Need circuit which is highly susceptible to ESD damage - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: October 14, 2017, 11:21:46 am
content: We would like to test to see if our production and test environment is ESD safe.. {ESDESD}One thing that we would like to own, is a super-ESD-sensitive circuit board that breaks and stops working at the most minor incidence of ESD.Say just flash a LED but stop flashing it when its broken due to ESD. I wonder if having small signal FETs ( eg SOT323, and not tying their gates to ground with a 10k resistor) would be good on it, because surely little FETs’ GS junctions are the things most sensitive to ESD damage?.......we could incorporate the sensitive component(s) into the circuit such that the LED stopped lighting when ESD damage had occurred.What do you think are the components, or methods of connection, that render a component most susceptible to ESD damage?Presumably tiny little (3mm x 3mm) 48 pin microcontrollers must be extremely ESD sensitive?Also, some opamps dont have ESD protection diodes in them, but which ones?

author: BrianHG
author_rank: Super Contributor
timestamp: October 14, 2017, 11:29:29 am
content: You know it's possible to design an ESD meter... I believe dave has a video showing a meter which can measure the electrostatic voltage around any material without even any contact. I believe it is designed with dual balanced j-fets with some volt-meter circuitry after it.

author: Cerebus
author_rank: Super Contributor
timestamp: October 14, 2017, 04:53:28 pm
content: RF small signal MOSFETs stop working if you evenlookat them in the wrong way. It's the only class of component that I unfailingly pull out all the ESD good practices stops for. Take the BF1107, abs max ratings: 3V drain to source, 7V gate to channel breakdown.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 14, 2017, 08:06:05 pm
content: This is studying a disease epidemic by putting more people into the danger zone and testing if they die.Not only is it an inefficient method, it's extremely unreliable. How do you know that precisely the same environment, the same actions, will occur to each individual?You don't.There's a reason ESD procedures are designed the way they are. You don't treat a disease epidemic by hooking leeches on people, you treat it by flushing the sewage away from the water sources.Tim

author: tggzzz
author_rank: Super Contributor
timestamp: October 14, 2017, 08:18:04 pm
content: Quote from: treez on October 14, 2017, 11:21:46 amPresumably if you wanted to test for high currents that might harm your equipment, you would ask for low current fuses of indeterminate value.Hint: you want to measure reliably, not unreliably destroy.

author: Nusa
author_rank: Super Contributor
timestamp: October 14, 2017, 08:30:20 pm
content: Prior to the 20th century, leeches were often the treatment of choice as it was thought that most diseases were caused by an excess of blood.Even in modern medicine, leeches actually have medically valid uses, if you can get past or hide the yuck factor. Skin grafts often use them to promote localized blood flow in the tissues, taking advantage of the blood thinners and painkillers leeches produce.

author: bd139
author_rank: Super Contributor
timestamp: October 14, 2017, 11:22:45 pm
content: Quote from: Cerebus on October 14, 2017, 04:53:28 pmRCA 40673 as well. I blew up about 3 of them from handling before I realised it. Oops. Turns out they're worth a lot of money now. Double oops.

author: medical-nerd
author_rank: Regular Contributor
timestamp: October 15, 2017, 12:23:14 am
content: Quote from: bd139 on October 14, 2017, 11:22:45 pmThanks for that advice on the 40673, I have a couple still in their packaging that I want to use and don't have a reliable ESD safe work area yet. I need to investigate some options suitable for a hobbyist.Cheers

author: Marco
author_rank: Super Contributor
timestamp: October 15, 2017, 12:31:47 am
content: Quote from: T3sl4co1l on October 14, 2017, 08:06:05 pmMore like canaries in a coal mine.The only way to know if your ESD procedures are correctly implemented is by statistics of failure rates of the most sensitive components. The proof is as always in the pudding.

author: BrianHG
author_rank: Super Contributor
timestamp: October 15, 2017, 12:42:55 am
content: So be warned, relying on an ESD sensitive device may fail you. Such devices may not be completely destroyed, just minor alterations to their performance or specs. Or, you may get un-lucky and have a device which just seems to survive the ordeal a few times before it actually dies. Build yourself a proper static electricity measuring detector.

author: Marco
author_rank: Super Contributor
timestamp: October 15, 2017, 01:23:30 am
content: Quote from: BrianHG on October 15, 2017, 12:42:55 amYou mean one of those antenna field meters or a proper volt meter with sub pF input capacitance and a couple 100 TOhm input resistance?