Has anybody else tried using stencils coated with Nano ProTek? I did find that I could reduce my cleaning frequency and squeegee pressure, which should help to increase stencil life, but I'm finding that it seems to wear off quicker than I thought it would. I'm still evaluating the value.
Anybody else have any thoughts they'd like to share?
It's a $40 adder to my stencils if I have them apply it. But I've just discovered that if you have THEM add it, they add it thru a stencil and only apply it to the appertures. (My guess is they do this because it allows them to use much less material and therefore save $$) If YOU add it you can coat the entire stencil. This has enabled me to reduce squeegee pressure slightly. It does seem to work in my application. I'm just curious what others have noted.
I have tried it, and it does what it claims. Don't know about durability yet, tested it on a short run.
Cost: $300 for a 10pak (10 stencils)
Tested a different stencil with Rain-X applied to it, so far same result, the paste does not clog the fine apertures where we used to have problems. We wipe the stencil underside every 10 PCBs now, compared to every 2 before. Been running >200 PCB over 3 shifts now on Rain-X. No signs of contamination from the stuff.
Yes, Rain-X, the stuff you buy at auto shop to treat the windshield so that the rain just rolls off the glass. Cost: ~$6 for 200ml, enough for ~100 stencils... I'm not proposing that other try it, if you do, I'm not responsible for any consequences you may encounter.
So far after ~1500 units printed with the stencil treated once with Rain-X, no issues were detected with solder joints. The only difference is no more solder bridges on fine pitch with .010" openings. The print is picture perfect on all pads, nice and even, flat across the top.
the appearance during the application was the same (to the eye). the feel to the touch is the same once it is dry and polished. The effect is the same when water is sprinkled on the treated surface. My understanding is that the product bonds to the surface and fills the pores. over 3000 pcbs printed, still perfect paste release. No problems with the solder joints.
Using AIM N.C. paste, just ran 10 panels to test after applying Rain-X to the stencil (pre-clean with IPA). Printing and release were slightly better (maybe my imagination), but not a large difference. Stencil remained cleaner longer. I could not tell the difference in finished product, but did not x-ray or chem analysis.
I plan on continuing test with increasingly more critical stencils. The previous test was with a very simple/easy job, just in case...
Rain-X is a "hydrophobic silicone polymer" according to Wikipedia. Silicone is not something I want around a soldering operation without a chemist I trust telling me it's OK. Having it work a few times without any obvious problems wouldn't be evidence enough to make me comfortable.
EDIT: I see Steve Gregory beat me to it. I cringe when I see poorly engineered "solutions" like this. Maybe being in the high reliability market colors my expectations of due care.
It's actually a "silane" according to the same article. Also, it "bonds" with the surface of the stencil. once bonded, it's not going anywhere. I'm not a chemist. I'm not promoting this product to be used on stencil. I'm just pointing out that what is sold as Nano coating for $300/10 pak may just be a derivative of a very cheap chemical. Which in this industry would not be a first. ;-)
I would be careful with trying Rain-X. Rain-X is a silanol treatment that is not durable. That is why you need to reapply it on a windshield many times. Also you could contaminate the paste as it will come off the stencil during the printing. From what I know of Nano ProTek it is permanently chemically bound to stencil. Also they say Nano Pro Tek coating is less than 5 nanometers thick whereas I think Rain-X is at least 50 -100 nanometers which will clog some apertures. I know Rain-X is cheap but we would not bring that into our facility.