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Ball Transfer Units For Panel Makers

Ball Transfer Units Run Smoother With DuPont™ Vespel® Parts

The search for a better way to handle sensitive flat-panel displays and photovoltaic panels led Japanese company ISB (Iguchi Kiko Co., Ltd) to the DuPont™ Vespel® business.

The result: a unique collaboration and a high-performance solution, which led to a joint patent and an ISC ball transfer unit and ball table uniquely designed to meet the demands of cleanroom environments.

The Challenge

Flat-panel displays and solar panels use sensitive semiconductors that can be damaged by even minute particles of dust or metal. The standard alignment method, which uses solid pins to align the delicate glass panels, can “generate particles and result in high friction, due to repeated abrasive motion,” said Hiroshi Kawai, marketing department director at ISB.

There was a strong need to improve the process, and a new system, using ball transfer units and tables, was seen as a promising idea, with potential to reduce the force and friction required to move the panels.

“But nobody believed that ball transfer units would solve the problem, because of the number of metal parts moving within them, which was seen as the source of contamination by cleanroom process engineers,” Kawai said.

After analyzing the problem, DuPont and ISB saw that a solution might be possible, by replacing metal with high-performance custom Vespel® parts. That was the start of a six-year collaboration, and an innovative new cleanroom application.

The Solution

Ball transfer units are used in industrial conveyer systems as part of ball tables, which transport products and materials by rolling rather than on belts. DuPont worked with the ISB team to create a cleanroom application that would eliminate steel in the balls and their housings, and with it the problem of contamination from metal powder created as panels moved over the ball transfer units.

In addition, DuPont was tasked with providing a replacement material able to stand up to heat and chemicals, both of which are also part of the panel assembly process.

“The proven performance of Vespel® parts and shapes in highly demanding semiconductor applications in terms of their purity, wear resistance and wide range of thermal resistance, was one principal reason to work with DuPont,” said ISB President Iguchi. “The other is the strong emphasis on development support for the material and testing.”

Early in the partnership, DuPont application experts determined that the high surface hardness and stiffness of Vespel® meant it could potentially replace steel, and solve the particle problem. What’s more, Vespel® would be able to match and, in some areas, improve on the performance of steel in phases of the assembly process involving chemicals and high heat.

Over a period of years, the DuPont team worked closely with ISB to create precise material specifications and an overall technical solution designed specifically for flat-panel display and solar panel manufacturers.

This work ultimately yielded a joint patent, awarded to ISB and DuPont, for new ISC ball transfer units for cleanrooms. The units use custom-designed Vespel® parts for the main body, the balls inside the units and the large ball on which the panels rest.

In addition to reducing particle generation, the ISB/Vespel® units provide excellent performance in high-heat portions of the process, while the erosion resistance of Vespel® parts prevents depositing of chemical substances, further reducing the risk of contamination.

Key Advantages

In general, the high surface hardness and stiffness of the Vespel® parts was the key advantage that made a steel-free cleanroom solution possible. It allows Vespel® parts to hold their shape under the weight of the panels, while its high heat deflection temperature (above 300°C or 572°F) controls deformation caused by the weight of panels.

A range of Vespel® series were chosen for different custom applications, including:

  • Vespel® SP-202, which decreases electrostatic loading in the manufacturing and handling of flat glass panels for liquid crystal displays, is ideal for use with products that are handled in high-temperature, in vacuums or in reactive environments.
  • Vespel® SCP-5000, which offers ultra-high purity and high stiffness.
  • Vespel® SP-1, which provides exceptional wear resistance, insulation, and a low coefficient of friction.

Initially designed for one client, the ISC ball transfer for cleanrooms has been chosen by flat-panel display and photovoltaic manufacturing engineers at manufacturers in multiple countries in Asia and North America. “With DuPont as a key development partner,” said ISB President Iguchi, “we will continue to develop new products, new applications and new markets.”

High-Performance Solutions

At DuPont, our design experts are ready to collaborate with you in finding high-performance solutions for flat-panel and solar-panel applications that last longer and lead to greater overall productivity. Call your Vespel® representative today, so we can begin development.