Tin Plating on Connectors
Tin Plating on Connectors
(OP)
Does anyone know of a study comparing tin plating of connectors such as hylugs to just straight aluminium? In addition would the etching on top of a tin plated connector (removing part of the tin plating) have any long term effects on that lug?






RE: Tin Plating on Connectors
In the simple sense, this typically constitutes modification of the connector, voiding any NRTL-listing [like UL 486B] and promoting decreased corrosion resistance of its aluminum-alloy body.
RE: Tin Plating on Connectors
http://www.gwelec.com/images/ca3-02pdf/p3,8,9.pdf
for:
Bi-metallic crimp type or migweld bimetallic
connector with silver plated
copper top and tin plated aluminum
bottom.
Any associated label, e.g. UL label may be applicable and required as hinted in the above posting.
Additional details pertaining to the original posting would help.
RE: Tin Plating on Connectors
We are considering etching civic addresses, onto the tops of tin plated aluminium lugs found in residental 120/240V transformers (outdoor transformers). The etching would be done on one lug, of the three which go from the transformer to the home.
The concern is after a number of years (10-15-20) will the etching off of part of the tin, cause connectivity problems. Perhaps if etching becomes standard, then tin plating might not be required?
RE: Tin Plating on Connectors
TTFN
RE: Tin Plating on Connectors
RE: Tin Plating on Connectors
Why not ask T&B, Penn-Union and Burndy directly?
RE: Tin Plating on Connectors
Aluminum won't corrode like steel, it forms a self-protecting layer of aluminum oxide (essentially sapphire) over itself almost immediately on exposure to air. As soon as that layer forms, oxidation almost completely stops. The sapphire is highly resistive, makes for bad connections, and is the cause for concern when using aluminum.
My guess is that if you keep your etching away from any contact areas, you should be OK. Etch anything in a contact area, and you're asking for problems.
I strongly agree with busbar and would check with the manufacturers. Be aware that you could potentially void the UL listing of your lugs, that is perhaps your biggest concern.
RE: Tin Plating on Connectors
peebee, your comments about aluminum forming a protective layer are only true if you have both a ~pure Al alloy (as EC grade) that is kept clean and away from any other metal.
Also, sapphire (a 'doped' crystalline alumina) only forms at very high temperatures, the low temperature oxide film is amorphous (glassy structure). You are correct about it causing conductivity problems.
Dodgee, Try using a polyurethane paint for labelling if there is sunlight (UV) exposure.
RE: Tin Plating on Connectors
In addition, dodgee's most likely using copper conductors, and these are most likely Al/Cu rated lugs. The copper will cause the tin to sacrifice anyway. I'm sure they accounted for this in the design of the lugs.
I'm not saying that I recommend removing tin from the lugs, or using uncoated Al lugs. But all in all, engraving an address in the back of the lug away from the contact area should have little or no effect on the life or reliability of the lug. I'd still recommend checking with the vendors and/or UL soley due to the litigious nature of our society.
RE: Tin Plating on Connectors
Damn near every outdoor chain-link fence I've ever seen is made from aluminum. The few steel exceptions are immediately obvious due to the red crusty oxide that forms on them. The reason for the extensive use of Al is the very low corrosion rate in air: 20-year old Al fences look remarkably similar to 1-year old fences. There's nothing particularly exotic about fence aluminum, and they are commonly bonded to steel, copper, concrete, dirt, etc., with no significant change in their rate of corrosion.
RE: Tin Plating on Connectors
I was concerned about corrosion over a 10+ years in what seems to be an exposed environment. I use both Sn-plated-Al & Cu lugs in a much more severe environment (anodizing & plating shop) for cathode & anode bar connections, fill the end of the cable w. EJC before lugging, coat the exterior with EJC, cover w. plastic film & then tape.
Haven't plated Sn onto Al, but Ni plated-Al fails the salt spray test if there is any porosity or scratches in the coating. The white Al hydroxide spreads underneath the plating.
Please check those aluminum chain-link fences with a magnet, maybe they're just better quality galvanized (with possibly a clear chemfilm). This is a good application for suitable aluminum alloys; I think it's uncommon due to cost.
I don't want a debate; just wanted to support earlier concerns re corrosion & why UL might not approve of the etching from the viewpoint of a metallurgist with lots of Al experience.
RE: Tin Plating on Connectors
- You're right, the environment is very exposed to the elements. Dust and water will settle into the etched area.
- The lug is Al with Sn plating (etching done on the top of the lug).
- Lug is about 3 inches in length.
- The lug is connected to a Cu busbar (side on the lug used to connect the lug to the bar)
- 120V phase to ground on the lug.
- fretting will also be an issue.
Thanks again.
RE: Tin Plating on Connectors
Don't fret too much about it
:)
RE: Tin Plating on Connectors
RE: Tin Plating on Connectors
If not, perhaps a tie-wrap and some paper in a laminated covering?
http://machinerunner.com/Laminating/Pouch-Laminators/Pouch-Laminators-49.html
Just a thought although not very high tech. Seems easier than etching onto the connector.
RE: Tin Plating on Connectors
Tags are the current way of doing this. The problem is that, with time, they fall off and disappear. People have even pulled them off from inside the TXs, which are locked. It seems a good way, for the long term, is etching. While tags are okay, they far from great. Etching would be perferred as long as it doesn't overly effect the connection.