When reading the datasheet for the Omron G5Q series relays, there are two options for enclosures: flux protection and sealed.


The price difference is almost a factor of two, with the former being the more expensive. Is there an application where flux protection is required, or where a sealed enclosure would suffice?


1 Answer 1


Relays can have a number of different levels of sealing, from being completely open to the atmosphere, to full hermetic sealing. Which you need depends on your application, but also how you plan to solder it to the board.

The technical guide would seem to be your go-to source. Take a look at page 2 (by the document's page numbering), and see how they define their levels of sealing. I would assume "Flux Protection" maps to "Semi-Sealed", and "Sealed" maps to "Fully Sealed", but you may need to contact Omron if you need more assurance than that.

If I'm right, then the major difference is often that during PCB Assembly you can do automatic washing after reflow with sealed relays. But read through the technical data to be sure that you're making the correct choice for your application. Other factors like environment and conformal coating can play a part.

  • \$\begingroup\$ Aye, good call. A colleague mentioned that one would use semi-sealed (a.k.a. vented) to help with off-gassing during arcs, which I assume refers to better heat dissipation. Fully sealed relays are used around combustible gases or when the circuit experiences a high pollution degree. \$\endgroup\$ Oct 23, 2018 at 12:40
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    \$\begingroup\$ @calcium3000 Your colleague is right that some relays have a wash seal that's meant to be unsealed in some manner after washing. TE has a nice application note on this. I couldn't tell you whether the concept automatically applies to Omron relays or not, though. The physics would seem to still apply, but there could be other considerations. te.com/commerce/DocumentDelivery/… \$\endgroup\$
    – 1N4007
    Oct 23, 2018 at 13:41

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