Control Electronic Static Discharge

How can I control Electronic Static Discharge in my automated handling equipment?

S. D.

Expert Panel Responses

Contact the manufacturer of the equipment for this information

Bob Black
North America Sales Manager
Essegi Automation

Mr. Black was the President and Co-Founder of Zevatech in 1977 and introduced first Pick and Place System at Nepcon West 1980. Bob is now the President, CEO and Co-Founder of Juki Automation Systems. He is also a Co-Founder of the SMEMA Council of IPC. He serves as a member of SMTA and SEMI..

In most cases, electrostatic discharge protection should be built into the equipment, it is difficult to retrofit, but I can give you some tips.

Talk to the equipment supplier. They should know how to control ESD on their equipment.
One of the most common sources of static charge is on the conveyor. See if the equipment supplier has some ESD belts or conveying chains and make sure the conveyor is grounded.
Get a digital static meter. You can find one on-line by Googling "static meter". Use the static meter to find areas where there is high charge and ground that area.
Ion fans are available. Again, Google is your friend. I tried "static discharge ion fan" and several came up. They help dissipate static charge, particularly in dry environments. They can help, but won't prevent a serious problem.
If you are in a very dry environment, consider small increases in humidity.
Look for areas where plastic or rubber is used to isolate metal parts, particularly those that have some electrical component on them. Create a ground path for these areas.

Alan Lewis
Director of Application Engineering
Asymtek

Mr. Lewis worked for The Aerospace Corporation for 6 years before joining Asymtek in 1993. He holds multiple patents in dispensing technology for electronics assembly and packaging. He has a Master's Degree in Mechanical Engineering from University of Missouri-Rolla.
NOTE: Mr. Lewis is no longer working at Asymtek.

Inside of the AHE (automated handling equipment) you have ESD events, called from CDM (Charged Device Model). This ESD event is very fast. For ESD control you shell first all metal parts are grounding and second you shell use an ionizer. The ionizer shell is placed inside of the AHE. The ionizer shell discharge the electronic device and the PCB directly before the electronic device placed on the PCB. If you have more questions, we have a very long experience in static control, also inside of machines or outside on workstation.

Hartmut Berndt
President
B.E.STAT group

Mr. Burndt has been in Electronics & Semiconductor Technology since 1980 and work in the area of Electrostatic (ESD) and electronic devices. He is President of the B.E.STAT group (Germany); expert in ESD audits, trainings, failure analysis and ESD control programs.

All equipment should be grounded through the power cord. If any portion of the equipment is isolated from the chassis ground then electrical connections should between all the pieces or sections of the equipment so it is all grounded. It can be as simple as having a conductive floor and using chains to drag onto the floor, or using metal pads for the feet of the equipment on the grounded floor. One should also review the equipment for any element which may not be static dissipative allowing an electrical charge to build up, for example a place where paper is slid across a non metallic surface or a conveyor that is supported by non metallic supports or isolated from the base system. When these conditions are evident, wires can be installed to ground the units together.

Leo Lambert
Vice President, Technical Director
EPTAC Corporation

At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee.

If you are referring to ESD events caused by the motion of the handling devices then the only method is to utilize localized ionization. The ionizer needs to be of the quality that will "knock down" a charge rapidly. There are several devices on the market that are capable of doing this that are made to go inside the cabinet without sacrificing a great deal of room. As far as the equipment itself, it is grounded via your electrical system.

Jerry Karp
President
JSK Associates

Based in. Northern California since 1971. Founded JSK Associates in 1979. Actively involved in soldering, cleaning, chemistries. 30 years experience in EOS/ESD control.

As Leo has so wisely pointed out, do not assume that all portions of any machine are grounded through the power cord. Also do not assume that if you have 0 ohms of resistance between the various parts of the machine and electrical ground, there is nothing to worry about. The electrical ground may only be for some parts of the machine, but the rails, fixtures, etc., should also be checked for grounding. Also, a machine that is grounded can still produce voltages that can damage the circuit card or components that it comes in contact with. These have to be checked as well, similar to the testing performed on a solder station.

Richard D. Stadem
Advanced Engineer/Scientist
General Dynamics

Richard D. Stadem is an advanced engineer/scientist for General Dynamics and is also a consulting engineer for other companies. He has 38 years of engineering experience having worked for Honeywell, ADC, Pemstar (now Benchmark), Analog Technologies, and General Dynamics.

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