ESD vs Moisture Barrier Bag
ESD shielding bags protect against static discharge. Moisture barrier bags (MBB) protect against humidity. Both are used in electronics packaging. Some bags combine both functions. Choose based on the threat: static, humidity, or both.
Detailed Comparison
| Aspect | Esd | Moisture Barrier Bag |
|---|---|---|
| Primary protection | Static discharge (ESD) | Humidity (moisture vapor) |
| Material | Metal layer (Al, Ni) + plastic | Foil layer + plastic |
| Surface resistivity | < 10^5 ohm | N/A |
| MVTR (moisture transmission) | 0.5-2 g/100in²/24h | 0.02-0.5 g/100in²/24h |
| Static shielding | Yes (>30 dB attenuation) | Some (if metalized) |
| Cost | Lower | Higher |
| Best for | Static-sensitive components | Moisture-sensitive (MSL) components |
| Common standards | ANSI/ESD S541, IEC 61340-5-1 | IPC/JEDEC J-STD-033, MIL-PRF-81705 |
Verdict
Choose ESD bag for: PCBs, ICs, semiconductors (dry environment). Choose MBB for: MSL components, overseas shipping, long-term storage. For both threats (most common), use a combo bag (ESD + MBB).
Can one bag do both?
Yes, combo bags (ESD shielding + moisture barrier) are common. They meet ANSI/ESD S541 and IPC/JEDEC J-STD-033. These are sometimes called 'ESD moisture barrier bags' or 'metal-in ESD bags with foil layer'.