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Unformatted text preview: /90 WGR. Transferring 38 wafers from Product A to Product C changes wafer quantities to 142/30/128 WGR, or 47/10/43%. This is the tool purchase point— the product mix at which a tool would just have to be
% OF TOTAL PRODUCTION VOLUME TOOL GROUP % OF LIGHTESTLOADING PRODUCT 21% 22% 29% 61% X Y W V 38 39 52 55 13% 13% 17% 18% Figure B: Distance from Forecast Mix to First Tool-Purchase Point, by tool group, sorted from smallest (i.e., most sensitive) to largest by number of wafers. DISCUSSION Although Figure B shows product mixes that will cause capacity shortfalls, this list is by no means all-inclusive. This is because, given the number of products in the model, with each product loading each tool group to a different degree per wafer, the combination of product mixes that can cause a capacity shortfall is overwhelming. By making the assumption that, for each tool group, unfavorable productmix changes only occur through the transfer of wafers from the lightest-loading product to the heaviest loa...
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This note was uploaded on 04/11/2011 for the course ECE 357 taught by Professor Subjolly during the Spring '11 term at National University of Ireland, Galway.
- Spring '11