Corrosion problem with LED lighting

[jimnrose]

We in the DIY forum are struggeling with a serious corrosion on led's components located 4" above the tank water level. Optically we want the light source as close to the water as reasonable but chemically, salt vapor and metal (gold & solder) is a nightmare.
Help needed:
First, identify a good anticorrosive product to remove the corrosion.
Second, identify a good product (marine grade) to coat the metal surfaces from the salt vapors/spray.

I'm hoping someone with chemical insight or mariner experience can recommend an anticorrosive product &/or sealant (2 part epoxy).
Thanks, Jim
P.S.
I think the LED lighting technology has been making great inroads in the lighting industry. I'm new to theis hobby but am very excited with the 72 led matrix I built for my 125 gallon tank. The corrosive problem will be solved and would have been avoided if I realized the environmental issues. Then we would ned to only indentify the protective sealant.:wave:

[Percula9]

I would cover the top of the tank with a glass top if possible. You can try to encase the lighting fixture in a acrylic housing. Acrylic is cheap and fairly easy to cut and glue together. I think weld-on 4 from home depot is what is needed to glue the parts together. You should have posted your thread in the lighting filtration and equipment forum.

[menthol]

Acrylic shield or at least protect the metal ring with LED optics.

[FishTruck]

I dont know about removing the corrosion.

What about "liquid electric tape" or "plasti dip" (that you can get in the hardware store) to protect the exposed metal? Just paint it right on.

With my DIY LED project, I painted all the exposed metal with this stuff, then used an acrylic sheild to cover the lights.

[JNicho]

Maybe a bit low tech, but I think the liquid tape or even super glue over the exposed connections might work...but then again, I'm just starting my LED build, so what do I know, LOL!

[okieman98]

there are 2 ways i can think of , i repair boat hulls and do bottom jobs on houseboats, first is what we have been doing to bass boats is also what the us navy is using and testing it. is spray in bed liner it seals and protects form salt. and it can be bought at most wally worlds and can get it in courts. the second is what is use on boat hulls,
Eco-Friendly Boat Bottom Paint
Easy-To-Apply Environmentally Friendly Antifouling Paints: Copper-Free, and Solvent-Free Boat Bottom Paints

also we also use the liquid tape on contacts inside of boat. but not to exposed, for that we use the heat shrink then coat it for a double tight seal.

just some thought

[mick243]

or, wherever you are buying your electronic parts from, ask them what waterproof PCB coatings they have available - should have a clear one in a spraycan....... just coat the whole thing.

[jimnrose]

Thanks everyone. I was avoiding an acrylic cover for two reasons. First, I was told that the water needs to be exposed to the air to absorb the oxygen.
Second, there would be a high maintainance problem keeping the acrylic cover clean for the light transmission.

Sorry for bringing this to the Chemestry forum but I was looking for guideance on anticorrosion products.
Jim

[Randy Holmes-Farley]

Do you have a link to a picture of what the device looks like, and a description of the exact metals involved?

Gold won't corrode, but exactly how to prevent metal from corroding depends a bit on what the metals are. Specific corrosion inhibitors, for example, are designed to interact with specific metals on the surface of the metal. More often than not, they will be designed for iron, which may not help a solder.

Are you sure it is actual corrosion and not just salt deposits?

[dipan]

One other thing to consider is to clean off the flux residue after you're solder. There is a specific cleaner for this at the electronics stores. Flux residue cleaner. Flux is itself an oxidizer, so you should probably remove it. I do plan on it for my build (any day now).

The spray coating that Mick refers to is a "conformal coating" ... look it up. There are many different kinds, but keep in mind that applying something like this will make repairs difficult. Besides you won't want to coat the emitters themselves.

May be best to use an acrylic shield in the end :)

[jimnrose]

dipan, I'm still not sure if an acrylic cover outweights the optical issue.

Randy, there is salt deposits but when I remove (mechanically) the salt the metal surface is corroded. there are four metal tabs for soldering the wires. Only two were needed therefore the two that were not used (no solder) also have the salt and uner the salt the metal was corroded. Also the solder strips (pads) connecting the led to the substrate (ceramic) has a green film.

Two leds failed (shorted internally). the site is: www.ledsupply.com/creexre.php

Thanks Randy and everyone for your time and feedback, Jim

[Chris27]

Please post pictures of the assembly - I can't provide much of a suggestion without seeing what you're having trouble with. Electronics and SW just don't mix, but there are some things you can do....FWIW, I spend a good deal of my time at work trying to keep electronics dry 100's of feet in the ocean.

[jimnrose]

Chris, I'll get the photos; that's the easy part. Never tried to upload thru photobucket but that was one of my 'new year's resoluations' . I'll get there.

Went out shopping but came back with most of the money I left with. I did getacrylic sheets to fab a cover. Thied to find wire brushes that were very small and in line with the brush handle; like small paint brushes but with brass wire. NO luck. I'm an OLD electronic guy and in the 50's we had these when cleaning solder pads on circuit boards, but that was in the 'pold days' when electronics entailed the talent & art of designing circuits with discrete components. Gone are the days..... I went to Radio Shack and back in the
corner were some components and soldering irons. Slim pickings and lots of dust.
Jim

[dipan]

A little bigger than a paintbrush, but a good abrasive in a pen config is this fiberglass spot sanding pen from 3M ... I've picked one up at Walmart automotive paint section next to the touch up pens. Probably at local autozone, pepboys, oreilly's, NAPA, etc. also

http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTt4xfELxTcEV76EbHSHVs6EVs6E666666--

[jimnrose]

dipan, thanks, I'll get one. Jim

[mick243]

oh, and to get the corrosion off, look for a product called "DE-OXit D5" (also a spraycan).

[dipan]

oh, and to get the corrosion off, look for a product called "DE-OXit D5" (also a spraycan).

Agreed ... I love that stuff.

[jimnrose]

mick243, the DEoxIT product from Craig Labs looks like what I need. It's sold in liquid bottle (with brush) #D100L-25C but I'm trying to locate a retailer. The sprays are popular but not what I need. Thanks, Jim

[Chris27]

I hear that brother - radio shack used to be a place where you could get some last min. parts in an emergency, now it's a place to buy cell phones.

Last time I was in there, the schmuck behind the desk asked me what I needed, so I gave him some 74X chip #'s and he pointed me towards a memory card for my camera...


Chris, I'll get the photos; that's the easy part. Never tried to upload thru photobucket but that was one of my 'new year's resoluations' . I'll get there.

Went out shopping but came back with most of the money I left with. I did getacrylic sheets to fab a cover. Thied to find wire brushes that were very small and in line with the brush handle; like small paint brushes but with brass wire. NO luck. I'm an OLD electronic guy and in the 50's we had these when cleaning solder pads on circuit boards, but that was in the 'pold days' when electronics entailed the talent & art of designing circuits with discrete components. Gone are the days..... I went to Radio Shack and back in the
corner were some components and soldering irons. Slim pickings and lots of dust.
Jim

[redfishsc]

Over your solder connections, clear fingernail polish will work fine.



Over the whole heatsink (cover your LED's) you can spray a couple coats of gloss DEFT lacquer from Lowe's (aerosol can). You can do this before mounting the LED's but tape off the spots where you'll put the LED's b/c the lacquer might interfere with the thermal transfer of the epoxy or thermal pads you use.


Lacquer isn't bulletproof but will work fine since you won't be tossing the heatsink around and scuffing it up.

[jimnrose]

redfishsc, thanks for the info but I can't coat (seal) the corrosive area until I get rid of the corrosion. I plan to scrape off (mechanicallly) as much of the corrosion and salt crystals as I can see but am still looking for a anticorrosive cleaner. Then I'll seal the areas. Jim

BTW, I originaly was following the suggestion NOT to cover the tank with a acrylic panel, but I now realize that a cover is required. I should have one on the tank by Monday evening. I'm curious as to what change there will be in the evaporation rate. Jim

[dipan]

Why not just put a glass or acrylic shield on the light?

[jimnrose]

dipan, it's much easier to put the cover on the tank (in sections for easy removal). Also there are risks of fish jumping out of the tannk thereby requiring either an acrylic or screen cover. I'm interested in monitoring the evaporation rate with the tank being covered.

The light fixture (the way I built it) would require a very complex cover. The fixture is 72" long (on a hinge) but in addition to the leds being mounted to the heat sink, I added aluminum fins that entend 1.5" down toward the tank. These fins not only improve the heat transfer but also act as a liight shield from the observers.

Bottom line: covering the tannk is much easier.

Take care, Jim