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Hello All, taking this opportunity I would like to ask iNARTE ESD engineers about IEC 61000-4-2 test voltage levels, what is the rationale behind specified 2 kV, 4 kV, 8 kV and 15 kV respectively as the default for both contact discharge and air discharge? 

Do you mean where the numerical values themselves came from, or why some are the same for both air and contact discharge?

Hello All, taking this opportunity I would like to ask iNARTE ESD engineers about IEC 61000-4-2 test voltage levels, what is the rationale behind specified 2 kV, 4 kV, 8 kV and 15 kV respectively as the default for both contact discharge and air discharge? 

Hello Shane, thank you for your reply. Yes I wish to learn more about the rationale of these ESD test voltage numerical values.

Could it be based on past experiments of human body capacitance modeling or something else? Why it is not start from 1KV? etc.    

Thank you very much!

Do you mean where the numerical values themselves came from, or why some are the same for both air and contact discharge?

Hello All, taking this opportunity I would like to ask iNARTE ESD engineers about IEC 61000-4-2 test voltage levels, what is the rationale behind specified 2 kV, 4 kV, 8 kV and 15 kV respectively as the default for both contact discharge and air discharge? 

This has been interesting for me to dig into. I'm not 100% certain everything I have is correct (e.g. not from the latest standards), but it helps to make sense of things.

The 2 kV level appears to be a "historical standard", representing the minimum voltage that a human will feel as a static shock.  I'll stick with 2 kV for the voltage discussion below. 

IEC 61000-4-2 defines four levels of environments, where Level 1 (the 2kV test point) is assuming a lab environment with ESD controls in place (wrist straps, humidity regulation, etc) and Level 2 (4kV) is your typical office/residential environment.

Actual testing:

• IEC 61000-4-2 and  MIL-STD-461 are both geared towards system testing as opposed to component testing.
• Both IEC 61000-4-2 and MIL-STD-461 utilize a 150 pF capacitor and 330 ohm resistor as the discharge network.

A discharge network of 330 ohms and 150pF will have a rise time of about 1 nanoseconds.  With 2kV, that will deliver a peak power of ~12.1 kW and be discharged to near zero in about 247 nanoseconds.

IEC 60749-26, JEDEC JS-001, etc:

• Still HBM
• Based on handling of parts at the component level
• Uses a 100 pF cap and 1.5 k ohm resistor
• Lower power, slower rise time, 
• May test at 50 V or even lower to determine thresholds and failure points.

A discharge network of 1500 ohms and 100pF will have a slower 25 nanosecond rise time. The slower rise time will give the internal ESD protections more time to redirect the current. The 1 nanosec pulse will like blow right past those protections.  At 2kV and a 25 ns rise, that will deliver a peak power of ~2.7 kW and be discharged to near zero by 750 milliseconds

So both system level and component level test methods have 2kV discharges defined, but the key difference is how the discharge networks discharge and what susceptibilities are being tested.  You can view the testing as being multifaceted.  "Does it physically survive?" Both electrical stress and heat effects.  Dielectric breakdown, microcontroller survivability, PCB delamination or trace burns, TVS protection circuits, power rails and grounding, etc.

The fast (1 ns) rise time also produces electromagnetic effects. It's broadband noise (300 MHz - 1 GHz), as opposed to a tunned susceptibility test, but can still reveal susceptibilities like bitflips or latching in software and hardware, data corruption due to interference, etc.

Hello Shane, thank you for your reply. Yes I wish to learn more about the rationale of these ESD test voltage numerical values.

Could it be based on past experiments of human body capacitance modeling or something else? Why it is not start from 1KV? etc.    

Thank you very much!

Do you mean where the numerical values themselves came from, or why some are the same for both air and contact discharge?

Hello All, taking this opportunity I would like to ask iNARTE ESD engineers about IEC 61000-4-2 test voltage levels, what is the rationale behind specified 2 kV, 4 kV, 8 kV and 15 kV respectively as the default for both contact discharge and air discharge?