portable fiducials?

Jun 25, 2021 Last reply: 5 years ago 9 Replies

Our new selective solder machine squirts solder on the bottom of a board to solder the thru-hole parts. But it needs fiducial marks for alignment, and most of our boards don't have bottonside fiducials.



Has anyone used portable fiducials? A fiducual might stick on or screw into a mounting hole or something. Alignment shouldn't need to be super tight for soldering.



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It doesn't seem to like using mounting holes or vias as fiducials. Picky.



It's picky about flux too. We'll have to use an exotic no-clean. We're doing a test board to see how that works.


fredag den 25. juni 2021 kl. 18.31.33 UTC+2 skrev snipped-for-privacy@highlandsniptechnology.com:

make a pcb with fiducials that fits like a frame around the pcb you are soldering?

Your roof doesn't appear to be insulated. Doesn't it get warm in your part of the world?

John :-#)#

probably insulated on the outside

Yes, we added a big layer of foam on top. But it's 59F right now. I wore a sweater to walk to work.

The side walls are concrete, but contact adjacent buildings on both sides.

So a bit of self-adhesive Kapton FPC with a fiducial?

I guess a fixture would be more efficient for any quantity.

We'd have to stick it in exactly the right place. I was thinking we could make some sort of gadget to poke into a few mounting holes, which every board has. Like a flathead screw or shoulder thing, with the fiducial on the flat.

Now I gotta find out what we use for these on our SS machine.

boB

We created a double-sided fiducial in our PADS library, so all new boards or revs get three fids on each side, plus some on the borders if panelized. But we have a lot of old boards without fiducials on the bottom, and don't want to rev all of them.

The ss machine is cool. What flux are you using? We just laid out a surface leakage test board to experiment with different fluxes. Most of our boards wouldn't care about a gigohm here and there, but some would. The ss machine people want us to use a no-clean flux that doesn't gunk up the machine.

Looks like we'll be all lead-free and all no-clean soon. The age of beautiful boards is past.

We are using a No-Clean flux in the SS and the wave solder machines.

Kester 985M

The SS machine also uses nitrogen injected into the solder to reduce slag.

Interesting.

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