What Are SMT Moisture-Sensitive Devices (MSD)? How to Manage Them? (Part 3)

3 Packaging Requirements for MSD

3.1 Dry Packaging Requirements

MSD dry packaging consists of a moisture barrier bag (MBB), desICcant packet, humidity indicator card (HIC), and a moisture-sensitive label on the exterior of the packaging bag.

Dry packaging for different MSL devices is strictly categorized. For details, refer to Table 4:
Table 4. MSD Dry Packaging Requirements

The required quantity of desiccant packets in an MBB can be calculated using the SIMplified formula:
Where:

• U = Desiccant packet usage
• M = Expected storage life (months)
• WVTR = MBB water vapor transmission rate (g/m²@24hrs)
• A = Exposed suRFace area of the MBB (m²)
• D = Desiccant water absorption capacity at 10% RH@25°C (if unknown, use a conservative value of D=1.4)

Notes:

• 3.1.1 According to JEDEC standards, the color-dot side of the humidity indicator card (HIC) must not be placed in direct contact with the desiccant (desiccant affects HIC accuracy).
• 3.1.2 MBBs must be vacuum-sealed. To prevent damage during handling and transportation, MBBs should be sealed using a heated sealing method. The internal packaging must not be fully vacuumed (a residual air volume is required, typically: tray packaging/80±5% vacuum level, tape-and-reel packaging/45±5% vacuum level).
• 3.1.3 For non-moisture-sensitive devices with sealing requirements (e.g., oxidation risk in humid environments), it is recommended to treat them as MSL=2.

3.2 Pre-Packaging Baking Requirements

MSD dry packaging must undergo pre-baking. Specific baking conditions are outlined in Table 5:
Table 5. Pre-Packaging Baking Requirements for MSD Dry Packaging

Notes:

• 3.2.1 The above MSD exposure environment conditions must be <60% RH, and the cumulative unpacking time by suppliers/distributors during transit must be ≤24 hours.
• 3.2.2 If the supplier’s pre-packaging process involves molding-cure or burn-in, baking time can be reduced or omitted.
• 3.2.3 Stacked packaging or embedded heat sink packaging may negatively impact moisture diffusion after baking. Consider increasing the pre-packaging baking time appropriately.
• 3.2.4 For MSDs with a package thickness >4.5mm, refer to the appendix of J-STD-033 for pre-packaging baking conditions.