IE33433B1 - Apparatus for coating by thermal evaporation - Google Patents

Abstract

1,250,544. Vapour deposition apparatus. LIBBEY-OWENS-FORD CO. Feb. 25, 1969 [Feb. 29, 1968], No. 9900/69. Heading C7F. Apparatus for coating sheets by vacuum deposition comprises an evaporation chamber A for containing a source of material to be evaporated 123, first evacuating means for establishing a vacuum in said chamber, means for evaporating said material, a coating chamber B adjacent said evaporation chamber, means in said coating chamber for supporting a sheet to be coated, second evacuating means 239 for creating a vacuum in said coating chamber B, a valve compartment located between said evaporation chamber and said coating chamber, a plate valve D mounted in said compartment for movement from a closed position between said evaporation and coating chambers where it separates and hermetically seals said chambers from one another to an open position placing said chambers in intercommunication, a shield 400 mounted in said evaporation chamber, and means for moving said shield into said valve compartment, said shield forming a conduit through said valve compartment and shielding said plate valve from evaporated material passing therethrough. The substrate sheet may be glass and the coating material may be Al, Cr, TiO 2 or MgF 2 . With the lid 206 in an open position Fig. 1 (not shown) plate valve D, horizontally slidable between chambers A and B, is placed in the closed position, and using a combination of pumps, chamber A is pumped down to operating pressure, about 4.5 x 10<SP>-6</SP> microns of mercury. The sheet of glass to be coated is placed on a rotating support in chamber B, and the lid 206 is closed and chamber B evacuated via conduit 239. This automatically energizes a glow discharge unit 265 Fig.12 (not shown), to clean the glass sheet, and the glow-discharge cleaning ends when the air-content of B will no longer sustain a discharge. Then, plate valve D is automatically retracted and cylindrical shield 400 which prevents accumulation of coating material on valve D is raised by piston 404 to a position such that it forms a conduit between chambers A and B. Evaporation source E, comprising an electron beam generator 435 and focusing magnets 437, 437, is activated after lifting of crucible lid 136, so that material in crucible 123 is evaporated, to coat the substrate. The coating thickness is monitored by a light beam L from source 445 which directs a beam through the substrate sheet and window 452 in lid 206 toward a meter 446, Fig. 3 and when a suitable coating thickness has been deposited on the substrate, the shutter 136 is put over crucible 123, the shield 400 is lowered, valve D is closed, and the pressure in chamber B is raised to atmospheric, and the lid opened for removal of the coated sheet. A shield 114 is provided in the chamber A to protect the light source and vacuum system 111, and means for replenishing the supply of coating material in the crucible without breaking the vacuum in chamber A, including a moveable cart 461 of material, is provided. The aim of the apparatus is to provide a coating process wherein the vacuum in the evaporation chamber need not be broken whilst the substrate is removed and replaced and the crucible re-loaded. The apparatus is described in detail, as are automatic control circuits therefor. [GB1250544A]