Proof testing of standard and high strength coverglasses (for solar cell arrays)

The development of techniques for producing high-strength coverglass with mean strength improvement factors of 12 is presented. The manufacture of apparatus to provide a repeatable proof strength test for standard and high-strength coverglass is also presented. The feasibility of the proof testing method and a potential benefit to both manufacturer and integrator is demonstrated. An additional advantage is that as a test standard it can be easily verified. A chemical process is described whereby the removal of surface material is used to modify the surfaces such that they are less susceptible to breakage under stress. In this way coverglasses achieve strength improvements of greater than ten times their original strength. The strength enhancement process can be used for edge or complete surface treatment to reduce handling losses and produce high-strength coverglasses of large size and reduced thickness. The process can be extended to make ultrathin coverglasses, i.e. less than 50 mu m thick.