One of our customers has given a new requirement for CDM voltage to be <50volts. The original documented requirement was to comply with ESDS 20.20 Standard which site is already complying. However, it is new requirement considering critical projects.
I would like to conduct a self-assessment and check our readiness for this requirement. So request your assistance to understand about this requirement in more details including measurement process and suggestions for compliance.
ANSI/ESD S20.20 applies to devices with sensitivities down to 200 volts CDM. It also says, “Processes that include items susceptible to lower withstand voltages may require additional control elements or adjusted limits.”
It is hard to tell you exactly what additional control elements you should add or determine any adjusted limits without an assessment of your process. Some things you may want to consider are:
Doing a process assessment per ANSI/ESD SP17.1 to determine what you need to protect the product below 50 volts CDM. This may include things like using dissipative tools and/or ionization
Possibly increase your frequency of compliance verification
Use some type of continuous monitors to ensure resistance measurements are constantly monitored
As Andy mentioned, following ANSI/ESD SP17.1 will provide the guidance needed to perform a process assessment. Since it is a lower CDM sensitivity, pay close attention to any tools, fixturing or other items that come in intimate or close contact with your device/assembly. Material selection for those will be a key component in protecting the device. Another useful document is the TR19 on High Reliability. It has several “better” practices that can apply in this situation.