What Are SMT Moisture-Sensitive Devices (MSD)? How to Manage Them? (Part 4)

3.3 Packaging Material Requirements

3.3.1 Moisture Barrier Bag (MBB)

MBBs must meet the requirements of MIL-PRF-81705 / Type I, with characteristICs including flexibility, mechanical strength, ESD protection, and resistance to moisture ingress.
The water vapor transmission rate (WVTR) of MBBs is tested according to ASTM F 1249. Under an environmental temperature of 40°C, the WVTR requirement for MBBs is:
WVTR ≤ 0.031 g/m² @ 24 hours.

3.3.2 Desiccant Material

Desiccant materials must comply with MIL-D-3464 / Type II, featuring dust-free properties, corrosion resistance, and a specified moisture absorption capacity. The basic unit of usage is per packet.
Each desiccant packet must have a minimum moisture absorption capacity of 2.85g at 20% RH @ 25°C. Commonly used desiccant packets are shown in Table 6:
Table 6. Common Desiccant Packet Parameters

Fresh or reactivated desiccant packets should be stored in the original supplier packaging container, with a humidity indicator card (HIC) placed inside the container (note: the HIC must not come into direct contact with the desiccant).
If the HIC indicates ≤10% RH, the desiccant can be used directly. Otherwise, the desiccant must be reactivated through baking.
Reactivation requires that the desiccant retains at least 80% of its initial absorption capacity (i.e., >2.85g × 80%).

3.3.3 Humidity Indicator Card (HIC)

HICs typically consist of absorbent paper made from fibrous material and a cobalt chloride solution. They must have a minimum weight of 225 g/m² and feature at least three color-changing indicator dots. As shown in Figure 3, referring to JESD-033C, the indicator dots represent 5%, 10%, and 60% relative humidity (RH) respectively.

As illustrated in Figure 3:

• For MSL=2 devices, if the 60% dot is not blue, the device needs to be baked.
• For MSL=2A to 5A devices, if the 10% dot is not blue and the 5% dot turns pink, the device needs to be baked.

For HICs exposed to environments with ≥60% RH, reuse is not allowed.
For HICs exposed to environments with <60% RH, they may be reactivated and reused under the following condition: 90°C for 3 hours.

Notes:

• 3.3.3.1 There are many types of HICs, some of which are custom-made. This standard refers specifically to HICs as exemplified in JESD-033C.
• 3.3.3.2 To ensure consistent management and interpretation of humidity levels on the production line, it is recommended to use JEDEC-compliant HICs featuring three color dots (5%, 10%, 60%) with a blue-to-red color change.
• 3.3.3.3 Due to the special handling requirements of HICs and desiccants, storage personnel must immediately seal the container after each withdrawal of these materials.