Totech Super Dry® - Dry Storage, Dry Cabinets, Dry Boxes - Frequently Asked Questions

> Frequently Asked Questions

 

Our customers often approach us with questions about our technologies. To make life easier for you, we’ve included a list of frequently asked questions below. However, if you cannot find the answer to your questions here, please do not hesitate to contact our team .

 

 

     

     

    • What is a dry cabinet?
      In short, a dry cabinet is a storage device that allows you to protect a wide range of products against humidity problems. A Desiccant Dry Cabinet is an enclosure with a supply of desiccant which maintains an internal environment of 1-50% RH. Desiccant dry cabinets are also called: desiccators, dry boxes, dehumidifying cabinets, and ultra low humidity storage cabinets.

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    • What should be stored in a dry desiccant cabinet?
      Any component classified as an MSD (Moisture sensitive device), particularly devices classified as level 4-5a. These devices are most susceptible to moisture related defects. Desiccant dry cabinets can also be used to store partially populated double sided boards. While waiting to re-enter production to complete 2nd side assembly, components begin to absorb moisture that could do harm once the PCB is introduced back to the reflow oven.

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    • What are the defects that I could experience related to moisture contamination of MSDs?


      Bond damage, wire necking


      Bond lifting, die lifting


      Thin film cracking, cratering beneath the bonds


      Corrosion due to ionic contaminants, popcorning


      Increase in thermal resistance due to delamination: Cracks & Paddle delamination

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    • How can I tell if I have MSD-related defects occurring on my floor?
      Initially you may not see any signs of some of the defects listed above. Other defects such as cracking may be visible to the eye, and ‘popcorning’ may actually be heard coming from inside your oven in severe cases. Still, it’s very difficult to detect these defects, even standard ICT may show no abnormalities. If you are interested in determining whether your process may be susceptible to moisture-related damage you could run the following test:

      Allow a tray of MSDs to flow through your process as they normally would while being assembled (including all dwell times and reflow). At the end of the process send the MSDs to an independent lab for scanning acoustic microscopy, or cross-sectioning. If defects are evident in the results then you can be sure that you would realise savings and reliability with the implementation of an MSD control program.

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    • Will storing my components in a Totech Super Dry cabinet satisfy IPC JEDEC J-STD 033?
      No is the short answer, arbitrarily storing your MSDs in any desiccant cabinet, dry box, N2 (Nitrogen) cabinet, hot air box, or any other dehumidification device will not on its own satisfy IPC J-STD-033. It will not automatically ‘Stop the clock’ However, the implementation and correct use (calculated storage duration based upon floor exposure, etc) of a desiccant dry cabinet capable of maintaining less than 5% RH (such as a Totech Super Dry), is a crucial part of a strong MSD control program.

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    • What is desiccant and how does it work?
      Desiccant is defined as; “A substance that has a high affinity for water and is used as a drying agent “- from Latin dsiccns. It is a generic term for a variety of materials, some names that you may be familiar with include: Montmorillonite Clay, Silica Gel, Indicating Silica Gel, Molecular Sieve, Calcium Oxide, Calcium Sulphate, and Zeolite. High quality desiccants have an ability to be recycled or refreshed easily and effectively, bringing them back to full strength.

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    • How do Super Dry desiccant dryers function?
      Our newly developed, dynamic high performance drying unit U-5002, achieves air moisture levels of under 0.17% RH, even at temperatures of 60°C. Unlike traditional technology, during cabinet door openings, air moisture levels barely rise above 5% and sink within a few minutes again to <1 %. Throughout the process the drying unit also consumes less energy than its predecessors. Whereas before it was necessary to regenerate the drying substance regularly (usually every 6 hours), it is now for the first time possible to control this process according to the load on the system. The desiccant is refreshed by heating and allows the trapped moisture to escape as vapor (H2O) through vents located at the back of the cabinet. Once refreshed the unit is ready to seal off the exterior venting, and re-open itself to the interior to continue dehumidification. Through a microprocessor the state of the drying substance is permanently monitored and compared with the input set point values. Only when the moisture content in the cabinet exceeds the absorption capacity of the drying substance, is the thermal regeneration started. The strength of this process in turn is fitted individually to the desired set point moisture in the cabinet. This has led to a drastic reduction of energy demand in cabinets which are infrequently opened. Often a regeneration of only 15 minutes suffices many weeks of component drying.

      In manufacturing environments, the regeneration behavior of the drying unit adapts itself dynamically to the needs of short opening cycles of the doors and multi-layer loading.

      Through this, the availability and efficiency is improved considerably in comparison to a fixed regeneration cycle.




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    • What is recovery time?
      This may be the single most important cabinet performance parameter, though Minimum RH level is the most frequently cited. Recovery time refers to the time required for the cabinet to reduce the RH level back to its set point after the door has been opened and closed. The latest Super Dry cabinets employ the newly developed U5002 dry unit which is measurably more powerful than any other technology. The graph below demonstrates how the MSD 1202 modular cabinet recovers following 4 door openings of 30 seconds. I addition this “Dynamic Dry Unit” is closed loop responsive to changes in demand and will regenerate at the frequency required to maintain the set point. Superior stability AND energy utilization.

      Measure your cabinet under similar conditions!



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    • Do Totech Super Dry cabinets use heat to dissipate moisture?
      With the exception of the M-Temp Series the dehumidification of the cabinet interior is carried out by desiccant alone, with no heat involved. M-Temp generates up to 60 Deg C to provide a low-temp bake at 3% RH, but desiccation is achieved through the same U-2001 dryer units that are in the Totech Hyper Super Dry, Super Dry, and Clean Series dry storage cabinets.

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    • Do Totech Super Dry cabinets require nitrogen?
      Totech Super Dry desiccant dry storage products do not require nitrogen to maintain the RH levels indicated within the specifications. However for applications that require extreme frequency of door openings and where plumbing permits an optional nitrogen purge may be installed.

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    • What are the benefits of desiccant dry cabinets over nitrogen?
      Desiccant cabinets have lower running cost. You can see a simple cost analysis here. N2 is void of all oxygen, it is unable to absorb O2, and as a result it is a less effective than desiccant when used as a drying agent. It is typically used under positive pressure to continually displace the oxygen within the cabinet. Totech Super Dry cabinets are portable with casters, and do not require plumbing, so they can be moved to a new location whenever required. Totech Super Dry cabinets will maintain their internal environment for extended periods (10-+24 Hrs) during power down situations, continuing to protect your components. Nitrogen cabinets use a constant positive pressure flow to void the cabinets of all O2; this nitrogen flows out into the productionfacility, reducing the oxygen density in the area, potentially causing discomfort to staff.

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    • What are the benefits of dry cabinets over moisture barrier bags (MBBs)?
      Saves labour; trays and reels can be placed directly into cabinet without having to be placed into MBB (moisture barrier bags) Save cost; Less desiccant (i.e. indicating silica gel), and MBB’s required. More secure, no need to be concerned with; Calculations to determine the correct amount of desiccant, the quality and remaining absorbency of the desiccant, and potentialmis-sealing, or possibility punctures of the bags themselves

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    • What are the benefits of dry cabinets over baking?
      Less costly than baking; with a monthly power consumption of only 40.4 kW it’s considerably less expensive than long duration bake cycles. More efficient; Components are being dehumidified while they sit in inventory, always ready for the next run. More convenient; Operators will be more inclined to place components into cabinets rather than taking the time to re-bag, especially for short duration exposures.

      Space saving; smaller outside dimensions than that of comparable burn in cabinets as a result of insulation, wiring, etc. Better Quality; Baking SMD packages may cause oxidation or intermetallic growths to form, which can reduce solderability. Component carriers may cause outgassing during baking, again, effecting the solderability, Less Concern; Standards suggest when baking between 90-125 deg C. a max time of 48 hours be observed, then deviations should be requested. With desiccant cabinet storage there is no maximum to observe. Less handling; there is no need to transfer components from their standard packaging to high temp carriers in preparation for the bake, possibly introducing physical damage to the component itself.

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    • Are Totech Super Dry cabinets clean room safe?
      The Totech Clean Series is designed to be a mobile class 100 clean room. With its powerful air purification system, HEPA filters, non dust generating stainless steel shelves, and dust free urethane casters it is a practical and quick moisture proof storage solution for your clean room requirements.

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    • Are Totech Super Dry cabinets ESD-safe?
      All M-Temp, Hyper Super Dry, Super Dry, and Clean series cabinets are ESD safe. Standard features include; Stainless steel shelves, conductive glass, conductive paint on all cabinet surfaces, and 1MΩ earth lead.

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    • What is the benefit of Totech’s ‘Auto-on’ feature?
      Totech’s auto-on feature provides an opportunity after each door opening to capture the newly introduced moisture before it has a chance to settle.

      The movement of the air (and its entrapped moisture) within the cabinet provides more opportunity for those moisture particles to pass within the desiccant’s reach.

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    • What is the benefit of Totech’s M Temp series circulation fan?
      The additional circulation fans (one lower, one upper) on the M-temp play double duty. It’s mounted on a false wall within the cabinet structure, (as seen in the diagram) and it provides significantly more air movement in the cabinet interior, again providing opportunity for those moisture particles to pass within the reach of one of the three dehumidification units designed into M-Temp.

      The circulation fan also minimizes variations in temperature caused by the heat generated from the shelves in the M-Temp; which provide the low-temp bake at 3% RH environment.



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    • Will the RH level remain constant in a Totech Super Dry cabinet?
      Studies have shown that Totech’s newest technology, as designed into the U-2001 dehumidification unit allows the cabinet to remain at the operator set RH without any difficulties. This chart shows the results of some of Totech’s competitive testing.



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    • What happens to my Totech Super Dry cabinet if the power goes off?
      Totech Super Dry cabinets are designed and manufactured to be able to maintain an environment of <5% RH for a period of 10 days, and <10% RH for a period of approximately 20 days if the cabinets remain closed and no new moisture is introduced.



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    • Does the number of doors represent the number of storage areas in a Totech Super Dry Cabinet?
      No, there are a variety of models, with a variety of door configurations. The interior of the cabinet is one environment. There is benefit however from a higher number of doors; there is less of an exchange of atmosphere when a smaller door is opened and closed.

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    • Can I change the configuration of the Totech Super Dry cabinet interior?
      We offer a selection of options to chose from that will make our cabinets more suitable to your particular application; additional shelves, reel rack (for taped SMDs), dividers, and slide out shelves, to name a few.

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    • Can I monitor my Totech Super Dry cabinets over a network?
      Currently the M-Temp is the only unit that offers communication as a standard feature. Its RS232C and RS485 (two lines) allows M-Temps to be ‘daisy chained’ inline, all reporting to a network server capable of data logging, and sounding alarms if necessary. HSD series cabinets may have SDS controllers installed optionally.

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    • Does the desiccant require replacing?
      No, the desiccant is extremely well suited to the task and should perform well under normal operating conditions for 10 years or more without replacement.

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    • Do Totech Super Dry cabinets require any maintenance?
      No required maintenance whatsoever.

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    • Do Totech Super Dry cabinets require calibration?
      Yes, Totech provide instructions regarding a short procedure that can be carried out in house at no cost. Suggested frequency - once per year.

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    • Where can I get replacement parts and service for my Totech Super Dry Cabinet?

Totech will be happy to respond to all of your service and spares requirements. Simply contact our team today.

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