ANNEALING METHOD USING FLASH LAMPS

Abstract

A process that anneals a surface of a substrate bearing a coating includes running the substrate under a flash lamp emitting intense pulsed light and irradiating the coating with the pulsed light through a mask located between the flash lamp and the coating. A frequency of the flash lamp and a run speed of the substrate are adjusted so that each point of the coating to be annealed receives at least one light pulse. A distance between a lower face of the mask and the surface of the coating to be annealed is at most equal to 1 mm. A shape and extent of a slit in the mask are such that the mask occults the coating to be annealed in all zones where the light intensity that, in an absence of the mask, would arrive at the coating to be annealed is lower than a threshold light intensity.

Claims

1-9. (canceled)

10. A process for annealing a surface of a substrate bearing a coating, said process comprising: running the substrate bearing the coating to be annealed under a flash lamp emitting intense pulsed light, the surface of the substrate that bears said coating being turned toward the flash lamp; and irradiating the coating to be annealed with the intense pulsed light emitted by the flash lamp through a mask located, in a fixed position relative to the flash lamp, between the flash lamp and the coating to be annealed and comprising a slit, a longitudinal axis of the slit being perpendicular to a run direction of the substrate, a frequency of the flash lamp and a run speed of the substrate being adjusted so that each point of the coating to be annealed receives at least one light pulse, wherein a distance between a lower face of the mask and the surface of the coating to be annealed is at most equal to 1 mm, and a shape and extent of the slit are such that the mask occults the coating to be annealed in all zones where the light intensity that, in an absence of the mask, would arrive at the coating to be annealed is lower than a threshold light intensity called a nominal light intensity.

11. The process as claimed in claim 10, wherein the distance between the lower face of the mask and the surface of the coating to be annealed is at most equal to 500 μm.

12. The process as claimed in claim 10, wherein the distance between the lower face of the mask and the surface of the coating to be annealed is at most equal to 100 μm.

13. The process as claimed in claim 10, wherein the slit has a substantially rectangular shape.

14. The process as claimed in claim 10, wherein the frequency of the flash lamp, a width of the slit, and the run speed of the substrate are such that at least 90% of the points of the coating to be annealed receive a single light pulse.

15. The process as claimed in claim 10, wherein a length of the slit is substantially equal to a width of the coating to be annealed.

16. The process as claimed in claim 10, wherein a width of the coating to be annealed is at least equal to 1 m.

17. The process as claimed in claim 10, wherein a width of the slit is between 1 and 50 cm.

18. The process as claimed in claim 10, wherein the run speed of the substrate bearing the coating to be annealed is between 0.1 and 30 m/minute.

19. The process as claimed in claim 10, wherein the coating to be annealed comprises at least one film of a metal.

20. The process as claimed in claim 19, wherein the at least one film of a metal includes a silver film.

21. The process as claimed in claim 10, wherein the coating to be annealed comprises at least one film of a transparent conductive oxide.

22. An apparatus for annealing a surface of a substrate bearing a coating, comprising: a flash lamp configured to emit intense pulsed light; conveying means for running a flat substrate bearing the coating to be annealed in front of the flash lamp; a mask located, in a fixed position relative to the flash lamp, between the flash lamp and the conveying means, said mask comprising a slit, a longitudinal axis of the slit being perpendicular to a run direction of the substrate, and the slit being positioned so that the light emitted by the flash lamp is projected through the slit in a direction of the flat substrate bearing the coating to be annealed; and means for adjusting a distance between the mask and the conveying means such that a distance between a lower face of the mask and the surface of the coating to be annealed is adjustable to a value lower than 1 mm.

23. The apparatus according to claim 22, wherein the distance between the lower face of the mask and the surface of the coating to be annealed is adjustable to a value lower than 500 μm.

24. The apparatus according to claim 22, wherein the distance between the lower face of the mask and the surface of the coating to be annealed is adjustable to a value lower than 100 μm.

Description

[0071] The invention is explained in greater detail with reference to the figures.

[0072] FIG. 1 shows a photograph of a substrate bearing a Planitherme® ONE coating irradiated under the conditions such as indicated above in the absence of a mask. Periodic horizontal striations can be seen, spaced apart by about 2.6 cm.

[0073] FIG. 2 is a photograph of a Planitherme® ONE substrate treated according to the process of the invention. The striations visible in FIG. 1 have completely disappeared by virtue of the interposition of a mask under the conditions according to the invention.

[0074] FIG. 3 is an explanatory schematic showing the operation of the process of the present invention and, more particularly, the appropriate position of the irradiation mask in relation to the light intensity profile of the lamps.

[0075] In this FIG. 3 a continuous flat substrate 1 bearing a coating 2 to be annealed is conveyed by rollers 6 in the run direction indicated by the arrow.

[0076] The coating 2 to be annealed is irradiated with light emitted by an array of lamps 4 and directed downward by means of a set of mirrors 5, through a mask 3. The distance between the two portions of the mask 3 corresponds to the width of the longitudinal slit.

[0077] The distance between the lower face of the mask 3 and the upper face of the coating 2 to be annealed is smaller than 1 mm.

[0078] In the bottom portion of the figure the intensity profile of a light pulse such as would exist level with the coating 2 to be annealed in the absence of the mask 3 is shown. The mask 3 is positioned such that light having an intensity lower than the nominal intensity is intercepted by the opaque zones of the mask.