2
\$\begingroup\$

I have a task to present the ESD safety practices in lab and at work in general. I want to make this interesting and for the freshers out of college, I want to let the importance of ESD precautions sink for long time.

I am planning to spoil the devices as a part of demonstration. Question: How can I do this?
enter image description here

The image tells me to start with FETs.. may be a simple timer and a LED connections and a FET. I am open to use other components as well.

\$\endgroup\$
  • \$\begingroup\$ Since most devices have build-in ESD protection, it can be a challenge to actually cause any damage by ESD. I would target MOS structures like CMOS logic and measure the leakage current before and after the ESD event. \$\endgroup\$ – Bimpelrekkie Feb 19 at 15:18
2
\$\begingroup\$

ESD damage can be very subtle and not easily demonstrable. The eventual failure may take years to surface. Or is only measurable by some change in parameters.

Exmaple, only visible by electron microscope:
https://nepp.nasa.gov/index.cfm/6095
enter image description here

Or here:
http://www.ti.com/lit/an/ssya010a/ssya010a.pdf
enter image description here

I do not think a demonstration will be very effective.

|improve this answer|||||
\$\endgroup\$
  • \$\begingroup\$ Probably would be more effective to demonstrate you don't need to feel a shock to short the FET and make the LED change state, but that's one-on-one, not for an audience. \$\endgroup\$ – DKNguyen Feb 19 at 15:02
  • \$\begingroup\$ Agree. Better to show some pictures like this, plus some stories and/or pictures of expensive product failures. Do some research, maybe there were some high-profile failures ($100M+ satellites?) where suspected to have been caused by latent ESD defects. \$\endgroup\$ – Mattman944 Feb 19 at 16:27
1
\$\begingroup\$

In our electronics lab at university somebody thought it was a good idea to buy cheap plastic chairs. Every time you stood up you would get zapped by sparks up to about 1cm in length. Painfully.

So, find an old chair like that, and get someone wearing nylon or some insulating polymer clothing and insulated trainers to sit on it. Then get them to stand up and hand a circuit board to someone who is already grounded. The spark to circuit board will definitely not be good for it. [Although I have seen boards survive that]

Then tell them it is good practice to touch the hand of the person you are handing the board to to discharge any static first.

|improve this answer|||||
\$\endgroup\$
  • 1
    \$\begingroup\$ It was a good idea. It was all part of the sinister conspiracy to sabotage capstone projects in the name of ESD training. \$\endgroup\$ – DKNguyen Feb 19 at 15:40
1
\$\begingroup\$

As I recall, the old 4000 (not 4000B) series ICs were quite sensitive to latchup and ESD damage compared to more modern parts. They're probably fairly hard to get ahold of in 2020. You could try a standard CD4001B for example, cheap and easily socketed for replacement.

Charging a small capacitor to high voltage and discharging it through the part with a low value or no capacitor may be able to demonstrate the damage. You can start with the usual human body model and make it less friendly (lower resistance, more capacitance, higher voltage) as necessary.

For demonstrating damage, I suggest a SPDT switch to a gate input with a high value resistor in series (maybe 22M or more), and the output driving an LED, so that any damage that causes somewhat increased leakage to either supply rail will be evident. Add a series resistor to the Vdd so latchup doesn't kill the chip if you want to zap it with the power applied.

Note that the ESD discharge that is guaranteed safe may be considerably less than what is required to typically cause measurable damage.

|improve this answer|||||
\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.