An Update on Component Shielding Effectiveness Testing

1
An Update on Component Shielding Effectiveness
Testing

• Joe Butler
• Chomerics Division of Parker Hannifin Corp.

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Shielding Effectiveness

• Commercial EMI Shielding Products
• EMI gaskets
• Conductive compounds
• Conductive coatings
• Shielded windows and air ventilation panels
• None of these products are typically measured by
  an industry consensus, shielding effectiveness
  test method. Vendor utilized test methods vary
  by manufacturer.

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Shielding Effectiveness

• Test Standards
• MIL-STD-285 Shelters - Withdrawn
• MIL-DTL-83528 Conductive Elastomer EMI Gasket
  Radiated Field and DC Volume Resistivity
• NSA 65-6, 73-2A, 94-106 Tempest Shelters
• IEEE STD 299 Shelters (replaced MIL-STD-285)
• IEEE STD 1302 Guide to EMI Gasket Test Methods
• ASTM D 4935 Planar Materials - Withdrawn
• ASTM E1851 Shelters (duplicates MIL-STD-285)
• Reverberation Chamber Tests, TEM Cells
• SAE ARP 1705 EMI Gasket Transfer Impedance
• SAE ARP 1173 EMI Gasket Radiated Field
• EN 50147-1 Anechoic Chambers
• IEC 61000-5-7 - Enclosures
• VG 95373 Part 15 Small Enclosures
• SCTE 48-1-2006 GTEM Cell Tests

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Shielding Effectiveness

• EMI Gaskets
• DC volume resistivity
• MIL - DTL - 83528
• SAE- AIR -1404 warning on relationship between
  resistivity and shielding effectiveness
• Transfer impedance
• SAE- ARP-1705
• Radiated field tests
• MIL-DTL-83528
• MIL-STD-285 or IEEE-STD-299 Modified
• Stirred mode/reverberation chamber testing
• Enclosure or equipment level testing

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Shielding Effectiveness

• Conductive Compounds
• DC Volume Resistivity
• Joint Through-Resistance
• Radiated Field Tests
• MIL-STD-285 or IEEE-STD-299 Modified
• Enclosure or Equipment Level Tests

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Shielding Effectiveness

• Conductive Coatings
• DC surface resistivity
• ohms per square _at_ recommended dry film thickness
• ASTM D4935 recently withdrawn
• Radiated field tests
• MIL-STD-285 or IEEE-STD-299 Modified
• Stirred mode/reverberation chamber tests
• Enclosure or equipment level tests

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Shielding Effectiveness

• Shielded Windows Air Ventilation Panels
• Radiated field tests
• MIL-STD-285 or IEEE-STD-299, Modified
• Stirred mode/reverberation chamber tests
• Enclosure or equipment level tests

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Shielding Effectiveness

• Current standards activity
• IEEE EMC Society actively working on revisions to
  IEEE STD 299 to create three sections addressing
  three sizes of enclosures
• SAE AE-4 Committee has discussed revising and
  updating SAE ARP 1173
• ASTM Committee D09 has stopped EMC standards
  development activities

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Shielding Effectiveness

• MlL-STD-285 (1956)
• Frequencies 150 kHz - 200 kHz, 200 kHz,
• 1 MHz, 18 MHz, 400 MHz
• Officially withdrawn but still used in industry
• Many undocumented/unapproved derivatives used -
  modified MIL STD 285
• Used extensively to rate shielding performance of
  EMI gaskets, conductive coatings, shielded vents
  and windows

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Shielding Effectiveness

• US National Security Agency Standards - NSA 65-6,
  NSA 73-2A, NSA 95-106
• NSA 65-6 (1964) - 1 kHz - 10 GHz,100 dB, 10 kHz -
  10 GHz
• NSA 73-2A (1972) - 1 kHz - 1 GHz, 50 dB, 10 kHz -
  100 MHz
• NSA 94-106 (1994) - 1 kHz 10 GHz, 100 dB, 10kHz
  10 GHz, (replaced NSA 65-6)

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Shielding Effectiveness

• IEEE STD 299 (1991)
• Frequency range 9 kHz - 18 GHz, (extendable to 50
  Hz and 100 GHz)
• Developed to replace MIL-STD-285
• Working group actively working on revisions
• Standard divided into separate parts for
  different size enclosures

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Shielding Effectiveness

• ASTM E 1851 (1997)
• Frequency bands - 140 - 160 kHz, 14 - 16 MHz, 300
  - 500 MHz, 900 - 1000 MHz,
• 8.5 GHz - 10.5 GHz
• Developed by US military shelter manufacturers as
  replacement for retired MIL STD 285 because
  they felt the proposed replacement, IEEE STD 299,
  was too complicated

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Shielding Effectiveness

• IEC 61000-5-7 (2001) Installation and mitigation
  guidelines - Degrees of protection provided by
  enclosures against electromagnetic disturbances
  (EM code)
• Frequency range 10 kHz - 40 GHz
• Establishes shielding code designation - EMABCDEF
  where ABCDEF indicates 6 frequency bands where a
  shielding designator value from lt 10 dB 0, to gt
  100 dB 9, is assigned

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Shielding Effectiveness
IEC 61000-5-7 Setup
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Shielding Effectiveness

• German VG 95373-15 (1998)
• Bundeswehr equipment procurement
• Frequency ranges 30 Hz - 3 MHz, 30 MHz - 1 GHz
• Society of Cable Telecommunications Engineers
  (SCTE) IPS-TP-212 (1996)
• RF ingress shielding measurement
• Frequencies 54 MHz, 100 MHz, 200 MHz, 400 MHz,
  700 MHz, 1000 MHz

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Shielding Effectiveness
German VG 95373-15 Setup
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Shielding Effectiveness
SCTE IPS-TP- 212 Setup
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Shielding EffectivenessASTM D 4935 Test Setup
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Shielding EffectivenessASTM D 4935 Test Samples
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Shielding EffectivenessDual TEM Cell Test Setup
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Shielding EffectivenessMIL-DTL-83528 Setup
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Radiated Test Setup
Chomerics Shielding Effectiveness Test
Setup
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Radiated Test Setup
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Radiated Test Setup
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Shielding EffectivenessSAE ARP 1173 Setup
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Shielding EffectivenessSAE ARP 1705 Setup
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Shielding EffectivenessIEEE STD 1302 Gasket
Comparison of Test Methods
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Shielding EffectivenessStirred Mode Chamber
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Shielding Effectiveness

• Some Relevant Reference Papers
• Stirred Mode Crawford, Koepke, NBS Tech Note
  1092, April 1986 Hatfield, Freyer, Rowan, 1992
  1994 EMCS Symposium
• Reverberation Chambers Holloway, Ladbury,
  Coder, Koepke, Hill EMCS Transactions,
• Reverberation Chambers Holloway, Ladbury,
  Koepke, Hill, Garzia EMCS Transactions, May
  2003

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Shielding Effectiveness

• Current Actions of Shielding Component Customers
• Not only asking for assurances of long term
  reliability but detailing test protocols to
  qualify products, e.g., accelerated life testing
  - high/low temperature cycling, heat/humidity,
  temperature soak
• More requesting UL 94 V-0 flammability ratings
• Increasing amount of individual corporate Green
  initiatives prohibiting certain hazardous
  substances
• European Union RoHS requirements
• Request for detailed elemental composition of
  materials beyond MSDS details
• Requests for shielding data against aluminum
  flanges with trivalent chromate treatment vs.
  hexavalent chromate

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Shielding Effectiveness

• Future Actions of Shielding Component Vendors
• Will try to maintain the status quo
• Will continue to have dwindling involvement in
  the SE standards development within SAE and IEEE
• If reverberation chamber shielding test data is
  necessary, most manufacturers will use outside
  test labs

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Shielding Effectiveness

• Thanks for your time!
• Questions???
• Joe Butler
• JButler_at_Parker.com
• 781-939-4267
• www.chomerics.com