Clean Room: Clean Robot

While certain industries have suffered under a straining economy, many requiring cleanroom manufacturing are growing. Cleanroom robotic solutions will play a key part in this growth. What do you need to know about cleanroom robots and equipment to service this market? How are they different from traditional robots? What about certification, maintenance and those pesky particles? Following is a quick guide to all things clean when it comes to robots.

By virtue of its name, cleanrooms control the level of particle contamination present that can potentially degrade the products being manufactured. Cleanrooms are classified according to the number and size of the particles permitted per volume of air. For example, a Class 10 cleanroom denotes that no more than ten particles of 0.5 µm or larger and zero particles of 5.0 or larger are permitted per square foot of air. Contaminants can be generated by people, process, facilities and equipment. In order to control contaminants, the manufacturing cell and in many cases the entire room must be controlled. Robots used in this environment must meet stringent cleanroom certification requirements to prevent them for acting as a source of contamination.

The Robots

Adept Viper 850CR: Six axis cleanroom robot

How do cleanroom robots differ from their standard counterparts? Much of the hardware used in a cleanroom robot is the same as any other robot with the important exception of a combination of sealed covers (to prevent particles from escaping the robot), stainless steel hardware, proper non-gassing lubricants and vacuum to evacuate any internally generated particles.

"Robots designed for cleanroom processes have special considerations for harnesses. From a design standpoint the harness can be a serious particulate generator and a major design challenge for clean applications," said Scott Klimczak president of CHAD Industries, a pioneer in the area of wafer and substrate handling WLP I (Wafer Level Packaging) applications. "Understanding the harness requirements and how the robot design will integrate a harness should always be stressed in the robot selection."

As a matter of practice, materials prone to particle generation are substituted or coated to eliminate the potential for contamination of the manufacturing area and ultimately the components being processed. Depending on your application, cleanroom robots can be linear, SCARA, six-Axis or delta/parallel-type robots but they all must meet strict cleanroom certifications.

Robot Certification

External harness example

Certification is done by counting the number of particles that are generated when the robot is in motion. For this process the industry employs particle counters which have to be calibrated to meet or exceed the standards set by NIST (National Institute of Standards and Technology). In addition to NIST traceable practices, other standards of particle counter calibration include Japanese Industrial Standard (JIS) B 9921, Light Scattering Automatic Particle Counter, and ASTM F 328-98, Standard Practice for Calibration of an Airborne Particle Counter Using Monodisperse Particles. It is important to fully understand your requirements and the standards they adhere to. Adept Technology, Inc. a leading U.S. based manufacturer of cleanroom robots tests robots both internally and through third party testing and certification to ensure integrators and end-users deploy their equipment appropriately.

"Our robots are designed for high speed, precision applications frequently involving vision guidance. The challenge with this market segment is that it demands careful consideration of not only the components used to develop a highly robust manufacturing process but the manner in which they are integrated has significant impact on the ultimate cleanliness of the cell," said Rush LaSelle director of worldwide sales and marketing for Adept Technology, Inc., a leading manufacturer of intelligent vision-guided robotics. "The success of an installation is heavily dependent on tightly integrating engineering and sales teams."

The Right Fit

There are numerous options when considering how to manipulate parts and automate the cleanroom processes. What should you consider when choosing the right robot? Because each company has unique requirements the best approach is to begin by determining answers to the following questions and work directly with the robot manufacturer to select the optimal robot configuration.

What is the cleanroom specification?

There are two accepted clean room specifications, the ISO 14644-1 spec and the Fed 209E spec. Confusion and the improper clean specification will greatly impact the design and the cost of the machine. Following is a table that correlates the two:

ISO

1

2

3

4

5

6

7

8

FED

n/a

n/a

1

10

100

1,000

10,000

100,000

What is the required cycle time?

What are the work envelope requirements and associated interferences?

What is the tolerance stack-up for the process and ultimate repeatability requirement for the robot?

Internal harness example

Does your robot partner maintain experience in deploying cleanroom robots to help guide you in integrating a clean solution?

Does the robot company have service engineers in the area to support them?

Cell Geometry

The cell geometry and the cleanliness requirements are important to define before selecting a robot. Depending on the cell design and the robot style selected, a lower class robot may be able to be used and still meet the overall system requirements if the system is designed appropriately. For example if you are handling a semiconductor wafer, a robot that can operate under the wafer with a vertical laminar flow of clean air present sweeping the particles away from the product, the ultimate requirement for the robot may be less stringent.

Moving Forward

ISO Class 2 Reticle Handling System from CHAD Industries

Once you've determined which robot best fits your application, installing the cleanroom robot requires additional attention to cleanliness. This is where your robot manufacturer and system integrator must be capable of providing direction to ensure a successful installation. The following are a few examples of how deploying a clean robot differs from that of cells in an ambient environment.

"Robots built for Class 1 environments are wrapped in several layers to protect them as they are shipped to the site," said Kevin Lonie, application sales manager for Clear Automation a Connecticut-based automation integrator specializing in the design, engineering, fabrication and installation of integrated robotic and machine vision systems. "Then at the site the equipment is moved through progressively cleaner spaces as the wrapping is wiped down and finally removed before entering its ultimate clean room destination."

To avoid spreading particles during installation, the robots and all other accessories should be wiped with cleanroom wipes to remove any foreign particles. Once this is done, it is a good practice to connect the robot to the plant's vacuum system and evacuate the robot for several hours to make sure all particles are purged completely. In the semiconductor and hard-disk drive industries, it is difficult to avoid having people working in a cleanroom because of monitoring tasks, non-robotic material handling steps, etc.

AdeptPython CR1ESD: Cleanroom linear module

But minimizing the number of people working within the cleanroom environment allows a manufacturer to better maintain a clean environment. So it's fortunate that today's highly reliable servo-driven robots require minimal maintenance. Industrial robots are being implemented increasingly in cleanrooms due to their exceptional meantime between failure (MTBF) rate when compared to conventional equipment. "Adept cleanroom robots use scavenging to remove the particles, so the amount of maintenance is minimal to none," added LaSelle.

Automating cleanroom processes will increase production, reduce cycle times and decrease manufacturer's costs. Value exists in fully understanding how to deploy robotics and related technologies in cleanroom environments in advance of commissioning to ensure a successful and clean process.

Rush LaSelle is director of worldwide sales & marketing for Adept Technology, Inc. Adept Technology, Inc. is a leading provider of intelligent vision-guided robotics and global robotics services
http://www.adept.com/products/robots

Chad Industries is a leading automation integrator providing advanced motion control, vision and robotics solutions http://www.chadindustries.net/about_us/index.htm

Clear Automation specializes in the design, engineering, fabrication and installation of integrated robotic and machine vision systems http://www.clearautomation.com/Clear03a.html