COVERSTORY
Repeatable accuracy goes modular
Many of the processes that are used in PV production have transferred from other industries, especially microelectronics’ manufacturing although currently not with the same exacting requirements. As the PV industry nears market acceptance, manufacturers need to develop unique selling points to differentiate from competition. More of the advanced manufacturing processes can come in to play to improve many aspects of devices. A key measure for manufacturers will be repeated reliable outcomes. DEK discusses the importance of repeatable accuracy for the PV industry and demonstrates how their offerings are meeting this need.
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ong used by the semiconductor and circuit board assembly sectors as a tool for maximising end of line yields, reliability, and bottom line performance, Cpk, or the Process Capability Index, is fast becoming critical for the PV industry too. A sophisticated and powerful metric that gives us an immediate measure for how appropriate our processes are for our current and future production needs, Cpk indicates at a glance how tightly controlled those processes are, and how comfortably they fit within our manufacturing specifications. In other words, Cpk describes the degree of repeatable accuracy within any given process. With growing pressure on manufacturers to increase solar cell efficiencies through new manufacturing techniques and technologies, Cpk will soon be key in providing invaluable information that will allow them to evaluate and compare equipment and make the right capital investment decisions for the future.
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One of the many reasons why Cpk is fast becoming so important, especially in the cell metallisation process, is Print on Print (PoP) technology, which is being developed to increase cell efficiencies by decreasing the surface area occupied, and therefore shadowed, by the collector grids. It does this by allowing grid
features to be printed to widths as narrow as 50µm without compromising their functionality. This is achieved by printing the grid twice over, increasing its height, and therefore its current carrying capacity.
As we at DEK know from our experience with the PoP procedure for the semiconductor and biomedical sectors, repeatable accuracy is key here. Primarily because without it, this degree of fine line work would simply be impossible. Furthermore, misalignment can wipe out the advantages of fine line PoP work by spreading line widths and therefore increasing the shadow effect. Accuracy is even more of an issue if we consider
DEK Eclipse 3600 metallization line
www.solar-pv-management.com Issue VI 2010
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