Are you telling me the MFG is selecting the paste now instead of the
design house? I thought material change is a major change, that
including the flux type used for the process. The designer better be
fully aware of the following:
(1) environmental operation condition and reliability (pad size and
filler size included)
(2) subsequent reliability issue related to the possible residue left on
the board (water soluble or no clean)
(3) components lead finishing and shelf life issue related to the flux
used and hopefully, different source of components terminal finishing
vs.. flux/process used (someone should take a overall responsibility if
it is not designer = personally, I think he should be the one, since he
is the one to select the components. We are not talking about the
draftsmen here).
Go back to the old argument now: send your designer walk the floor for
3-6 month (if you got Union to prevent him actually do the hands on) and
make sure he understand the issues before doing design.
My 1.28 cents.
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Marcus Wheeler
>Sent: Tuesday, January 14, 2003 10:50 AM
>To: [log in to unmask]
>Subject: Re: [TN] Stencils
>
>
> The board designer has no idea which process the PCB will be
>run i.e. water soluble vs noclean. The stencils for a
>water-soluble paste would less likely include home plate and
>other aperture modifications. Therefore it is my opinion that
>it must ultimately be the Mfg, Engineer 's job designing the
>actual stencil.
>
>Marcus Wheeler
>Sr. Mfg. Engineer
>Apsco International
>[log in to unmask]
>440-352-8961 * 530
>
>
>
>
>
> "Cyker, Howard A
>
> (Howie)" To:
>[log in to unmask]
> <[log in to unmask] cc:
>
> > Subject: Re:
>[TN] Stencils
> Sent by: TechNet
>
> <[log in to unmask]>
>
>
>
>
>
> 01/14/2003 10:16
>
> AM
>
> Please respond to
>
> "TechNet E-Mail
>
> Forum."; Please
>
> respond to
>
> "Cyker, Howard A
>
> (Howie)"
>
>
>
>
>
>
>
>
>
>
>I agree with Mr. Croslin with supplying a 1:1 stencil layer
>artwork to the EMS provider so they can tailor the stencil
>design to their materials and assembly processes. One other
>consideration during stencil design is attachment reliability
>requirements. If the board designer has specific solder
>volume requirements (beyond industry (IPC) solder joint quality
>standards) to meet product reliability requirements, then
>these requirements must be communicated to the EMS provider
>for consideration when they design the stencil.
>
>
>
>Howard A. Cyker
>Lucent Technologies
>Engineering Infrastructure - New Product Engineering
>
> Email [log in to unmask]
> Phone 978-960-2964
> Fax 978-960-2964
> Pager 888-961-2336
>
>
>-----Original Message-----
>From: Croslin, Robert [mailto:[log in to unmask]]
>Sent: Tuesday, January 14, 2003 9:58 AM
>To: [log in to unmask]
>Subject: Re: [TN] Stencils
>
>
>From a design standpoint, we provide our CEM houses with a
>one-to-one stencil layer embedded in our Gerber files. This
>allows them to adjust it appropriately based on their
>equipment, processes, stencil manfacturer, etc.
>
>
>Bob Croslin
>
>Nielsen Media Research
>-----Original Message-----
>From: Donald Kyle [mailto:[log in to unmask]]
>Sent: Tuesday, January 14, 2003 9:33 AM
>To: [log in to unmask]
>Subject: [TN] Stencils
>
>
>I would like your opinion on who would be more suited to
>design stencils for SMT PWBs; the board designer or the
>contract-manufacturing engineer.
>
>What do you do and why?
>
>
>
>
>Donald Kyle C.I.D.+
>281-285-7528 ---------------------------------------------------
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