[sdiy] Storing ICs (and static sensitivity) - how much to worry?

[Tristan]

Ooops, in paragraph 2 I meant to say:

It is the high voltages typically involved in static discharge, combined 
with a path of HIGH conductivity, that leads to high currents between the IC 
pins and damage to the circuit inside. 

-- 
Best regards,
Tristan                            mailto:tu at alphalink.com.au

Thursday, May 29, 2008, 11:10:36 AM, you wrote:

T> Hi Julian,

T> If you are concerned about static then you should always try to keep
T> ICs in their antistatic tubes, antistatic bags and/or in antistatic
T> foam (usually black or pink). Do not store them loose in plastic
T> drawers or in white polystyrene foam! Some people spray polystyrene
T> foam with a conductive coating or cover it with foil but these are not
T> a good solution as the high conductivity can be a problem if a static
T> charge is applied.

T> The materials used in antistatic bags and foam etc are conductive but
T> have a relatively low conductivity. If you touch the antistatic
T> material when you are statically charged the charge spreads through
T> the material slowly, thus only producing a small local differential
T> between pins on ICs. It is the high voltages typically involved in
T> static discharge, combined with a path of low conductivity, that leads
T> to high currents between the IC pins and damage to the circuit inside.

T> For best protection you should also use an antistatic bench mat where
T> you are working and an antistatic wrist strap. The antistatic mat
T> should be grounded to your electrical earth through at least several
T> Meg ohms and your wrist strap should be connected to the mat or ground
T> through several Meg ohms as well. Synthetic clothing and shoes can
T> also generate or allow the build up of static charge on your body, as
T> can walking across synthetic carpets etc.

T> In the electronics labs where I work all benches and flooring have
T> antistatic coatings and we are required to wear antistatic shoes or
T> heel straps while working in the lab. The benches and equipment racks
T> also have antistatic wrist straps to use when handling boards and ICs.
T> Despite all these precautions I have still seen boards destroyed by
T> careless people taking off synthetic clothing.

-- 
Best regards,
Tristan                            mailto:tu at alphalink.com.au