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I just figure out today that I always manipulate chips with the "Electrostatic sensitive devices" sign by hand. I never use a grounding bracelet or even a clamp. Even if I doesn't take such precaution, chips behave as expected. Is that normal?

What come in mind is that maybe a particular part of a chip can get damage instead of another. (particularly on µC) Is that true?

What can I do to reduce these effects? I have no grounding bracelet but I can use a clamp (a small one usually use for hairs).

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    \$\begingroup\$ As a hobbyist, not everything can be afforded - diligence and acceptance of risk often suffice for the intrepid hobbyist. My advice is to always think about equalizing potentials. Be diligent about equalizing a bag of components to yourself before reaching inside. Grab your tweezer first, then touch it to the bag for a few seconds, then reach inside and get your component. Always touch the PCB ground to yourself and your component bag before dumping the contents out and sifting for your part. I've never lost a part on a home project to ESD - simply follow the basics. \$\endgroup\$ – Smith May 31 '17 at 20:30
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Even if I doesn't take such precaution, chips behave as expected. Is that normal?

Yes, ESD is an unpredictable event, and you can't see it (most of the time, sometimes you can see damage on IC's). Sometimes it only damages a trace partially and it could take months or years for a chip to fail, sometimes the effect is immediate and the circuit ceases to function. The only way to know exactly what damage occurred is to take the IC apart and etch the packaging away and look at the damage to the silicon with nice expensive microscope. This takes a lot of time and most engineers don't have access to etching tools and high resolution microscopes so we try to avoid ESD at all costs.

enter image description here

Source: All about circuits

What come in mind is that maybe a particular part of a chip can get damage instead of another. (particularly on µC) Is that true?

Yes, there are certain areas of an IC that are more prone to failure. Many modern IC's come with some kind of ESD protection on the inputs, like diodes. A failure is a failure and there is no way to tell exactly when where or how a device will fail after ESD damage.

What can I do to reduce these effects? I have no grounding bracelet but I can use a clamp (a small one usually use for hairs).

If its an expensive device then I'd buy the protection equipment. If you already have multiple devices and they are low cost, its probably not the worst thing if it fails. The biggest problem with ESD is having intermittent problems where the device is not functioning in normal operation and time is wasted in figuring out why and replacing the part.

I would do your best to be ESD safe. As a hobbyist this can be difficult.

Here are some ESD tips:

  • Surfaces should be conductive and connected to ground, if you have a metal surface, this could stand in place for a mat but you couldn't turn the device 'on' while it was resting on top of the conductive surface.
  • The pink bags are bad because the conductive coating wears off, the mylar (aluminum coated bags) are good and conductive.
  • Some materials like clothing, paper and plastics can develop charges that generate fields in the thousands of volts range and blow out transistors on sensitive devices so keep non-esd safe materials away from sensitive electronics.

If you don't use a grounding wrist strap, then you run the risk of shocking the part when you use tweezers or an ESD gun to build or service it. Do your best to minimize charge building up on materials by equalizing potentials.

ESD prevention tries to equalize all potentials so charge cannot build up on a surface and create an electric field.

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  • \$\begingroup\$ So are there studies on what the likelihood of damage / failure is? i.e. Under some sort of controlled conditions if ESD protection was not adopted what's the probability of damage? \$\endgroup\$ – curious_cat Jun 1 '17 at 4:53
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Electrostatic discharge is a random kind of thing. Some devices are more sensitive than others and of course it also depends on what else you have been doing with your hands, what you are wearing, what the work surface is made of etc etc etc. Up till now you may just have been lucky. However there is no guarantee you have not significantly reduced the lifespan of the devices.

Best bet is to go buy a wrist strap and work mat.

Making sure you are grounded by touching something known to be grounded before opening the bag can also be helpful. But nothing is better than the appropriate equipment.

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  • \$\begingroup\$ I will buy the appropriate equipment soon. But, for now I will use what I have. What can be known as ground in a house? I'm a hobbyist so I have no "ground ref" in my selfmade "lab" \$\endgroup\$ – M.Ferru May 31 '17 at 16:52
  • \$\begingroup\$ @M.Ferru DO you have any test equipment..... or other electrical stuff that's attached, with a ground, to the mains? \$\endgroup\$ – Trevor_G May 31 '17 at 16:58
  • \$\begingroup\$ Yes I do. I'll then touch the ground pin of my oscilloscope. \$\endgroup\$ – M.Ferru May 31 '17 at 17:00
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    \$\begingroup\$ @M.Ferru If you have some wire you can make a temporary wrist strap with a 1M resistor at one end. \$\endgroup\$ – Trevor_G May 31 '17 at 17:05

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