How to Make a Dry Package for Your Electronic Printed Circuit Boards
This blog assumes you already know WHY you need a dry package for your circuit board. If you don’t know why, just know that moisture + PBC = bad things.
Okay, so you need to make a dry package for your PCB to protect it from moisture and static. And for that you need five things (simplified definitions below):
- Moisture Barrier Bag (MBB)
- Humidity Indicator Card (HIC)
- Moisture Sensitive Label (MSL)
- Vacuum Sealer
You’ve seen Moisture Barrier Bags (MBBs) before, surely. They’re basically fancy baggies, made of layers of film which shield from moisture and static. Need help selecting a bag? Try this chart.
You’ve also seen desiccants before, in shoe boxes most likely. They’re little packets of tiny balls that often say “Do Not Eat” on them. There is bound to be some unseen moisture enclosed in the bag once you package it up, and the desiccant will absorb it. When not in use, they should be stored in airtight containers for obvious reasons.
Humidity Indicator Cards (HICs) are kind of like mood rings for electronics, and they go inside. They’ll change color depending on the humidity so the end-user can decide if the component needs to be baked or not.
Moisture Sensitive Labels (MSLs) are the alarm clocks, and they go on the outside. They tell the user how long the part can stay outside the bag before being soldered onto the board.
Vacuum sealers are machines you mostly see in kitchens, preserving food for crazy amounts of time. You’ll want to get one suitable for electronics.
Okay, you’ve got your supplies. Now what? Let’s make a Dry Package!
- Calculate how much desiccant you need with this calculator.
- Place the appropriate amount of desiccant and an HIC onto the device-carrying apparatus (most likely a tray).
- Place the MSL label on the MBB and mark the proper level on the bag. (Have a blank level box? Try looking on the barcode label…)
- Put the device, desiccant, and HIC inside the MBB.
- Vacuum seal some of the air out of the bag (but not all!) and heat seal it.
Voila! Nice job!