Silicon type to use around or on PCBs

Dapdan Solar Expert Posts: 330 ✭✭
Hey Guys,

What is the best type of silicon to use around electronic circuitry, PCBs and copper wiring. I have a panel to install on a boat where the J-box is not 100% sealed and I want to apply some type of silicon on the connecting terminals or maybe on the PCB that has diodes installed on them. I know that regular silicon give off toxic gases that may corrode the existing PCB and connection terminals. Or maybe you guys could suggest a better approach to sealing the J-Box inside and out to prevent corrosion from the elements. This panel is being installed on a fishing boat which on many occasion will have actually sea water splashing all over the panel.

Any suggestion would be greatly appreciated.



  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Silicon type to use around or on PCBs

    Use natural cure NOT acid cure,, Unfortunately silicone is not 100% waterproof so it is never possible to guarantee corossion wont happen eventually.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,497 admin
    Re: Silicon type to use around or on PCBs

    Believe it or not--The solution maybe to seal the box lid and drill a small hole on the low spot of the box to allow any pooled moisture to be forced out of the bottom of the box. Did it on my home solar GT system boxes/low spots. Also did that on a sea going 5,000 ton research vessel's communications gear.

    One issue with silicon (and silicon grease) is that they out gas silicon which can form "glass" in switch and relay contacts that switch under load (arc will form silicon oxides).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Silicon type to use around or on PCBs

    Dielectric Grease might be the way to go in that situation:
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    Re: Silicon type to use around or on PCBs

    MG Chemicals 422 Silicone conformal coating. I apply it to all circuit boards that go into my remote controlled electric model boat. It has been under water few times and everything survived. It's better than encapsulating because it can be removed with Acetone.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Silicon type to use around or on PCBs

    Dow 738 1 part.
    A noncorrosive cure mechanism
    that produces no exothermic
    heat or corrosive by-products; can
    be used in corrosion-sensitive
    electrical and electronic
    equipment (on copper and other
    sensitive metals) with no adverse
    effect; can be used in work areas
    where sealant curing odors would
    be objectionable
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