Author Topic: Potting PCBs with SMT components - what compound to use?  (Read 13930 times)

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Offline CJay

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #25 on: June 26, 2017, 10:27:26 am »
Dow Corning make some lovely silicone potting compounds for electronics in harsh environments and have/had a nicely responsive tech team who can help you, they'll even send out samples for you to test.

Worth an email if you've a company email address.
 
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Offline DigitalDeath

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #26 on: June 27, 2017, 08:45:25 am »
832FX - BLACK FLEXIBLE EPOXY ENCAPSULATING AND POTTING COMPOUND
MG Chemicals.
 
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Offline DTJTopic starter

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #27 on: June 27, 2017, 09:57:34 am »
832FX - BLACK FLEXIBLE EPOXY ENCAPSULATING AND POTTING COMPOUND
MG Chemicals.

The 832FX looks good but I can't find it at any Australian suppliers.   :(
http://www.mgchemicals.com/products/potting-compounds/epoxy-potting-compounds/black-flexible-epoxy-encapsulating-and-potting-compound
 

Offline DigitalDeath

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #28 on: June 27, 2017, 07:08:35 pm »
You can also go to a local industrial epoxy resin supplier and ask for encapsulating epoxy and a compatible toughener additive. The additive makes the resin resistant to impact by making it flexible. It adds some sort of elastomer process to the mix.
 
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Offline sdouble

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #29 on: July 14, 2017, 12:21:20 pm »
I'm hacking that thread since I have a similar need.
For a high impedance circuit (a charge integrator) which needs to be included into a detector, I need a potting which exhibits the following characteristics :
-Low outgassing
-very high resistivity
-high voltage capable ( 1kV / 1mm)
-moderates cure temperature if applicable
-SMD compliant.
I'm currently using an epoxy bought from RS, but not a big fan : outgasssing is not specified and obviously quiet strong, even after 1 week of cure.
Money is not a major issue : I don't need kilos.
thanks for you help !
 :)
 

Offline DTJTopic starter

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Re: Potting PCBs with SMT components - what compound to use?
« Reply #30 on: July 14, 2017, 01:04:10 pm »
Not sure if it helps you Sdouble (I initiated this thread).........

I've ended up using a two pronged solution. I needed waterproof potting for SMD parts.

I'm spraying the boards with the polyurethane coating first, then potting in a grey PUR from RS.

So far it seems ok. I'm part way through testing the water proofing an will do the temp cycling tests in the next week or so.

https://www.crcindustries.com.au/products/corrosion-protection-and-inhibitors/urethane-seal-coat

http://au.rs-online.com/web/p/potting-compounds/1991395/
The RS potting compound sets quite firmly - probably comparable to a firm jogging shoe sole hardness.
I've been cold curing, the data sheet says its a 34 hour cure but I found it was pretty much fully set after 12 hours at less than 20°.

 


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