How to troubleshoot ICT and Depanel Machine while connected to Ground
How can you troubleshoot ICT and Depanel Machine while it’s connected to ground? Of course you must look for fields, make sure there is continuity to ground from all metal in critical path. However, we developed a very effective technique of analysis that has helped us identify cause of problems in the manufacturing process. First, you must clear your mind of preconceived causes and measure the process objectively as outlined in the EPCA Technical Report, below.
This document is based on our original work described in Process Capability & Transitional Analysis, also below.
http://www.prostatcorp.com/files/white-papers/esd-process-capability-assessment.pdf
http://www.halperinassoc.com/Downloads/ProcessCapability_TransitionalAnalysis.pdf
If you took the SH&A Level 1: ANSI/ESD S20.20 Plant Auditor class, the measurements you need include everything you used in the Level 1 plus use of a Prostat® PGA-710B Autoanalysis System and CVM-780 Contact voltmeter.
In direct process control you are measuring devices and subassemblies before and after every transport or process step to determine (a) where the charge is generated, and (b) where discharge occurs. Both documents generally describe how to do this. Often analysts believe that the point of discharge is the most import part of defining ESD problems; however, we believe one must know where the charge was originally generated in the process…this is the cause of the problem. We also use a technique to determine what type of ESD event is occurring, i.e., HBM, CDM, FIM or MM.
In depanel machine operations sawing, guillotine cutting, or punching board segments generate charge. How much charge? We measure the assembly ground plane voltage with a CVM-780 – in some cases (if the panels are large enough) you can use a field meter such as the PFM-711A. How do we control this operation? With ionization during and after the depaneling process and certainly before handling the depanelled assemblies.
Take a look at the documents we have hyperlinked for more information.
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