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| Vitex Edge-Seal |
To obtain economies of scale, all flat panel displays in production are made by
fabricating multiple displays on a single glass substrate. At a later stage of
manufacture, the individual displays are separated by cutting the glass along
the borders of each display.
If the Barix™ coating were to extend continuously over the full glass
substrate, the cut edges would expose the polymer layers to the atmosphere.
This would, over time, result in the diffusion of water vapor into the polymer.
Since all the layers would be cut, the water vapor would have a much shorter
diffusion path and result in an unacceptably short lifetime for the device.
| NOTE: Layer and display thicknesses are not to scale |
| Cut surfaces |
To overcome this problem, Vitex has developed a patented and proven
method to provide an edge-seal inside the cut surfaces of the 'mother glass'.
The method of sealing the edge is accomplished through limiting the extent of
the polymer to just less than that of the barrier, while still extending over the
device to be protected.
The figure below shows three examples of encapsulated metallic calcium thin
films. These samples have completed accelerated aging for 750 hours at 60
degrees Celsius and 90 percent relative humidity. The three samples on the left
show encapsulation that does not use any method of edge seal. The barrier
and polymer layers extend to the edge of the glass. The shape of the calcium
rectangle has become rounded as water vapor has diffused in from the edges
and reacted to form transparent calcium oxide.
The middle set of three samples have an edge seal that has been made using
an ineffective process. The barrier performance is worse than no edge seal.
This shows the importance of implementing a robust method of edge seal.
The three samples on the right were prepared using Vitex's edge seal. Even
after the accelerated aging of 750 hours at elevated temperature and humidity,
the rectangles of calcium have retained there sharp corners and edges.
The Vitex edge-seal is a capability that is available on the Guardian™ thin-film
encapsulation systems. When used with CCD vision alignment and precision
hardware, the Vitex edge-seal has been implemented with an edge-seal width
of less than 0.5 mm (< 500 microns).
