Design data from ICT Programmer is processed to provide drill file and wiring files. Large hold down gate and pushers electronically placed by autofix software.
Analysis
of top and bottom side forces show that pusher rods will not be enough,
solid vectorless plate /pusher assemblies are needed to balance large concentrations
of probes at bga devices and main multiline connectors. 25thou test targets
means that a guide plate will need to be fitted to guarantee probe accuracy
with such a large pcb. Stage 2
Drill prover shows that data is consistent with the bare PCB and permission to drill probe plate is granted. The probe plate drilling process takes four days! What about the dress plates, ground plates, strengthening plate and power planes? This is a lot of drilling!! Simultaneously the GR228LX interface is wired with 7000 wires and the base pan is assembled with lifting handlesl, vacuum guage, safety catches, and damping springs etc.
Stage 3
Nodel
wiring is a seven-day process and towards the end it is very difficult to
track those probes under this mass of wire. Point-to-point verification
testing confirms no wiring errors! The drilling section manufactures all
vectorless test probes/pushers. The perspex mounting plate is drilled and
assembled and pcb z heights reconfirmed.Stage 4
Final
assembly. All sub assemblies are assembled into the final fixture and the unit is mechanically inspected with the target pcb. Vacuum is applied to ensure that the fixture operates correctly and is free from any leaks.
Stage 5
Testing.
All mechanical tests verifying operation, probe accuracy and probe compression pass without a hitch Strain guage testing is greeted with apprehension. We have our largest most expensive fixture ever built and yet it could still be useless unless this test is passed. Two hours of testing reveal success with all bga's well under the 600 microstrain limit. This confirms the excellence of Elite's design that in this application has balanced three tons equivalent of force so that the high cost critical components are unscathed!! The fixture is now ready for debug and a minimum of 500,000 care free operations. Job well done!