Page 47 - Building A Succesful Board-Test Strategy

What is a Test Strategy? 33

Figure 1-11 A different view of the example in Figure 1-10. This time, the analysis
shows the failure rates for individual board types. Clearly, types A and B fail more than
three times as often as the other varieties.

and-repair operations. One maker of locomotive electronics, for example, supplies
local transportation departments, one of whom mandated not only spare boards
but also test equipment, fixtures, and test programs to allow full-blown testing in
the field. This arrangement added considerably to the manufacturing cost of the
product, consequently raising its price.
Another company is setting up service facilities around the world, trying to
furnish all of them with testers comparable to equipment in the factory. One con-
sequence of proliferating sophisticated and expensive test equipment in the field
is the maintenance burden. This burden includes not only keeping the equipment
up and running but also distributing machine, fixture, and test-program updates
to ensure that everyone is measuring the same parameters in the same way. Other-
wise, boards will fail that should pass, and vice versa, and available data for
manufacturing-process and design improvements will be less meaningful.
Another drawback to this approach is that oftentimes people conducting tests
at field installations are much less familiar with the product and the test program
than are their counterparts in the factory. New boards may contain technology that
field people have rarely seen. As a result, board testing and repair can take much