Ciruit Board Protection

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I have an all-in-one AC/furnace sitting outside. The circuit board was replaced a very short time ago, about two months ago. It is already showing signs of degradation (rust on a diode lead). Is there any spray coating I can put on this to prevent further degradation, assuming it is still in operating condition?
This is a link to the type of unit I have http://www.americanstandardair.com/Products/Pages/productsCategory.aspx?cat=Packaged+Systems
Mike D.
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Michael Dobony wrote:

What will probably do the job is something called "conformal coating".
Here's one example:
http://www.mgchemicals.com/products/422a.html
=============Silicone Conformal Coating
Ideal for high temperature environments. Silicone Conformal Coating (422A) is a flexible finish product that provides a protective coating for printed circuit boards against moisture, corrosion, and thermal shock. It protects and insulates electrical and electronic components and assemblies, including generators, motors, transformers, relays, and solenoid coils. For spraying, liquid can be thinned using M.G. Thinner Cleaner. Thin up to one half part thinner to one part coating. Also available in a micro tip pen format. ============= I'd remove the board, clean it by pouring some drug-store alcohol over it while scrubbing it with a soft brush, let it dry completely and then apply the coating.
If the board is relatively clean, then maybe just turn off power the the AC unit and spray the board with the coating without taking it out.
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http://tangentsoft.net/elec/movies/tt05.html
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Oil floats on water, not the other way around. It evaporates quickly, so it's not a good lube.
That being said, sometimes after I wash electronics with water, Then spray with wd40, and continue drying with heat.
Aside from usual conformal coatings, when clean and dry, might spray with Krylon crystal clear varnish coating. Then bake.
Greg
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It's more like automotive enamel. Don't use lacquer, a poor barrier against moisture.
Greg
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What electronics do you wash with water?
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On 11/16/2011 9:01 PM, Ron wrote:

I've washed hundreds of circuit boards with a water based solution and rinsed with plain old hard well water. Usually but not always I use compressed air to blow the water off the board. Just so it's dry before being powered up it's fine. I even ran some through the dishwasher once just to prove my point. I did use baking soda instead of dishwasher detergent. All of them survived.
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Ron wrote:

Much of the electronics in the world has been washed in water as part of the assembly process. There are components that can't stand it, so you gotta be careful. I wash circuit boards in Simple Green cleaner, then alcohol then water then do it again. Blow off the water with compressed air between washes, then repeat again. Some gunk is soluble in simple green, some in alcohol, you need both. Scrub with a toothbrush at every stage. Doesn't do much good to dissolve the stuff then let the solvent evaporate. Blowing off is critical to the process. Get all the liquid out from under parts. Space under a surface mount IC can be tiny. Dry it then dry it again then dry it some more. Works wonders on removing residue from leaky electrolytic capacitors.
Some people use the dishwasher. I don't because It's harder to mask components that can't be washed. General rules of thumb include: 1)don't get solvent into anything that changes properties under the influence. 2)don't get solvent into electromechanical stuff. 3)don't get solvent into anything that it can't easily get out of. It's really easy to let contaminated solvent seep into a switch, but it's very difficult to get it ALL out. Evaporation is not an option, cause the process deposits more gunk and leaves it behind.
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On 11/16/2011 6:42 PM, mike wrote:

commercial board washer. I think the temp is around 140 degrees F. Looks like a very expensive dish washer. All water is recirculated through tanks to clean and deionize the water. We have a regular Sears dish washer for backup and that water goes down the drain.
After the washer tries to dry the boards, the excess water is blown off using deionized compressed air, being extra careful to clear all water from under components. After that, they are air dried for a while.
All components that can't be washed are hand added after washing. Flux from that operation is cleaned with IPA, isopropal alcohol. Sometimes a manufacturer fails to state on their component spec sheet that the unit can't be washed and then there is trouble, but most do tell you.
Paul
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Had some problems with some German caps that were not totally sealed. From the board manufacturer had leakage that didn't work with the circuit which did not tolerate leakage. Had to replace each by hand. Even had board leakage under components. Switched to another type cap and got better washings, problems went away.
Deionized compressed air. I like that one. I think my solder station had that, and heated with temperature settings. Often used 100 watt bulb to bake boards.
Greg
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On Nov 16, 9:22pm, "Stormin Mormon"

Most circuit boards that dont have switches or variable resistors or variable caps can be cleaned in a dishwasher just fine.I have cleaned many boards in an ultrasonic cleaner using water.
Jimmie
Jimmie
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Most anything that might have salt, coke, orange juice, etc. ASAP. Many electronics boards are washed to remove contaminants, sometimes in the dish washer. Today's boards mostly need water to flush the water based flux.
Greg
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In that case, I need to put my keyboard in the dishwasher <G>
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Honestly, if I dropped a soda on something like that, I would immediately drop an equal or more amount of water over the same area. This would not go over too well doing a gig.
Greg
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Ron wrote the following:

Where I used to work, I was in charge of the computer system, among other things. (not programming or repair, just in charge of the personnel and computer purchase) People used to drink coffee or tea, or even eat while at the computer spilling all sorts of stuff on the keyboards. When this happened, I just replaced the keyboard. I took the old keyboard into the lunch room and flooded it with warm water and hung it to dry. When dry, I tested it and if it worked, returned it to the replaceable keyboard stack.
--

Bill
In Hamptonburgh, NY
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wrote:

it's mostly kerosene,dewaxed.(around 70%) Check the MSDS....carefully.

spray your circuit boards or electronics with WD-40 and heat,and you'll end up with a gummy PCB/unit that attracts dirt. you want to REMOVE oils,not add them. If you want to remove water,use >90% isopropyl alcohol,then air dry.
At Tektronix,I washed PCBs,blew them off with air,and then dried them in an oven at 140degF. I used to spray-wash entire instruments(oscilloscopes,signal generators,etc),just to get all the dirt,oil and grease off them. Even tobacco film.(yecch) then 3 days minimum in the drying oven. I even used a home auto dishwasher and Calgonite to clean/degrease high-Z voltmeter PCBs.
--
Jim Yanik
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On Wed, 16 Nov 2011 16:45:47 -0600, Michael Dobony

and SHOULD be standard equipment on all circuit boards in things like furnaces , washers, dries, etc. You can easily buy them from electronics supply houses and apply them yourself (spray cans), taking care to protect connectors etc. The only problem is it makes board repair somewhat difficult - but the majority of circuit boards on equipment today is pretty much non-repairable anyway.
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On Wed, 16 Nov 2011 18:51:35 -0500, "Stormin Mormon"

LPS2 - but at best it is also only a temporaty protection - and it holds dirt etc.
Like I said before - silicone conformal coating - applied to a CLEAN board when new.
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Ever try LPS3 ? Waxy coating, but sticky.
Greg

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On Wed, 16 Nov 2011 18:16:59 -0500, Home Guy wrote:

I looked at the info on these coatings. They need to be baked on after application.
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