Electric Relays - Principles and Applications - Gurevich (CRC, 2006).pdf

Electrical Contacts - Fundamentals, Applications and Technology - Braunovic, et al (CRC, 2006).pdf

Electrical Contacts - Principles and Applications, 2nd ed - Slade (CRC, 2013).pdf

Engineering Reference - Relays (Fujitsu, 2009).pdf

Modern Relay, The (SDS Relais) - Eichmeier (Verlag Moderne Industrie, 1988) [2up scan].pdf

https://standards.nasa.gov/sites/default/files/standards/NAS... - WORKMANSHIP STANDARD FOR CRIMPING,INTERCONNECTING CABLES, HARNESSES, AND WIRING

hard to know how to help without more detail regarding specific application

the Omron document and some of it's links have lots of pragmatic actual in service information for contacts, some hard to find otherwise, eg section "Load Conditions and Contacts" and flashover voltages

if you are specifying/making wiring harnesses then metallurgical considerations are only a small part of overall reliability, see NASA document as just one example of a lot of such info from them

One of the big points very often missed is that, depending on contact material, relays can have a minimum current rating, which can get you in trouble when using a contact to switch a PLC input for example. This to ensure the tarnish gets wiped.

You can get around this by using gold flashing, but this is also extremely easy to burn off with unexpected over-current, eg capacitive or inductive switching, which can result from just a cable run.

There are also recommendations for things like contacts that are open but wetted with DC for long periods of time, like some protection circuits, eg contact material and which face should be more negative/positive.

The optimum DC control voltage is 48VDC, but it is not the most practical due to availability.

Look around at metal specific industry groups that often publish highly specific useful material, eg Copper Development Association and same for Silver, MIL specs.

I have found you pick up bits and pieces over the years and you just have to build up your personal library over time.

Final one, not metallurgy but depending on your industry might save you one day, dangers of AC control voltages with distance.

https://www.newark.com/wcsstore/ExtendedSitesCatalogAssetSto...

I got a bunch more, if you have a specific problem then DM me.

Thanks, I will re-format any future questions I have.

buescher I should pick up a materials science textbook and maybe some inorganic chemistry books too. I've found that the FAEs for our suppliers are pretty slow and we'd have to shut our factories down due to lack of parts if we waited for them, although I do still interact with them. Obviously, that's supplier specific.

a_finkelstein you are my hero!!!

I'm working on a high stakes project right now (which is part of what prompted this thread), so in my scramble I found this white paper: https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandm...

And I bought the journal articles it references to get a good enough understanding to design an experiment around the specific application. There's apparently a whole conference for this stuff: https://ieee-holm.org/

Can't say I'll ever go, but good to know where the repository of truth resides.

Thanks, Patrick Taliaferro

If you're thinking about this stuff, you'd probably find a good undergraduate materials science textbook fascinating.

NASA has a good page regarding whiskers. https://nepp.nasa.gov/whisker/

What also matters is electrochemical migration. I don't have a reference handy.