Wednesday, January 16, 2013

ESD Static Control


What is ESD?
ESD, or electrostatic discharge, is described as the abrupt transition of electricity between two objects with different electric potential. ESD is responsible for lightning, as well as the shock a person feels when he or she grabs a metal doorknob after rolling around on a carpeted floor in a wool sweater. While the consequences of lightning can be devastating as compared to the trivial pain of a small static shock, neither example necessarily compares to the financial liability that many companies face when manufacturing things like integrated circuits and other sensitive electronics.

ESD losses can happen at any point in the process, from manufacturing to the field. In other words, the small shock that may give you a giggle can completely fry an integrated circuit (which is expensive to manufacture in the first place) and cost a company millions of dollars.

ESD Causes and Types
ESD can be caused two ways, through tribocharging and electrostatic induction. Tribocharging occurs from friction, like when someone runs a plastic comb through dry hair. Electrostatic induction occurs when an electrically charged object is placed near a conductive object isolated from ground. Here is a quick list of ESD types:

  • •sparks
  • •corona discharges
  • •brush discharges
Sparks have the potential to cause large explosions because of the high temperatures contained in one. Both methane and coal dust explosions have been caused by electrostatic discharges, leaving damaging results.

A corona discharge occurs between a highly curved electrode (e.g. the tip of a needle), and an electrode of low curvature such as a flat surface.

A brush discharge occurs between an electrode with a curvature anywhere from 5 mm to 50 mm, and a voltage of around 500 kV/m. The resulting discharge looks like a brush, hence the name.  

ESD and Modern Man
It took thousands of years, a few wonderful minds like Nikola Tesla and Ben Franklin, and learning from a history of disasters (some experts believe that ESD was responsible for the Hindenburg disaster in the early 1900's. The ship flew through a lightning storm before arriving at its destination, and it is thought by some that an ESD spark was produced after the mooring ropes were let down to the ground for docking), but our knowledge has finally progressed to the point that our ignorance is out-leveraged, empowering humans to successfully build the very things that we use every day and all too often take for granted. ESD can occur almost anywhere. For instance, someone may know how to do basic computer repairs, but if they open up a computer indoors while there is a lightning storm outside, they may be in for a shock, both figuratively and literally. The extra static under such conditions may very well be transferred from the person to sensitive parts of the computer, effectively destroying them. In this scenario, it is recommended that the person do something to ground themselves so that the static never has a chance to destroy the computer.

Controlling ESD
Nowadays, any company that manufactures sensitive electronics should have anti-static devices in place to stop the problem of ESD before it even starts. Here at Janel Inc., we offer anti-static wristbands, Desco ESD mats, static shield bags, and heel straps to keep human workers grounded at all times. They also offer ESD Static Control coatings that form a conductive surface in order to dissipate static electricity on surfaces like concrete floors. Janel Inc. is a huge supplier of Desco, 3M, Protektive Pak, O.C. White, Scienscope and Flambeau ESD prevention devices with literally thousands of products in stock and available at their website, www.janelonline.com.  

About the Author
Janel Incorporated has been supplying the production assembly and electronics manufacturing industries for over 50 years. Janel Inc. distributes products from manufacturers such as Kester Solder, JBC Soldering Tools, Henkel Loctite, Techspray, Excelta, and Desco.

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