esd stm3.1-2000 ionization - sematech · esd stm3.1-2000 • scope - standard establishes...
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ESD STM3.1-2000IONIZATION
THE ESD ASSOCIATION
May14, 2003
ESD STM3.1-2000
• Presented by: Gary Seale - V.P. Membership - Texas ESD Association
• Regional Manager - Simco Ionization
• Scope, Purpose, & Application
• Definitions
• Safety
• Specific Requirements
ESD STM3.1-2000CONTENTS
• Room Ionization
• Laminar Flow Ionization
• Worksurface Ionization
• Compressed Gas Ionizers-Guns/Nozzles
• Test Equipment
• Annex A
ESD STM3.1-2000
• Scope - Standard establishes measurement techniques, to determine ion balance and charge neutralization
• Purpose - Standard provides test methods & procedures for evaluating air ionization equipment & systems
• Application - Provide performance data, qualify equipment for use
ESD STM3.1-2000
• Definitions
• Air conductivity - Ability of air to conduct current under influence of an electric field.
• Air Ions - Clusters of 10 molecules bound by polarization forces to a singly charged oxygen or nitrogen molecule.
• Charge decay - Decrease/neutralization of net electrostatic charge
ESD STM3.1-2000
• Charge plate monitor - Instrument used to measure decay times
• Compressed gas ionizers - Ionizer tools used to neutralize charges and remove particles with high pressure gas
• Corona - Production of positive & negative ions by a very localized high electric field
ESD STM3.1-2000
• Discharge Time: Time necessary for a voltage to decay from an initial value to some arbitrarily chosen value. (typically 10% of beginning value)
• Emitter - A conducting sharp object, needle or wire, which will cause a corona discharge when kept at high potential
ESD STM3.1-2000
• Neutralize - Canceling the effect of a field from a given charge, by conducting the field to ground, or introducing an equal opposite charge.
• Offset voltage - Observed voltage on a charge plate that has been placed in an ionized environment.
ESD STM3.1-2000
• SAFETY REQUIREMENTS
• Electrical - Peak current limited for installation (emitter tips)
• Ozone - Generation not to exceed limit defined by OSHA 1910
• Radioactive - License from N.R.C.
• Mfg. to meet all requirements of Title 10, Part 20, Code of Federal Regulations
ESD STM3.1-2000
• Installation - Conform to any applicable electrical, mechanical, and safety codes.
• Noise exposure, PSI used, relief design
• Discharge test time - Plate charged to initial voltage and discharged to 10% of that value. Time required for both polarities monitored and recorded.
ESD STM3.1-2000
• Offset voltage test - Ground plate to “zero” Monitor plate in ionized environment for deviation from zero.
• Locations - See Table 1
• Same conditions for all tests, no equipment adjustments.
• Peak offset voltage - DC ionizers measured for peak voltages and reported.
ESD STM3.1-2000• Table 1- Test Setups and Test Locations
• Equipment Figure References Number of Test Locations Offset Voltage/Time Interval CPM Initial Voltage
• Room Ionization
• Grids, AC 3 2 1-5 Min. 1000
• Bars, Pulsed & DC 3 2 1-5 Min. 1000• Single polarity emitter 4 3 1-5 Min. 1000
• Dual DC line 5 3 1-5 Min. 1000
• Pulsed DC emitter 6 2 1-5 Min. 1000
• Laminar Flow Hood• Vertical 7 & 8 7 1-5 Min. 1000
• Horizontal 9 & 10 5 1-5 Min. 1000
• Worksurface Ionization• Bench Top 11 12 1-5 Min. 1000
• Overhead 12 & 13 12 1-5 Min. 1000
• Compressed Gas Ionization
• Guns and Nozzles 14 1 10 sec. - 1 Min. 1000
ESD STM3.1-2000
• Room Ionization
• Testing - Monitor clear 5’ horizontal area, System on for 30 minutes previously.
• Test person grounded - 5 feet outside area
• Discharge time for 1000 to 100 volts - both polarities
ESD STM3.1-2000
• Laminar air flow velocity recorded
• Measurements taken 5’ under emitters & recorded
• Discharge and offset voltage
• (1 min. test criteria) taken and recorded
ESD STM3.1-2000
• Example: Room Ionization Emitters
ESD STM3.1-2000
• LAMINAR FLOW HOOD IONIZATION
• Test area unobstructed, surface area dissipative and properly grounded
• Test person grounded
• Discharge time from 1000 to 100 volts measured for both polarities, + Offset V.
• Air flow recorded - test positions as per specification - See slide 17
ESD STM3.1-2000
ESD STM3.1-2000
• Discharge time measured & recorded, offset voltage measured (1 minute min.) & recorded
• Example: Laminar flow bar
ESD STM3.1-2000
• WORKSURFACE IONIZATION
• Test in unobstructed area, surface static dissipative and properly grounded
• Test person grounded, discharge for both polarities, 1000- 100 volts measured
• Measure w/heater on & off, w/filters, at min & max airflow, air velocity measured and reported
ESD STM3.1-2000
ESD STM3.1-2000
• S3.1 Test Criteria
ESD STM3.1-2000
• Benchtop test results
ESD STM3.1-2000
• Example: Benchtop product
ESD STM3.1-2000
• Overhead Test Criteria
ESD STM3.1-2000
• Overhead test - Side view
ESD STM3.1-2000
• Discharge time and offset voltage (1 min.) should be measured at each test location
• Example - Overhead Ionizer
ESD STM3.1-2000
• COMPRESSED GAS IONIZERS - GUNS AND NOZZLES
• Test w/out obstructions to airflow, test personnel grounded, surface dissipative and grounded
• Discharge 1000 to 100 volts, both polarities.
• 30 psi input pressure, 6’ from charge plate
ESD STM3.1-2000
• Discharge time and offset voltage measured and reported as per drawing #14.
ESD STM3.1-2000
• Example - Compressed air ionizing gun
ESD STM3.1-2000
• TEST EQUIPMENT - Charge Plate
• 6” x 6” conductive plate -minimum/maximum capacitance limits
• Construction criteria - no more than 10% discharge of plate voltage in 5 minutes
ESD STM3.1-2000
• ANNEX A
• Air ions - Definition - Natural ions discussion - Radiation and corona induced ionization
• Mobility and ion current - Formula review, ion movement, current density
• Neutralization current - Neutralization current proportional to charge & opposite conductivity of the air
ESD STM3.1-2000
• Neutralization rate - Charges decay relative to the conductivity of the air.
• Ion depletion - Charged fields may partially deplete the air of ions. Which may slow discharge rates. Air velocity significantly reduces this effect
• Charge Plate definition/capabilities
ESD STM3.1-2000
• Offset voltage definition/acquisition of.
• Importance of ionization equipment maintenance - cleaning, emitter replacement, nuclear replacement, insure full volume of air flows