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Need help on improving design - Automatic Pick & Place Coil

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#80816

Need help on improving design - Automatic Pick & Place Coil | 1 August, 2018

Need all your experts out there for tips & tricks to make things work. I been giving a task to help redesign a simple board; only to load two components. The challenge is to use pick-n-place machine to load the coil onto the 50up array panel. Previous Design the coils pad is too big, causing twist and pull during reflows(misalignment & other issue). Please see the attachments. On new design I modified pad size and the to have stencil with home-plate aperture design, tried to solve the solder pulling issue. But homeplate design unable to keep the coil hold still, coils would rolls away with slight vibrations. The new design seem like helped a lot from solder pulling problem, but now I am having pick-n-place issue. Have anyone encounter similar design before? Any tips and tricks would be appropriated.

Attachments:

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dwl

#80817

Need help on improving design - Automatic Pick & Place Coil | 1 August, 2018

One option might be to convert the coil to through hole and use intrusive reflow AKA pin in paste. the coil leads would have to be formed perpendicular to the board instead of parallel. you would have through holes instead of SMT pads, but you would still apply solder paste and place the component with the pick-n-place machine.

If that's not an option, you might consider applying a dot of adhesive to the PCB prior to placing the component. Something like Loctite chip bonder. the viscosity of the adhesive should hold the part in place long enough to reflow. The downside is it requires an additional process step. If volumes are low, you can b a manual dispenser, if they are higher you can get a dispenser option on many printers, or purchase an inline dispenser.

If you are having trouble picking the part up, consider using a mechanical chuck instead of a vacuum nozzle. You'll have to find out if your brand of pick and place machine can be equipped with one.

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#80818

Need help on improving design - Automatic Pick & Place Coil | 1 August, 2018

dwl, thanks for your feedback. The 1st option would not be possible, due to customer wants to keep the board as it is. Epoxy would be one of the next thing I would do if no other possible design that might works. I am not sure of the volume yet, I am guess it's going to be high volume. But I don't think purchasing an inline dispenser would be an option as this assembly is too simple; even though it's 50up array, still not worth it to purchase an additional equipment just for that one job. There isn't much of pick nor place issue from the SMT machine, I already tune the package. It's just the matter of the coil would hold it without rolling or twisting before and during reflow.

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#80819

Need help on improving design - Automatic Pick & Place Coil | 1 August, 2018

A few times I have had success limiting movement in the oven by splitting up the paste apertures. In this case it might work if you had three bricks perpendicular to the leads.(maybe more) The trick would be making the gap between them big enough to be effective but small enough to not have unacceptable gaps in the solder joint. It might be doable because all you really have to do is make it be not one big pool of solder for the part to float on. You might also want to see if you can get already encased coils with a flat bottom.

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#80842

Need help on improving design - Automatic Pick & Place Coil | 6 August, 2018

I just found out we are unable to epoxy it. As the customer need to pull it up and open to tune the product. Which means the only way to solve it is by fine tune the pad and/or stencil design.

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dwl

#80844

Need help on improving design - Automatic Pick & Place Coil | 6 August, 2018

What about some kind of surface mount clip? Solder the clips to the PCB and then insert the coil manually? IT adds a little labor but at least your coil won't move.

For reference here's a company that makes that sort of thing. There are plenty of others as well. https://www.harwin.com/product-highlights/smt-cable-clips/

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#80845

Need help on improving design - Automatic Pick & Place Coil | 6 August, 2018

If I understand customer's intention correctly, it would be fastest, mass production with fully utilizing the Pick-N-Place machine capacity with minimum manual labor which won't break the bank. They used to manual hand soldering the coil to the board. That's way to much labor time, that's why need a much efficient way to do it with SMT. The goal would be custom pad and/or stencil design that would able to hold the coil still long enough so it's not skew/twist/turn during reflow. Would be best just print, run, and reflow only, without another extra steps addin to it.

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#80847

Need help on improving design - Automatic Pick & Place Coil | 7 August, 2018

V-cut pads partially(wide angle) so they become slotted in a way. leave paste as is. I would place slot under coil but there is a trace if Im not wrong

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#80849

Need help on improving design - Automatic Pick & Place Coil | 7 August, 2018

Don't suppose the coil manufacture could make the coil with the leads coming straight out from the winding on opposite sides and on the same plane. Then it can't roll around. SMT pads may have to be staggered a bit. Just a thought.

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#80851

Need help on improving design - Automatic Pick & Place Coil | 7 August, 2018

we did something similar in the past but the leads had a L shape on the end which kept them stable.

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