Moisture-Sensitive Devices: Ignore Them, and Your PCBA Dies in the Reflow Oven

If you work in PCBA, you know the worst feeling: the boards are done. X-ray passed. AOI passed. Then you power it up — and nothing.

It's not a design issue. It's not a soldering profile issue. It's a component that "popped" inside the reflow oven.

Why Do Moisture-Sensitive Devices "Pop"?

Moisture-sensitive devices — BGA, QFN — have packaging materials that absorb moisture from the air. Leave them out on the line after opening, and over time, water vapor seeps in.

Then comes reflow. The oven hits around 260°C. At that temperature, water turns to steam and expands over 1,000 times its volume. If that steam can't escape, it builds pressure inside the component — like a popcorn kernel — cracking the package and breaking internal connections.

You can't see it from the outside. X-ray might catch some, but if the crack is internal, even X-ray can miss it. The board fails test. You remove the component and find it's already cracked inside.

How to Prevent Moisture Damage

Check the MSL rating. BGAs are typically MSL 3, meaning they must be soldered within 7 days of opening.

Bake if you exceed floor life. 125°C for 8–12 hours. After baking, the clock resets. Don't gamble.

Keep workshop humidity at 30–60% RH. Unused components must be re-vacuum-sealed. Don't leave them sitting on the line overnight.

Moisture-sensitive devices aren't something you can just "be careful" about. You need a process, records, and someone paying attention.

Get it right, and your boards are fine. Get it wrong, and you'll only find out after reflow — when it's already too late.

If you're not sure whether your BOM has moisture-sensitive devices or expiry risks, send it over. We'll check it for you. No charge. Feedback within 24 hours.