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How to Choose Anti-humidity Cabinets

Home How to Choose Anti-humidity Cabinets Electronic and the Manufacturing Industries.

2 Electronic and the Manufacturing Industries.

Moisture-proof application for the electronic and the manufacturing industries

(Semi-conductors, electronic components, consumer electronics, communication technology, information technology, photonics, industrial instruments, etc....)


    

        Do you knowthat trace moisture”has great impact on the quality of electronic components and electronic circuits? Resultsfrom surveys suggest that more than,25% of industrial defects, including defects from the industries of photonics, semi-conductors, electronics, biotechnology, food, drugs, and optics, are caused by a lack of low humidity storage. At present, manufacturing defects encountered by the electronic industry, can happen at the following stages:

1. Damage due to micro-cracks in the heating process during SND/IC sealing and packaging;

2. The water hazard during SMT reflow soldering because of returned water temperature in the baking process;

3. IC oxidation caused by damped packaging materials;

4. Damp and moldy LCD boards; 

5. Delamination of PCB multilayer printing and circuit boards caused by temperature difference and humidity; 

6. Weld leg oxidation due to humidity caused poor solderability.…等。

Therefore improving the condition of trace moisture for manufacturing, quality control, R&D, and warehousing is indispensible.


      
 Moisture Buster uses J-STD-033B protocol as the foundation for organizing ways to resolve or reduce damp problems caused by trace moisture in the industry and explains conditions in which floor life be reset or paused.

        MSL If SMD components of MSL2 or above are not stored in dry packs (must be within the floor life), these components have to be re-dehydrated. If the required components are frequently dried repeatedly or for a long time in the oven, reliability of the components still can drop. In this case, room temperature dehydration is extremely important. For majority components, storing them below 10% RH fulfills the J-STD-033B protocol, and in this case, one no longer need to worry any possible negative effects caused by baking at high temperature and for long time or repetitive baking.

 



Table 4-3 Resetting or Pausing the ‘‘Floor Life’’ Clock at User Site

MSL Level Exposure Time @ Temp/Humidity Floor Life Desiccator Time @ Relative Humidity Bake Reset Shelf Life
2, 2a, 3, 4, 5, 5a Anytime
≦40°C/85% RH
reset NA Table 4.1 Dry Pack
2, 2a, 3, 4, 5, 5a > floor life
≦30°C/60% RH
reset NA Table 4.1 Dry Pack
2a, 3, 4 >12 hrs
≦30°C/60% RH
reset NA Table 4.1 Dry Pack
2, 2a, 3, 4 ≦12 hrs
≦30°C/60% RH
reset 5X exposure time
≦10% RH
NA NA
5, 5a >8 hrs
≦30°C/60% RH
reset NA Table 4.1 Dry Pack
5, 5a ≦8 hrs
≦30°C/60% RH
reset 10X
exposure time
≦5% RH
NA NA
2, 2a, 3 Cumulative time
≧floor life
≦30°C/60% RH
pause Anytime
≦10% RH
NA NA

 

 
Moisture sensitivity levels (MSL) is listed in ascending order, and smaller numbers suggest better moisture proof capacity, while bigger numbers suggest that a shorter exposure to environmental humidity is required.
  • MSL 2, 2a, 3 and 4 components’ exposure time ≦ 12hrs + environmental humidity ≦ 30°C/60% RH. Therefore, by placing the components in the electronic dehydration cabinet at 10%RH or below for five folds the time the components are exposed to the atmosphere, there will be no need to bake the  components for resetting the original floor life of SMD
  • MSL 5 and 5a components’ exposure time ≦ 8hrs + environmental humidity ≦ 30°C/60% RH. Therefore, by placing the components in the electronic dehydration cabinet at 5%RH or below for ten folds the time the components are exposed to the atmosphere, there will be no need to bake the components for resetting the original floor life of SMD.
  •  If components have been exposed in a factory environment for more than one hour, putting them into dry packs or dehydration boxes may not be able to stop or reset the accumulation of floor life. If SMD components have been exposed to an environment that is below 30℃ and 60%RH, one can use desiccants or a dehydration cabinet to dehydrate the SMD components according to Table 4-3 of J-STD-033B.
  • It is mentioned in 5.3.3 of J-STD-033B that dehydrated air or nitrogen gas can be used to maintain low humidity condition. It is important to return to the initial balanced humidity within an hour after opening the low humidity dehydration cabinet. Nevertheless, using dehydrated air requires some additional components for the air compressor as well as oil and water filters. This would increase material cost, and thus is not cost efficient for a long run. If nitrogen gas is used, then nitrogen gas has to be refilled every time the cabinet is opened. That is, if you open the cabinet ten times, you would have to fill it with nitrogen gas ten times. In a year, you would have to refill nitrogen gas for 3650 times, and each time it would take 1,300L of nitrogen gas. It is easy to tell that maintaining a low humidity environment is expensive (the fact that SMD should be prevented from exposing to oxygen is not discussed here). Therefore, by using Moisture Buster’s ultra-low humidity cabinet, one can easily maintain humidity below 5%RH for a long time. Moreover, each time the cabinet is opened, the original humidity balance can be reached within 30 minutes, which is far better than standards specified in J-STD-033B. Furthermore, none of the materials used for the electronic dehydration box has a high unit price (e.g., oil filter, water filter and nitrogen). Therefore, it is truly the most effective and efficient storage means
  • It is stated in 5.3.3.1 of J-STD-033B that if the humidity of an ultra-low humidity dehydration cabinet cannot reach 10%RH or lower, it cannot be considered as a SMD standard qualified dry pack. In this case, refer to Table 7-1 of J-STD-033B for storage time and humidity. If the accepted humidity and time standards are exceeded, the components have to be re-baked to reset the floor life (See 4-2).
  •  
  • The total SMD exposure time only needs to fulfill standards specified in Table 5-1 and 7-1, i.e., placing the components at an environment with humidity lower than 10% RH, to pause or stop the accumulation of floor life.


Table 5-1 lists floor life of components with different moisture sensitivity level at 30℃/60%RH (If a component is exposed to air for more than one hours, follow the operation listed in Table 7-1)
Table 5-1 Moisture Classification Level and Floor Life

Level

Floor Life (out of bag) at factory

ambient  30°C/60% RH or as stated

1
Unlimited at ≦30°C/85% RHNo control is required as long as ≦30°C/85%
2
1year
2a
4 weeks
3
168 hours
4
72 hours
5
48 hours
5a
24 hours
6
Mandatory bake before use. After bake, must be reflowed within the time limit specified on the label.


Table 7-1 Shelf life (in days) for different moisture sensitivity level at different moisture preservation environment  


It can be found from the above table that as long as humidity is maintained under 10%RH and 5% RH, shelf life of components can be infinitely extended. It is especially true when the components are stored in an environment with humidity below 5% RH.
       
It can be found from the above data that during the manufacturing process of electronics, it is important to effectively control trace moisture to elevate the yield rate. Trace moisture is an important issue for components, parts, solder balls, solder paste, etc. In fact, to elevate products’ yield rate effectively, the component stage is much more important than the semi-product or final product stage. 

        


 

 
Dry box, Dry cabinet , Desiccator cabinet, Ultra dry storage<5%RH application
 
Integrated circuits (QFP, CSP, PGA, BGA, SOP, TQFP), PCB, diodes, transistors, rectifiers, LED, solar panels, SMD, resistance device, capacitance device, conductive materials, printed circuit boards, welding materials, solder balls, solder paste, dehumidifiers, optical fibers, chemicals, quartz crystals, quartz oscillators, mica, ceramics, molds, machine parts, samples, etc.