Macaos has developed a simple and cost-effective jig for in-circuit testing. The test fixture module allows you to design a test fixture by simply clicking on the test points in your board, and assigning each pint with a pin type (and appropriate labels for a wiring list, if desired).
Test fixtures
A "Bed of Nails" test fixture is a plate with an array of spring-loaded test pins (or Pogopins) which are mounted in the fixture so that they will make contact with desired test points on the PCB. In addition, a few guide pins are placed at mounting hole locations in order to properly align the PCB with the test pins. The PCB is placed on top of the pins and then pressed down so that the pins make good contact with the test points. Ideally, all test points should be accessible from the bottom side of the PCB.
The lower fixture of our standard test jig is a box with hinged top and bottom. It is delivered with holes drilled for the test pins, guide pins, connectors, etc. as specified in the test fixture module. Test pins and other accessories may be ordered together with the test jig and fixture, directly in Macaos Enterprise.
The standard jig is delivered with an upper fixture with slots that allow you to place press pins where appropriate. For boards with test points on both sides, it is possible to design an upper fixture with test pins.
Test pins
Typically, test pins consist of two parts: 1) a receptacle which is mounted in the fixture plate and wired to a connector, and 2) a spring loaded pin which is inserted into the receptacle. The spring-loaded pins are available with a variety of different pin heads, which are chosen according to the type of test point contact to be made (via hole, solder pad, component pin, etc).
