1. For PCB board technology, MSD (Moisture Sensitive Device) storage considerations are crucial.
2. Typically, after the material is removed from the placement machine, it should be stored in a dry environment, such as a dry box, or repackaged with a desiccant until it is used again.
3. Many assemblers believe that once the device is stored in a dry environment, they can stop counting the exposure time.
4. However, this is only true if the device was dry to begin with.
5. In reality, if a device has been exposed for an extended period (more than an hour), the absorbed moisture remains within the device’s packaging and gradually penetrates into the device itself, potentially causing damage.
1. The findings clearly show that the duration a device remains in a dry environment is as crucial as its exposure time in a humid environment.
2. Recently, a PLCC device with a humidity level of 5 (normal unpacking life of 48 hours) showed that after 70 hours of dry storage, only 16 hours of exposure would exceed its lethal humidity level.
3. Studies indicate that the Floor Life of an SMD device, once removed from the MBB, has a specific functional relationship with external environmental conditions.
4. Conservatively speaking, it is safer to adhere strictly to Table 1.
5. However, since external conditions often fluctuate, actual environmental conditions might not always meet Table 1’s requirements.
6. Table 2 outlines the changes in Floor Life as external or storage environments vary.
7. If an MSD device has not been exposed to moisture and the exposure time after unpacking is brief (within 30 minutes), with humidity not exceeding 30°C/60%, the device can be stored in a dry box or moisture-proof bag.
8. When stored in a dry bag, the original desiccant can continue to be used, provided the exposure time does not exceed 30 minutes.
9. For MSDs of Levels 2 to 4, as long as the exposure time does not exceed 12 hours, the holding time for residual treatment is five times the exposure time.
10. The drying medium can be sufficient desiccant, or a drying cabinet can be used, with the internal humidity of the cabinet maintained below 10% RH.
11. Additionally, for Levels 2, 2a, or 3, if the exposure time does not exceed the specified Floor Life, the duration the device is kept in a drying box at ≤10% RH or in a dry bag should not be counted as part of the exposure time.
12. For MSDs of Levels 5 to 5a, if the exposure time does not exceed 8 hours, the holding time for re-drying is ten times the exposure time.
13. Sufficient desiccant or a drying cabinet, with internal humidity kept below 5% RH, can be used for drying.
14. The device’s exposure time can be considered from zero after the drying process.
15. If the humidity in the drying cabinet is maintained below 5% RH, it is equivalent to storage in an intact MBB, and its Shelf Life is not restricted.
16. Many companies opt to repackage unused MSDs.
17. According to standards, the basic packaging materials include MBB, desiccant, HIC, etc.
18. Packaging requirements vary for different MSD grades.
19. Devices of Levels 2a to 5a must be dried (dehumidified) before sealing in MBB.
20. The drying method usually involves baking with a dryer.
21. Since trays containing devices (e.g., Tray trays, Tubes, Reel tapes) affect humidity levels in the MBB, these trays are also dried as compensation.
22. Common drying methods involve constant temperature drying of the device at a specific temperature for a set period.
23. Alternatively, sufficient desiccant can be used for drying and dehumidifying the device.
24. The drying process varies based on the device’s humidity sensitivity level, size, and ambient humidity conditions.
25. After proper drying, MSD’s Shelf Life and Floor Life can be recalculated from scratch.
26. If MSD exposure time exceeds the Floor Life or if temperature/humidity conditions exceed requirements, the IPC/JEDEC standard can be referenced for drying methods.
27. Devices sealed in MBB must be dried before sealing.
28. Level 6 MSDs need re-drying before use and reflow soldering as per the moisture-sensitive warning sign instructions.
29. When baking MSDs, note the following: Devices in high-temperature trays (e.g., high-temperature Tray trays) can be baked at 125°C unless otherwise specified by the manufacturer.
30. Devices in low-temperature trays (e.g., low-temperature Tray trays, tubes, and tapes) should not be baked above 40°C to avoid damage.
31. Remove paper/plastic bags/boxes before baking at 125°C.
32. Pay attention to ESD (Electrostatic Sensitivity) protection during baking, especially as the environment can become very dry and prone to static electricity.
33. Control the baking temperature and time; excessive temperature or time can lead to oxidation or intermetallic compound formation, affecting solderability.
34. During baking, ensure no unidentified gases are released from trays, as this could impact solderability.
35. Always maintain a baking record to monitor the baking time.
36. For MSD repair, if the device on the main board is removed, local heating should be used, keeping the device’s surface temperature below 200°C to minimize humidity damage.
37. If the temperature of some devices exceeds 200°C and surpasses the specified Floor Life, the motherboard should be baked before rework.
38. The baking method is described in the next paragraph; within the Floor Life, the device’s temperature tolerance is equivalent to reflow soldering.
39. When analyzing defects in removed devices, follow the above recommendations to avoid humidity-related damage masking the defect’s root cause.
40. If the device is to be recycled after removal, adhere to the above recommendations.
41. MSDs are not a substitute for drying after multiple reflow solderings or reworks.
42. Some SMD devices and motherboards cannot tolerate prolonged high-temperature baking, such as some FR-4 materials, which cannot endure 24-hour baking at 125°C.
43. Additionally, some batteries and electrolytic capacitors are sensitive to temperature.
44. Considering these factors, choose an appropriate baking method for PCB boards.
2. Typically, after the material is removed from the placement machine, it should be stored in a dry environment, such as a dry box, or repackaged with a desiccant until it is used again.
3. Many assemblers believe that once the device is stored in a dry environment, they can stop counting the exposure time.
4. However, this is only true if the device was dry to begin with.
5. In reality, if a device has been exposed for an extended period (more than an hour), the absorbed moisture remains within the device’s packaging and gradually penetrates into the device itself, potentially causing damage.
1. The findings clearly show that the duration a device remains in a dry environment is as crucial as its exposure time in a humid environment.
2. Recently, a PLCC device with a humidity level of 5 (normal unpacking life of 48 hours) showed that after 70 hours of dry storage, only 16 hours of exposure would exceed its lethal humidity level.
3. Studies indicate that the Floor Life of an SMD device, once removed from the MBB, has a specific functional relationship with external environmental conditions.
4. Conservatively speaking, it is safer to adhere strictly to Table 1.
5. However, since external conditions often fluctuate, actual environmental conditions might not always meet Table 1’s requirements.
6. Table 2 outlines the changes in Floor Life as external or storage environments vary.
7. If an MSD device has not been exposed to moisture and the exposure time after unpacking is brief (within 30 minutes), with humidity not exceeding 30°C/60%, the device can be stored in a dry box or moisture-proof bag.
8. When stored in a dry bag, the original desiccant can continue to be used, provided the exposure time does not exceed 30 minutes.
9. For MSDs of Levels 2 to 4, as long as the exposure time does not exceed 12 hours, the holding time for residual treatment is five times the exposure time.
10. The drying medium can be sufficient desiccant, or a drying cabinet can be used, with the internal humidity of the cabinet maintained below 10% RH.
11. Additionally, for Levels 2, 2a, or 3, if the exposure time does not exceed the specified Floor Life, the duration the device is kept in a drying box at ≤10% RH or in a dry bag should not be counted as part of the exposure time.
12. For MSDs of Levels 5 to 5a, if the exposure time does not exceed 8 hours, the holding time for re-drying is ten times the exposure time.
13. Sufficient desiccant or a drying cabinet, with internal humidity kept below 5% RH, can be used for drying.
14. The device’s exposure time can be considered from zero after the drying process.
15. If the humidity in the drying cabinet is maintained below 5% RH, it is equivalent to storage in an intact MBB, and its Shelf Life is not restricted.
16. Many companies opt to repackage unused MSDs.
17. According to standards, the basic packaging materials include MBB, desiccant, HIC, etc.
18. Packaging requirements vary for different MSD grades.
19. Devices of Levels 2a to 5a must be dried (dehumidified) before sealing in MBB.
20. The drying method usually involves baking with a dryer.
21. Since trays containing devices (e.g., Tray trays, Tubes, Reel tapes) affect humidity levels in the MBB, these trays are also dried as compensation.
22. Common drying methods involve constant temperature drying of the device at a specific temperature for a set period.
23. Alternatively, sufficient desiccant can be used for drying and dehumidifying the device.
24. The drying process varies based on the device’s humidity sensitivity level, size, and ambient humidity conditions.
25. After proper drying, MSD’s Shelf Life and Floor Life can be recalculated from scratch.
26. If MSD exposure time exceeds the Floor Life or if temperature/humidity conditions exceed requirements, the IPC/JEDEC standard can be referenced for drying methods.
27. Devices sealed in MBB must be dried before sealing.
28. Level 6 MSDs need re-drying before use and reflow soldering as per the moisture-sensitive warning sign instructions.
29. When baking MSDs, note the following: Devices in high-temperature trays (e.g., high-temperature Tray trays) can be baked at 125°C unless otherwise specified by the manufacturer.
30. Devices in low-temperature trays (e.g., low-temperature Tray trays, tubes, and tapes) should not be baked above 40°C to avoid damage.
31. Remove paper/plastic bags/boxes before baking at 125°C.
32. Pay attention to ESD (Electrostatic Sensitivity) protection during baking, especially as the environment can become very dry and prone to static electricity.
33. Control the baking temperature and time; excessive temperature or time can lead to oxidation or intermetallic compound formation, affecting solderability.
34. During baking, ensure no unidentified gases are released from trays, as this could impact solderability.
35. Always maintain a baking record to monitor the baking time.
36. For MSD repair, if the device on the main board is removed, local heating should be used, keeping the device’s surface temperature below 200°C to minimize humidity damage.
37. If the temperature of some devices exceeds 200°C and surpasses the specified Floor Life, the motherboard should be baked before rework.
38. The baking method is described in the next paragraph; within the Floor Life, the device’s temperature tolerance is equivalent to reflow soldering.
39. When analyzing defects in removed devices, follow the above recommendations to avoid humidity-related damage masking the defect’s root cause.
40. If the device is to be recycled after removal, adhere to the above recommendations.
41. MSDs are not a substitute for drying after multiple reflow solderings or reworks.
42. Some SMD devices and motherboards cannot tolerate prolonged high-temperature baking, such as some FR-4 materials, which cannot endure 24-hour baking at 125°C.
43. Additionally, some batteries and electrolytic capacitors are sensitive to temperature.
44. Considering these factors, choose an appropriate baking method for PCB boards.
