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Electronics => Projects, Designs, and Technical Stuff => Topic started by: mblyman89 on June 01, 2021, 02:30:48 am

Title: Flex seal on bottom of pcb
Post by: mblyman89 on June 01, 2021, 02:30:48 am
Hello, I am curious if anyone has coated the bottom of their pcbs with liquid tape or flex seal to protect it and insulate it and if that is a practical solution to protecting the bottom of a pcb. If not, is there a suggested method for protecting the bottom of a pcb? I’ve seen some pcbs have a non conductive foam padding on them, but that stuff is really expensive. Thank you!
Title: Re: Flex seal on bottom of pcb
Post by: ataradov on June 01, 2021, 02:59:18 am
There are specially designed polyurethane conformal coating compounds. I would not use any random hardware store stuff.  A lot of it  acidic and will eventually damage the PCB.
Title: Re: Flex seal on bottom of pcb
Post by: notsob on June 01, 2021, 03:17:26 am
you could try something peters conformal coating

https://www.peters.de/en/products/elpeguard-conformal-coatings (https://www.peters.de/en/products/elpeguard-conformal-coatings)
Title: Re: Flex seal on bottom of pcb
Post by: Pete66 on June 01, 2021, 07:39:47 am
It depends what you are protecting it against.  I normally use lacquer.  It works great and comes off with acetone when you need to take it off.  I just use my wife's nail polish - its free. ;)
Title: Re: Flex seal on bottom of pcb
Post by: fcb on June 01, 2021, 08:33:43 am
Hello, I am curious if anyone has coated the bottom of their pcbs with liquid tape or flex seal to protect it and insulate it and if that is a practical solution to protecting the bottom of a pcb. If not, is there a suggested method for protecting the bottom of a pcb? I’ve seen some pcbs have a non conductive foam padding on them, but that stuff is really expensive. Thank you!
What are you trying to achieve protection from? Issues with chemicals (which?) Physical media? Voltages present? Temperatures?

We use silicone conformal coating for sealing against humidty.  Mylar sheets for high-voltages held onto PCB with plastic rivets. Tufnol for high-voltage high-current stuff.
Title: Re: Flex seal on bottom of pcb
Post by: rsjsouza on June 01, 2021, 12:09:18 pm
I have been using the conformal coating below (MG Chemicals 4223F) for about ten years on PCBs in the pool equipment (heavy chemical, dust and humidity environment) without a problem

https://www.mgchemicals.com/products/conformal-coating/polyurethane-conformal-coatings/urethane-conformal-coating/ (https://www.mgchemicals.com/products/conformal-coating/polyurethane-conformal-coatings/urethane-conformal-coating/)

I have seen silicone-based glues and caulks warp or otherwise damage PCBs during the curing process, so I would be very careful when using something not proper for the task.
Title: Re: Flex seal on bottom of pcb
Post by: mblyman89 on June 01, 2021, 05:06:28 pm
Thank you all for your input! I’m not sure what I’m protecting the circuit from really, it’s a 12v 1A firework controller, and it’ll always be protected from the elements and such, mostly. I just wasn’t sure how to protect the pcb so it would last a long time from just normal usage. I’ll look into the conformal coatings and epoxy solutions for now.