As the trend in the increase of board complexity continues, the capabilities of automated test equipment or in-circuit testers are challenged and even exceeded. This could be due to the lack of or limited physical access (test points) to components or, limited tester channels or, the cost of fixture design and fabrication, especially for large node count boards.

Flying probe test systems require no test fixturing, have few restrictions on board access, and can test boards with virtually unlimited number of nets. These systems also allow developers to complete test programs in a short time.

In order to optimally fulfill the contacting requirements, various test probes are available. These differ in terms of installation height, grid size (possible distance between probes), tip style, and type of connection – see following illustration. The electrical connection is achieved either with a solder cup or wire-wrap, with or without cable (wireless).