Greetings,
As a QA guy and an ISO guy, I get to argue with everyone else in the plant,
about traceability. Whatever your documented procedure is follow it, and if
you don't have one make one up. (Even informally, if it becomes 'tribal
knowledge' it satisfies most requirements until something formall can be
approved.)
Mine looks like this
1) Customer spec.
2) IPC
3) Then Inhouse spec (unless stricter than IPC-we have a few)
4) Sign, initial, date, confirm, and or document everything so you have
traceability.)
So changes, when required, should get approved unless you are intimate with
the product or the customer, in which case there should be a docuemnt
stating your free reign to make such decisions without their consult.
Not much help on lead length, but I hope I've added some value to the
discussion.
Steve MacDonald
Mass Design Inc.
----- Original Message -----
From: "Graham Collins" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October 31, 2002 9:38 AM
Subject: Re: [TN] Lead protrusion
> Hi Jim!
> Hmm... (taking a slurp of coffee, I'm not a dew addict) - it depends.
>
> If the customer has to approve drawing changes, then yes.
>
> We build two types of boards here: ones we as a company own the design of,
and ones we build for other people.
>
> If it is a board for which we are the design authority then we as a
company are responsible for design changes, and can do things like change
lead length. Typically this is on a board that goes into a full box, so CCA
issues are transparent to the customer, but there are cases where we ship
individual boards.
>
> If it is a board we make for someone else, to their design, we have to ask
them to change the drawing. We do this all the time on new stuff, for
example - we have a new board that has a couple of relays mounted to them.
The leads are so thick that we would need bolt cutters to trim these (OK,
maybe I'm exaggerating a bit, but the folks in production would attack me if
I told them they had to trim these things). The lead protrusion is about
.2" - which is pretty long, but there is a gap of about .5" under the board
so not a problem from a spacing perspective.
>
> I guess the answer is thus that the drawing has to be changed per whatever
change practices are in place, otherwise the ISO 9000 auditor opens a can of
whupp-ass in your office.
>
> Back to the coffee!!!
>
> regards,
>
> Graham Collins
> Process Engineer,
> Northrop Grumman Canada Corporation
> Halifax
> (902) 873-2000 ext 6215
>
> >>> [log in to unmask] 10/31/02 09:41AM >>>
> 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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