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by many unrelated subcontractors transfers boards in batches
between machines on the manufacturing floor. This results in
inventory buildup and increases the defect rate due to reduced
quality controls.
After assembly, the PCA's are tested to guarantee that the
PCA is functioning properly. There are two types of tests that
Compaq U.S. performs: In-circuit tests (ICT) and functional
tests. The more precise of the two is ICT. Compaq U.S. uses
GenRad testers and specific test programs to perform ICT's and is
able to pinpoint specific defects. Functional tests generally
detect whether there are defects in the PCA. If an error is
found, additional procedures must be performed to locate the
specific error.
These tests monitor quality by scrutinizing first-pass
yields, the percentage of PCA's that pass tests the first time
tested. PCA's that pass these tests the first time are
considered to be of higher quality. A PCA that fails either the
ICT or functional test is repaired or reworked until the PCA
passes the tests and meets the Compaq U.S. quality standards. If
the PCA cannot be repaired, it is scrapped. The time and
personnel required to debug and rework a board add to the PCA's
cost and degrade the PCA's quality and reliability.
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Last modified: May 25, 2011