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Is it equivalent for these two ESD ZAPs?

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chang830

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esd zap means

Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks
 

chang830 said:
Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks

What do you mean by equivalent?
 

scottieman said:
chang830 said:
Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks

What do you mean by equivalent?

If I want to investigate the dischagre path for the negative ESD strike from pin1 to pin2, can I analysis it equivalently from pin2 to pin1 with positive ESD zap?

Or put anaother words, are these two ESD condition has the same mechanisim?

Thanks
 

chang830 said:
scottieman said:
chang830 said:
Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks

What do you mean by equivalent?

If I want to investigate the dischagre path for the negative ESD strike from pin1 to pin2, can I analysis it equivalently from pin2 to pin1 with positive ESD zap?

Or put anaother words, are these two ESD condition has the same mechanisim?

Thanks

In general, NO. The discharge path and mechansim between Pin 1 and Pin 2 should be different. For example, a GGMOS is connected between Pin 1 and 2. One discharge path is the body diode and another is the due to the snap back action of MOS device.

Hope it helps
Scottie
 

In general, NO.
In general, YES.
Consider that like blackbox with 2 pins. Negative or pozitive is depending on reference point.
 

scottieman said:
chang830 said:
scottieman said:
chang830 said:
Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks

What do you mean by equivalent?

If I want to investigate the dischagre path for the negative ESD strike from pin1 to pin2, can I analysis it equivalently from pin2 to pin1 with positive ESD zap?

Or put anaother words, are these two ESD condition has the same mechanisim?

Thanks

In general, NO. The discharge path and mechansim between Pin 1 and Pin 2 should be different. For example, a GGMOS is connected between Pin 1 and 2. One discharge path is the body diode and another is the due to the snap back action of MOS device.

Hope it helps
Scottie

But what you mean is the positive ZAP from pin1 to pin2 is different with the positive ZAP from pin2 to pin1. What I eman is the positive ZAP from pin1 to pin2 vs. the nagative ZAP from pin2 to pin1. Any descranpancy?

Added after 3 minutes:

Fom said:
In general, NO.
In general, YES.
Consider that like blackbox with 2 pins. Negative or pozitive is depending on reference point.

Hi Fom,
For my ESD test, I found when I exert the negative ZAP from pin1 to pin2, I found the pin2 failed. But when exert the positive ZAP from pin2 to pin1, it is OK.

:?:
 

chang830 said:
scottieman said:
chang830 said:
scottieman said:
chang830 said:
Hi,
In the ESD test, for pin1 and pin2, if exert a ESD positive zap from pin1 to pin2, is it equivalent to the ESD negative ZAP from pin2 to pin1?

Thanks

What do you mean by equivalent?

If I want to investigate the dischagre path for the negative ESD strike from pin1 to pin2, can I analysis it equivalently from pin2 to pin1 with positive ESD zap?

Or put anaother words, are these two ESD condition has the same mechanisim?

Thanks

In general, NO. The discharge path and mechansim between Pin 1 and Pin 2 should be different. For example, a GGMOS is connected between Pin 1 and 2. One discharge path is the body diode and another is the due to the snap back action of MOS device.

Hope it helps
Scottie

But what you mean is the positive ZAP from pin1 to pin2 is different with the positive ZAP from pin2 to pin1. What I eman is the positive ZAP from pin1 to pin2 vs. the nagative ZAP from pin2 to pin1. Any descranpancy?

Added after 3 minutes:

Fom said:
In general, NO.
In general, YES.
Consider that like blackbox with 2 pins. Negative or pozitive is depending on reference point.

Hi Fom,
For my ESD test, I found when I exert the negative ZAP from pin1 to pin2, I found the pin2 failed. But when exert the positive ZAP from pin2 to pin1, it is OK.

:?:

Haha, I guess I was do sleepy when read your question :p
If your ESD structure is as simple as a diode, of course, they should be teh same.
However, I still can think of a difference when GGMOS with gate resistor is used.

Scottie
 

Even for GGMOS or any other structure both of these cases are equal.
Suppose you are inside of black box that has two wires from outside. And you noticed trough these wires somebody outside apllies 5V pulses. Can you recognize they are negative or positive. So the device will response to the voltage difference only. But difference the same for both cases.
Hi Fom,
For my ESD test, I found when I exert the negative ZAP from pin1 to pin2, I found the pin2 failed. But when exert the positive ZAP from pin2 to pin1, it is OK.
How many devices did test?
 

Fom said:
Even for GGMOS or any other structure both of these cases are equal.
Suppose you are inside of black box that has two wires from outside. And you noticed trough these wires somebody outside apllies 5V pulses. Can you recognize they are negative or positive. So the device will response to the voltage difference only. But difference the same for both cases.
Hi Fom,
For my ESD test, I found when I exert the negative ZAP from pin1 to pin2, I found the pin2 failed. But when exert the positive ZAP from pin2 to pin1, it is OK.
How many devices did test?

I agree that they should be the same if we just look at that device as a black box. However, can the real situation be that simple? How are the capacitor coupling between the internal nodes? As ESD is "a kind of quick event", I do believe every details are important to find out the root of problem.
Moreover, what I am talking is a GGMOS with a resistor in between the gate and source. This resistor is mainly used to "speed up" the snap back action of a GGMOS according to my understanding.

Anyway, let me know if I am wrong :)
Scottie
 

Capacitor coupling between internal nodes also has no influence. But capacitor coupling between internal nodes (or any third pin) and an external node can cause current path for leakage and can cause difference in test result.
 

Fom said:
Even for GGMOS or any other structure both of these cases are equal.
Suppose you are inside of black box that has two wires from outside. And you noticed trough these wires somebody outside apllies 5V pulses. Can you recognize they are negative or positive. So the device will response to the voltage difference only. But difference the same for both cases.
Hi Fom,
For my ESD test, I found when I exert the negative ZAP from pin1 to pin2, I found the pin2 failed. But when exert the positive ZAP from pin2 to pin1, it is OK.
How many devices did test?

Hi Form,
I do the standard HBM ESD test. Every test mode need three test(chips). So I think it is not an occasional case.

Some one told me that when exerting positive ZAP from pin1 to pin2, the pin1 is the object of strike, while exerting negative ZAP from pin1 to pin2, the pin1 is still the object of strike. If it is seen as black box, the pin2 instead of pin1 in negative ZAP should be the object of strike. I was more puzzled with it.....:cry:

Thanks
 

Hi chang830,

Can you let us know what is the ESD sturcture under test?
I think it may help for us to see any possible reason of your case.
 

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