Advertisement

Tips on Electrostatic Discharge (ESD Protection)

esd protection logoThe Ideal Setup

This includes a conductive bench top, conductive flooring, conductive stool, conductive slippers, conductive parts bins, wrist strap, air ionizer, humidifier, grounded everything, etc. While all of this is nice and perhaps essential for high reliability manufacturing, it is well beyond the financial reach of the experimenter.

The following lists minimum recommendations for ESD protection of the experimenter:

  • Humidity
    What you really need depends upon your environment — if you live in a dry environment such as the desert or a heated building, it is highly recommended that you have a source of humidity such as a humidifier or hot teapot nearby. If you live in the tropics, static is almost a non-issue unless you work in a highly air-conditioned building.
  • Bench top
    While a conductive bench top is recommended, a metallic tabletop is to be avoided. A Formica bench top can hold an electrostatic charge, but if treated with anti-static spray it should be acceptable. If the bench top is old (like mine), it is so contaminated with conductive matter that there is little concern.
  • Wrist strap
    I rarely use a wrist strap, but keep one in your bag of tricks. It makes sense to use one when servicing your $1000 computer.
  • Soldering iron
    Your soldering iron must be grounded via a high-meg resistor — a hard grounded (no resistor) soldering iron is a real killer.

Everything else is in the handling

If you follow these simple handling instructions, you will have minimal problems.
human body esd (electrostatic discharge)
Your body, an ESD free workstation

Both hands are electrically connected so you may safely pass components or boards from one hand to the other. The main problem is how it is transferred to or from your body. Next on ESD protection:

Real killers and how to protect against them

  • Picking up a component or PCB from a conductive surface, or placing one on such — first ground your body by touching the surface to discharge any potential charge, and then handle the component.
  • Passing a component or PCB from person to person — first make skin contact with the other person’s hand to equalize any potential charge, and then pass the component.
  • Hard-grounded soldering iron — an ungrounded soldering iron is far safer than one that is hard grounded — ground via a 1M or higher resistor.
  • Synthetic carpeting — one can hardly move without generating a charge — avoid carpeting in your work area
  • Cathode ray tubes (oscilloscopes or monitors) can be dangerous sources of ESD — keep static sensitive components a safe distance away from the screen and avoid touching the screen.

Photos of solder stations with ESD protection

Note that many older solder stations have hard-grounded tips. This is easy to check via reading the resistance with a multimeter — mine reads 4.41M. Older ones that caused me much grief required the addition of a 1M resistor in the ground circuit.

Another cause of failure (not related to ESD), involves the accidental grounding of a circuit with a grounded soldering iron before the power is removed — can make SPARKS! — this has happened to me more than once… Unreasonable rules and regulations regarding the grounding of equipment often introduce additional problems like this (unintended consequence).

Undocumented words and idioms (for our ESL friends)

bag of tricks – idiom — a bag carried by a magician. In electronics it refers to various solutions that are at your disposal.

unintended consequence – an allusion to The Law of Unintended Consequences in which government regulations cause more problems than solutions — not unlike Murphy’s Law. While the following link discusses mainly economic issues, it is obvious that this phenomenon spills over into virtually all aspect of life, including engineering.

http://www.econlib.org/library/Enc/UnintendedConsequences.html

2 Comments

Join the conversation!

Error! Please fill all fields.
Looking for the latest from TI?