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October 2002

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Subject:
From:
Barry Gallegos <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 31 Oct 2002 07:26:25 -0700
Content-Type:
text/plain
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text/plain (168 lines)
It would be my understanding that all customer drawings are requirements
That overrule IPC/J-std.
IPC-A-610 is merely a pictorial document that is derived from J-STD.
With other areas not covered such as cleanliness req. or Markings etc.
I believe that I would move create a deviation for those devices and still
follow
Class III in all other areas as long as you say that I would not violate and

Electrical clearance issues.

Of course, all have their own interpretations.

Barry.


 -----Original Message-----
From:   Marsico, James [mailto:[log in to unmask]]
Sent:   Thursday, October 31, 2002 6:41 AM
To:     [log in to unmask]
Subject:        Re: [TN] Lead protrusion

Correct me if I'm wrong, but I thought that the drawing only overrules the
spec (J-STD-001) only when it is approved by the customer.

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879


        -----Original Message-----
        From:   Graham Collins [SMTP:[log in to unmask]]
        Sent:   Thursday, October 31, 2002 8:34 AM
        To:     [log in to unmask]
        Subject:        Re: [TN] Lead protrusion

        Hi Keith
        We build some similar stuff.  You have two options other than the
hand trimming:

        Run the DIP packages through a forming and trimming machine, to trim
the leads to an acceptable length.  This is typically what we do, so we end
up with enough lead that the CS-400 can crimp it but not too much for
protrusion.

        Alternatively - have a drawing note added to increase the allowable
lead length to 90 thou or whatever is reasonable in the applications you
have.  The drawing note overrules the IPC requirement, so you are in the
clear.



        regards,

        Graham Collins
        Process Engineer,
        Northrop Grumman Canada Corporation
        Halifax
        (902) 873-2000 ext 6215

        >>> [log in to unmask] 10/31/02 09:04AM >>>
        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,

        and have two Contact Systems CS400-D thru hole insertion machines
that
        we use to populate these boards.  Discrete parts are not a problem,
as
        the leads are crimped to retain the parts in the boards for wave
        soldering.  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.


          Keith Calhoun
          Manufacturing Engineer
          Sierra Research, an Integrated Defence Technologies company
          485 Cayuga Road PO Box 222 Mail Stop 334
          Buffalo
          New York
          14225
          USA
                                                 Fax: (716)631-7849
                                                Work: (716)631-6434
                                                <[log in to unmask]>

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