Clean
Room: Clean Robot
Automating cleanroom processes will increase production, reduce cycle times and decrease manufacturers' costs.
Written
By:
Rush LaSelle, Director, Adept Technology, Inc.
Published
on IndustryWeek.com March
2010.
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
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. |
Adept
Viper 850CR: Six axis cleanroom robot |
Robot
Certification |
|
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. |
External
harness example
|
"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?
o 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?
* 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
o
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.
|
Internal harness example
|
Moving Forward
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.
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. |
AdeptPython CR1ESD: Cleanroom linear module |
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
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