| Basic Knowledge |
Strain test in factory application?
Assembly and test processes like in-circuit test (ICT), cutting board, or final verification test (FVT) involve holding the board in some form of a fixture and then performing a task. If these fixtures are not designed properly, they tend to apply higher than safely allowed stresses on the PCBs. Even well-designed fixtures tend to apply higher stresses over time on the PCB inside.
To proactively avoid failures and identify problematic designs or processes, you can implement a strain gage test on the PCB to characterize these potential high-stress-inducing processes for maximum stresses and make sure they are within the allowed limits. If measured stress values exceed the maximum allowable stress level for the board, you can rework or redesign the fixture or change the process as required to bring these values within allowed limits. The generally method is to adjust the thimble which can reduce the pressure between the PCB and the thimble when testing. The IPC/JEDEC-9704 guideline identifies problematic assembly and test processes and provides systematic steps for implementing a PCB strain gage test. |
Berore adjustment
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After adjustment
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Industry Automation
