Arduino Forum

Development => Suggestions for the Arduino Project => Topic started by: perjarle on Aug 16, 2012, 01:38 pm

Title: ESD Safety
Post by: perjarle on Aug 16, 2012, 01:38 pm
Hello all
I just received a brand new Arduino UNO R3

It came beautiful packaged inside a cardboard box together with some plastic covered stickers.

Since we are talking about unshielded electronics, and a microcontroller I was expecting to receive it wrapped in ESD safe materials.

There are big chances that the microcontroller is already damaged even before I open the box.

/Per-Jarle
Title: Re: ESD Safety
Post by: Tom Carpenter on Aug 16, 2012, 02:34 pm
The microcontroller is part of a circuit board which contains a large ground plane. This in itself will protect the IC. There is also regulation and filter circuitry onboard which will also offer some level of protection.
Title: Re: ESD Safety
Post by: perjarle on Aug 16, 2012, 02:52 pm

You never know where a 20 000 Volt static spark hits.
If it hits the common ground then you may be lucky.

Ship the boards wrapped in ESD safe materials and show the world that you care about quality.
Title: Re: ESD Safety
Post by: dxw00d on Aug 16, 2012, 03:01 pm
How many have been returned due to ESD damage? If it was a significant number, I'm sure the packaging would have been changed.
Title: Re: ESD Safety
Post by: perjarle on Aug 16, 2012, 03:19 pm
Noone is able to see if a component is damaged by ESD.
If it left a brown mark with bad smell, then it would be easy.

Most users probably expose the board with even more ESD (laying on ungrounded tables etc).

How many cent would it cost to wrap the boards safely?

/PJ

Title: Re: ESD Safety
Post by: kg4wsv on Aug 16, 2012, 03:23 pm
If this is some sort of mission critical system, where failure would be very expensive and/or impossible to fix, then ESD protocols should be followed.

The vast majority of Arduinos will live in an ESD-unsafe (maybe even ESD-hostile) environment for the rest of their lives once they're removed from the box.  This does not appear to be a problem to date.

-j
Title: Re: ESD Safety
Post by: Tom Carpenter on Aug 16, 2012, 03:35 pm
How do you think ESD materials work? They are simply a conductive material on which charged electrons repulsed by all having the same charge, move away from each other which forces them onto the outside of the bag and away from the component.

If you take a microcontroller, it is not conductive, apart from the pins. This means that the ESD builds up on one or more of the pins creating a potential difference across the IC of anywhere upwards of 10kV. This can damage the IC.

If however you take an IC connected to a board with a ground plane. Where does the ESD go? Well, all the electrons can happily transfer to the ground plane which is nicely conductive and move away from each other, and critically away from the IC. This means there is no buildup of potential across the IC pins.


As a side note while that board is nicely inside its cardboard box, where does an electrostatic discharge come from? Last time I checked the box isn't particularly conductive, so it is unlikely that a discharge will jump to the box, and if it does, it will built up on the outer surface - just like an ESD bag.
Title: Re: ESD Safety
Post by: dxw00d on Aug 16, 2012, 03:39 pm
Quote
Most users probably expose the board with even more ESD (laying on ungrounded tables etc).


I certainly do that. I don't use my earthed wrist strap when handling it, and coffee spillages are not unheard of.

I've not had any trouble, even with the cat pawing at it. Arduinos are impressively robust, probably due to the relatively low tech design.
Title: Re: ESD Safety
Post by: drjiohnsmith on Aug 16, 2012, 08:58 pm
rugged uno.

http://ruggedcircuits.com/html/ruggeduino.html (http://ruggedcircuits.com/html/ruggeduino.html)

Title: Re: ESD Safety
Post by: oldPGMguy on Aug 17, 2012, 04:36 pm
never used any ESD protection....only thing I ever zapped was a basic stamp 1 clone....
Title: Re: ESD Safety
Post by: drjiohnsmith on Aug 17, 2012, 09:07 pm
ESD damage.

You are rarely lucky enough to know you have ESD damage, till later....

101 on ESD damage.
    Typically affects on outputs, not inputs.

Output circuits, although shown on the 'schematic' for the chip as a pair of up / down fets , are in fact a number of fets in parallel, typicaly 3 to 5.
   
the reason for this is speed / power. The output fets are different sizes, small ones, can drive fast, but not much current, up to the big one that drives biggest current, but is slower.

ESD damage tends to blow the smaller of the fets. This has two effects.
    the output is slower, and typically it has a small short circuit on it from the blown fet.

so the output will still 'work', but not as fast as it should, it will typical have more running on it than it should, and the output will get worse over time.


Analogous to driving too big a load, the output can do it, but I'd not want to for anything that is meant to be reliable over time.

SO ESD,  dont do it.
     it will bite you in the but some time ,


Title: Re: ESD Safety
Post by: polymorph on Jan 29, 2014, 07:16 pm
That last post bears bumping.

I think a lot of newbies are discouraged by damaged devices, thinking that they are doing something wrong. More and more distributors are shipping with partial or no ESD safety precautions.

Sure, modern ICs have more built-in ESD protection, but why stress it? There is a misunderstanding about how static charges build up, that it requires conductors. It does not. Usually at least one side is an insulator, or both. At one of my jobs, we took all kinds of ESD precautions, but then big nylon web belts were loaded into grey plastic buckets. Sometimes a huge charge would build up inside the bucket, causing the outside metal carrier to be charged by induction. You'd get a rather hefty shock from grabbing the metal, then reach inside and really get hit.

It generally takes a few thousand volts charge for you to feel, hear, and see it. But it may take as little as 20V to blow a MOSFET or BJT.
Title: Re: ESD Safety
Post by: drjiohnsmith on Jan 29, 2014, 09:51 pm
As an aside,

I once worked for a company when ESD started becoming a concern.

the stores team were told all electrical stuff was ESD sensitive, so they spent a fortune earthing and lining all the draws with a nice metal shield ( tin foil to you and me ).

It took us a while to work out why the new AA batteries from stores always seemed to be flat !!!


Title: Re: ESD Safety
Post by: polymorph on Jan 29, 2014, 10:15 pm
Metal foil!?! Wow, they really didn't get it.

Some of the cleaning staff here thinks that they can't mop our grounding floor mats "because they're wired to electricity". Well, if it stops them from mopping them, we leave well enough alone. It isn't their job to know.