Static Solutions CT-8900 Combo Tester Instructions 1/15/2015
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TERMINOLOGY
Static fields can build up on humans as they walk along an insulative surface such as a carpet. A person with a high voltage static
charge can destroy or damage an integrated circuit or FET device either by touching or coming close to it. Thus most electronic
assemblers wear wrist straps or heel grounders to keep the wearers at the same voltage potential as the parts they are assembling.
Wrist straps and heel grounders/shoes may also be worn at chemical plants, explosive materials factories and storage areas.
A wrist strap is simply a resistorized conductive cord that connects the wearer’s wrist to a grounded conductive mat that covers the
assembly bench. The resistor protects the static sensitive device as well as the worker.
A heel grounder is a small resistorized strap that connects the wearer to their special conductive floor surface. This requires that
the floor be covered with a grounded conductive carpet, tile, mat or dissipative floor wax or paint (available through Static Solutions).
It is important that two heel grounders/shoes be worn to achieve proper static discharge.
Wrist straps and heel grounders simply act as a wire to drain off charges. However, to prevent accidental electrocution of the wearer
(should the wearer inadvertently touch an external high voltage source) a high resistance is built into the strap. The resistance is
typically between .5 to 2 megohms.
Thus straps and heel grounders have to be tested for two different malfunction conditions. If there is an open circuit or too high a
resistance, then it will fail to prevent high voltage build up and no longer control dissipation. If there is a short circuit or too low a
resistance (such as wet shoes), then it could fail to prevent electrocution, or could cause a rapid discharge which could emit a spark
or cause a secondary effect.
The Wrist Strap and Dual Heel Tester checks the controlled conductive integrity of wrist straps and heel grounders/shoes for both
of the fault conditions mentioned above. It can be attached to a free stand or can be a wall mounted. For use, the wearer simply
inserts their wrist strap banana plug into the instrument, and stands on the foot plates (if wearing heel grounders or shoes), and
presses the button. An LED display shows the results of the test (OK, low or high), and an alarm sounds if the resistance is not
within its preset limits, and if the correct person and/or card is correctly identified from the data base. If the card or person is not
recognized, there will be no LED lights and there will be a buzzer sound emitted.
If the computer data logging option is used then the actual resistance is displayed on the monitor, is automatically recorded in the
computer, and can be printed in a daily/monthly report. If the resistance is changing day by day, the CT-8900 can be a valuable tool
to predict failures before they occur.
Unlike other testers, the CT-8900 Dual Heel Tester tests both feet and wrist at once and separately, and does not require the wearer
to shift feet and repeat the test. This saves time, and can insure proper testing. The CT-8900 cannot be fooled by a wearer who
dislikes wearing two grounders and merely presses the button twice while stepping on the footplate with the same foot.
The EOS 20/20 standard mandates that a company must record the results when a person tests their wrist/heel straps to enter a
static sensitive area, or must use a constant wrist strap monitor. In either case, when using shoes or heel grounders, a record must
be kept. If a constant wrist strap monitor is used, the CT-8900 will test it as well, and notify the user if it has failed.
The tester software can generate a number of reports, including informing the supervisor if the wearer does not perform a test once
or twice a day.
CALIBRATION VERIFICATION
The CT-8900 meter is calibrated to NIST traceable standards. The meter self calibrates itself with each use by comparing the
surface mounted 1-megohm resistor value and capacitor against the unknown value. After one year of use, the meter can be sent to
Static Solutions, Inc. to be re-calibrated and be issued a new NIST traceable certificate. Please call Static Solutions for the cost of
this service.
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