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pneumatic paste dispensers any good?
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pneumatic paste dispensers any good?

by ag3c on Fri Jul 15, 2011 1:04 pm

I've been doing a lot of short-run board assembly lately, prepping the boards for the reflow oven by using a syringe to dot paste on pads, and then doing the pick & place by hand as well. It kind of sucks to do by hand, and I'm about to do a board that's got 5-10x more pads than the ones I've done before. I'm not sure that I'm ready to move to stencils though, since I'm often doing just a single board at a time. (And also, I don't have any stencils at the moment.)

So:
1) Has anyone used pneumatic dispensers like this: http://sra-solder.com/product.php/6066/5 ? If you're not using stencils, are pneumatic dispensers like this the bees knees? Any specific things to avoid, or brands/features to look?

2) What do people recommend for prepping boards to accept paste? Strictly chemical: acetone or isopropyl alcohol? (I've never tried acetone: does it attack conformal coatings?) Or mechanical roughing with a scotch-brite pad?

3) I ask about #2 because my paste (still fresh, I think) sometimes pulls away from the pad rather than remaining on it. It's definitely not as fluid as the stuff in this video: http://www.youtube.com/watch?v=tPjFQ15Zdp0

Thanks!
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Re: pneumatic paste dispensers any good?

by Alphatronique on Fri Jul 15, 2011 3:17 pm

Hi

i have here a EFD 2400 dispenser that i use for past and flux (way to much expensive for doing this)

but based on my as experience whit dispenser for solder past only you not need
a really good dispenser or one whit vacuum pull back ,solder past was so think
that it not really Mather , so any used EFD or other dispense may do the job

as for solder past fresh past was the secret ,old solder past will have reflow problem
like bad flux ,past/flux separation , oxidation on solder ball

so i buy a 500 gram jar every 4 time /year and put remain on garbage
i also not put back used past on jar except if it resume production in next 12 hour

that raise next big question were find fresh past past last 6 banned so if you distributor have it stock for 4 banned

you got only 60 day before it expire ,even digi-key see unable to keep fresh past ,or ship it on cold ice pack
i finally to find local specialized distributor that sell huge volume past and i chose one of it best seller for ensure it fresh

ok here i will reveal one on my company secret for small batch stencil ...
if found that Cantastic 2000 may read a Gerber past layer and save it back as a nc drill file :mrgreen:
so i use that drill file on my lpfk pcb milling or taig cnc and make stencil whit flashing aluminium sheet
for most passive part solder past not really Mather that hole was round (drilled)
since you may sand aluminium it make more shoot that laser etch stencil and it really low cost
that wly i keep my old lpkf machine

Best regard
Best regard
Marc Lalonde CID.
IPC Certified PCB Designer.
Alphatroniqe inc.
www.alphatronique.com
http://ca.groups.yahoo.com/group/MyData_Group
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Re: pneumatic paste dispensers any good?

by ag3c on Sat Jul 16, 2011 1:02 pm

Thanks!

I came across this earlier this morning -- it was also pretty helpful:
http://www.youtube.com/watch?v=pdGSFc7VjBE
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Re: pneumatic paste dispensers any good?

by mikeselectricstuff on Sat Jul 16, 2011 6:14 pm

Shelf life of paste varies a lot by maker - I have stuff several years old that's still fine. EFD seems pretty good.
Keep it in the fridge to maximise lifetime.
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