If you're on the component side with an IC placed vertically, 0 degrees indicates pin is top left (or at least that's what I've concluded) -- so if I'm using an 0805 package LED (vertically) on the component side, what would indicate the anode ?
The same 0 degrees? Anode at the top?
Thanks. (Newbie at P&P data).
and to clarify, my pcb program just has a generic 0805, not an actual led part so maybe I'll just have to give special instructions or something?
Pick up a copy of IPC-7351 (preferably version B, but any version will do, and you can find them online). All your questions are answered therein. :-)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:
think I'm going to make the LED's THT -- reading many horror stories online about SMD LEDs and inconsistencies from manufacturers.
Very wise... I have found in the same 'series' of LEDs in different colours have ( in one colour) a different 'ident' to indicate anode. NOT funny if missed !
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Yes, horrible issues with this in SMT. I wonder if that "different color" was superbright red?
THT isn't a sure cure there's at least one maker that has a through-hole LED where the long lead is different for the super-red (cathode rather than anode), presumably so they didn't have to have a different lead frame just for that color.
--Spehro Pefhany
This is between you, your CAD package, the CAM function that exports the P&P file, and the P&P machine itself. You SHOULD have a dedicated diode or LED component created in the CAD package at the schematic level, and a matching footprint part in the PCB side of the CAD. Then, you need to see what it does when the CAM function created the P&P file. Then, you need something that converts the CAD/CAM system's native format to the P&P format. I wrote my own little C program to do this, but it is specific for MY CAD/CAM software and my P&P machine. It takes in a file that lists the part description, feeder #, nozzle and rotation offset. For instance, an SOIC in a tube has pin 1 at front-left, but an SOIC in a tape has it at rear-left (90 degree rotation). So, the program makes that adjustment while building the P&P file.
Jon
I have had good results with LEDs, with a few caveats. One is, my machine doesn't handle "domed" LEDs at all. But, you can get flat-top LEDs, and it does fine with 0805 and 1210 sized LEDs. They have 0603 LEDs, but the top of them is just too small for my nozzles, so I get a lot of pick-up fails.
Jon
I usually use Altium and it always bugged me that their Pick Place format seems incompatible with everything else.. their rotations come from an alternate universe and it doesn't even sort. Have to run it through sort -V then use a custom program to correct the rotations and output a standard centroid file. Also have run into assembly houses that have their own made-up standards, requiring a different version of the conversion program. I always include a note saying to manually verify against the docs/silkscreen so if they get it wrong it's on them.
Terry
Hmm, lovely!
I've always generated the files, but I don't know that they've ever been used. I seem to be priviledged in that most boards I've designed have been made at a large, full featured CM that does excellent work. I think they only care about ODB++ and a BOM.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
When it works without too much fuss
Never used ODB++, our current USA assembler likes the Altium ASCII format, which is really Protel 5. Other assemblers including Screaming Circuits and Myro want Gerber files and the simple centroid format with IPC-standard rotations. Altium saves the Gerbers with an X/Y offset added, and the centroid file has the offsets removed, so far that's never caused a problem.
Terry
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