What are test fixtures?

The test fixtures provide mechanical support for the DUT and make connections to it. Most often the connections are made by spring probes that contact test points on the PCB. In the most simple case the fixture may just act as a connection interface, with the spring probes being wired to a rear panel connector that is used for connecting the test instrumentation. The fixture may includes some simple electronics to help with testing e.g, small power supplies, some filtering, level shifters between the DUT and test equipment, etc.

If the tests are simple enough, sometimes fixtures are entirely self-contained. For example, a small acquisition board and some simple interface circuits fitted inside might be all that is required to test a simple board and provide a Pass/Fail indication.

We are using Autodesk Fusion 360 to design and engineer the parts of the fixture, to ensure their aesthetics, form, fit and function.

From design phase

ATX MMI-MEWK-B interchangeable cassette
3D CAD file example of an ATX MMI-MEWK-B interchangeable cassette, in the development phase

Before starting the manufacturing process, we agree with our client regarding different important aspects

  • positions of the board marking probe
  • contacting test points vs. contacting pins or connectors
  • position of automatic DMC scanner
  • bottom and/or top probing

To final product

ATX cassette after manufacturing phase
ATX cassette after manufacturing phase with top&bottom probing

After the fixture manufacturing process on the CNC machine is ready, other important processes follow, like

  • fitting test probes & board marker probe
  • fitting additional control boards needed for testing
  • mounting and adjusting the DMC automatic scanner
  • wiring
  • documentation and acceptance test