A coworker built the best squeegee I’ve ever used: he took two sheets of 2mm aluminum as a handle, and between them sandwiched two sheets of scrap stencil, one sticking out about 3mm, the other about 6mm (so that the 3mm is extra support for the 6mm sheet). The stencil metal is flexible, but with the added support, still rigid enough to allow definite pressure.

Very good

Good video on the subject. I would like to bring few recommendations. 1. Can you use a camera view to show the pad and stencil during the alignment process? 2. Instead of locating the post leg to be locked underneath the PCB put it outside then you can lock it while in place. It is much more easier and accurate. Keep the good work.

What happens between completing one panel and the next one? Do you need to clean anything?

7:53 Oh. Oh no. You’re not applying enough pressure, which is why the stencil is only being squeegeed clean on one side. No matter how many times you go over it, if paste is rolling out the sides and landing on previously-squeegeed-clean sections, then when you lift the stencil, those pads will have much too much paste. You want one single pass if at all possible, with enough pressure that NO paste is left on the stencil above a pad aperture.

I think its better to avoid the second pass with the solder pass. But for this sizes and tolerances it doesn't really matter.

@BABALOOEY46

3 жыл бұрын

Yes good thinking.... a scraper the same width as the stencil and one clean pass. Best way to control quality.

@Core-Electronics

3 жыл бұрын

Good point, thanks Jonas. Perhaps we should have mentioned that along with it's only worth doing another pass if you have concerns with the first. If the supports/angles are fine, then everything should be a-ok with another go

@MichaelRuppe

3 жыл бұрын

@@BABALOOEY46 we've upgraded to a wider squeegee - this one's a bit narrow isn't it?

@danielrioux54

Жыл бұрын

When you show the results under the microscope, you can see that too much pressure was applied on the solder paste shown by the paste spreading at the base. I am less concern the uneven top surface because during the reflow process everything will become even.

Modified silkscreen printer

@Core-Electronics

3 жыл бұрын

If only solder paste layer artwork made for good T-Shirts :)

Jesus, what a mess. You never do more than one pass with the paddle, because the stencil will never sit exactly over the board. Which means its flopping around over the board and squashing the previously placed paste. Ideally you need to fully support the board from underneath so that you can apply significant pressure to the stencil, and the squeegee needs to be able to be flexible.

I have no idea but I’m guessing 45 degrees is optimal squeegee angle. I think it is for a jackhammer.... but hey those two things are not so similar 😂

@BABALOOEY46

3 жыл бұрын

I would also like to suggest a bevel on the scraper.... like a fine point.. there needs to be rubber under the pcb to support everything I think as there is leakage out the side due to flexing I presume.

@Core-Electronics

3 жыл бұрын

Thanks Steve, very interesting! We're yet undecided between fairly rigid scrapers vs flexible, more experimentation needed :)

this doesnt explain how to make a stencil