PADS, ASCII output question: Scale factor?

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

They don't really need the P&P file. It just makes it a little faster to program the machine.

Chris

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.

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.

Its the x and y coordinates

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

Which brings up a question: Do you do contract assembly? Looked on your web site but it's under construction.

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.

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.

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.

Joerg wrote:

...and has been for >3 years.

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.

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

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.

The people I traditionally sell to aren't real interested in websites. Somehow I manage to stay busy...

Chris

My machine can handle boards up to 12"x10", and passives down to 0603.

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

Same here. The only thing they sometimes want to look at is what services can be provided.

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 ;-)

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: