1. **The Certification and Upgrade of Moisture Sensitive Water-Based MSL**
(1) **Certification MSL**
The process of certifying moisture-sensitive water-based MSL for PCB circuit boards begins with new products that have not yet been certified. These products must initially be classified at the lowest level (Level 6) in Table 1. After successfully passing the Level 6 test, they can be upgraded to Level 5a, and then to Level 5, and so on. This process continues with incremental upgrades until the highest level is reached, at which point the product is declared to be at Level 1.
(2) **Upgrade MSL**
For products that have already been certified to Level 1 and wish to be upgraded further, an “additional reliability test” is required. This test involves two batches of 22 samples in total, with each batch drawn from two or more non-contiguous production lots. The appearance of the products from each batch should be as consistent as possible, and every production batch must first pass all required manufacturing processes.
Each batch will consist of 11 samples, which must also undergo all necessary manufacturing processes. For samples undergoing the upgrade test, a moisture absorption test, as listed in Table 5-1, must be performed, followed by subsequent electrical and visual inspections. Before submitting the samples for further certification, the supplier must conduct self-certification and affirm the product’s current level.
(3) **Moisture Absorption Technique**
The contents of Table 5-1 outline the initial “hygroscopic conditions” testing for a specific type of water and Huai table, followed by various electrical tests, visual inspections, and a “C-SAM” (Ultrasonic Scanning Microscope) inspection of the bottom line. However, the goal of this specification is not to address the “layering” of the initial inspection but to establish the “Huai Rules” for determining acceptance or rejection.
Seals designated for testing must be baked in an oven at 125°C for 24 hours to eliminate moisture, ensuring that the moisture absorption test is conducted under dry conditions. However, for tests involving the second highest and highest moisture levels, baking and dehumidification requirements can be adjusted depending on the actual situation and other factors before carrying out the “Double Eight Five-Year” moisture absorption test for 168 hours (7 days).
**2. Moisture Absorption in the Front Section and Reflow in the Back Section**
(1) **Moisture Absorption Test**
Place the semiconductor packages to be tested for moisture absorption in a clean, dry tray, ensuring they do not touch or overlap. They must adhere to JESD625 standards throughout the process, and precautions should be taken to avoid “static damage.” The components listed in Table 5-1 represent semiconductor package types, categorized into eight levels of moisture sensitivity (MSL). After opening the package and before completing assembly and soldering, the time limit for exposure to the factory environment is specified, along with the conditions for the moisture absorption test.
(1). The standard test must be conducted under the conditions specified in the example, or based on the widely accepted diffusion activation energy range of 0.4–0.48 eV. After the test sample undergoes moisture absorption in the front section and reflow in the back section, if failures such as damage or poor electrical performance occur, further verification should be done based on the “acceleration equivalent” conditions outlined on the right side of the table. These acceleration conditions cannot be applied in normal tests. The duration of the accelerated test can be adjusted flexibly depending on the characteristics of different molding and encapsulating materials.
(2) The “Biaohuai Moisture Absorption” time corresponds to the “Manufacturer’s Temporary Exposure Time” (MET) before PCB semiconductor manufacturers perform baking, dehumidification, and bag storage. If the exposure time does not exceed 24 hours in total after being removed from the bag at the distributor’s facility, it can be considered within acceptable limits. If the actual MET is less than 24 hours, the moisture absorption time can be shortened. For instance, at “30°C/60% RH,” the moisture absorption time can be reduced to 1 hour. However, if the MET exceeds 1 hour at “30°C/60% RH,” the moisture absorption time should be increased by an additional hour. If the MET exceeds 24 hours, the moisture absorption time should be extended by 5 hours.
(3) If the PCB supplier deems the product to be at risk or unsafe, they may choose to extend the moisture absorption time accordingly.
(2) **Reflow in the Back Section**
After the sample has been removed from the temperature and humidity chamber following the moisture absorption test, it must be kept for 15 minutes, but not longer than 4 hours, before proceeding with the reflow process. This should be carried out in accordance with the specific guidelines detailed in Tables 5-2 and 5-1. A total of three reflow tests must be completed, with the interval between each reflow not to be less than 5 minutes and no greater than 1 hour. If the sample is not reflowed within the specified 15-minute to 4-hour window after removal from the temperature and humidity box, the batch number must be re-baked and re-absorbed following the previously described procedure.
Once all tests are completed, the PCB seals must undergo a visual inspection under a 40x microscope to check for any breakage. Following this, electrical testing must be conducted, and all samples must be evaluated against the acceptance criteria outlined in the catalog or according to the factory’s existing specifications. Finally, C-SAM imaging should be used for internal failure analysis.
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(1) **Certification MSL**
The process of certifying moisture-sensitive water-based MSL for PCB circuit boards begins with new products that have not yet been certified. These products must initially be classified at the lowest level (Level 6) in Table 1. After successfully passing the Level 6 test, they can be upgraded to Level 5a, and then to Level 5, and so on. This process continues with incremental upgrades until the highest level is reached, at which point the product is declared to be at Level 1.
(2) **Upgrade MSL**
For products that have already been certified to Level 1 and wish to be upgraded further, an “additional reliability test” is required. This test involves two batches of 22 samples in total, with each batch drawn from two or more non-contiguous production lots. The appearance of the products from each batch should be as consistent as possible, and every production batch must first pass all required manufacturing processes.
Each batch will consist of 11 samples, which must also undergo all necessary manufacturing processes. For samples undergoing the upgrade test, a moisture absorption test, as listed in Table 5-1, must be performed, followed by subsequent electrical and visual inspections. Before submitting the samples for further certification, the supplier must conduct self-certification and affirm the product’s current level.
(3) **Moisture Absorption Technique**
The contents of Table 5-1 outline the initial “hygroscopic conditions” testing for a specific type of water and Huai table, followed by various electrical tests, visual inspections, and a “C-SAM” (Ultrasonic Scanning Microscope) inspection of the bottom line. However, the goal of this specification is not to address the “layering” of the initial inspection but to establish the “Huai Rules” for determining acceptance or rejection.
Seals designated for testing must be baked in an oven at 125°C for 24 hours to eliminate moisture, ensuring that the moisture absorption test is conducted under dry conditions. However, for tests involving the second highest and highest moisture levels, baking and dehumidification requirements can be adjusted depending on the actual situation and other factors before carrying out the “Double Eight Five-Year” moisture absorption test for 168 hours (7 days).
**2. Moisture Absorption in the Front Section and Reflow in the Back Section**
(1) **Moisture Absorption Test**
Place the semiconductor packages to be tested for moisture absorption in a clean, dry tray, ensuring they do not touch or overlap. They must adhere to JESD625 standards throughout the process, and precautions should be taken to avoid “static damage.” The components listed in Table 5-1 represent semiconductor package types, categorized into eight levels of moisture sensitivity (MSL). After opening the package and before completing assembly and soldering, the time limit for exposure to the factory environment is specified, along with the conditions for the moisture absorption test.
(1). The standard test must be conducted under the conditions specified in the example, or based on the widely accepted diffusion activation energy range of 0.4–0.48 eV. After the test sample undergoes moisture absorption in the front section and reflow in the back section, if failures such as damage or poor electrical performance occur, further verification should be done based on the “acceleration equivalent” conditions outlined on the right side of the table. These acceleration conditions cannot be applied in normal tests. The duration of the accelerated test can be adjusted flexibly depending on the characteristics of different molding and encapsulating materials.
(2) The “Biaohuai Moisture Absorption” time corresponds to the “Manufacturer’s Temporary Exposure Time” (MET) before PCB semiconductor manufacturers perform baking, dehumidification, and bag storage. If the exposure time does not exceed 24 hours in total after being removed from the bag at the distributor’s facility, it can be considered within acceptable limits. If the actual MET is less than 24 hours, the moisture absorption time can be shortened. For instance, at “30°C/60% RH,” the moisture absorption time can be reduced to 1 hour. However, if the MET exceeds 1 hour at “30°C/60% RH,” the moisture absorption time should be increased by an additional hour. If the MET exceeds 24 hours, the moisture absorption time should be extended by 5 hours.
(3) If the PCB supplier deems the product to be at risk or unsafe, they may choose to extend the moisture absorption time accordingly.
(2) **Reflow in the Back Section**
After the sample has been removed from the temperature and humidity chamber following the moisture absorption test, it must be kept for 15 minutes, but not longer than 4 hours, before proceeding with the reflow process. This should be carried out in accordance with the specific guidelines detailed in Tables 5-2 and 5-1. A total of three reflow tests must be completed, with the interval between each reflow not to be less than 5 minutes and no greater than 1 hour. If the sample is not reflowed within the specified 15-minute to 4-hour window after removal from the temperature and humidity box, the batch number must be re-baked and re-absorbed following the previously described procedure.
Once all tests are completed, the PCB seals must undergo a visual inspection under a 40x microscope to check for any breakage. Following this, electrical testing must be conducted, and all samples must be evaluated against the acceptance criteria outlined in the catalog or according to the factory’s existing specifications. Finally, C-SAM imaging should be used for internal failure analysis.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
