3. Making a claim that you never lost a component because of ESD, regardless of what ever handling practice is in place, is displaying ignorance of the damage caused by ESD.

hi MrC,
If this quote was directed to me, I would point out that I was referring to IC storage, not bad handling techniques.

By having the foil covering the poly grounded as I stated, every time one of my assembly workers removed an IC from the foil he/she automatically grounded himself.
Also the soldering iron handles were wrapped in conductive foil, which was grounded via a 1meg resistor.
Wrist grounding bands were also compulsory, we took ESD damage control very seriously.

Eric

 

hi MrC,
If this quote was directed to me, I would point out that I was referring to IC storage, not bad handling techniques.

By having the foil covering the poly grounded as I stated, every time one of my assembly workers removed an IC from the foil he/she automatically grounded himself.
Also the soldering iron handles were wrapped in conductive foil, which was grounded via a 1meg resistor.
Wrist grounding bands were also compulsory, we took ESD damage control very seriously.

Eric

Your response is acknowledged and understood. The point is we never know what storage technique and handling practice work or don't work.
The best we can do is follow best practices as recommended by the experts in this area. These are the folks that disassemble solid state devices and examine actual device features under electron microscopes.

 

I think is Better doing both grounding and shorting out the pins using the Alum' foil .. This way I can be safe, at least from the view of the two prospectives.

 

Good suggestions, all. How do you get the ICs when you buy them? Continue that use. Or, ignore these practices all together. I use a lot of CMOS chips but do not religiously use any method. My bench area is pretty "low static" by design. I don't run into any failures I could trace back to static electricity.
Do you generate a lot of static electricity at present? If you feel it you are way beyond a safe limit and should use something, foam as suggested or antistatic bags.
Yes, the dull black antistatic foam does corrode easily.

 

I haven't finished reading all posts on this but I JUST NEED TO SAY THIS:

hi #12,
Used this method commercially, for over 40 years, NEVER lost an IC device due to ESD during that time.... your fears are ungrounded, [ pun intended]

Eric

MANY IC's that are affected by static don't always fail right from the start. ESD stands for Electro-Static Damage. EOS stands for Electrical Over Stress. Meaning it can be damaged but not blown out. Those are the components that test well enough on the test bench but fail far short of their expected life-span. An IC that should last 5 years might last only 5 days after an EOS event.

#12 hates styrofoam for DAMNED GOOD REASON! It's one of the worst offenders of static generation. It's VERY high on the "Tribo-Electric Effect" chart.

Like I said, I haven't finished reading all the posts, but someone asked if foil can act like a Faraday cage. Well, yes. Same as a metal cage can contain a vicious lion. But you wouldn't want to be sticking your legs inside the cage - would you?!

Electro Static energy is energy of a static level. It could be sitting around at several thousand volts to several hundreds of thousands of volts. Static means it's going no where. And you could store a million or more IC's in such an environment with absolutely no harm to the device. It's like being inside a cloud during a lightning storm. As long as current is not moving there is nothing more than a fuzzy feeling. But once those electrons find a short path to a different energy level (usually ground) then lightning strikes. Just like when you grab the door knob on that cold dry day and you get that darned bang that shakes your arm all the way past your elbow - that WAS "Static" electricity until you provided a path to a different potential. The door knob was at several thousand volts lower than your body.

So when you push your IC's through foil into foam you're sticking it's legs in a proverbial lion's cage. it's going to get bit. And just like the real thing (lion biting your leg) it might not die immediately. But damage has been done in very serious ways.

Imagine a roadway on a hillside. A heavy rain washes out part of the road. NOT COMPLETELY WASHED OUT - you can still get by, but the road is damaged and can no longer carry as much traffic. So too is the fine pitch traces on the substrate of the chip. You can burn them without burning them out. However, the weak spot becomes the weak link in the chain. It's the first place that will fail when stressed to - possibly no where what the chip was designed to handle. Under test you might stress it to 10% of it's intended service load and it passes the test. But as soon as circumstances demand 90% of the service load - poof - out comes the smoke.

Styrofoam? Bad idea all around. Even worse when wrapped in foil. Just like a capacitor - the electrons inside want to go somewhere. Piercing the foil with the legs of a chip you're holding and BANG!

I mentioned static voltages of differing levels. You can store a chip - lets just say at 10,000 static volts. If you handle the chip and YOU are also at 10,000 static volts then there is no damage. Energy always flows from the higher potential to the lower. So if you're standing at a static voltage of 9,000 volts you can blow the chip because of the 1,000 volt difference. If you're grounded (and that's another topic of "Relative" terminology) and you handle a chip in a styrofoam block sitting at 10,000 volts - need I say "Bang" again?

What generates static? Separating atoms. No, not "Splitting" atoms, simply separating them. Different materials are more prone to generate static than others. Scotch tape is another highly dangerous Tribo-Electric source. (Tribo-Electric means static generating) So simply handling styrofoam is going to generate a whole lot of static. Just like #12 said, those damned styrofoam peanuts that you can't get them to leave you alone - it's "Static Cling", or the attraction of dis-similar charges; positive and negative. And yes, some tribo-electric generators can generate positive ions while others can generate negative ions.

Static electricity is one subject I CAN speak with confidence on.

 

2- this one might not be related but I have noticed, in some posts, people talking aboit a common ground that can be an issue when say for example when connecting two circuits one uses a USB connected to computer and the other is a circuit running using mains !!
What could go wrong?

What could go wrong? REAL LIFE EXPERIENCE: Bought a new home. (old house) Hooked computer to one outlet (three pronged) and the printer to a different outlet (also three pronged). Between the two there was a repair where one of the former home owners crossed hot and neutral. The second owner decided to "Upgrade" the plugs and put in three pronged outlets. Only he used neutral as the ground (jumping neutral and ground together). Doing so with the crossed wiring meant that my computer case was no longer case ground but it was now "Case HOT". The INSTANT I touched the USB cable to the back of the computer - well, I saw the light! Destroyed the printer and blew a hole in the back of the computer (about the size of a small nail). What could go wrong? A WHOLE HELL OF A LOT CAN.

And on the point of using a resistor of such high value - it speaks to the flow of electrons - current. Juice. If you recall grabbing the door knob and getting a shock - that's what you don't want to have happen to your IC's. By slowing down the flow of electrons using a 1 meg Ω resistor (or higher) you protect your physical self from dangerous and potential life ending shocks as well as protecting your IC's from deadly sudden rushes of current. The resistor is not there for looks. It's there to save lives. Yours and your IC's.

 

Yes i guess shorting out all pins will put them at 0V potential but I think that grounding is a proper way to work with such things. IMHO Grounding is an important prenciple that needs to be taken in consideration.

Great idea if you can absolutely guarantee that ALL PINS GROUND AT THE SAME EXACT TIME. Otherwise the first pin to make contact will carry the brunt of the rush of static.

 

Another "REAL LIFE EXPERIENCE": At Northrop Grumman, they were testing a satellite on the stand. A worker moved a cart that was "ESD Safe and grounded" had a failed grounding system. Passing within a few feet of the satellite, the satellite quite working. Why? Because of the presence of a nearby static electric field.

You don't have to "Touch" a chip to blow it out. Since satellites run on extremely low power their chips have to be designed to operate on very low power levels. That makes them highly sensitive to static electricity. Setting a chip on a static grounded mat and placing your hand above the chip without you being grounded can result in blowing out some of the more sensitive chips. Granted, most chips you handle will never be as static sensitive as a NASA satellite or a Military Intelligence orbiter. The point is that static can move without a visible or tactile pulse of energy.

Sandwich baggies? Not good practice. Styrofoam cups on the work bench? People have gotten reprimands for such in the industry I come from. And I can imagine some may have even been fired.

Ordinary paper is also a banned item in this industry; along with medical devices. When lives depend on electronics working - you don't want a chip that has suffered an EOS event. Your mother's life may depend on a defibrillator and just at that moment it gives up the ghost - along with mom. When you fly on a commercial jet - you don't want EOS chips manifesting their latent damages. When planes crash people die.

Someone before me said they use styrofoam and aluminum in their industry. I hope they only made children's toys. Such a practice would make Honeywell go elsewhere with their business if they ever found a PCB manufacturer using styrofoam and foil to protect their chips. If you've never had to sit on a board while the FBI wanted to know why something failed - be glad. I've had to. The "Railroad Safety Bureau". Had to explain why their trains were catching fire. And yes, it WAS my fault. I knew there was a problem. Even rejected the item. However, I later accepted it because I could find on solid basis for the rejection. Still, I knew there was a problem. Apparently so did the RSB. And I got lucky. I didn't have to go to jail. But the company had to pay a hefty fine. Shortly thereafter I found my next job at Northrop.

Every word of this is true.

Stay away from styrofoam. As a fellow hobbiest, I know certain things won't present much of a danger to the chips I use, still, you won't see plastic wrappers, sandwich bags - and especially styrofoam on my work bench. OK, resistors come in baggies. They get put into the steel cabinet and only come out when I need a specific resistor. Same with caps, transistors and all other electronic components that may go into a project. Things like the bare boards themselves - I'm not worried about those. Switches and such items that can't be damaged by ESD and EOS.

 

All these horror stories CAN be very real.

 

hi Mozee,
If you carefully follow my advice regarding storage of your IC's you will not get ESD failures.

Don't let all the doom and gloom rhetoric in posts #25 thru #28 put you off. I am speaking from many years commercial practical experience and other companies using this method, without problems.

E

 

I am speaking from many years commercial practical experience and other companies using this method, without problems.

COMMERCIAL experience? In many cases now-a-days commercial specs outpace military specs. And in nearly 40 years of experience I've NEVER ONCE HEARD OF ANY COMPANY USING FOIL AND FOAM. NEVER!

Doom and gloom? Well, it's your choice. Work hard and watch your efforts go to waste or practice some simple, tried and true methods and never have to learn harsh lessons.

While some of my experiences may have been (to some) extreme, it's intended to highlight what CAN go wrong. Honestly, in my hobby experiences I've never encountered any problems using standard practices. I've managed to come across conductive foam pads - which are not 0Ω resistance. Off hand I don't know what the ohms per cubic inch may be - I've never investigated that. However, conductive foam will NOT cause a sudden rush of electrons, so there IS some resistance to it. I just don't know what that resistance is. Aluminum foil? I can guarantee its resistance is on the order of ZERO ohms, and anything you plug into it will experience the clear chance of harm.

Eric speaks of years of experience. I can't say he doesn't have the experience he claims. I CAN say I'm somewhat dubious of his claims but I'll stop short of calling him anything but sincere in his claims. Personally I'd never employ any of his techniques. My experience comes from mostly military grade components and construction techniques. That trumps "Commercial" experience. If you look at consumer goods, much of the market is flooded with things that work. But that's the extent of their abilities. They work. Your hobby bench may be equally equipped - they will work. But military grade, when they launch an ICBM they want to know the circuitry contained within is GOING TO WORK. When an adversary fires a missile at a US War Plane, they NEED TO BE CONFIDENT the counter-measures will work. No if's, ands or buts about it.

In the world of ESD control I'm somewhat of an expert. Foam and foil is foolish. There's a better chance your electronics will suffer no harm if you don't package them in anything - versus putting them through foil into styrofoam.

Many people speak out against the practice. One speaks for it. What does that tell you? Experience of many outweighs the experience of a single person. Unless Eric can get more support behind his claim - I'd suggest you consider carefully exactly what practice you wish to incorporate in your hobby.

I wish you well. Eric may be 100% correct in his experience. But so far I haven't been hit by lightning. Still, that doesn't mean I'm going to go stand out in a thunderstorm just because "In the past" it hasn't hit me.

Make your choice. All I can do is offer very real experience and what I believe to be good advice. If you take the advice of someone else - so-be-it. Good luck; and Good Designing.

Peace all!

 

Went and did some research (not much, but I found this: http://hollandshielding.com/content/Filemanager/PDF_5770 - Conductive Foam CSA 03 With conductive self adhesive_January-25-2016-906am.pdf )

According to the spec sheet its resistance is 0.1 ohm MAX per square millimeter. The part in particular is 200 mm by 200 mm, that's 40,000 square mm. So its total surface resistance is around 4KΩ (this particular product). Safe enough to plug through hole IC's into without the fear of the onslaught of current rushing through your component when it may come in contact with something that has zero ohms per square foot.

OK, I'm done here. Let the others have at their arguments, I'm out of it.

[edit] After looking closer at the spec sheet I think this is for RF shielding and not static foam for storage of through hole IC's. Like I said, I didn't do much research. So this may be totally wrong. I'm not afraid to admit to being wrong - if such is the case. I'll continue to research conductive foam but I think I've said enough. Feel free to e-mail me if you desire.

[edit] (last edit) Found this spec sheet: http://documents.desco.com/PDF/12100.pdf

 

I wish you well. Eric may be 100% correct in his experience. But so far I haven't been hit by lightning. Still, that doesn't mean I'm going to go stand out in a thunderstorm just because "In the past" it hasn't hit me.

Hi Tony,
I honestly hope you will never be hit by lightning.
Lightning can strike without a thunderstorm being present, so how much protection should be one need to be 100% safe.?
Electrostatic fields are always with us, so without due care IC's can be damaged

My argument would be the degree of prevention that we need to minimise the ESD risk of damage to sensitive components, should be in the context of the 'builder' and his wallet.

I would agree that any company building safety critical systems should have the highest possible levels of ESD protection

Basically we are not in disagreement, its just about the level of protection required.

Eric

 

I would say that depending upon aluminum foil to protect an IC from static is problematic.
There's no assurance that all the pins are in actual contact with the foil when you push the pins through the foil.
Also aluminum readily forms an oxide on it's surface that has a very high resistance.
Stay with conductive foam or other conductive packaging or containers.

 

Eric: Thanks for your words. Honestly I was expecting an argument.

This is my OPINION: Styrofoam wrapped in aluminum foil may be more dangerous than simply storing IC's in a cardboard box. Yes, cardboard is also an ESD Prohibited material, but the chances of damage from cardboard are minimal. Not negligible for military or medical devices, but nevertheless, should not present as much a danger as compared to styrofoam and foil. Again, I clearly state this as "My Opinion". I could be wrong.

Styrofoam when handled tends to generate TONS of static. Since I've never employed your method I have no practical experience on how well the foil will prevent the generation of static within the styrofoam. But potential friction from the foil and the foam - I'd be in fear of generating a charge that might want to find a way to escape the cage - hence the piercing of the foil.