I have a few questions regarding the revised CDM requirement and would appreciate your help in clearing my doubts.
Our customer has revised the CDM requirement from <200V to <50 V considering for their product requirement and sensitivity level. They have also specified an offset voltage of 8.5 V and insulator voltage of <30 V. To meet these requirements, they have recommended using different types of DC ionizers, such as Bench Top, Overhead, Bar, Ionizer Gun, and In-built Machine Bar Ionizers.
I would like to understand the difference between AC ionizers and DC ionizers.
What standard equipment is required to measure CDM <50 V?
We would like to assess our current process to check whether our existing controls meet the CDM <50V requirement or if any additional controls are needed. Could you please suggest an expert who can perform an onsite assessment and recommend any required improvements?
Thank you very much for your guidance and support. I look forward to your suggestions.
I think your questions are very valid in today’s lower CDM requirement environment. There have been recent discussions to lower the 200 V CDM limit in ANSI/ESD S20.20. Your answers are below starting with number 2.
AC ionizers use AC power to vary the positive and negative ions. This can cause a local ion imbalance that cannot be picked up with lower frequency charge plate monitors. That is why a constant voltage DC ionizer is recommended as it provides a constant supply of both positive and negative ions. This can become imbalanced over time, but there are DC ionizers with a built-in charge plate monitor that automatically adjusts to maintain the offset voltage to a low voltage.
To measure the actual static voltage on a part, the best equipment to use is a high impedance contact voltmeter. You could also try to use a non-contact voltmeter but the measurements may not be as accurate
I would recommend contacting the ESDA LLC at the below website. They should be able to perform a process assessment to determine your process capabilities and areas for improvement.
I think the ESDA LLC should be able to help you with this. They have two people who are doing full-time ESD evaluations at customer sites as requested. You can contact them at lpimpinella@esda.org to get a quote.
Greetings of the day from India to all the members on this forum.
It is indeed an interesting discussion to know & understand more on CDM topics by one and all. I had slipped this topic some how by mistake and while scrolling back previous ones, I could see quite a number of postings related to CDM issues in the past five years.
I feel the ANSI/ESD SP5.3.3 for Charged Device Model (CDM) Testing - Component Level Low-Impedance Contact CDM and, ANSI-ESDA-JEDEC-JS-002-2025 and few articles from In compliance magazine of January & April 2026 on Small form factor CDM tests etc, may help Mr. Rahul and, everyone as it is for the first time perhaps all of us are hearing such a critical requirement from an user .
It is good that Mr .Rahul has brought it to the knowledge of this Forum so that our ESD Gurus/ESDA experts will look into it and guide the global industry accordingly.
It is true that major ESD damages are by CDM and will be further more become critical as the packaging density reduces and surely , the detection and prevention avenues to this effect is very essential.
