Innovative design exposes all parts of display manufacturing facility
U-shaped cleanroom gives operators a view of the outside, engineers/managers a view of the process line, and customers a view of the manufacturing area.
By Norm Verboort, Planar Systems
When Planar Systems (Beaverton, OR) officials began to plan the design of the company`s new manufacturing facility for thin film electroluminescent (TFEL) flat panel displays, they were faced with quite a challenge. They had completed a study that mapped the existing process flow, which had product travelling 1,500 lineal feet while crossing mid-stream, and a preferred process flow, which followed a 400-foot straight line with no doubling back in the process.
How would they maintain a straight line flow concept while integrating process equipment, allowing for thin film expansion capabilities, limiting cleanroom space, allowing direct cleanroom viewing for customers, engineers and production supervisors, allowing production workers a view of the outside world, and fitting all of this into one of two buildings available for use? The answer: a U-shaped design.
The final U-shape design incorporated windows every 4 feet on the outside of the U. The outside wall was increased to 12 inches deep to handle the amount of return air required. Air returns were placed between the windows with adjustment dampers every 4 feet. Product is fed into one leg of the U and out the other leg. From start to finish the product never back tracks or crosses paths. Production equipment was through wall mounted to save on cleanroom space, and larger pieces of equipment were manufactured so that load and unload could be done from one end. Equipment was mounted on the inside of the U only, allowing room for over 40 windows on the outside of the U.
The cleanroom support equipment was placed on a mezzanine over the production equipment gray area in the center of the U. Planar elected not to go with packaged air handlers but instead went with six mid-cost utility fans. Each utility fan has its own cooling coil but is tied into a common duct that allows facility managers to maintain some level of cleanliness even if they lose an air handler.
Temperature and humidity control is handled through an Alerton Direct Digital Control system. With this system cleanroom employees control temperature at 68 degrees Fahrenheit ± 2 degrees and humidity at 45 percent ± 5 percent. They also use this system to vary the airflow as needed.
With this design company officials accomplished what they set out to do. Operators now have visibility of the outside world. Engineers and managers can keep an eye on process flow and have direct eye contact with the operators for quicker response and better communication. And customers can view the manufacturing area. Planar also created an optimum process flow while limiting the amount of cleanroom space required.
Planar acted as its own general contractor during the design and construction of this project. The facility was completed in 18 months from design to finished construction.
Facility details
Planar`s cleanrooms are used in the manufacture of TFEL flat panel displays. The process consists of two photolithography processes, thin film deposition, back plate assembly and product phosphor aging.
Cleanrooms are an important part of the manufacturing process at Planar. Two levels of cleanroom are used: Class 100 and Class 100,000. The Class 100 is used for all thin film and photolithography processes while the Class 100,000 is used for aging and glass assembly. It is imperative to good product performance and yield to maintain product cleanliness throughout the manufacturing process.
The new manufacturing building (Hillsboro, OR) consists of a 33,000-square foot warehouse, which was converted to 3,600 square feet of Class 100 cleanroom space and 5,600 square feet of Class 100,000 cleanroom space, where glass assembly and burn-in takes place. The balance of the facility is for production support personnel and cleanroom support equipment. This site is a stand-alone site dedicated to the manufacture of product with only maintenance, engineering, production and first line production managers on site. When in full production, 75 people will be employed in this facility across three shifts.
This ex pansion will more than double Planar`s manufacturing capabilities for TFEL in the United States.
Final costs of the facility were $3.2 million. This figure includes all costs including cleanroom and cleanroom sup port equipment. The only cost excluded was the building shell, which is leased.
Contamination control
While Planar`s display products are sensitive to contamination they are not as sensitive to the smaller particles as an integrated circuit (IC) would be. Yet the displays are more sensitive to the number of larger particles. One large particle in the 10-micron-and-higherrange may ruin the whole panel whereas a particle on a wafer will ruin only one die.
In the Class 100 cleanrooms, operators are required to wear full bunny suits including hoods, beard guards and cleanroom shoes. While in the Class 100,000 cleanroom, lab coats with hair nets and beard bags are required.
The air handling system was designed so the amount of air recirculated from 40 lfpm to 75 lfpm could be varied. This enables Planar officials to tailor the actual airflow to their needs. They reduce airflow during off shifts and return it to optimum airflow when the room is in full production. This results in a significant reduction in operating costs with no reduction in yields.
Norm Verboort is facilities director at Planar Systems, where he is responsible for all facilities and cleanroom construction projects. The projects have ranged from 700-square-foot cleanroom additions to the 33,000-square-foot manufacturing plant, just opened in Hillsboro, OR. He has spent over 20 years in facilities/maintenance in the electronics industry, of which the past 14 years have been at Planar Systems.
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Photos and floor plan courtesy of Shur Associates Architects (Portland, OR).
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A view of a section of the U-shape Class 100 cleanroom processing area. Windows give operators a view of the outside, while giving customers and engineers a view of the manufacturing line.
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A view of the office cubicles that surround the Class 100 cleanroom, giving engineers and process managers a view of the process flow.
Key facts:
Company background: Planar Systems was started in Beaverton, OR, in 1983. It is an information display company with manufacturing capabilities in the U.S. and Europe.
Size of new facility: 33,000 square feet of which 3,600 square feet is Class 100 and 5,600 square feet is Class 100,000.
Cost of facility: $3.2 million
Purpose of facility: To manufacture thin film electro luminescent flat panel displays.
The design/build team for this project consisted of:
General — Planar Systems; Architect — Shur Associates; Mechanical Engineer — Pacific Rim; Electrical — Oregon Electric; Mechanical — Harder Mechanical; Ducting — Superior Air Handling; Perimeter HVAC — Air Flow Controls; Structural engineers — TM Rippey; Floors and window coverings — Taggarts Interiors; Walls, ceilings, and mezzanine — C.G. Construction