I recently purchased RV1S and learned pretty much everything about the machine from this forum. Thanks for an invaluable resource!
I have a problem with the machine, there is X/Y distortion when placing the components. I have a 145mm x 120mm panel I'm placing and I can see that there is placement error as the components are being placed closer and closer to the edge of the PCB. The distortion happens both in X and Y axis. I managed to overcome this issue by offsetting the fiducials, but there are still issues with placement. Any suggestions on how I could fix this or is this the dreaded calibration issue?
Also I can't use the fiducial camera, because it seems to be making the distortion even bigger as I suspect it's not calibrated correctly, however I've read on this forum that it's possible to use the machine without it and I've successfully done it.
Hi there - can you post some pictures of the board once parts have been placed? Will help show/explain the problem.
I've set up my machine now to place the boards so don't want to mess it up.
(http://agileinnovative.co.uk/clients/blinkstick/rv1s-misplace.png)
Bottom left fiducial is the first one, top right is the second reference. Components next to first fiducial are placed correctly, but the whole panel is shifts gradually as displayed near the second fiducial. Fiducials are set up with tool 1. I have to move the bottom fiducial down by 10thou and top fiducial by 20 thou to right and 25 thou down in order to get correct placement all over the board.
I also calculated the exact position of the two caps placed at the top corner in reference to the bottom left fiducial and moved the machine to the exact location from bottom left fiducial as the reference point. The position was exactly where the component was misplaced.
Have you programmed the job as a complete panel or as a single board and used the step/repeat to duplicate?
If you have used step/repeat you could check the distances you entered are exactly correct. I'd look at the panel gerber data in CAD to measure exactly. Even if they are correct, you could tweak the values to correct for whatever is causing the errors, and then your fiducial alignment may be correct again. This would at least make alignment of each panel simpler again.
You say you are not using the fid camera, how are you aligning each panel then? By moving the head down to touch the board? sounds pretty painful for each panel.
dooh! Eureka moment.
You need to apply a rotational offset to the board (when you set up PCB, there are 4 boxes for board offsets). Try something like 8 (positive) for the A offset. That should at least start to bring it in line then you may need to add small x and/or y offsets to centre it but those ones are easy to guess in comparison to A offset.
You will of course have to undo all the fudge factors you've just done though, but at least you can align on the fiducials again.
It's programmed as a complete board.
I'm setting up the other side of the board and will try to apply the rotation. Should this be based on guessing?
What I normally do is start off with the fids dead-on, test-place a couple of parts nearest each corner, then estimate the error near each corner by eye and work out the required offset for the fid positions.
After a couple of iterations doing this it's usually close enough over the board for the whole batch.
'educated guesses' is a nicer way to put it! Yes the value I suggested is based on my experience of my machine. It should at least be a good starting point.
Mike, that's how I've been doing: double sided tape in various positions on the board to test the placement. This way I tweaked the CDFs and found out placement issues.
phonoplug, seems that your suggestion probably worked at least with the bottom side of the PCB which has a lot less components, but a micro USB socket which needs very precise placement. Had to push a few components here an there into their correct positions, but probably just a vision correction problem which needs more tweaking. I'm placing mostly 0603s. Everything looks good after reflow.
Wondering whether checking tool 5 before placing components is crucial for correct placement...
I don't understand why you would tweak CDFs (except for oddball asymmetrical parts).
The tool 5 thing is a bit of a mystery, not least why it does it sometimes and not others. I think it's probably mostly to do with the fact that the camera is analogue, so it's a good idea to check centering and aspect ratio periodically.
Mike, mostly I had to tweak CDFs with threshold adjustment to get consistent imaging. Had quite a bit of fiddling with micro USB connector as it's a very non standard shape.
If I specify to check the tool 5, it will always do that when I enter the pick and place UI, but it will always place no matter if it measures the tool correctly or not. I suspect that placement is somewhat better when the tool is measured correctly, but I need to prove this theory :)