What could cause contact failure due to oxide film during microload switching?

AaronRollens · August 4, 2023, 4:37pm

Question:

Answer:

The relay may generate an oxide film at the contact point during repeated load switching. However, microload switching cannot break the film by a cleaning effect, which leads to poor contact.

Explanation:

As a guideline to destroy the oxide film, a load of 48 V or more and 100 mA or more has a cleaning effect.

Countermeasure
For microload switching, it is recommended to use a plastic-sealed relay that is not susceptible to the operating environment.
Since gold (Au) is not susceptible to oxidation, select a relay that uses gold alloy contacts suitable for microloads.
For more information, fefer to The SOLUTIONS [General-purpose Relay Edition]: case 09 Contact Failure by Carbons.

Quick tips

Select a relay with a contact structure suitable for microload switching.
Ag alloy < Ag < Au-plated (clad) < Au-plated (clad) twin crossbar structure
Select a relay less susceptible to ambient environments.
Flux resistant < Plastic sealed
Relay models: G6J-2P(F)-Y, G6K-2P(F/G), G6S-2(F/G)

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Relays | Digi-Key Electronics

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natasham6900 · August 9, 2023, 10:52am

Contact failure due to oxide film during microload switching can occur in electrical circuits and connections. This phenomenon is commonly referred to as “oxide film formation” or “oxide layer formation.” Here’s an explanation in English:

In electrical systems, when you have two metal surfaces that come into contact with each other, they form an electrical connection. However, over time, especially in conditions where there is humidity or exposure to oxygen, a thin layer of oxide can develop on the surface of these metal contacts. This layer is commonly known as an “oxide film.”