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Conductive Sealant/Adhesive for aluminium

Conductive Sealant/Adhesive for aluminium

(OP)
Hello All,

We have enclosure with electronics inside. The outside of the enclosure is painted with ppg mil grade paint. The top side of the enclosure is open and can be closed with a lid. The contact surface between the lid and the enclosure is alodined aluminium for conductivity. all this has been working fine. But now we want to water proof the box. We found some conductive sealants mostly silicon based and conductive adhesive that are epoxy based. The inside needs to be accessed during repairs. This crosses epoxy out of our list. By the way the lid is held in place with 4 socket head screws.

Which leaves us with silicon based conductive adhesives. The problem I face with them are that once the silicon cures it will still be very hard to pull the lid out (as there is not much leverage). I can soak the thin profile of the silicon paste that is visible with iso-propyl alcohol for a while and make it soft. But does any one know of any conductive paste that even after curing it remains jelly like semi-solid? and also easy to remove? Also considering die cut gaskets with adhesive on one side, but may be tedious to install due to the narrow width of contact face (2mm) and size of the gasket (85mm by 75mm with 3mm bends). Looking at the thickness to be around 0.2mm to 0.5mm. Yes they have metal reinforced in them, so i hope that they are stiff to some extent and thus avoiding any wrinkles and stretching which may not allow it to function properly (also making the installation process a little bit easier). Also getting just 100 gaskets made will be very expensive that is if I find someone to make this quantity!

I am open for any suggestions for which my might be cheaper or even if there are any other products that I could consider. Appreciate your help in advance!!

Thanks,

Varoon

RE: Conductive Sealant/Adhesive for aluminium

I would favor some metal (nickle graphite) filled silicone gaskets instead of messy adhesives. The cost per gasket will be offset by the reduced labor time during repairs or maintenance. Consider a 2-part design, L-shaped, to reduce cost/waste. One company I have had good results from in the USA is Stockwell.

http://www.stockwell.com/esd-emi-data-sheets.php

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RE: Conductive Sealant/Adhesive for aluminium

Why not just use a bonding wire to ground the lid to the enclosure?
Simply adding something like a pem stud to the lid so you can attach the bonding wire and then attach it somewhere in the enclosure.

No fancy conductive goop at all..

RE: Conductive Sealant/Adhesive for aluminium

Put a piece of Teflon tape on the mating surface until the silicone cures. Then remove the silicone tape and you'll have contact with no sticking.

RE: Conductive Sealant/Adhesive for aluminium

Conductive alodine does not have very good corrosion resistance on its own. Depending on the level of electrical bonding you require at the housing interface, you might want to use something like electroless nickel plate on the faying surfaces.

A less expensive option would be to machine a chamfer on the outer edge of both flanges and use conductive alodine on the faying surfaces. After bolting the cover to the housing and verifying the continuity between them, you would apply a bead of RTV silicone into the groove around the flanges. This is a technique that provides a moisture tight seal at the extreme edge of the electrical bond interface. It is also easy to remove and replace without damaging the electrical bond faying surfaces.

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