Fixture Maintenance Procedure For Forwessun Test Fixtures

Test Probe Maintenance

Typically test probes have a cycle life of about 50,000 operations .The operations counter on the fixture should be checked and if the number exceeds 50,000 then the fixture should be re-probed. If the fixture is used for high volume testing then the operations counter should be checked daily. Less frequent checks can be done on lower volume testing

The probe sizes and styles are detailed on a label on the test fixture. All probes can be re-ordered from Forwessun. The address will be on a blue label on the side of the fixture

A test probe colour coding plate should be used to check probe tip styles. This plate has different colour marking for all the different style test probes that the ICT fixture is provided with. The plate contains holes at each location where a test probe is located and the test probes can fit through these holes.

A test probe removed plate should be used to check that probes that should be missing for test purposes are not present.

A probe alignment sheet should be used to ensure all test probes are straight and are hitting the centre of the test pads. The alignment sheet test should be run every time a batch of boards is tested.

Cleaning Probes

Test probes can collect foreign material such as dirt and flux; you should clean these probes periodically so that they continue to maintain good electrical contact with the circuit board being tested.

Use a short-bristle, stiff, plastic or nylon brush to lightly brush the probe heads. Be careful not to brush the probes so vigorously that you bend them. Replace any probes that do not clean up with just a light brushing.

Non-oiled air pressure can be used by blowing up and around probe field.

Do not use solvent to clean probe tips. The probe mechanism contains lubricant which can be diluted or washed away by solvent. Without this lubricant, probe life will be significantly reduced.

Mechanical Parts

Gas stays should be checked weekly that they are secure and not leaking oil.

Fixture handles should be periodically checked to ensure they are secure.

Fixture seals should be checked weekly for any damage or wear.

Check all tooling pins are fitted and are secure every time a batch of boards is tested.

TestJet / VTEP plates and amp boards should be checked before each batch of boards is tested.

If the fixture has top probing make sure the bearing pins are greased regularly.

Please use Castrol LM grease or equivalent for lubrication.

Re-greasing should be done each month.

Check the fixture is dust free especially around the test probe area.

Pushers / Support Spacers

Spacers – Make sure that all spacers are firmly attached to the support plate; replace any that are not, or have fallen off.

A weekly check on all pushers should be done. Check all are the same height and are not bent or worn.

A Perspex pusher location plate should be used to ensure all pushers are present in the fixture.

A Perspex top plate spacer location plate should be used ensure all UUT support spacers are present and the correct height.

Fixture Handling and Storage Tips

Never do the following:

  • Store fixtures on painted shelves. The bottom of the fixture will scrape small particles of paint off the shelf which will fall into and contaminate the Testhead’s interface pins.
  • Store fixtures on paper, cardboard, or carpet-covered surfaces. These materials could contain corrosive substances that would react with the gold-plated personality or pin-block pins.
  • Store fixtures on wooden shelves. Wood splinters can be carried on the bottom of the fixture to the Testhead, which can contaminate Testhead interface pins.

Based on our experience, chrome-plated or plastic-coated wire shelves work very well for fixture storage.

Maintaining Alignment Plates and Pin Blocks

Alignment plates and pin-block assemblies normally need very little maintenance. Just inspect them for foreign material and bent pins, and then blow them off with non-oiled compressed air.

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