Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report. Page: 33 of 66
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Types of Circuitry. One of the early evaluations was directed toward deter-
mining if there existed a packaging technique and a particular circuit type
that could be considered representative of the present and future telemetry build.
In one telemetry assembly, 80 to 90 percent of the electrical circuit components
were mounted on some type of printed circuit board. Some of these boards
had over 90 percent of their components integrated into sealed packs, where-
as others employed only discrete components. Over 90 percent of the
circuitry was switching or pulse circuitry, and a majority of these circuits
were logic switches of some type.
The technical problems associated with verifying that integrated circuit
components meet their component requirements are indeed different from
those used to verify that a discrete resistor or capacitor meets requirements,
The integrated circuit has many components that are not accessible from the
outside of the sealed package, making a functional check of the individual
package necessary to verify the electronic validity of the component. Dis-
crete components may be more precisely evaluated by measuring parameters
such as resistance and capacitance. This is true only when parallel-circuit
guarding can be accomplished.
The typical fabrication errors were found to be very similar. Some of the
more common errors were shorts between adjacent component leads, mis-
located or interchanged components, misoriented components, improper
wiring, missing components, solder-splatter and wire-clipping shorts, and
open welds or solder joints.
Functional evaluations of integrated circuit logic, in general, are more
easily accomplished than evaluation of linear circuitry, since only one low-
voltage B supply is necessary, and excitation voltage amplitudes are often
Universal Tester Versus Individual Testers. Feasibility studies were
.extended to evaluating the choice between a large automatic universal type
of tester that could be adapted to a large number of assemblies versus a
series of small, relatively inexpensive testers designed to test specific cir-
cuitry. The main advantage of the universal type of tester is the economic
gain resulting from long term program-to-program usage. These gains can
be realized only if product configuration is standardized to the point that the
features required to make the tester universal remain simple enough to make
the tester economically feasible. The small tester is more flexible in
application, and can be located in the production line, so the assembler can
evaluate each assembly immediately after build. This results in rapid
feedback to the production line. A group of smaller, specialized testers may
also require less initial cost than the universal type of tester because ex-
pensive computer or tape-type controls can be eliminated when design is
optimized toward testing specific circuitry.
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Losure, J. A. Diagnosis of Malfunctions in Complex Electronic Assemblies. Final Report., report, January 1, 1971; Kansas City, Missouri. (https://digital.library.unt.edu/ark:/67531/metadc1031893/m1/33/: accessed March 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.