Question:
If the side of a relay is coated with silicon that contains siloxane (low molecular-weight siloxane reducer) in the coating agent, will contact failure occur? What about urethane coating?
Answer:
Use a siloxane-free coating agent. Even low molecular-weight siloxane-reduced agents may cause contact failure of relay contacts. Urethane-based coating agents can be used.
Explanation:
If a coating agent, packing resin, etc., enters the relay, contact failure and/or malfunction may occur. Please prevent them from entering the relay. For coating and packing, use a plastic-sealed relay. Use silicon-free coating and packing resin.
| Type | Usability | Features |
|---|---|---|
| Epoxy | Applicable | Excellent Insulation A little Difficulty in coating workability |
| Polyurethane | Applicable | Excellent insulation and coating workability Don’t allow the solvent to adhere to the relay during work |
| Silicon | Not Applicable | Excellent insulation and coating workability Silicon gas may cause relay contact failure. |
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Siloxane
Siloxane is highly permeable and penetrates into the interior of plastic-sealed relays.
Even a siloxane-reduced agent contains siloxane, which only prolongs the time it takes to enter the relay.
After entry, a silicon oxide film is formed on the contact, causing contact failure. Therefore, silicon-based coating cannot be used, even on only the side of the relay. -
Urethane/epoxy
Urethane and epoxy coating agents can be used but they may contain a small amount of siloxane. Please check the ingredients before use.
- Other coatings
Please use siloxane-free (silicon-free) resin molding, potting, and packing on the PCB surface.
For more information, see Safety Precautions for All Relays
Quick tips
When a coating (including mold, potting, and packing) is applied, make sure that the insulation property does not deteriorate and that the material (resin or metal) used for the relay is not affected before selecting.
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Relays | Digi-Key Electronics
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