LitePlacer.com forums

When I "measure" a board, meaning the LP finds the fiducials and registers on them, and then from the JOB table I select a fiducial and click the 'go to measured' location, shouldn't the camera be centered on the fiducial? Every time I try this the camera ends up at least a Fiducial radius away from center. I can load the camera setting for the fiducial and then check the 'find circles' box and the circle is perfectly placed on the fiducial mark. I'm just wondering if this may account for my parts (mostly 0603) not being well placed on the PCB. I've tried this with several different boards, some with bona fide fiducials, some with vias used as fiducials. Same result.

Anyone else have this problem?
-Corwin

> I select a fiducial and click the 'go to measured' location, shouldn't the camera be centered on the fiducial?

Yes, this should be spot on. I need more information to find the cause:

- If you set a coordinate point (a movement bookmark), are you able to return on that accurately? From all directions?
- Are you using slack compensation?
- Is the error random or always on the same side?
- What are your optical homing results? Also, I'd like to see a log of that to see if it takes abnormal amount of iterations.
- When it is supposed to be on the fiducial, click "measure" on the fiducial box. Note the result in the log window. Move the machine a known amount (like shift+F5 = 1mm to left). Measure again. Did you get a 1mm difference?
- Any other symptoms?
- On tapes tab, give a number in the part # box, select a cell in one of the tapes row and click "show part". Does the camera center on the part? If not, can it show the hole?

> I'm just wondering if this may account for my parts (mostly 0603) not being well placed on the PCB.

Certainly. If the machine does not have an accurate idea where the PCB is, the placement results are not going to be very great.