Which components need ESD protected packaging?

[beaker353]

I’ve reached the point that cardboard boxes and zip lock bags are no longer cutting it for storage of all my random components I have acquired over the years.  I now in possession of some storage bin drawer thingies that everyone is going into.  As I started to sort through the random mess, I started creating three piles.  Components that were not ESD sensitive and didn’t need any protection, component that I knew should be stored inside side static shielding bags, and ones that frankly, I was unsure about.  In particular diodes, both normal and the light emitting type.  I understand the concept of semi-conductor junctions and the damage that high voltage discharge can cause.  I think I’ve sometimes received them from the distributor in static shielding bags and sometimes not.  Is there an easy way to tell or some guidelines that can help me figure out if they belong in a bag or just tossed in a bin?  Keep in mind I live in the desert, so humidity levels can easily dip into the teens inside my house.  Thanks!

[IanB]

In general it is anything that has capacitive (voltage driven) rather than resistive (current driven) inputs, in particular FETs and things built from FETs like CMOS logic. Static discharge can punch a hole in the insulation of the gates and damage them.

Since an LED is not built like this it is generally safe from static discharges in normal handling. The same applies to normal diodes and BJTs.

(But when you consider the painful zap that you sometimes get when touching metal surfaces, I doubt anything is really safe from that kind of discharge...)

[beaker353]

Thanks IanB!  I know all too well about the power (and pain) of static discharge.  Still not sure who exactly had the built up charge, but my cat came over to me wanting attention one day and when I moved my hand over to pet her, a good half inch spark went from the tip of my thumb to her nose.  She hasn't touched the couch in months now, but can't exactly  say I blame her... Anyhow...

That's some good guide lines.  I am amazed how unhelpful Google was in digging up this type of information.  And I guess it would be too much to ask the manufacturers to put this on their data sheets.  Are there any non-semiconductor type components that I should be aware of that I should treat as a static sensitive device?

Just noticed I have some small zener diodes with the same generic part number but packaged differently from the distributer.  Mouser has it in a static shielding bag, Digikey uses standard clear plastica bag.  Interesting...

Thanks again!

[vk6zgo]

I think some suppliers work on the basis of "One in,all in",reasoning that, even if the ESD packaging material is more costly,there are savings in not having different handling for some components.

I have seen  things that would not be affected by ESD,like terminal lugs & electrolytic caps,dutifully packed in ESD protection material.

VK6ZGO

[IanB]

Just noticed I have some small zener diodes with the same generic part number but packaged differently from the distributer.  Mouser has it in a static shielding bag, Digikey uses standard clear plastica bag.  Interesting...

Since I doubt that static dissipating bags are much more expensive than regular bags it may make sense just to ship everything in a protective bag. It avoids shipping and handling staff having to select the right bag each time and prevents the possibility of mistakes.

Zener diodes should be fairly safe, since they are designed to pass current in the breakdown direction during normal operation. There is nothing that is really going to be damaged by the microamps in a typical static discharge.

CMOS logic chips, CPUs and memory chips are different: if they are designed to operate at say 5 V or 3.3 V and their inputs get charged up to hundreds of volts by static then they won't stand a chance.

[ejeffrey]

MOSFETs are the most sensitive, whether discrete or in CMOS integrated circuits.  Even big beefy power switching MOSFETs are quite sensitive.

Anything based on PN junctions: diodes, but also BJTs, JFETs, and integrated circuits built on them are somewhat sensitive, but less so than MOSFETs. 

Regardless of technology, RF devices are much more sensitive than low frequency devices as they have less parasitic capacitance and often narrower junctions so the same discharge current has a higher current density.  Low frequency ICs generally have more effective ESD protection circuits built in: unless they are designed for extremely high input impedance they don't mind a few pF extra capacitance.

[kyle]

I was thinking of ESD today. I understand how there's a possibility of potential difference between a person and a sensitive component, where a discharge from a person would damage the component, but is the other way around true also? E.g. energy flowing from a component to a person, would that do a damage? And how would that happen--can a mistreated component retain high charge? Would it be wise to say that you never want a component to get energized so for example you wouldn't store your electronics in a drawer or in a box but in an ESD safe wrap so in case the [component+wrap+box] changes its charge due to external factors the ESD safe wrap would slowly either charge or discharge to balance the component's charge with respect to the environment (air, your desk, etc)?