Protective film for electrical connections

[john61ct]

Usually cheaper to just swap out the board than make repairs, so not worried about removing.

Just want the best protection, and would prefer brush application.

Also looking at full epoxy potting to protect against reverse-engineering.

[Scatterling]

Originally Posted by john61ct

Usually cheaper to just swap out the board than make repairs, so not worried about removing.

Just want the best protection, and would prefer brush application.

Also looking at full epoxy potting to protect against reverse-engineering.

My question was more about protecting electrical cable connections rather than PC boards.

[Reefmagnet]

Originally Posted by john61ct

Usually cheaper to just swap out the board than make repairs, so not worried about removing.

Just want the best protection, and would prefer brush application.

Also looking at full epoxy potting to protect against reverse-engineering.

Coating PCB's with polyurethane of the solid colour variety works well to hide the details and is a good solution if relays, trimpots or connectors etc are present.

[GeneM]

I use CRC on connections I might want to maintain and liquid tape on more permanent coupling. You can get liquid tape at Walmart or West Marine for twice the price.

I also use CRC to cover electrical components like relays.

[CarinaPDX]

Originally Posted by john61ct

So what do you suggest for those wanting to protect their custom PCBs in marine conditions?

I don't. I have never had a problem, although once it was close. I used a Denon cassette car stereo for two decades, and the external steel had a few rust spots but everything worked fine. More than a decade while in salt water with a Mac and no problems. Oki laser printer was like new when I gave it to the Goodwill. The one time I had a problem was from a bad pooping which sent seawater in copious quantities down the companionway, and some splashed up and into a connection opening on my Icom M802 (mounted behind the carling between deck beams). It rusted the plated steel mount for the GPS BNC connector, and that bled onto the board. It still worked, but I learned that it did have a very thin conformal coating. I cleaned it with isopropyl alcohol and recoated with LPS3. I haven't been using it lately but it certainly passed the visual test. Bottom line: the best defense is to prevent seawater to get to the PCBs. I do use plastic hobby boxes for small PCBs to keep the water out, and I try very hard to keep things away from water - location matters.

Greg

[Stu Jackson]

Originally Posted by john61ct

There are two completely different product groupings here.

Dielectric - electrically **insulating**

as opposed to **assisting** electrical conductivity.

Be very careful to choose the right category for your application.

Really would be best IMO not to discuss both categories in the same thread.

Thank you, john, for noting this.

And in ALL of the discussions about this recurring topic, I rarely read of anyone mentioning how they use the products they tout.

Does one make the connection "bare" and spray the material on top of the "made" connection?

Do you slather first or after?

Serious question.

[Reefmagnet]

Originally Posted by Stu Jackson

Thank you, john, for noting this.

And in ALL of the discussions about this recurring topic, I rarely read of anyone mentioning how they use the products they tout.

Does one make the connection "bare" and spray the material on top of the "made" connection?

Do you slather first or after?

Serious question.

It probably doesn't matter in most instances. I prefer afterwards because it saves messy fingers but sometimes dipping a wire in goop before crimping or clamping works better.

[john61ct]

The conductivity **promoting** anti-corrosion stuff obviously goes in before crimping

no one's soldering here right? 8-D

or bolting, whatever.

The dielectric stuff goes on after, but as noted can go inside the heatshrink.

I know people say dielectric goop is OK to put in first, it gets squozen out of the joint, but yeesh, not for me.

I have a homemade terminal design I'm working on, where the two flat contact surfaces require a conductive paste between, then while under pressure, the edges get sealed with conductive **epoxy**, and then once that's cured, the whole assembly gets potted with thermally conductive but electrically insulating potting compound.

Fun stuff

[john61ct]

Originally Posted by Reefmagnet

Coating PCB's with polyurethane of the solid colour variety works well to hide the details and is a good solution if relays, trimpots or connectors etc are present.

MG's 4229 Connector Coating (black) looks superior to Liquid Tape.

4228 is a bright red, interesting.

But all the urethane ones specifically intended for PCBs seem to be non-opaque, nor do I see mention of pigments.

[Reefmagnet]

Originally Posted by john61ct

MG's 4229 Connector Coating (black) looks superior to Liquid Tape.

4228 is a bright red, interesting.

But all the urethane ones specifically intended for PCBs seem to be non-opaque, nor do I see mention of pigments.

Electric motor winding polyurethane is opaque. Available in spray cans.

[redsky49]

Originally Posted by Scatterling

My question was more about protecting electrical cable connections rather than PC boards.

I carry a couple items, based on need/application. Boeshield T-9, and its lesser performing brother Corrosion-X, for light duty protection of electrical terminals/connections in protected areas.


For larger, heavier-duty applications I use a conducting grease (not dielectric!) such as the copper powder type as sold by Burndy, Penetrox E. I was just looking at some cables/terminals I made up in 2005 for my boat, and they appear just as they were at initial application - no corrosion. And my boat has been in tropical salt water environments most of that time.



At my level of competence with electronics, I figure I might do more harm than good, but with basic electricity these three items work for me. I also have lanolin aboard, but have restricted its use lately to rigging screws and similar uses. Same for silicone grease. Great for O-rings, plumbing, etc., but not electrical.

[Alita49DS]

For joining wires and other near permanent connections, any views on self amalgamating tape?

I have used it for years and it seems to be very robust.

[svMarite]

Ok gurus, I'm confused and quite the neophyte. I was told and understood dielectric grease was to be used on the inside of a crimp and heat shrink...now you're saying not to.
Of late, I just stick the wire in lanolin and crimp it. Heat shrink.
So from what I've been following, I can continue the lanolin but use deoxit, T9 or LSP over top?

[Reefmagnet]

Originally Posted by Alita49DS

For joining wires and other near permanent connections, any views on self amalgamating tape?

I have used it for years and it seems to be very robust.

I use it for external wiring and really moisture exposed stuff like bilge pump connections, but it's overkill and a PITA to remove to make it a first choice for wiring with reasonable protection from the elements.

[Reefmagnet]

Originally Posted by svMarite

Ok gurus, I'm confused and quite the neophyte. I was told and understood dielectric grease was to be used on the inside of a crimp and heat shrink...now you're saying not to.
Of late, I just stick the wire in lanolin and crimp it. Heat shrink.
So from what I've been following, I can continue the lanolin but use deoxit, T9 or LSP over top?

The dielectric value is a measure of the point in which the grease will breakdown and start conducting electricity (arcing, usually). If grease starts conducting electricity, it probably won't end well for the circuit it's slathered on to in general. When a wire with grease applied is clamped or crimped, the grease will be pushed out of the way by the pressure and contact between the conductors will be made unhindered. It would take a really, really bad connection before the protective grease prevented conductivity although it can happen if you get too slap happy with the stuff around switch and relay contacts.



If you're heat shrinking anyway, best to use the dual wall stuff which negates the need for grease because it includes a hot glue style sealant. I still wouldn't use grease under regular heat shrink all the same.