Jeffrey,

  I would agree that the designer can and should specify which process they
would prefer. But it is ultimately a team choice as you say. We allow our
customers to interact completely with our Mfg. Engineering and design
departments. But it is the Mfg. Engineers that are guaranteeing the quality
of the product. So I still believe they have the final say so.


Marcus Wheeler
Sr. Mfg. Engineer
Apsco International
[log in to unmask]
440-352-8961 * 530



                                                                                                                       
                      "McGlaughlin,                                                                                    
                      Jeffrey A"               To:       "'TechNet E-Mail Forum.'" <[log in to unmask]>,                  
                      <McGlaughlin@BATT         "[log in to unmask]" <[log in to unmask]>                      
                      ELLE.ORG>                cc:                                                                     
                                               Subject:  RE: [TN] Stencils                                             
                      01/14/2003 11:31                                                                                 
                      AM                                                                                               
                                                                                                                       
                                                                                                                       




Marcus -

While I agree with you that the manufacturing engineer needs to be able to
tailor the stencil to match the process used. As a designer I hope I would
know what process is being used. I may even specify the process to be used,
where it becomes critical next level of processing (i.e. potting, conformal
coat, or oil submersion). The concept needs to be team work, not
throw-it-over-the-wall when developing new products for manufacturing, and
verify *before* change once the product is "in-the-pipeline".


Jeffrey A. McGlaughlin CID
Sr. Designer
Battelle Memorial Institute
[http://www.battelle.org]
Columbus Ohio
[log in to unmask]

-----Original Message-----
From: Marcus Wheeler [mailto:[log in to unmask]]
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

---------------------------------------------------

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
---------------------------------------------------

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

---------------------------------------------------
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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