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Conformal coat material dispensed through epoxy needle?

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Tom

#76978

Conformal coat material dispensed through epoxy needle? | 31 January, 2017

We're looking to add conformal coating to some of our pcb's which range from 2x2" to around 6x6". I would like to use a coating material that is not nasty smelling requiring ventilation or filtration if possible. Are there conformal materials that are easily dispensed from a needle on an epoxy dispenser instead of a sprayer? What other options might we have?

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#76979

Conformal coat material dispensed through epoxy needle? | 31 January, 2017

Dow Corning 3-1953 is widely used when it comes to silicone based conformal coatings. Low odor, medium viscosity, can be atomized or needle dispensed. We have our operators fill syringe cartridges for any minor touch up.

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Tom

#77005

Conformal coat material dispensed through epoxy needle? | 1 February, 2017

Thanks, I'll give that a try!

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#77029

Conformal coat material dispensed through epoxy needle? | 3 February, 2017

Not sure exactly what kind of coverage your looking to get but we use Dow Corning 3-1944, it's room-temp cure and rather thick, (think warm honey). But we have found it useful on several projects.

http://www.dowcorning.com/applications/search/products/details.aspx?prod=03356035&type=PROD

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Tom

#77030

Conformal coat material dispensed through epoxy needle? | 3 February, 2017

Thanks, we'll try this too. We aquired an asymtek millenium for dispensing selectively. It is setup for epoxies with a needle dispense head so we'll try to make it all work for us. One-part silicones seem to be the popular solution.

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#77032

Conformal coat material dispensed through epoxy needle? | 3 February, 2017

You should have no problem. We use a very dated Asymtek machine (Automove 303) retrofitted for dispensing, air over syringe. It took time and some tinkering with. But all things considered, we're able to achieve remarkable results. I would recommend picking up a needle sample kit, so you have various sizes and styles to play around with. It was something that proved very helpful to have on hand.

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Tom

#77047

Conformal coat material dispensed through epoxy needle? | 6 February, 2017

Great, that is encouraging. I did order a few needle sizes from McMaster to try out when we get the machine setup. What do you recommend for clean up the equipment?

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#77050

Conformal coat material dispensed through epoxy needle? | 6 February, 2017

So I had the same question too when I was setting ours up.

My lazy (and cheap) solution was: for each program I have a universal path that is used up to the first dispense instruction and after the last one then I covered the surfaces underneath that path with vinyl. Anytime significant amounts begin to build up, we peel the vinyl off and put a new piece on. To us, it's just not worth the time/effort spent cleaning. Other than that, replace syringes and needle tips when necessary. You'll be able to see when your flow rate is affected from clogging tips, if you have a lot of idle time while running production it may be more frequent, but it's all dependent on atmospheric conditions.

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Tom

#77056

Conformal coat material dispensed through epoxy needle? | 7 February, 2017

Thanks for the tip. I'm still getting familiar with the machine by reading the manuals as I have time. Was wondering what type of solvent you use to clean the dispensing mechanism parts? Or do you not clean anything and simply dispose of the syring parts? Our machine looks to be setup with a servo dispense head (pic attached) so we'll need to clean those bits .

Attachments:

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#77059

Conformal coat material dispensed through epoxy needle? | 7 February, 2017

Oh yeah, so we have a auger valve similar to that on one of our other machines that we use for dispensing SMT glue, and solder paste also. We have a conditioner that we flush it with at EOD when in use, then we just let it sit idle with the conditioner in it when not in use.

I have had to disassemble and clean it 3 or 4 times over 5 years. For cleaning I just let all parts soak in MEK over night, and then scrubbed/rinsed with MEK in the morning.

The conditioner we use, (not sure if it'd work with conformal coat): https://www.amazon.com/Techon-Systems-7305XCON-Rotary-Conditioner/dp/B00L0VGK16

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Tom

#77126

Conformal coat material dispensed through epoxy needle? | 20 February, 2017

We tried both of these suggestions and the 3-1953 is less viscous than the 3-1944 so it will flow better on the board for our conformal coating application.

What cleaning solvent is recommended for cleaning off the auger parts, etc.? I haven't been able to find any clean-up information in the product literature or msds.

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#77138

Conformal coat material dispensed through epoxy needle? | 22 February, 2017

https://webaps.ellsworth.com/edl/Actions/GetLibraryFile.aspx?document=2922&language=en

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Tom

#77139

Conformal coat material dispensed through epoxy needle? | 22 February, 2017

Great; which do you recommend, 10, 20 or 30? Seems to me the 10 is most concentrated and 30 is least concentrated according to the flammability properties table. I'm not sure which would be best and I'd rather not try them all.

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