Desiccators in the Cleanroom: What are the Options?

 

1. Glass Desiccators

Desiccators in cleanrooms are usually glass jars used to store pre-dried samples of hygroscopic chemical reagent. They’re sometimes also used to cool substances that were heated in a beaker. In a laboratory, they are very useful, but in a cleanroom, they can be a contamination hazard.

One of the primary issues with glass desiccators is that cleanrooms usually require very precise humidity controls. The devices manufactured in semiconductor, medical device, and pharmaceutical cleanrooms are moisture-sensitive devices (MSDs). The desiccators cannot maintain these extremely low levels of relative humidity.

Desiccators create a drying effect through adsorption using a desiccant powder like calcium chloride or silica gel on the bottom. The sample sits on a small platform, and the jar is sealed using silicone grease. Once this system reaches its saturation point, it can’t provide moisture protection. Saturation is visible when the powder changes color from blue to pink. To return to its adsorptive abilities, the desiccant has to be regenerated through a 24-hour heating cycle to bake out the moisture.

At this point, the desiccator has to be manually handled. This is both disruptive to processing and poses a risk of contamination. In any case, these jars generally provide insufficient drying.

The vacuum desiccators will effectively dry samples that can withstand the vacuum environment. However, the entire system brings noise and contaminants to a cleanroom.

2. Desiccant-based Dry Cabinets

What are your options for using desiccators in a controlled environment like a cleanroom?

Dry cabinets alternate between two desiccant modules that cycle in and out of the airflow unit. One provides moisture adsorption and the other undergoes regeneration through an integral heating module fan. In this way, the cabinet offers better storage capacity at a controlled RH level.

This kind of system is perfect for long-term bulk storage of microelectronic components, moisture-sensitive optical devices, and other similar applications. The cabinets eliminate the need for manually removing and restoring saturated desiccant. The products are easily accessible, thereby not obstructing the process. The even set point control and low relative humidity monitoring offer benefits to this kind of system over the static, or glass jar system. However, the dry cabinet is more complex and expensive to own and operate.

For the most stringent cleanroom environments, the dry cabinet still poses some issues. Fans are used in these systems, which can cause particles to enter the airflow. HEPA filters can be added to capture the contaminants, but they also add an additional moisture load, which can compromise drying efficacy. The fans can also cause turbulence outside of the cabinet, disrupting the essential laminar airflow.

3. Variable-purge System

When traditional desiccators aren’t clean enough to use in your controlled environment, what are your options?

For a cleaner alternative than the two previously mentioned, dry nitrogen gas is the best desiccating medium. Without contributing particles, a nitrogen-purged system provides superior RH control with automated set points far below 5% RH. It maintains an inert environment for anything that is sensitive to humidity or other chemical vapors.

The variable-purge system uses highly precise RH sensors and effective airflow engineering to minimize humidity recovery times while conserving nitrogen. All things considered, these systems are the most cost-effective for any product that will experience high defect rates with even a little exposure to moisture in the air.


Do you need cleanroom certification or validation? Looking to build a modular cleanroom? Our experienced staff at Gerbig Cleanrooms has 30 years of expertise that you can depend on. Call us at 888-628-0056 or email info@gerbig.com.

Is your Cleanroom Training Effective for Millennials?

Years ago, “Millennial” seemed like a dirty word. As they began infiltrating our workforce, generations above them judged harshly, finding them entitled and lacking a work ethic. Now that they are fully immersed in our working culture, we have found that they bring opportunities for growth and evolution. However, the youngest of this generation are getting their first jobs out of college, and their worlds are very different from those of us who have been working for fifteen years or more. The question is how do we train these young people?

It’s important to recognize that Millennials do have different needs when it comes to learning a job. Their reality has always included advanced technology. They have access to an infinite amount of information. They learn and process information differently than generations before, so if you current training strategy has been the same for a decade, you do need to make changes to help this group to succeed.

Here is what your training should include:

  • Use technology. Incorporate the platforms they prefer to use, like mobile devices.
  • Create modules and lessons that are short, digestible chunks of information. Give them relevant pieces that they can absorb quickly. They are used to a fast pace and will get distracted if they feel they don’t need what you’re telling them.
  • Deliver key concepts using videos and other animated images. These often get information across in a more effective way than text or speech.
  • Ask for their feedback before and during training. Millennials want to participate in shaping the company and their own jobs. Ask them for ideas and suggestions about how they will get the most value out of their training and how they best understand information.
  • Include your company values. These employees want to work for a business whose company values match their own. They want to believe in the company leaders, and they want to feel good working for the company.

You don’t need to completely overhaul your current training strategy. You are the expert. Use what is successful, but deliver it in a way that will align with the needs of the Millennials.

If you need cleanroom verification, certification, or construction, contact Gerbig Engineering Company. We have thirty years of experience that will guide you to success. 952-960-4400info@gerbig.com.

Pros and Cons of The Marangoni System in the Cleanroom

If you’re looking to avoid evaporation as a drying technique in a cleanroom, you may be interested in the Marangoni System.

When water evaporates, because it is leaving as a gas, it leaves behind water spots. In a controlled environment, this is something to avoid; the water spots are basically made of contaminants. In order to remove water, then, some people consider the fascinating Marangoni System.

James Thomson found that gradients in surface tension arise from concentration differences in solution. After that, Carlo Giuseppe Matteo Marangoni found that liquid will flow along a gas-liquid or a liquid-liquid interface from areas of low surface tension to high. These two combined discoveries led to the Marangoni System.

The Marangoni effect is stimulated by anything that reduces surface tension. A cleanroom dryer would use a DI water bath with a headspace of IPA in nitrogen. IPA dissolves in water, resulting in lowered surface tension, allowing water to flow away from the surface of the object being cleaned, thereby leaving it dry. The object experiences the effect as it is slowly withdrawn vertically from the bath.

The huge benefit to this method is that all the unwanted water – containing soluble materials like minerals – is removed as a liquid. Therefore, they are not left behind as water spots.

Unfortunately, only flat surfaces can be dried with this approach. Fluid force produced by differential surface tension is diminished when in competition with other forces like convection or gravity.

Also, the slow rate of withdrawal yields only about 1 to 10 single pieces dried every two minutes. This really limits the application when you need multiple pieces dried. What may benefit most from this method, then, are large flat surfaces, like flat panel displays.

As with any cleanroom decision, the efficacy of the Marangoni System will depend on the application. If you need cleanroom validation or certification, contact the experts at Gerbig Engineering Company. 888-628-0056; info@gerbig.com.

Renovating or Building a Cleanroom? What to do and What to Avoid

Whether you’re renovating or building a cleanroom, there are numerous factors that come into play. Without the right planning and preparation, your cleanroom build can be a headache at best and a disaster at worst.  The purpose of your cleanroom and your unique facility are individual to you, so do your homework. Here is a quick list of do’s and do not’s.

You Should Definitely:

  • Know the purpose and functions of the space. Clearly establish this by using a recognized standard like ISO 14644. You want to set the class of cleanliness and criteria like humidity setpoints and temperature.
  • Have clearly identified requirements for maintaining your operations during construction.
  • Create requirements for vibration performance.
  • Make sure you have adequate space for mechanical systems by checking vertical clearance. Also check the vertical clearance for moving equipment – do you need to use elevators?
  • Check that there is enough vertical shaft space from the cleanroom to the roof for your exhaust ducts. Also make sure they’re accessible.
  • Find out what kind of hazardous materials will be used, and make sure your building can accommodate a hazardous occupancy if need be.
  • Establish what utilities, capacities, and quality are required.
  • Understand that your power requirements will change and confirm your source is sufficient for growth.
  • Budget with a contingency for unexpected conditions and atypical line items like cleanroom certification and temporary setups during construction.

What Not To Do

  • If possible, don’t locate the cleanroom on an exterior wall.
  • Cleanrooms are ideally located where a dedicated mechanical room is directly above it; don’t put one beneath wet laboratories.
  • Don’t assume that all users have completely considered their requirements.
  • Don’t assume the design team has experience with cleanroom design; you need to verify.
  • Don’t expect any contractor without experience building cleanrooms to be able to complete this work.
  • Don’t assume your contractor understands what “building clean” means. Establish in writing how to start the project correctly, how to get the space clean, and how to keep it clean.
  • You do not want air intakes above a loading dock or service yard.
  • You do not want exhausts at grade level or in building sidewalls.
  • Don’t underestimate the amount of space required for support equipment.
  • As you read these tips, surely it is clear what kinds of catastrophe can occur if you miss a step. You don’t want to lose any time or money fixing what could have been avoided to begin with.

If you are considering a modular cleanroom, choose an expert with sufficient experience and a strong reputation. Gerbig Engineering Company has over 30 years of expertise in cleanroom design, manufacturing, installation, and validation. Contact us at 888-628-0056 or email info@gerbig.com.

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