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 -- _______________________________________________________________________ Integrated Controls, Inc. Tel: 415-647-0480 EXT 107 2851 21st Street Fax: 415-647-3003 San Francisco, CA 94110 www.integratedcontrolsinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *