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Subject:	Re: Lead protrusion
From:	"Sauer, Steven T." <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Thu, 31 Oct 2002 08:22:38 -0500
Content-Type:	text/plain
Parts/Attachments:	text/plain (42 lines)

Good Morning Keith,
The easiest solution is to create a note on your drawing that states the
maximum lead protrusion shall not exceed .xxx".  The drawing requirments
take precedence over any referenced standard unless otherwise stated in
contractual documentation with your customers.

The additional drawing note can limit the applicability of the "excess" lead
protrusion by stating "for leads of U1-U4, S1" etc.

Steve Sauer
Mfg Engineer
Northrop Grumman, Xetron

-----Original Message-----
We are having a vigorous discussion about how to deal with lead
protrusion on our thru hole boards.  We build mainly IPC class 3 boards,
Our area of concern is DIP packages along with sockets, and
connectors.  When we insert DIPs we clinch two opposing corner pins,
connectors and sockets are retained with temporary solder mask (goop).
we are finding that the leads on these parts tend to exceed the max lead

protrusion permitted for class 3 boards when used in .06 nominal
thickness boards, but do not want to get into the quagmire of trimming
leads and inspecting or reflowing after trimming.  These boards will
meet the class 2 requirements, and there is no danger of violating the
minimum electrical spacing requirements when these boards are installed
in our systems.

Anyone else having this problem?  If so, how did you resolve it?  Your
support is greatly appreciated.

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