ESD models - CDM and MM

[FreshmanNewbie]

I am just trying to understand the differences between the ESD models in this article.

The CDM and MM models are very similar. Is the MM model the reverse of CDM model.

I have this confusion as CDM and MM are similar in definition but their waveforms of peak current are different.

Can someone tell me what is the difference and how to understand the difference in peak current?

 

[FvM]

Read thoroughly, the difference is in the impedance, specifically series resistance. Personally I won't bother with MM because it doesn't play a role in common ESD tests. Relevant test setups are HBM (human body model) and CD (contact discharge). CD uses lower voltage and lower impedance.

 

[FreshmanNewbie]

Read thoroughly, the difference is in the impedance, specifically series resistance. Personally I won't bother with MM because it doesn't play a role in common ESD tests. Relevant test setups are HBM (human body model) and CD (contact discharge). CD uses lower voltage and lower impedance.

Thank you. Yes, I understand there's a difference in CDM and MM model due to the impedance. But since the practical scenarios seem to be the same, why is there a difference in impedance?

 

[dick_freebird]

MM is to represent a packaged device "handler" in an automated
test environment. Big rollaround parts feeder and "bin" sorter, all
kinds of metal (so all MM has for you is an inductor, more or less,
to "use for cover".

CDM is for PCB assembly, pick & place at the end of an insulating
vacuum wand, but you got your part body charged somehow.
Fortunately only the part's self-capacitance, which is low (as are
expectations).