Adjust probe height and speed when outlining/positioning over pads

[mharris]

I've found that the probe is too high to accurately line up boards precisely when running the outline. When I want to have edge connectors I need the board lined up quite precisely with the edge, or the height mapping stage goes off the board. It can look aligned when the outline is done, but sometimes its a bit too quick to check how well it is lined up, especially with the height.

Would it be possible for the outline step to have +/- buttons for setting the probe height, and the same for feedrate?

The same issue makes setting pad centre difficult for me too - I don't always have huge amounts of light in the lab so getting the paste precisely centred on a pad is difficult. If the probe was closer to the pad it would be easier to determine where the probe is relative to the pad.

[troy]

I like the idea of adjustable speed and height in outline. but before I enter a feature request for that, i have a question: Could you use an aligned print for this? If not then what would it need in order to work? fyi, I'm adding the ability to change the pads used in the align step (part of adding support for template boards).

For pad measurement, i should retract less. I use a constant right now, but it should retract by the probe displacement plus some margin. I'll add that to my todos. Someone requested a button to touch and retract without advancing to the next step...so that you can see the point of contact. Seemed like a good idea, but maybe reducing the retract will achieve the desired precision without adding steps.

[mharris]

I don't think I can use an aligned print for something that doesnt have anything to align to? When doing ink deposition on custom substrates I have no features to line up with on the substrate.

If i'm doing an aligned print (such as paste deposition) - when the probe is too high I find it hard to figure out exactly where the probe is relative to the pad which makes it much more of a challenge to get it aligned than if it was say 0.5mm above the surface or lower. It could just be my eyesight (too many years staring at 0402s and smaller) and/or poor lighting (lots of lights up very high, which the voltera gantry turns to shadows)... not sure how many other people find this an issue.

Next week i'm hoping to print on some 0.05mm thick material which means the probe is even further away from the top of my material, making alignment even harder if I want to have features right near the edge of the material. For now I think I'll need to add an outline trace to print in ink, then cut the material on that line. That however won't work for other boards I'm working on.

[a2retro]

mharris, for aligned print you do a locate (1 of 2) for rough adjustment, lower the probe and then use the arrows again for fine adjustment ( the probe is still not on the the surface of the board) Then you click measure. Then move to next pad and repeat for the second reference point.

The first time I did this I was nervous as I thought the probe may have been touching the surface but it's not.

[a2retro]

Printing graduated markers on the holds down bars might also help give a close target for centering a board left to right which is where most of my alignment issues come when doing a non aligned board setup

[mharris]

The aligned print for me is OK when doing solder paste, but its still 1mm or so above the surface, when you get to the step of being able to click pads and have it go tap them, they all get tapped but I can still be 0.2-0.4mm off centre which makes a difference on smaller pads. Even on 0603 pads its visibly off and I had pretty bad solder joints that day (all the parts fell off after an hour - that might be more to do with very short paste life once exposed though - I couldnt find one of my parts). Plus I have backlash in my machine, so it depends on which direction it approaches the pad as to how much off the place will be compared to where it thinks it is

For ink printing though, I wouldn't want to use aligned print as I don't have any reference point on the board, I'd hate to skew or stretch/compress my print when trying to get it to the right place by picking positions blindly.

[a2retro]

Sounds like your machine its kinda out of whack. It should behave the same way as you see in the in-app demo videos.

[jazozaya]

Not much to add on my side but ....

Plus I have backlash in my machine, so it depends on which direction it approaches the pad as to how much off the place will be compared to where it thinks it is

I'm sure Matt mentioned this to you but we already have a fix for this and it will go out in the next update.

I'd hate to skew or stretch/compress my print when trying to get it to the right place by picking positions blindly.

Just a heads up, an aligned print will never stretch or compress your print.

The first point is used to measure the XY translation of your board.
The second point is used to measure the angular rotation of your board.

If you notice your paste dispensing is consistently offset in the same direction then it implies the first point was measured wrong.
If you notice your paste is dispensing sometimes correct on some pads and wrong on other pads, then it might be your second point.

Correct me if I'm wrong @mharris, but from my understanding some pick and place systems will actually measure the location of 3 fiducials, where the 3rd point is used to measure scaling in both X and Y. Scaling issues could be in manufacturing defects in the PCB itself (unlikely), cameras playing tricks or a wonky linear system.

[mharris]

Ah, i wasnt sure if you were figuring out stretch or just angular offset. Good to know it wont mess with my shapes.

My offset is consistently in one directly, its just me badly setting up the centre of the pad!

PNP machines do indeed use 3 fiducials for the reasons you mention. For commercial machines its rarely the camera in the machine, or the mechanics of the machine - its all in the PCB. PCBs have pretty interesting effects, the prepreg can shift a little bit as it cures which will move the copper a touch - the copper can be etched with lens effects from the exposing of the etch mask (depending on the method of exposure) - cheaper enlarger lenses will 'warp' the copper, if its not a digital exposure then the film can be less than perfectly flat behind the enlarger/reducer.. if its directly printed the printer might not be perfectly calibrated either. On small boards these effects are virtually unnoticeable across pcb.. but get to something like a motherboard size and you can notice them. Another fun one is thermal expansion - of both the machine and the PCB. Copper and steel expand fairly similarly as does FR4, but if you have a hot machine and a cool board then the machine might be bigger than the board.. so the machine thinks the board is the same size relatively speaking - if you're dropping 0201s on opposite corners of the board it only takes 10-20*c or so to make those not line up nicely with a larger board.