| T O P I C R E V I E W |
| Ampdoctor |
Posted - 04 Dec 2024 : 16:37:34
This will hopefully be a simple one to solve for the experienced users on here.
When generating X/Y pick and place CSV data, the origin seems to be set to the working area origin.
Can this be set to the relative origin, so that I can set this at the lower left corner of the PCB with all X/Y dimensions referred to this?
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| 5 L A T E S T R E P L I E S (Newest First) |
| Peter Johnson |
Posted - 05 Dec 2024 : 13:51:35
I've had a look but there doesn't seem to be a recognised standard for pick and place files, with variation between different manufacturers requirements. The instructions I've been able to find seem universally related to top side placement so it's not clear how bottom side co-ordinates should be addressed.
Given the lack of standards, the current system of using positions as viewed from the top would seem to be the most sensible. If the board is reversed, corrections to the co-ordinates will need to be applied, but which will depend on whether the board is flipped on the long or short edge, so leaving the manufacturer to correct the positions seems to be the best strategy. This is likely to be a common issue which any commercial pick and place control software should address with ease. |
| edrees |
Posted - 05 Dec 2024 : 11:36:06
This also reminds me of a query I posted some time back regarding pcbs with components on both top & bottom sides. I neve got any feedback!
Assuming that the origin is the bottom left hand corner of a rectangular pcb, the Pick & Place info is correct for top side components, but when the pcb is flipped (to place the bottom side components) the X data generated is still positive, -despite the Origin now being on the bottom right hand corner of the pcb, (viewed from below).
I have always provided "positive" X (and Y) co-ordinates and left the problem for the CEM to sort out!
I assume that the co-ordinates are always looking from the top side view of the pcb (similar to copper layer numbers). Is there an industry recognised "convention" for this?
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| Peter Johnson |
Posted - 05 Dec 2024 : 10:40:34
There's a little trick you can do here as well. If you set the relative co-ordinate to the bottom left corner, you can open [Settings], [Relative Co-ordinates] then copy and paste the figures from the bottom (relative) boxes to the top (absolute) ones.
You do need to be a little careful here because if you're generating the board outline data from a Gerber plot, manufacturers tend to use the centre line of the plot, but if you're using the drill data option, the board profile is converted to milling instructions, so it's the inside edge of the profile that's used.
There's a further consideration with pick and place data in that the original footprint orientation is always taken as zero rotation, which can introduce a consistent error depending on whether the footprint was created in portrait or landscape orientation. It's not usually a problem as it's an issue for most programs so manufacturers are used to correcting for it. |
| Ampdoctor |
Posted - 04 Dec 2024 : 17:33:38
That's done the trick, thank you! |
| edrees |
Posted - 04 Dec 2024 : 17:03:02
Select the bottom pcb board edge then set it as the system origin. With a bit of luck you will set the origin as the bottom left hand corner. Else select the left vertical pcb edge and repeat. Add a text callout on bottom left hand corner as "Origin" for everybody to know. |
