we looked at SMTPlus
but as i understood it, they don't do protel

did you have to create the footprints from dwgs?

Dennis Saputelli


Frances Wheeler wrote:
> 
> I have been using SMTPlus for years for footprints
> http://www.smtplus.com/  they have the expertise and my customers have
> always been pleased with the production results. They will develop a new
> footprint quickly and get it back to you the same day. Check it out they
> have saved me lots of time and therefore lots of money.
> Fran
> 
> -----Original Message-----
> From: Leo Potjewijd [mailto:[EMAIL PROTECTED]
> Sent: Wednesday, March 10, 2004 5:24 PM
> To: Protel EDA Forum
> Cc: [EMAIL PROTECTED]
> Subject: Re: [PEDA] Common PCB footprint specifications
> 
> At 10-03-04 18:36, Ray Mitchell wrote:
> >I'm sure this is a repeat, but is there a simple specification readily
> >available that gives the "commonly accepted" (if there is such a thing)
> 
> >dimensions for 0402, 0603, ..., SIOC-14, etc., and all the other
> >"standard" footprints?  I don't really want to wade through a bunch of
> >technical stuff to derive all of this myself and I certainly don't want
> to
> >trust a priori the patterns that come with Protel or any other
> >product.  It's really annoying when part manufacturers don't provide
> these
> >footprints, assuming they are common knowledge.
> 
> Others have already refrenced the s'standards' (IPC). I'm a little more
> sceptical.....
> 
> To my knowledge, there is no such thing as a standard footprint.. Was it
> not the CEO of Sun Micro Systems who said at one time "I just LOVE
> standards, because there are so many of them".
> 
> In short, even a simple shape such as a 0805 is implemented differently
> by
> different manufacturers.
> Weird? I'd say so. Surprising? Not really: OUR wheel is MUCH
> rounder.....
> New and improved...... New formula......  You know the buzz.
> 
> I use a spreadsheet (not ready for the public yet, but I'll post it
> sometime in the not-so-distant future to the Yahoo list) to calculate a
> footprint from the dimensions and tolerances of the component given by
> the
> mfgr. The differences are sometimes quite large (as in: HUGE); in fact
> so
> large that a component from anoher  mfgr will not fit  on the same
> footprint (we lost a complete production run on that one).....
> 
> I'd still say to look up the mfgr datasheets (whenever available) and
> derive your own footprints from that information using a combination of
> guidelines (IPC, JEDEC) and common sense, seasoned with a tuch of
> practicality (you don't want 73 mils distance on 0805 pads when you're
> using a 5 mil grid).
> Hey, I even round off pad sizes that were designed in mm to an integer
> number of mils.....and I'm in the metric part of the world ;-) Find
> values (IPC, JETEC, your own fab house) for things like placement
> accuracy, heel and toe solder fillets and ask your board stuffer what
> component clearances (and directions) are needed for what processes and
> machines they use.
> All of these (and then some) will influence the final optimum
> footprint...... Last but not least: small series (50+) can most of the
> time get away with
> minor deviations from optimum, big series (500+) usually can not, huge
> series (10k+) never can.
> 
> A lot of work, yes, but one only uses so many different components......
> 
> I found it worthwile to invest the effort: I have no production failures
> 
> yet on my boards (apart from that one that was designed for Philips TSOP
> 
> and could not accomodate Fairchild).
> BTW, I am designing boards for just 10 years now, so I really don't know
> 
> much about the subject yet. In fact, I'm still learning, every single
> day.....
> 
> To qoute another frequent poster to this list: "I hope this helps".
> 
> Regards,
> 
> Leo Potjewijd
> hardware designer
> Integrated Engineering B.V.
> 
> [EMAIL PROTECTED]
> +31 20 4620700

-- 
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2851 21st Street                    Fax: 415-647-3003
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