Reference: http://www.esdsystems.com/newsletters/v2issue3.htm

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• HOT TIP of the MONTH (Angle Banana)
• ESDA’s RTP for 5/19/99
• Silicon Valley EOS/ESD Society Tutorial for 4/20/99
• ESD Q&A CORNER (ESD Safe Areas)
• PRODUCT UPDATES (Mini Continuous Monitor & Overhead Ionizer C/E)
• Dr. ZAP (ESD Safe Area)

For additional information, contact the ESD Association, 7900 Turin Road, Bldg. 3, Suite 2, Rome, NY 13440-2069. Ph: 315-339-6937, Fax: 315-339-6793. E-mail: eosesd@aol.com.

The International Disk Drive Equipment and Materials Association is sponsoring an ESD Discovery '99, held April 20^th, 1999 at the Westin Hotel in Santa Clara, CA, and presented by Silicon Valley EOS/ESD Society. This is a one day tutorial on ESD awareness. This educational program will cover: ESD Basics, ESD Protective workstation design and evaluation, ESD control program implementation and audit, ESD material selection and evaluation techniques, Device level ESD testing and failure analysis, understanding & solving ESD issues in magnetic recording, and featuring the ESD exploritorium……fun hands on ESD experiments.

For additional information, contact the International Disk Drive Equipment and Materials Association:

IDEMA, 3255 Scott Blvd, Suite 2-102, Santa Clara, CA, Fax: 408-492-1425. http://www.idema.org and http://www.esdsv.org.

The following questions and answers are selected from our FAQ WEB Page: http://www.esdsystems.com/question.html concerning Questions about ESD Safe Areas.

Q1: What is the minimum distance between an ESD protected area and a passageway non ESD protected (let's say from the end of a working table to the passageway)? Which ESD standard, if any, specifies this distance?

Thank you in advance for any valuable information. - Anonymous, Dorval, QC, Canada Answers

A1: EIA-625 specifies keeping a non-grounded personnel a distance of 12 inches from an ESDS area. My recommendation would be to add three feet to this yielding a total separation of 4 feet. The reasons for the additional 3 feet are that charge induction may not have been considered and even though your body may be 12 inches from an ESDS area, extending your arm could cut that down below 12 inches depending on whether or not you are leaning, have long arms, etc.

Q2: What is the accepted spec for an ESD safe work station, i.e., must all things at the work station be less than 100 V potential or some other potential? And in what specification would I find this information? - Anonymous, Indianapolis, IN

A2: The spec for an ESD safe work station is entirely predicated on the sensitivity of the product being worked on. With some customers, this may be 200 volts, while with others, it may be 20 volts! Consult the component manufacturers data sheet.

Mini Continuous Monitor, Model # 41122

Real time monitor of ESD workstation
no wires to connect
new small size
monitors any single wrist strap
reliable wave distortion technology
two pairs of red and green LEDs to indicate grounding status

Overhead Ionizer C/E (Critical Environment), Models # 43461 (24"), 43462 (48")

Removable emitter cartridge
front panel display with maintenance LED signal
lockout key with front panel indicator
I/O jack - automates calibration and real time data
closed-loop feedback electronic balance system
minimal contamination ionizer (good for clean rooms)
sealed plenum chamber around each fan
overhead mounting
ionization output adjustable at each fan
IEC input and output connectors (can daisy chain up to 10 units)

 

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Topic: ESD Safe Area, gleaned from a paper "CONTROLLING STATIC AT THE SERVICE BENCH", located at: http://www.esdsystems.com/whitepapers/wp_staticbench.asp

The best-equipped service bench in your shop can be a real moneymaker when set up properly. It can also be a source of frustration and lost revenue if the threat of ElectroStatic Discharge (ESD) is ignored. Static electricity is nothing new; it's all around us and always has been. What has changed is the proliferation of semiconductors in almost every consumer product we buy. Couple that with the fact that as device complexity becomes greater, often it's static sensitivity increases. Some semiconductor devices may be damaged by as little as 20-30 volts!

A typical scenario might be where an electronic product is brought in for service, properly diagnosed, repaired, only to find a new and perhaps different symptom, necessitating additional repair. Damage from static electricity cannot be ruled out, unless the technician understands the ESD problem and has developed methods to keep it in check.

It is important to note that we are addressing the issue of ESD in terms of control, and not elimination. The potential for an ESD event to occur cannot be totally eliminated outside of a laboratory environment, but we can greatly reduce the risk with the proper training and equipment. By implementing a good static control program and developing some simple habits, the problem can be effectively controlled.

As mentioned earlier, static is all around us. We occasionally will see or feel it by walking on carpet and touching something or someone, and feeling the "zap" of a static discharge. The perception level varies, but the static charge is typically 2000-3000 volts before we can feel it. Remembering that the sensitivity of some parts is under 100 volts, it's easy to see that we might never know that an ESD event has occurred.

Even though carpet may not be used around the service bench, there are many other, more subtle, static "generators" frequently found around or on the service bench. The innocent-looking styrofoam coffee cup can be a tremendous source of static. The simple act of pulling several inches of adhesive tape from a roll can generate several thousand volts of static! Many insulative materials will develop a charge by rubbing them or separating them from another material. This phenomenon is known as "tribocharging" and it occurs often where there are insulative materials present.

People are often a major factor in generation of static charges. Studies have shown that personnel in a manufacturing environment frequently develop 5000 volts or more just by walking across the floor. Again, this is "tribocharging" produced by the separation of their shoes and the flooring as they walk.

A technician seated at a non-E.S.D. workbench could easily have a 400-500 volt charge on his or her body caused not only by friction or tribocharging, but additionally by the constant change in body capacitance that occurs from natural movements. The simple act of lifting both feet off the floor can raise the measured voltage on a person as much as 500-1000 volts.

An effective static control program doesn't have to be expensive or complex. The main concept is to minimize generation of static and to drain it away when it does occur, thereby lessening the chance for an ESD event to happen. The ingredients for an effective ESD program are:

--EDUCATION--to insure that everyone understands the problem and the proper handling of sensitive devices.

--WORKSTATION GROUNDING--through the use of a dissipative worksurface material and dissipative flooring materials as required.

--PERSONNEL GROUNDING--using wrist straps with ground cords and/or foot-grounding devices.

--FOLLOW-UP TO INSURE COMPLIANCE--all elements of the program should be checked frequently to determine that they are working effectively.

The ESD "threat" is not likely to go away soon, and it is very likely to become an even greater hazard, as electronic devices continue to increase in complexity and decrease in size. By implementing a static control program now, you will be prepared for the more sensitive products that will be coming.

Need your own copy? Want to subscribe to this Newsletter? All you or your colleague(s) need to do is simply fill out the subscription form at http://www.esdsystems.com/forms/esdmail.asp

This Newsletter is never sent unsolicited. To unsubscribe from this mailing, send an e-mail to ESD_Newletters@esdsystems.com and put " UNSUBSCRIBE ESD_Newsletters" in the subject.

Let us know what you think. Tell us what you would like to see in future issues. Want to contribute articles or other related information to our Newsletter? Send your comments to the editor@esdsystems.com