Conformal coating for oil and gas electronics

[fun2design83]

Hi all,

I am trying to manufacturer a PCBA which is required to operate on a nasty environment.
Application: downhole OIL and gas
temp:-50C to 125C, lots of shock/vibration and humidity.

the PCB is a flexible PCB, so I can not pot it. I also have bunch of PTH components. I used MG422B, two times spray, and let it dry on the room temperature, still there is no coating on the sharp edges of PTHs.
any suggestion on better material or better technique for the confromal coating. Thank you so much in advance.

 

[Kajunbee]

Re: conformal coating for oil and gas electronics

Does the coating your using look like it is adhering but not staying thick on the corners? Are does it look like it's beading off? if its beading away there maybe something on the surface that needs to cleaned off. If it's just not staying thick on the corners there's not much you can do to stop it. This is a problem that just about all paints and coatings have.
The only suggestion I have is to liberally coat the board and then turn it upside down while it dries. Hopefully some of the coating will slump down and thicken up on the component corners. I'm a little doubtful, but it doesn't hurt anything to try.

 

[KlausST]

Re: conformal coating for oil and gas electronics

Hi,

* Maybe potting with silicon-gel is possible. There are different ones. Some of them stay very sticky, which is good, because it dampens mechanical vibrations. Temperature range shouldn't be a problem.

* a couple of years ago I was at a company. They were specialized on coatiing PCBs. One option was to do this with vapourized plastics jn vacuum. It gives a very uniform thickness especially around corners. I don't know about temperature range. A clear, thin, invisible film. They put this bare looking PCB in front of my eyes in saltwater ...while it was still working. The company is in Nurenberg, Germany.

Klaus

 

[fun2design83]

Re: conformal coating for oil and gas electronics

Klaus,
Thanks for reply, May I get the contact info of the company in Nurenberg please.

- - - Updated - - -

Does the coating your using look like it is adhering but not staying thick on the corners? Are does it look like it's beading off? if its beading away there maybe something on the surface that needs to cleaned off. If it's just not staying thick on the corners there's not much you can do to stop it. This is a problem that just about all paints and coatings have.
The only suggestion I have is to liberally coat the board and then turn it upside down while it dries. Hopefully some of the coating will slump down and thicken up on the component corners. I'm a little doubtful, but it doesn't hurt anything to try.

No it doesnt beading away.
I tried also to turn it upside down, it didn't work so far , maybe I should try more.

 

[KlausST]

Hi,

long time ago, so I had to look for it...

I was at "Hegutechnik GmbH & Co. KG" https://www.hegu.de
They use polymeric coating in vakuum. From vapour phase directely onto your PCB.
I assume there are other companies that can do this also.

Klaus

 

[Kajunbee]

Applying more coats will eventually get the millage that your looking for. But what you will probably notice is that the flat surfaces will get thicker also giving the appearance that the corners are inadequately protected.
Klaus idea of potting in silicone sounds like a great idea. I'm not sure how thermally conductive silicone is or if it's even and issue with your application.

 

[fun2design83]

Re: conformal coating for oil and gas electronics

@Klaus, I already sent request from their webform seek for help if they are interested.
@Kajunbee, the place I have PTH parts, there is nothing generates heat. so i should be ok.

Does anybody know other companies in north america that are experts on conformal quoting or offer such service?

 

[Kajunbee]

If you search " conformal coatings for oil and gas" you will find numerous products and services. One in particular is Moxa.com.

 

[fun2design83]

sorry my bad, what I meant was is there any other company you have worked with that has expertise on conformal coating?