EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: batteksystem on November 26, 2021, 11:49:39 am
-
I am designing some RJ45 connection and to protect them against water ingression, I would like to pot the whole PCB, but I am worry how to protect the epoxy from going into RJ45, which is vertically oriented, there are some perforation at the bottom of the connection, should I use conformal coating or RTV silicone to seal the compound first?
Thanks.
-
Most connectors, and RJ-xx in particular, rely on the idea that a spring corrects for any displacement. The spring is the metal wire / pin. It needs the freedom to move.
Displacement will come from thermal expansion / shrinkage. Shock. Vibration.
If you disable the spring, then you no longer have a guaranteed connection over time…
Potting in epoxy is a perfect way to disable a spring.
-
I wouldnt, gunk will find a way in. Get a sealed RJ45 https://www.aliexpress.com/w/wholesale-ethernet-rj45-waterproof-panel-mount-connector.html (https://www.aliexpress.com/w/wholesale-ethernet-rj45-waterproof-panel-mount-connector.html)
-
You can use a more viscous material to seal around the connector before potting the PCB, but you'll need to make sure the two are chemically compatible. It may also be possible to seal the connector with tape or something before potting, depending on the geometry.
-
Bonjour, Neutrik makes liquid sealed RJ-45X. Made in Germany not China.
Potting generally decreases reliability due to chemiques and mechanical stress.
It can be done but required a lot of technique and experience.
Bon Chance
Jon
-
Thanks for all the information!
-
Also if you're considering potting, you're probably much better served by a circular M8 or M12 connector and cables. Cables are available as standard products, between various ends including to 8p8c.
Your first option should be a sealed (IP65+) enclosure with bulkhead connectors. Circular or sealed 8p8c ("RJ45") connectors can be used. If condensation or leakage can occur inside the box, then conformal coating should be considered. If that is insufficient, finally, potting should be used.
Note that potting serves two primary purposes: physically occupying space so that liquid water cannot condense, and supporting the contents mechanically. A flexible material is generally preferred, to avoid stressing the components. Hard epoxy is likely to shear components completely off the board. There are soft epoxies, or silicone or urethane compounds. The choice depends on desired durometer (rubber firmness), thermal conductivity, chemical compatibility, etc.
Tim