The new standard from ESDA see ESD ground
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The electrostatic discharge association (ESDA) new ground standard has revealed some establish EPA earthing system problems. The standard the revision will simplify the ESD control plan implementation of some work. Hope this information will help engineers to updated ANSI/ESD S6.1 familiar and understand, eliminate ESD control in earth's question.
In a given area will all the electrostatic conductive materials and static dissipative material objects in electrical connection and access the earth, can make the area at the same potential; At the same time, electrostatic conductive materials and static dissipative material equipotential earth shall ensure that potential to ground to 0 v, these are based ESD protection area, reduce the area of the electrostatic sensitive device in take put and operation of potential difference leads to discharge the basic principle of risk, but this kind of reserve is what we call the electrostatic reserve (EPA).
In addition, because in a grounded electrostatic conductive materials and static dissipative material is not gathered electrostatic charge, as long as the earth, even if the original materials with the electrostatic charge, also can get relief.
ESDA about earth's latest standard ANSI/ESD S6.1-2005 on the original standard the correlation content has carried on the significant adjustment. The new S6.1 standards for ESD technical design personnel and other related technical personnel in the EPA grounding and electrical connection gives a clear guidance. Standard before the revision, standard writing experts carefully study the fire protection association NFPA70 standards and other relevant state wire connection content.
We hope that this paper can on domestic electronic product manufacturing enterprises based on the standard establish ESD ground the system to provide the useful information.
The new term
Updated S6.1 standard definition and use of several new terms, some of which in this paper will also mention, because it has not been well known's sake, here we first as an introduction.
Connection conductor bonding conductor: one for connecting two * * * * of electrostatic conductive material or static dissipative material object of conductive device, the device can be conductor, bus, flange or other conductive device.
Common connection point common connec - tion point: their own resistance less than 1 ohm a device or position, used to connect two or more ESD technology items (such as the pad, the hand WanDai, etc.), let them without grounded through the equipotential connection to ensure that in the same potential.
ESD grounding/connection point of reference The ESD grounding/bonding reference point: The most suitable for equipment or site ESD earth grounding system, it can be AC ground, auxiliary grounding or equipotential connection.
ESD technology items ESD technical element: EPA used in the static control of materials and articles, equipment, tools and equipment, such as wrist band, shoe joint zone, ESD workstation and anti-static floor, etc
Level 2 technical items A Level 2 techni - CAL element: connect to have connection common joint site (to point ground) or common connection point (common connection point) of ESD technology items (ESD technical ele - ment), such as standing in anti-static floor wear shoe joint zone of people.
The choice of grounding system
We are set up EPA first consideration when may is to choose the most suitable grounding system. In the standard gives several ESD grounding/connect the choice of reference point. The equipment grounding is the vast majority of factory first choice, followed by auxiliary grounding and equipotential connection.
Ac earth. In most cases this is North America 120 v standard ac socket in the third line, the use of green or yellow stripe green wire, there are some countries use other color line. This line is equipment grounding conductor, it from the socket connection to the ground wire coil, and the latter and connected to the total power distribution cabinet of the neutral wire coil (such as distribution cabinet into the line of the power cord plate).
In most factories, wiring duct and equipment earthing electrode potential is same, so it can be used for equipment ac earth. Of course, this is the correct connection as the prerequisite, even connection no problem, should also hold first by the inspection of electrical engineers. This in the new standard in constructed.
Auxiliary grounding. Some time, need to consider using auxiliary grounding system is EPA best grounding way, because the equipment is not earth can remove any ESD and electromagnetic wave caused by the signal interference, but to do so shall be after carefully study and discussion. At first, static grounding standard drafting team thinks, such doing can make two ground have different potential, become a very difficult problem. The working group members find equipment ac earth and separate auxiliary grounding potential difference between sometimes more than 500 v. If this in workstation appear, cannot provide ESD sensitive device take put the OV operating environment.
The problem in the back of the S6.1 statement given to solve description: no matter what circumstances, auxiliary grounding and equipment ground shall conduct connection. In some cases, auxiliary grounding for some special activity is necessary, then must keep in mind is that, auxiliary grounding and equipment ac ground potential is different.
Equipotential connection. This choice in most cases is applicable to far away from production workshop is not easy to set up EPA areas and equipment. Will all ESD technology items, area of the staff and work equipment through the electrical connection to together, make them have the same potential. In fact, in the system inside and grounding connection of potential may be increased, but all items will still be in the same potential.
This method will be within the system object different potential or electrostatic potential into equipotential bit, so, carries on the
