Charged Board Event Simulation for Validating ESD Control Program of Hard Disk Drive Assembly Processes

The ESD control program based on the CDM classification of HDD assembly process was currently set at less than 1000V; thus, the HDD PCBA should be able to withstanding the CDM voltage at least 1000V. The work validates that the ESD control program under 1000V provides a sufficient margin for protecting HDD PCBAs. Moreover, an experiment on HDD PCBA failure caused by CBE was performed under a CDM framework at 1500V for an extra margin. A particular failure analysis tool was employed for identifying an indication of PCB degradation using three parameters; magneto resistive resistance, variable gain amplifier and track error margin. The experiment of HDD PCBA enforced with CBE revealed that the HDD PCBA was still properly functioned after the test. The degradation was monitored by changes of analyzed parameters. The results show that there was no sign of degradation. Therefore, the ESD control program under 1000V provides a sufficient margin for a safe environment of HDD PCBA. This simulated CBE on HDD PCBA is useful to classify an ESD sensitivity class for assisting the design and protective apparatus for ESD susceptible items in the HDD assembly processes.