Manufacturing Test Strategy Cost Model

The selection of an adequate set of test and inspection techniques to verify the quality and functionality of a product, as well as, the integrity of the manufacturing process can be a complex task. This selection process would normally require a detailed technical assessment on the effectiveness of each test technique, trade-off analysis among alternate test techniques/platforms and an economic evaluation of the various options available. In industry today, there are many methodologies utilized to derive the Return-On-Investment (ROI) analysis of a particular manufacturing test strategy. Although, industry methodologies may have strong similarities, they also highlight unique differences in the approach towards justifying a particular approach. The Test Strategy Project of the National Electronics Manufacturing Initiative, Inc. (NEMI) completed, in April 2003, the development of a Manufacturing Test Strategy Cost Model that could be utilized by Printed Circuit Assembly (PCA) manufacturers to benchmark and measure the financial impact of selecting a particular test strategy, perform trade-off analysis among various test strategies and gain visibility on the impact of field failures on warranty costs. This model embraces the best practices and methodologies used by the participating companies (Agilent Technologies Inc., Delphi Delco Electronics Systems, HP, Intel Corporation, Solectron Corporation and Teradyne Inc.). At the same time, the test cost model seeks to standardize and simplify the process of performing an economic evaluation of a manufacturing test strategy. Background Model Description The NEMI Test Strategy Project was organized to address the loss of physical access and fault coverage at In-Circuit Test (ICT) caused by the physical space constraints of increasingly dense interconnections and electronic packaging designs. Project activities were organized into three working groups: test coverage analysis, test vehicle analysis and test strategy cost model. Electronic manufacturers are finding that they can no longer utilize a single test method to verify the quality of a PCA and are increasingly combining various electrical, structural and inspection test techniques. Through a technical assessment one can determine which method or combination of methods will provide the best test coverage. However, an electronic manufacturer will make a decision based on the results of the effectiveness of a test technique or sets of techniques, as well as, on the financial impact of a test strategy to a company’s bottom line. The test strategy cost model can help drive quick decisions by demonstrating the value of adding or removing test stages vs. utilizing sampling strategies vs. 100% inspection methods. Users of the model can determine the drivers of making a test strategy a viable option such as PCA volumes, PCA costs, investments vs. returns, etc. The model is available as an Excel spreadsheet and it is intended to be used on post-reflow PCA test strategies. It comprises of 4 major sections: Inputs, Defaults, Calculations, and Outputs Sections (See Figure 1).