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Electronics Forum / CAD / June 2007PADS, ASCII output question: Scale factor?
Hello Folks, We weren't able to sort this out. The layouter said this is the usual file that SMT assemblers use to program their pick&place machines but the assembler said they can't use it since the scale factor or data format for the coordinates is unknown. PADS was set to the American dimensioning of "mils" (1/1000th of an inch). Contacting Mentor resulted in no help. Here is one example from the ASCII file: R75.2 R66.2 -190690500 289179000 1 381000 1024 TEARDROP N 90 90 -190690500 287274000 31 381000 512 TEARDROP P 90 90 What does "-190690500 289179000" mean in terms of mils, or millimeter?  SignatureRegards, Joerg http://www.analogconsultants.com > Hello Folks, > [quoted text clipped - 10 lines] > > What does "-190690500 289179000" mean in terms of mils, or millimeter? That actually looks like gerber info to me. I just generated a pick and place file out of Protel99SE, here's what part of it looks like: Designator Footprint Mid X Mid Y Ref X Ref Y Pad X Pad Y TB Rotation Comment U33 SO-8 1790mil 310mil 1915mil 385mil 1915mil 385mil B 180.00 LM2672M-5.0 U34 SO-8 840mil 310mil 965mil 385mil 965mil 385mil B 180.00 LM2672M-5.0 R304 0805_-_100MIL 4275mil 4605mil 4320mil 4605mil 4320mil 4605mil B 180.00 6.04k R302 0805_-_100MIL 3555mil 4335mil 3600mil 4335mil 3600mil 4335mil B 180.00 10.0k R301 0805_-_100MIL 3555mil 4235mil 3510mil 4235mil 3510mil 4235mil B 360.00 10.0k U54 SO-18_WIDE 3380mil 11330mil 3170mil 11130mil 3170mil 11130mil B 360.00 ULN2803AFW U53 SO-18_WIDE 3380mil 9730mil 3170mil 9530mil 3170mil 9530mil B 360.00 ULN2803AFW They don't really need the P&P file. It just makes it a little faster to program the machine. Chris >>Hello Folks, >> [quoted text clipped - 35 lines] > They don't really need the P&P file. It just makes it a little faster to > program the machine. Thanks, Chris. Maybe the layouter generated the wrong file. Anyhow, since he's traveling now they went ahead and started programming the machine by hand. Over 500 parts... SignatureRegards, Joerg http://www.analogconsultants.com >> They don't really need the P&P file. It just makes it a little faster to >> program the machine. >Thanks, Chris. Maybe the layouter generated the wrong file. Anyhow, >since he's traveling now they went ahead and started programming the >machine by hand. Over 500 parts... What's the error rate on "hand" programming? Reducing sources of errors seems like a good idea to me. SignatureThese are my opinions, not necessarily my employer's. I hate spam. >>>They don't really need the P&P file. It just makes it a little faster to >>>program the machine. [quoted text clipped - 6 lines] > > Reducing sources of errors seems like a good idea to me. It's surprisingly low. In the late 80's it was all hand-programming and the errors were usually zero. But we do not have a choice here because the layouter can't be reached right now and the stuffed boards must be at the client Monday morning. It's 80% analog and I'll find a stuffing mistake pretty quickly. The only drag would be that we'd then have to correct it about 40 times. SignatureRegards, Joerg http://www.analogconsultants.com > >>>They don't really need the P&P file. It just makes it a little faster to > >>>program the machine. [quoted text clipped - 19 lines] > > http://www.analogconsultants.com I had a company make errors on a pcb we sent to them so 0% is a bit of an exageration. The board came back with all the holes in the right places but not a piece of copper etched ! >>> They don't really need the P&P file. It just makes it a little faster to >>> program the machine. [quoted text clipped - 6 lines] > > Reducing sources of errors seems like a good idea to me. My machine uses mechanical centering (vs laser centering) and tends to be off a little from the values the P&P file generates anyway. Manual programming is actually done with the camera, so placement errors are not really an issue. Most boards are easy to program manually, so not having the P&P file is not really a big deal. Chris >>>>They don't really need the P&P file. It just makes it a little faster to >>>>program the machine. [quoted text clipped - 12 lines] > really an issue. Most boards are easy to program manually, so not having the > P&P file is not really a big deal. Which brings up a question: Do you do contract assembly? Looked on your web site but it's under construction. SignatureRegards, Joerg http://www.analogconsultants.com Christopher Ott wrote: >>Most boards are easy to program manually, >>so not having the P&P file is not really a big deal. >> >Which brings up a question: Do you do contract assembly? >Looked on your web site but it's under construction. ...and has been for >3 years. http://web.archive.org/web/*/http://ottelectronics.com Already has all the business he can handle?? > Christopher Ott wrote: > [quoted text clipped - 8 lines] > > Already has all the business he can handle?? Well, sometimes you need a domain only for communications. Email, FTP and so on. My web site isn't that hot either but for now good enough. Promise to spiff it up some, but only when the workload eases off a bit. SignatureRegards, Joerg http://www.analogconsultants.com > Christopher Ott wrote: >>>Most boards are easy to program manually, [quoted text clipped - 7 lines] > > Already has all the business he can handle?? The people I traditionally sell to aren't real interested in websites. Somehow I manage to stay busy... Chris >>Christopher Ott wrote: >> [quoted text clipped - 11 lines] > The people I traditionally sell to aren't real interested in websites. > Somehow I manage to stay busy... Same here. The only thing they sometimes want to look at is what services can be provided. SignatureRegards, Joerg http://www.analogconsultants.com >>>>>They don't really need the P&P file. It just makes it a little faster >>>>>to [quoted text clipped - 16 lines] > Which brings up a question: Do you do contract assembly? Looked on your > web site but it's under construction. I do small volumes of control electronics, but so far it's just been my own stuff. I can certainly look at your boards to see if I could run them though. You can email me direct for more info. Chris >>>>>>They don't really need the P&P file. It just makes it a little faster >>>>>>to [quoted text clipped - 22 lines] > > Chris I'll do that when the next round comes. It's mostly fine-pitch SMT stuff, up to 6U VME sizes (but not full length), some TSSOP and 0603. Occasionally I have to drop down to 0402 sizes. SignatureRegards, Joerg http://www.analogconsultants.com >>>>>>>They don't really need the P&P file. It just makes it a little faster >>>>>>>to [quoted text clipped - 26 lines] > up to 6U VME sizes (but not full length), some TSSOP and 0603. > Occasionally I have to drop down to 0402 sizes. My machine can handle boards up to 12"x10", and passives down to 0603. 0402's take a special feeders which I don't have. I've never tried TSSOP's on it, but I can place 50mil pitch IC's no problem. No BGA's or anything requiring x-ray inspection though. Incidentally, if you're ever shopping for a P&P machine, laser centering is a must. Mine uses the older mechanical jaws to square the parts on the head before placement. It's effective, but it's also the primary limitation when placing smaller than 25mil pitch parts. Chris >>>>>>>>They don't really need the P&P file. It just makes it a little faster >>>>>>>>to [quoted text clipped - 36 lines] > before placement. It's effective, but it's also the primary limitation when > placing smaller than 25mil pitch parts. My boards are rarely larger than that. But TSSOP would be 25mil pitch. And I stay away from BGAs whenever possible because they are all but non-inspectable. But I won't shop for P&P machines, I'll leave that work to the experts like you. Or, as the poker players say, you've got to know when to fold'em ;-) SignatureRegards, Joerg http://www.analogconsultants.com > My machine can handle boards up to 12"x10", and passives down to 0603. > 0402's take a special feeders which I don't have. I've never tried TSSOP's [quoted text clipped - 7 lines] > > Chris Which machine do you have? Andrew >> My machine can handle boards up to 12"x10", and passives down to 0603. >> 0402's take a special feeders which I don't have. I've never tried [quoted text clipped - 11 lines] > > Andrew It's a Manncorp ECM98. Chris Its the x and y coordinates www.ckp-railways.talktalk.net/pcbcad21.htm > Its the x and y coordinates > > www.ckp-railways.talktalk.net/pcbcad21.htm Sure, but what is the scale factor to get to inches, or millimeters? When we measured by hand and using a Gerber viewer the results totally did not corroborate the numbers in the PADS file. SignatureRegards, Joerg http://www.analogconsultants.com Joerg, The ASCII output is in PADs "basic units". If you have a PADs manual there is usually a section in the rear of the manual (at least the older manuals) that explains the basic ACSII format output and I believe it may also explain the basic units measure. Today it is maybe in a PDF or text file in one of your install directories or just left uninstalled on your original install CD. From memory (I haven't used PADs consistently for more than 8 years) the basic units are something like 254 microinches (or was it 25.4 microinches). It is the base unit of measure that the PADs database uses and allows them to easily convert metric to inches and back again without round-off errors. You should be able to look at a component or two, do some math and confirm the basic unit measure knowing the components real location from the database zero-zero point. The line that you quoted would seem to be a trace between R75 Pin 2 and R66 Pin 2, with teardropping. The first line will be the location of the one end start point and the second line will be the location of the end point. The "-190690500 289179000" are the base unit measures, the other data relates to both trace width and the teardrop sizing and orientation. That is my best recollection anyway. SignatureSincerely, Brad Velander. >> Its the x and y coordinates >> [quoted text clipped - 3 lines] > we measured by hand and using a Gerber viewer the results totally did not > corroborate the numbers in the PADS file. > Joerg, > The ASCII output is in PADs "basic units". If you have a PADs manual [quoted text clipped - 18 lines] > relates to both trace width and the teardrop sizing and orientation. That is > my best recollection anyway. Thanks, Brad. Now I know where to look for the next round. Or actually where our layouter could look because I don't have PADS. I just wish Mentor had told our assembler that (our layouter was traveling so he couldn't call them). But they more or less brushed him off. Anyhow, now they have programmed the machine by hand and the boards are coming off the reflow this afternoon. SignatureRegards, Joerg http://www.analogconsultants.com > > Its the x and y coordinates > [quoted text clipped - 8 lines] > > http://www.analogconsultants.com 25.4mm = 1 inch www.ckp-railways.talktalk.net/pcbcad21.htm Joerg, There is a way to interpret that, but I use an unsupported script under VB scripts in Layout to make my X-Y sheet. Some 3rd party programs that some assemblers use can directly read a PADS ASCII file, that is why they asked for that, but apparently yours cannot so use the built in script under VB scripts. BTW I thought you were on the PADS ListServer as well. Probably get better answers there than here. Hawker On 5/16/2007 10:38 AM, The digits of Joerg's hands composed the following: > Hello Folks, > [quoted text clipped - 10 lines] > > What does "-190690500 289179000" mean in terms of mils, or millimeter? > Joerg, > There is a way to interpret that, but I use an unsupported script under > VB scripts in Layout to make my X-Y sheet. Some 3rd party programs that > some assemblers use can directly read a PADS ASCII file, that is why > they asked for that, but apparently yours cannot so use the built in > script under VB scripts. My layouter wants to do something like that next time. He said he has some conversion routines he can try out. Anyhow, too late now as the boards are out of reflow and the remaining specialty items are being hand-soldered on. The first batch is actually already on the UPS truck. > BTW I thought you were on the PADS ListServer as well. Probably get > better answers there than here. Sorry but I am not. Only on the Cadsoft Eagle server because I switched to that software (but I don't do layouts except for some really nasty RF stuff). SignatureRegards, Joerg http://www.analogconsultants.com > Hello Folks, > [quoted text clipped - 15 lines] > > http://www.analogconsultants.com I would send them a file with a 1 inch square on it and let them work out teh scaling factor. www.ckp-railways.talktalk.net/pcbcad21.htm >>Hello Folks, >> [quoted text clipped - 20 lines] > > www.ckp-railways.talktalk.net/pcbcad21.htm They didn't want to experiment but get it done. So they entered it all by hand. Guess what, no mistakes and the boards run just fine now. SignatureRegards, Joerg http://www.analogconsultants.com |
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