# Relay contact alloy?



## Chumbawamba (Oct 21, 2010)

I tore apart this relay and found it to have interesting contacts, so I looked it up and found the datasheet:

http://relays.tycoelectronics.com/datasheets/OSA.pdf

This is a model OSA-SS-212DM3. The "Contact Data" section says the contacts are a "Ag-GS alloy".

What the heck is GS?


----------



## rusty (Oct 21, 2010)

Chumbawamba said:


> "Ag-GS alloy"



An innovative composition made of 10 percent gold and 90 percent silver

From another manufacture we have,

Miyazawa employs a gold-silver (GS) alloy and contains 10.5% gold and 89.5% silver and other semi-precious metals.


----------



## Anonymous (Oct 21, 2010)

Hopefully your relays are the DM3 type with the gold in them.

Jim


----------



## rusty (Oct 21, 2010)

james122964 said:


> Hopefully your relays are the DM3 type with the gold in them.
> 
> Jim



DM3 are phosphor bronze - gold plated.

If it were me I would rather have the Ag-GS which has gold 10% gold.


----------



## Anonymous (Oct 22, 2010)

I must have missed something, I read the DM3 as Ag-GS and the DM5 as silver tin oxide.

Jim


----------



## Chumbawamba (Oct 22, 2010)

james122964 said:


> I must have missed something, I read the DM3 as Ag-GS and the DM5 as silver tin oxide.



Now that you mention it, I'm as confused as you are.

The relays I have are the DM3 series. According to the data sheet, that makes the contacts "Ag-GS". I'll buy that the "GS" means gold and silver. I'll even buy that the alloy is Ag10/Au90. I would prefer a source citation as I, myself, have not been able to come up with anything on my own.

But why "Ag-GS"? If it's already Ag, then why GS?


----------



## butcher (Oct 23, 2010)

this may help?
http://www.datasheet4u.com/html/G/S/-/GS-SH-205T_GS.pdf.html
I believe Dm 3 is a measurement, but still not positive what GS stands for have seen it as gross substitute?


----------



## g_axelsson (Oct 23, 2010)

My guess is that GS = "Gold on Silver"

From the above reference...


> Main Feature
> 1. 92/8 gold silver alloy on silver palladium contact type is suitable for low level switching application.



Sounds like gold alloy (Au/Ag 92/8) plated on a silver/palladium core.
For low level switching gold is used to protect against oxidation of the contact surfaces. At higher currents the spark created when switching off is burning off residues on the surface and cleans it.
There is no reason to have massive contacts in gold for small signals.

To test it, take one contact point that looks golden, scratch the surface or edge and put it in nitric acid. If the core is made of silver then you should get a hollow golden foil.

I have collected some golden contact points but I haven't processed them yet but I always assumed they were gold plate on silver.

Reality sucks! :mrgreen: 

/Göran


----------



## Chumbawamba (Oct 23, 2010)

g_axelsson said:


> To test it, take one contact point that looks golden, scratch the surface or edge and put it in nitric acid. If the core is made of silver then you should get a hollow golden foil.



Göran, thanks for the good analysis. I think that pretty much explains it.

The contacts I extracted from the relay are far too small to do any sort of reasonable analysis upon them. Each is about the size of a gun powder grain (can't think of anything better to compare to). I would need a hundred to even begin to do anything with them.

That being said, I'm actively collecting them up


----------



## solar_plasma (Feb 9, 2014)

I have found an interesting chart about contact point alloys and would like to share this. Only look at page 9 of 10 or page 8 of 9, on the right.

http://www.e-t-a.de/fileadmin/user_..._allgemein/0_pdf_deutsch/TechInfo_d_11-12.pdf

*It shows the common alloys in relation to the voltage and current.* In the range of micro- and milliampere real pm's (Au, Pd, Pt, Rh) are used. In the middle up to 5V pure Ag or Ag/Pd and above this typically combinations with Ag.


----------

