Question RE Moisture-Sensitive Components

[meshtron]

Most of my components are simple passives, but I have a few parts that are (according to their packaging) moisture sensitive:

- LEDs
- MCUs
- One other IC chip

I'm fine keeping those dry prior to board assembly, but I'm not clear on how to treat them after that.  I'm assuming the moisture sensitivity has to do primarily with finishes on pads corroding and plastic(s) absorbing moisture that could "pop" during reflow.  If that's true, the same plastics should have the same propensity to absorb moisture post-reflow, but the pads should all be covered.

My product is used outside and will be in a IP67(ish) housing.  Do I need to add a desiccant pack in the housing?  Or a membrane to allow water to escape when heated?  I can't "pot" my board because it has switches and terminals that need to remain accessible and operative.  I also have copper pours that I'm using to dissipate heat so any coating on the board would inhibit that.

I might be pondering an issue that doesn't exist, but thought I'd ask.

[ataradov]

The issue with absorbed moisture is that it start to boil inside the device while soldering. Once soldered, it does not matter.

If you are worried about any moisture-related issues, then simple conformal coating will address most of those. And connectors are usually not a problem, you can temporarily cover them. And in mass production there is a way to apply conformal coating to the parts of the PCB.

[meshtron]

The issue with absorbed moisture is that it start to boil inside the device while soldering. Once soldered, it does not matter.

If you are worried about any moisture-related issues, then simple conformal coating will address most of those. And connectors are usually not a problem, you can temporarily cover them. And in mass production there is a way to apply conformal coating to the parts of the PCB.

Thanks!  That all makes sense.  I will keep an eye out during testing to see if there's any issues I need to address and stop worrying about it for the time being.