.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jason Lineback
Sent: Monday, September 19, 2005 10:58 AM
To: [log in to unmask]
Subject: [TN] Lead protrusion of wire terminals

Greetings

We build an assembly that has a wire harness soldered to the board. The
end of the wires on the board end have crimped terminals similar to
http://www.molex.com/pdm_docs/sd/008700060_sd.pdf The initial lead
protrusion once these terminals get soldered in the board is about
.150".

Provided there is no electrical clearance issues or customer print
governing lead protrusion, what would govern the lead protrusion?

Would the IPC-A-610 regulations for lead protrusion apply? In this case
it would mean trimming the terminals down to .098".

I have researched this both on the net and in IPC/WHMA-A-620, but I have
yet to find anything regarding the soldering and / or clipping of these
terminals.

Any help would be much appreciated.

Thanks
Jason Lineback

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