Two Basic Elements of Controlling ESD

 

The integrity of many products built in a cleanroom is compromised by electrostatic discharge (ESD).  Semiconductors, disc drive, and flat panel manufacturers are particularly at risk when static electricity attracts contaminates. An effective ESD control program is multi-faceted and continually improving. There are many elements in an ESD program; here we will focus on the basics of training and garments. 

Training

The major generators of static electricity are people and machinery in the cleanroom or controlled environment. Cleanroom workers and engineers inadvertently promote static electricity because they do not know what causes ESD or why it is bad. According to Jan Eudy in her “Testing ESD Garments” article in Controlled Environments, engineers are often the worst offenders when it comes to ESD. 

Therefore, no ESD program will be successful without separate training courses for every level of personnel affecting ESD. This includes engineers, operators, and managers. Each group needs to know specific ESD protocol for their jobs and why it exists. When people are educated on an issue, they both care more about it and are more compliant. 

Remember that if training veteran employees, old habits are heard to break. People carry out actions without even thinking about them, so it is wise to have people look out for one another. For example, a worker may be sitting in a chair with his feet tucked back to rest on the chair rather than on the grounded floor. 

Garments

 Cleanroom garments are vital elements of an ESD program. There are 3 ways that garments can control static:

  • Connect to a groundable point
  • Establish an electrical path to the groundable point
  • Establish electrical resistance from one point to another within the garment.

 

The last kind of garment is the most commonly used. It is important to know that the seam construction, fabric, and ESD yarn in an ESD garment for a cleanroom is different than those in an ESD garment for a controlled environment. Pockets and emblems are not recommended on ESD garments. 

Other apparel plays an important role in ESD protection. Eudy’s article states, “Specially designed ESD shoe covers, heel straps, or shoes are used to impart some ESD control when a facility has a dissipative grounded floor. Grounded static dissipative garments, when worn correctly, are designed to minimize the charges that may or may not be present on an operator’s undergarments. However, it is recommended that other measures of ESD control are also used.” 

Wrist straps are also available. When properly worn and connected to the ground, a wrist strap keeps its wearer near charge neutral. 

For all ESD apparel, daily testing is recommended.

Gerbig Engineering Company, Burnsville, MN has completed a procine extraction facility

MiromatrixGerbig Engineering Company, Burnsville, MN has completed a procine extraction facility consisting of several ISO class 7 cleanrooms.  The facility takes in special porcine organs and processes them such that they contain no porcine cells.  The organ is then ready for implantation into humans.

The Miromatrix Medical technology has the potential to enable the creation of fully biological replacement organs for the human body. In addition to the Company’s internal efforts focused on the development of its first product – a biological mesh for hernia repair – scientists around the globe are working with the Company’s technology and are taking critical steps toward the creation of human organs including the liver, lung, kidney, pancreas and heart. While our biological mesh development program has been conducted internally, our intent is for current and future products to be developed both at Miromatrix and in partnership with the best among those external groups already working with our technology in order to utilize this pre-existing expertise to develop individual products in the most efficacious, cost-effective and timely way possible.

Successfully Developing an ESD Program

Contaminates are attracted to charged surfaces, meaning electrostatic discharge (ESD) can devastate product, equipment, and potentially the reputation of a company. The right program to eliminate ESD will benefit productivity, profits, employees, and consumers.

Controlled Environments Magazine offers some great resources on ESD, including Richard Bilodeau, PE’s article, “Championing an ESD Control Program.”

“The bottom line to remember is that an effective ESD program must be comprehensive in its analysis and identification of ESD impact, comprehensive in its development and execution, and comprehensive in its training, effectiveness assessment, and modification against future requirements” (Bilodeau.)

Here is a summary of what he suggests.

  1. Develop a case for the program. In order to convince the right channels to buy into the program, solid, factual, statistical data must support your cause. Your case must be compelling, and you need information to accomplish this. Bilodeau says, “Pull together data on losses attributed to ESD, past incidents, vulnerable product and process points, and the potential yield, along with financial and operations impacts that a well-crafted ESD control program will deliver.” As with any business document, ask peers to review and proof your drafts.
  2. Obtain the buy-in. Decide who in your organization are key members of management. Address everyone who can impact the funding and approval of the program as well as its execution. Failure to get this buy-in will render even the most brilliant of plans a waste of time.
  3. Assemble a strong team. The success of the program hinges on the competency and commitment of your team. Recruit members from each area of operations that the plan affects, including internal communications and training.
  4. Evaluate the needs of the facility and company. Assess all the components that affect ESD record, including purchasing and receiving, warehouse and shipping, equipment, product, processes, materials, and procedures.
  5. Create your plan. Bilodeau advises that an electronic presentation with concise, bulleted points is preferred. “Make sure your ESD control plan covers the full range of your operations. Clearly delineate responsibilities, procedures, and required reviews. Subdivide the plan into rational sections that can be intuitively and quickly navigated.”
  6. Roll out the plan with buy-in. Happy customers, a boost in profits, and business success should be main themes in gaining buy-in to roll out the plan. Give senior management a prominent role in the plan, and prioritize communication across the company.
  7. Establish a training program. Training is an essential component to the success of any plan, and a training program can also be used to help market the initiative.
  8. Establish a review and assessment plan. Any good initiative is fluid and not static. Continuous improvement should be your goal; identify metrics and benchmarks as well as a timeline to implement this plan.

While these steps translate into a lot of time and effort, they are a necessary and worthwhile formula to success. Remember: people value what they work hard for. To read Bilodeau’s full article, go here.

 

General Conduct and Safety in the Cleanroom: Converting Short-Term Memory into Long-Term

certification_1Cleanroom safety training is extensive, and rightfully so. Even the smallest of mistakes can compromise production. Materials and progress may have to be completely scrapped to start over from scratch. Therefore, remembering all the rules, even the simplest ones, is paramount.

While long-term memory can hold an indefinite amount of information, short-term memory can handle about 7 – plus or minus 2 – pieces of information at a time. Those pieces of information can be separated or chunked. For example, when remembering a10-digit phone number, the area code is often one chunk of information because it is already memorized and recognized.

In a cleanroom, there are many more than 7 pieces of information to remember, so the material needs to convert to long-term memory. Once there, the knowledge will be automatic. For example, when learning to drive, a person has to consciously proceed step-by-step when stopping, accelerating, turning, etc. With enough practice, a person doesn’t need to think about the steps to operating a vehicle in order drive successfully. Cleanroom workers need all of their safety steps to be automatic.

The most basic way to convert short-term memory into long-term is repetition. Whether mental repetition or physical rehearsal, the more frequently information is reintroduced, the longer it will stay in the short-term memory, and eventually it will become automatic.

Here are some general guidelines to conduct and safety in cleanrooms to study. Add to the list as needed. Chunk related information together so that rather than remembering multiple things, it feels like one. As you or your employees practice repetition with these, remember to skip over or omit the items that have converted to long-term memory. As the list grows shorter, it will seem less overwhelming.

  • Always wear proper cleanroom attire and your cleanroom badge
  • Don’t run – just walk at a normal pace
  • Do not shake your hands
  • Do not scratch your face
  • Do not enter the cleanroom if sick
  • Don’t spray chemicals near wafers
  • Wafers should be in boxes with the owner and date labeled, and the process flow
  • Be careful with the nitrogen guns – be aware nearby items
  • Always put a chemical label on your dish, and if you no longer need your chemical dish, don’t leave it sitting out
  • Computers need to be shared. Only use them when you need to, and don’t close out other people’s programs or windows
  • Always clean up your messes
  • No food or water allowed in the cleanroom
  • Normal paper, pencils, and pens are prohibited in the clean room
  • Don’t block fire extinguishers
  • Be aware of gas detection lights
  • When the IPA or acetone runs out, fill all bottles, not just the one you’re using
  • Properly clean everything you use, including dishes, spinners, and other machines.
  • If a machine you’re done using does not need to be kept on, turn it off to conserve energy

When people take tests, they can memorize facts long enough to pass, but information can fade quickly thereafter. When first learning to work in a cleanroom, job tasks, guidelines, and rules should not just be memorized, but actually rehearsed to help glue the information into long-term memory. As mentioned in the “Improve Retention in Cleanroom Operator Training” post, a great way to learn information is to teach it. Tasking employees with creating presentations, videos, or training seminars to teach each other is a very useful way to convert important information into long-term memory.

How Vacuums Add to the Cleanroom

Cleanroom maintenance requires meticulous and devoted attention to detail. There is a constant effort to prevent airborne, fluid, and/or transfer particulates. Many cleanrooms rely solely on the most basic regulatory cleaning methods like wipe-down and dusting. Would using an industrial vacuum make a difference?

In Controlled Environments’ “Cleanroom Maintenance: Sanitation via Filtration,” author Rob Decker writes, “While companies cannot absolutely omit all potential sources for unwanted matter, they can mitigate risk by investing in reliable, efficient cleaning equipment. Portable industrial vacuums easily remove and dispose of contaminants with minimal risk to users.”

Let’s review some of Decker’s main points that lead him to this conclusion.

First we should know a few things about the vacuums themselves. The vacuums on the market today are quite sophisticated. They use HEPA or ULPA filters, and some also have a graduated filtration system. This is a series of progressively finer filters to ensure the entrapment and retention of particles in the vacuum. The machines have “upstream” and “downstream” filters installed before and after the motor. The filtration is impressive; Nilfisk writes about its filtration on its website: “These filtration systems… can increase retention efficiencies up to 99.999% of particles, down to and including 0.12 microns in size.” Industrial vacuums are also made of non-particle generating material, often stainless steel, and are designed to be easy to use and clean.

So vacuums collect a significant amount of particulate, making the air and equipment cleaner while keeping particles safely contained. According to Decker’s article, they also:

  • Protect users from potent compounds – the user does not have to contact wet or dry material
  • Offer flexibility – vacuums can access hard-to-reach spaces as well as easily clean overhead areas and maneuver around equipment.
  • Remove airborne particles – other cleaning methods only remove particles from surfaces, not the air itself. This can help extend the life of the cleanroom filter(s).
  • Removal of dust and other particles is more thorough – not only do they access more areas with ease, vacuums are more reliable to remove what the eyes cannot see.
  • By buying more than one vacuum, facilities can create an even more effective maintenance schedule. Decker says about using multiple vacuums: “…Facilities can streamline cleaning procedures, increase efficiency, and establish proper protocol for maintaining a cleanroom’s integrity.

Surely there are facilities where it would not make sense to buy a vacuum cleaner for the cleanroom(s). In many cases, however, it seems that these industrial vacuums offer superior protection and also an easier means of cleaning for employees. As always, a person should research products before investing. If a cleanroom operator decided to look into buying a vacuum, his options promise to be diverse and impressive. Guidance is always available from the manufacturers as well as colleagues and industry forums.

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