1. An Update on Component Shielding Effectiveness Testing
Joe Butler
Chomerics Division of Parker Hannifin Corp.
November 19, 2018

2. 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.

3. Shielding Effectiveness
Test Standards
MIL-STD-285 – Shelters - Withdrawn
MIL-DTL – Conductive Elastomer EMI Gasket Radiated Field and DC Volume Resistivity
NSA 65-6, 73-2A, – 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ASTM D 4935 – Planar Materials - Withdrawn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 – Anechoic Chambers
IEC Enclosures
VG Part 15 – Small Enclosures
SCTE – GTEM Cell Tests

4. Shielding Effectiveness
EMI Gaskets
DC volume resistivity
MIL - DTL
SAE- AIR 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

5. 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

6. Shielding Effectiveness
Conductive Coatings
DC surface resistivity
ohms per 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ASTM D4935 – recently withdrawn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

7. 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

8. 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

9. Shielding Effectiveness
MlL-STD-285 (1956)
Frequencies: 150 kHz 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Officially withdrawn but still used in industry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 18

10. Shielding Effectiveness
US National Security Agency Standards - NSA 65-6, NSA 73-2A, NSA
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 MHz
NSA (1994) - 1 kHz – 10 GHz, 100 dB, 10kHz – 10 GHz, (replaced NSA 65-6) 18

11. 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 18

12. Shielding Effectiveness
ASTM E 1851 (1997)
Frequency bands kHz, MHz, MHz, MHz,
8.5 GHz 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 18

13. Shielding Effectiveness
IEC (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 < 10 dB = 0, to > 100 dB = 9, is assigned 18

14. Shielding Effectiveness
IEC Setup

15. Shielding Effectiveness
German VG (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 18

16. Shielding Effectiveness
German VG Setup

17. Shielding Effectiveness
SCTE IPS-TP- 212 Setup

18. Shielding Effectiveness ASTM D 4935 Test Setup

19. Shielding Effectiveness ASTM D 4935 Test Samples

20. Shielding Effectiveness Dual TEM Cell Test Setup

21. Shielding Effectiveness MIL-DTL-83528 Setup

22. Radiated Test Setup
Chomerics Shielding Effectiveness Test Setup

23. Radiated Test Setup

24. Radiated Test Setup

25. Shielding Effectiveness SAE ARP 1173 Setup

26. Shielding Effectiveness SAE ARP 1705 Setup

27. Shielding Effectiveness IEEE STD 1302 Gasket Comparison of Test Methods

28. Shielding Effectiveness Stirred Mode Chamber

29. 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

30. 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

31. 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

32. Shielding Effectiveness
Thanks for your time!
Questions???
Joe Butler