NEMI Project: free model compares costs of test strategies.The Test Strategy Project of the National Electronics Manufacturing Initiative (NEMI NEMI National Electronics Manufacturing Initiative NEMI National Environmental Methods Index , Herndon, VA, www.nemi.org) has released a manufacturing test strategy cost model designed to help printed circuit assembly (PCA (tool, programming) PCA - A dynamic analyser from DEC giving information on run-time performance and code use. ) manufacturers determine the financial impact of selecting a particular test strategy. The model, which uses an Excel-based spreadsheet format, is intended for use on post-reflow PCA test strategies. The project was organized to address the loss of physical access and fault coverage at in-circuit test (ICT (1) (Information and Communications Technology) An umbrella term for the information technology field. See IT. (2) (International Computers and Tabulators) See ICL. 1. (testing) ICT - In Circuit Test. ) caused by the physical space constraints of increasingly dense interconnections and packaging designs. Project activities were organized into three working groups: test coverage analysis, test vehicle analysis and test strategy cost model. Reduced fault coverage, combined with limited diagnostic resolution at ICT and functional test (FT), can lead to excessive debug times. Electronics manufacturers are finding that they can no longer use a single method of test for PCAs and are increasingly combining ICT with automated optical inspection Automated Optical Inspection (AOI) is an automated visual inspection of PCB(or LCD,transistor manufacture) where a camera autonomously scans the device under test for both catastrophic failure (eg. missing component) and quality defects (eg. (AOI AOI Area Of Interest AOI Automated Optical Inspection AOI Art of Illusion (3D modeling software) AOI Associated Oregon Industries AOI Angle Of Incidence AOI Age of Innocence (David Hamilton book, also a band) ) and automated x-ray inspection Automated x-ray inspection (AXI) is a technology based on the same principles as automated optical inspection. It uses x-rays as its source, instead of visible light, to automatically inspect features, which are typically hidden from view. (AXI) techniques. However, knowing which method--or combination of methods--will provide the best results is often difficult. Six companies participated in the test cost model project team: Agilent Technologies Inc.; Delphi Delco Electronics Systems; HP; Intel Corp.; Solectron Corp.; and Teradyne Inc. The cost model they developed estimates the cost of finding and repairing manufacturing assembly defects using various types of test and inspection strategies. Users of this model should be able to define the potential advantages and disadvantages of each test technique and to understand the impact of removing test stages vs. sampling strategies vs. 100% inspection or test methods. The output of the model provides a description of the yield and defect levels achieved at each test stage, a summary of costs, a graphical cost comparison of the strategies, ROI (Return On Investment) The monetary benefits derived from having spent money on developing or revising a system. In the IT world, there are more ways to compute ROI than Carter has liver pills (and for those of you who never heard of that expression, it means a lot). metrics and time-to-market savings. The manufacturing test strategy cost model and detailed user's guide are available free of charge at www.nemi.org/projects/TSCM/ test_strat_cost_model.html. |
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