Even in the very early days of electronic components, failures appeared. Despite enormous development and production improvements this situation has not changed. Even automated equipment faults continue to be created on circuit boards There is not a single manufacturing technique that will guarantee the 100% fault-free circuit board. Each new technology creates new challenges and test methodologies to ensure fault-free boards.

The increasing density and complexity of the components is a prime candidate for producing faults. However, the situation still remains the same; faulty assemblies must not be delivered and the requirement for testing is obvious.

Several test technologies are available, each have their own unique requirement and effort. It doesn't matter if it is the in-circuit-test (ICT), the flying probe test (FPT), the functional test (FT), the automated optical inspection (AOI) or the boundary scan test, each technology has its pros and cons. But one factor is going to be more and more decisive: the costs. But which costs are caused by which technology depends on the purchase costs and, essentially, on the effort to implement the test process.