Macaos Enterprise helps you to quickly and economically set up a platform for in-circuit testing of a PCB assembly. Using the Test fixture module, you can quickly design test fixture(s) by simply clicking on PCB holes or pads.
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.
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).
The test fixture is mounted on the base of the test jig. The PCB is placed on the pins of the test fixture. An upper plate then presses the PCB onto the test pins, so that they make contact with the test points on the PCB. Once contact is made, test measurements may be made as desired.
For a more detailed description of the test fixture design process, see the user guide.
Test jigs and pins are available for purchase in the Test accessories folder of the Macaos Enterprise product browser.