Fixture Testing

Test Fixtures are developed to detect failures occurring on the production line however, this is only possible if the test fixture itself is free of failure.

All too often PCB assemblies are damaged or degraded or the test process is disrupted due to a malfunctioning test fixture. Misplaced pushdown rods or PCBA supports, wrong probe height or force, an insufficient pressing force due to vacuum leakages or mechanic defects can damage the PCB assembly or generate pseudo failures that disrupt and disqualify the testing process. This problem may occur on all types of vacuum, pneumatic and manual fixtures. A thorough test on any fixture is and absolutely necessary step in any fixture development.

Our Fixture Testing Process is divided into several areas, each of them focusing on a different aspect of quality or functionality:

Visual Check: In this area, we look for failures or missing assembly concerning the overall fixture look and feel as well as the required labeling, identification, and safety features. During this test, we check for scratching or damaged surfaces, unfinished assemblies, proper customer labeling and component identification, correct safety indications and spare parts.

T-19 Photo of a fixture place on the test table focusing on the interface and or VTEP labels

Design Check: In this area, we make sure that the fixture’s components and assemblies correspond with the designed model. We check and measure the height profile of the fixture, the probe set height and probe stroke distance as well as the correct dimension and set high of any fixture component such as capacity probes, optical or magnetic sensor, and light emitters. The main part in this area is the Pointing Accuracy Test that checks and measures the pattern of the contact marks on the test pad.

T-20 Photo of several Test Pad with few contact marks

Mechanic and Vacuum Check: In this area, we test the correct function of different mechanics and pneumatic parts as well as the correct values of pneumatic and vacuum pressure. One important part of this area is the Vacuum and Pneumatic Long-Time Test. We operate the fixture under standard working vacuum and pneumatic pressure for several cycles to check for leakages and variation in the operating pressure levels.

T-21 Photo of a fixture showing pneumatic open/close pneumatic cylinder

ESD Test: In this are we measure the ESD values and electric insulation on the fixture plates and fixture components that are in contact with the PCB assembly during the test.

T-22 Photo of the ESD measurement device performing a measurement on a moving plate

Wiring and Electrical Check: This is the longest and most intensive part of our Fixture Testing Process. In this area, we check the correct function of the electrical components such as switches, counter, capacity probe, sensors, etc as well as the complete fixture wiring. All probes wiring are tested with our Wiring Test Machine that automatic test each electrical wire between probes and the interface pins. All power and external device wiring are then manually tested.

T-23 Video of an automatic probe wiring test with the Wiring test Machine

Test Report: Finally all checking, measured values, and test results are registered in a Test Protocol that is supplied with the fixture.