Here be dragons: Preventing static damage, latchup, and metastability in the 386

Are the techniques described in the article still in use today or have they been superseded?

I damaged an embedded development board by walking across a carpeted room before touching it. When I touched it I heard, felt, and saw the zap and one of the IO ports was stuck after that.

Part of it is that the incentives are different for you and for the chip manufacturer. You're not going to notice if, hypothetically, one in a hundred processors gets fried from careless handling. But a 1% return rate is a huge cost to Intel that they would want to avoid.

Is wonder if there's a strong correlation between whether you experience static zaps in your daily life and your propensity to fry chips with ESD.

When you fry a chip is it obvious because you experience a zap?

If so, then that would make all this "make sure you're grounded" ceremony less mysterious — because unless you feel a zap (even a tiny one) you probably haven't fried a chip, and it doesn't generally happen in environments where you don't feel zaps.

Obvious caveat: "feeling" a zap is not a precise measurement. But perhaps "zaps fry chips" is a lie which reveals a greater truth.

I never have, and I've been in embedded for ages. So I've dealt with my fair share of chips, consumer electronics and not.

But one vital thing to understand is that a lot of those "vendor recommendations" exist to cover for rare 1% to 0.1% edge case failures.

You can put together 20 PCs, with none of them dying from ESD, and conclude that ESD "isn't a real issue". But if you have a company that puts together tens of thousands of PCs per month? Then those ugly 0.1% edge case failures WILL pop up and they WILL cost you. And if you employ enough people, one of them might be a son of Zeus with a wild Wimshurst machine hairstyle - capable of emitting two high power ESDs, complete with an audible crackle and a visible spark, per minute. So ESD straps it is.

The same applies to things like humidity control or reflow profiles for electronics. Not an issue ~99% of the time. The remaining ~1% can fuck you over in mass manufacturing, so disrespect the vendor at your own peril.

Decades ago I was in the PC manufacturing and repair business. I religiously used anti-static mats, straps, And diffusers, but I still destroyed several thousand dollars of equipment over those years from equipment/ grounding failures, or even picking a PC up (accidentally touching a port) to put it on a bench.

It was interior Alaska, where humidity is low enough that an orange turns into a passable golf ball in a week and a half, so that was definitely a factor.

TLDR static electricity is bad for electronics, and damage does not necessarily show up as failure but often manifests as flaky behavior.

As far as I know, same here. The only thing I do is grab a ground lug from a electrical outlet before handling chips and boards. Which may be superstition and ineffective. I may be doing the right thing or I may be using up my luck and one day fry something expensive.

You will fry something if you don't use anti static measures and work on enough boards.

Moisture, clothing, habits play a role so it's highly variable.

The higher the feature density, the likelier a discharge of a given voltage will cause physical damage?

One thing I remember from my time in the CPU industry is that ESD damage can be cumulative and also can have a delayed effect. So just because you handle a device without precautions today, doesn't mean it won't fail at some time in the future as a result. That said, I've never used precautions in home/hobby projects.

When you’re digging around in tens to hundreds of PCs each day, the odds of zapping something are higher. I’ve killed a few chips and boards.

Yeah I'm pretty sure I've seen processors and memory both get eaten by ESD. Of course its impossible to prove but techs that didn't use protection had higher RMA rates on components so it gots to a point where the conclusion drew itself.