Newsroom
NEMI's Test Strategy Project Releases Cost Model that Allows PCA Manufacturers to Compare Costs of Alternative Test Strategies
HERNDON, Va. - May 14, 2003 - The Test Strategy
Project of the National Electronics Manufacturing Initiative (NEMI) has
released a manufacturing test strategy cost model designed to help
printed circuit assembly (PCA) 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. It is available to industry (free of charge) on
the NEMI website at http://www.nemi.org/cms/projects/TSCM/test_strat_cost_model.html.
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 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
AOI (automated optical inspection) and AXI (automated x-ray inspection)
techniques. However, it is often difficult to know which method - or
combination of methods - will provide the best results.
"Our team's goal was to develop a simple cost modeling tool that
could be utilized to make decisions between manufacturing test
strategies," said Rosa Reinosa, test program manager for HP and leader
of the test cost model team. "Our approach was to create a generic,
industry-standard economic model, leveraging our companies' respective
economic models to produce a common solution."
Six companies participated in the test cost model project team:
Agilent Technologies Inc., Delphi Electronics, HP, Intel Corporation,
Solectron Corporation 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 NEMI test strategy cost model is intended to enable companies to
make trade-off analyses and decisions based on the financial impact
that a strategy may have on an organization. The model has the ability
to compare two different PCA test strategies and, for each strategy,
provide cost, yield enhancement savings, defects escaping out of the
strategy, DPMO or yield for each test stage, ROI (return on investment)
metrics and time-to-market savings.
Several cost variables are considered in the model, including
equipment, maintenance, scrap, repair and field return costs. To
determine the ROI, the tool utilizes the initial investment, payback,
net present value and internal rate of return calculations. For the
time-to-market analysis, investments in R&D, cost of goods sold
(COGS), sales and marketing, and general administrative costs are
factored into the equation. A detailed user's guide (also available on
the NEMI website) walks users through all of the steps and the inputs
required for the calculations.
"The model can compare two different test strategies and provide
visibility to strategy costs and potential savings in warranty costs,
test effectiveness and yield improvement," explained Carlos Michel,
test engineer for HP and co-leader of the test cost model team. "The
user enters into the spreadsheet detailed information about the PCA to
be tested and about the test strategies under evaluation. Of course,
the more complete and accurate the information entered, the more
accurate the outputs of the model will be. However, if an input is
unknown due to lack of data because there is no history on the
product's strategy, the user can enable the model's default values,
which are built into the tool."
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 metrics and
time-to-market savings.
"We would like to see industry-wide adoption of this test strategy
cost model," said Michel. "The methodologies utilized across industry
today generate different results because they are not based on a common
set of financial drivers. Standardization of the economic analysis of
production test strategies will bring consistency to the overall
approach for determining the financial impact of various test
techniques."
About NEMI
The National Electronics
Manufacturing Initiative's mission is to facilitate leadership of the
North American electronics manufacturing supply chain. Based in
Herndon, Va., the industry-led consortium is made up of approximately
65 electronics manufacturers, suppliers, industry associations and
consortia, government agencies and universities. NEMI roadmaps the
needs of the North American electronics industry, identifies gaps in
the technology infrastructure, establishes implementation projects to
eliminate these gaps (both business and technical), and stimulates
standards activities to speed the introduction of new technologies. The
consortium also works with government, universities and other funding
agencies to set priorities for future industry needs and R&D
initiatives. For additional information about NEMI, visit http://www.nemi.org/.
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For further information:
Cynthia Williams
207-871-1260
cynthiaw@maine.rr.com