Issue 3, March 1999: Volume 2
Sender : ESD SYSTEMS, 19 Brigham Street #9, Marlboro, MA 01752-3170
Phone : 508-485-7390
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This is a free monthly newsletter, which specializes on issues in static control in the workplace.
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IN THIS ISSUE:
HOT TIP of the MONTH(Angle Banana)
When grounding via a wrist strap and the operator is very active (consistently putting tension on the coil cord) the probability increases for the banana plug to disengage from the banana ground jack.
There are right-angled banana coil cords that when plugged into your ground jack decreases the probability of the plug being pulled out. The right angle plug increases the torque, which increases the amount of force needed to disengage the plug via direct tension on the coil cord. This will ensure that an active operator remains grounded when plugged into the workstation's common point ground.
Note: There is a mechanical safety feature built into every ESD Systems standard or premium wrist strap, where the cord will disengage from the buckle with greater than 5 pounds force. This feature meets the ESD S1.1-1998 standard for wrist straps. This is intended top protect the operator from being pulled into heavy machinery or other undesirable situations.
ESDA’s RTP for 5/19/99
The ESD Association is sponsoring a Regional Tutorial Program (RTP) on electrostatic discharge May 19, 1999 at the Doubletree Hotel—Lloyd Center in Portland, Oregon.
The tutorial is designed for persons who want to learn the basics of static control, as well as for more experienced individuals who want to focus on specific topics. The tutorial is a program designed to meet the specific educational needs and interests in the Northwestern U.S. The tutorial is specifically developed for manufacturers, contract assemblers and users of ESD sensitive electronic parts, assemblies, and equipment. It is targeted for production, design, engineering, technical, quality and reliability, failure analysis, and sales and marketing personnel.
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:email@example.com.
Silicon Valley EOS/ESD Society Tutorial for 4/20/99
TheInternational Disk Drive Equipment and Materials Association is sponsoring an ESD Discovery '99, held April 20th, 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 theInternational 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.
ESD Q&A CORNER
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?
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.
PRODUCT UPDATES (NEW!)
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.
THE SOURCE OF THE PROBLEM
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.
This is a free monthly newsletter, which specializes on issues in static control in the workplace.
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 athttp://www.esdsystems.com/forms/esdmail.asp
This Newsletter is never sent unsolicited. To unsubscribe from this mailing, send an e-mail toESD_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 firstname.lastname@example.org
Copyright © Desco Industries, Inc. 1999