Photonic curing

Photonic curing is the high-temperature thermal processing of a thin film using pulsed light from a flashlamp.[1] When this transient processing is done on a low-temperature substrate such as plastic or paper, it is possible to attain a significantly higher temperature than the substrate[2] can ordinarily withstand under an equilibrium heating source such as an oven.[1][3] Since the rate of most thermal curing processes (drying, sintering, reacting, annealing, etc.) generally increase exponentially with temperature (i.e. they obey the Arrhenius equation), this process allows materials to be cured much more rapidly than with an oven.[3][4]

It has become a transformative process used in the manufacture of printed electronics as it allows inexpensive and flexible substrates to be substituted for traditional glass or ceramic substrates. Additionally, the higher temperature processing afforded by photonic curing reduces the processing time exponentially, often from minutes down to milliseconds, which increases throughput all while maintaining a small machine footprint.

Uses

Photonic curing is used as a thermal processing technique in the manufacturing of printed electronics as it allows the substitution of glass or ceramic substrate materials with inexpensive and flexible substrate materials such as polymers or paper. The effect can be demonstrated with an ordinary camera flash.[5] Industrial photonic curing systems are typically water cooled and have controls and features similar to industrial lasers. The pulse rate can be fast enough to allow curing on the fly at speeds beyond 100 m/min making it suitable as a curing process for roll-to-roll processing. Material processing rates can exceed 1 m2/s.[3][6]

The maturing complexity of modern printed electronics for customer applications demands high throughput manufacturing and improved device function. The functionality of the printed electronics is critically important as customers demand more out of each device. Multiple layers are designed into each device, requiring ever more versatile processing techniques. Photonic curing is uniquely suited to complement the processing needs in the manufacture of modern printed electronics by providing a fast, reliable and transformative processing step. Photonic curing enables a lower thermal processing budget with current materials, and it can provide a path to incorporate more advanced materials and functionality into future printed electronics.

Development

Photonic curing is similar to Pulse Thermal Processing, developed at Oak Ridge National Laboratory, in which a plasma arc lamp is used. In the case of photonic curing, the radiant power is higher and the pulse length is shorter. The total radiant exposure per pulse is less with photonic curing, but the pulse rate is much faster.[7]

References
  1. K. A. Schroder, Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Trade Show, 2, 220-223, 2011.
  2. "Mechanisms of Photonic Curing™: Processing High Temperature Films on Low Temperature Substrates" (PDF).
  3. K. A. Schroder, S. C. McCool, W. R. Furlan, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, 3, 198-201, 2006.
  4. "In flexible electronics, it's all about protecting the paper". Research & Development. Archived from the original on 25 July 2012. Retrieved 24 December 2014.
  5. US Pat. #7,820,097.
  6. "NovaCentrix R&D 100 Award Winner, 2009" (PDF). Archived from the original (PDF) on October 1, 2011. Retrieved July 18, 2011.
  7. "Materials Process Group, OakRidge". Archived from the original on October 1, 2011. Retrieved July 19, 2011.
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