|“Today’s System is
tomorrow’s IC”. Let’s learn about IC
test history and how it can help System Test
|Reviewing IC test
history can help to understand where PCB and System Test methodologies are
today and the direction they will go in the future. The dates that will be
shown are just generalizations on the industry, some companies will have
different time lines.
Mid-1980s Functional Test dominated
digital IC test methods.
functional test development times and decreasing stuck-at fault coverage
drove development of internal scan
chains that were inserted in the IC design.
Internal scan enabled ATPG
(Automatic Test Pattern Generation) tools to generate test patterns for high
stuck-at fault coverage.
companies/vendors using ‘ad-hoc’ approaches and non-structured DFsT such as
‘partial scan’. At-Speed tests were normally performed with Functional
Test. Some companies (HP, IBM) have advanced methods for at-speed tests using
|Late 90s-2000 – All
companies using ‘partial scan’ gone. All digital IC test include structural
scan-based test for stuck-ats. Scan
infrastructure in IC is standard. BIST
|2000-Present – Test
times (due to IC density) and capital equipment costs have driven embedded IC
test (BIST). IC functional speeds
surpass speed of ATE, hence on-board or scan-based at-speed structural test
is adopted by many companies
|Beyond - More standardization on at-speed structural
test either embedded or executed with low cost/low speed tester. Noise, crosstalk, signal integrity test
problems need to be solved. Standards
such as P1500 enable test re-use, so test vectors follow building blocks.