spore: profile
id: conductive-elastomer-silver-aluminium
spore_version: 0.2
family: conductive-elastomers
name: Silver-aluminium filled conductive elastomer (EMI gasket)
abbreviation: Ag/Al elastomer
role: EMI shielding gasket for enclosure seams
category: shielding
type: spot-shields
summary: |
  Silver-aluminium filled conductive elastomers are EMI shielding gaskets for enclosure seams. Parker Chomerics CHO-SEAL 1285, with a silicone binder, is a MIL-DTL-83528 Type B material printed with at least 100 dB of plane-wave shielding at 10 GHz and a volume resistivity of 0.0080 ohm-cm. CHO-SEAL 1287, with a fluorosilicone binder, is a Type D material printed with at least 90 dB at 10 GHz and 0.012 ohm-cm. Both figures come from a reseller listing that attributes its data to Chomerics; no Parker datasheet could be opened in this run.
best_for: Enclosure seams in military and aerospace electronics that need a conductive gasket to MIL-DTL-83528 (CHO-SEAL 1285, Type B, at least 100 dB at 10 GHz, plane wave)
weakest_at: 'Long-term corrosion and shielding loss: the sources give only general galvanic guidance, and no outgassing, flight or chemical-resistance result for CHO-SEAL 1285 or 1287 was read in this run'
identity:
  formula: Silicone (CHO-SEAL 1285) or fluorosilicone (CHO-SEAL 1287) elastomer binder filled with silver-plated aluminium particles, printed as Ag/Al
  source: lp-chomerics-1285
  where: 'CHO-SEAL 1285 page, Descriptive Properties (Binder: Silicone; Filler: Ag/Al); CHO-SEAL 1287 page, Descriptive Properties (Base polymer: Fluoro-silicone; Filler: Ag/Al) and Material Notes (silver-plated-aluminum-filled fluorosilicone elastomer)'
  designations:
    - system: Trade name
      code: CHO-SEAL 1285
      source: lp-chomerics-1285
      where: Page title and Trade Name field
    - system: Trade name
      code: CHO-SEAL 1287
      source: lp-chomerics-1287
      where: Page title and Trade Name field
tags:
  environments: []
  stresses:
    - thermal-cycling
    - vibration
  applications:
    - electronics-and-chips
properties:
  - benchmark: density
    label: Specific gravity, CHO-SEAL 1285 (silicone binder)
    value: 1.75
    value_high: 2.25
    bound: range
    unit: g/cc
    scope: material
    conditions:
      product: CHO-SEAL 1285
      temperature: not printed on the page
    method: Range printed as specific gravity with test standard ASTM D792 (the page labels it specific gravity, not density)
    status: ground
    source: lp-chomerics-1285
    where: Physical Properties table, Specific Gravity row
  - benchmark: hardness_shore_a
    label: Hardness, Shore A, CHO-SEAL 1285
    value: 58
    value_high: 72
    bound: range
    unit: Shore A
    scope: material
    conditions:
      product: CHO-SEAL 1285
      scale: Shore A
    method: Range printed with test method ASTM D2240
    status: ground
    source: lp-chomerics-1285
    where: Mechanical Properties table, Hardness, Shore A row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at break, CHO-SEAL 1285
    value: 1.38
    bound: lower
    unit: MPa
    scope: material
    conditions:
      product: CHO-SEAL 1285
      printed_as: 1.38 MPa or more (200 psi or more)
      test: ASTM D412
    method: Minimum printed with test method ASTM D412
    status: ground
    source: lp-chomerics-1285
    where: Mechanical Properties table, Tensile Strength at Break row
  - benchmark: elongation
    label: Elongation at break, CHO-SEAL 1285
    value: 100
    value_high: 300
    bound: range
    unit: '%'
    scope: material
    conditions:
      product: CHO-SEAL 1285
      test: ASTM D412
    method: Range printed with test method ASTM D412
    status: ground
    source: lp-chomerics-1285
    where: Mechanical Properties table, Elongation at Break row
  - benchmark: tear_strength
    label: Tear strength, CHO-SEAL 1285
    value: 5.25
    unit: kN/m
    scope: material
    conditions:
      product: CHO-SEAL 1285
      printed_alongside: 30.0 pli
    method: Typical value printed with test method ASTM D624
    status: ground
    source: lp-chomerics-1285
    where: Mechanical Properties table, Tear Strength row
  - benchmark: compression_set
    label: Compression set, CHO-SEAL 1285
    value: 32
    bound: upper
    unit: '%'
    scope: material
    conditions:
      product: CHO-SEAL 1285
      temperature: 100 °C
      time: 252000 sec (70.0 hours as printed)
      test: ASTM D395 Method B
    method: Maximum printed with test method ASTM D395 Method B
    status: ground
    source: lp-chomerics-1285
    where: Mechanical Properties table, Compression Set row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, CHO-SEAL 1285
    value: 2.2
    unit: W/m-K
    scope: material
    conditions:
      product: CHO-SEAL 1285
      pressure: 2.07 MPa (300 psi as printed)
      test: ASTM D5470
    method: Value printed with test method ASTM D5470 at the stated pressure
    status: ground
    source: lp-chomerics-1285
    where: Thermal Properties table, Thermal Conductivity row
  - benchmark: max_service_temp
    label: Maximum service temperature in air, CHO-SEAL 1285
    value: 200
    unit: °C
    scope: material
    conditions:
      product: CHO-SEAL 1285
      environment: air
    method: Value printed; the page lists the test method as Not listed
    status: ground
    source: lp-chomerics-1285
    where: Thermal Properties table, Maximum Service Temperature, Air row
  - benchmark: min_service_temp
    label: Minimum service temperature in air, CHO-SEAL 1285
    value: -65
    unit: °C
    scope: material
    conditions:
      product: CHO-SEAL 1285
      environment: air
      test: Flex TR10; ASTM D1329
    method: Value printed with test method Flex TR10; ASTM D1329
    status: ground
    source: lp-chomerics-1285
    where: Thermal Properties table, Minimum Service Temperature, Air row
  - benchmark: electrical_resistivity
    label: Volume resistivity, CHO-SEAL 1285
    value: 0.008
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1285
      state: without pressure-sensitive adhesive
      test: MIL-DTL-83528
    method: Value printed with the test named in the conditions
    status: ground
    source: lp-chomerics-1285
    where: Electrical Properties table, Volume Resistivity row (first)
  - benchmark: electrical_resistivity
    label: Volume resistivity after tensile set, CHO-SEAL 1285
    value: 0.015
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1285
      state: post tensile set
      test: MIL-DTL-83528
    method: Value printed for the post-tensile-set condition
    status: ground
    source: lp-chomerics-1285
    where: Electrical Properties table, Volume Resistivity row (second)
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1285, 200 kHz H field
    value: 60
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1285
      frequency: 200 kHz
      field: H field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 60 dB' in the listing
    status: ground
    source: lp-chomerics-1285
    where: Shielding Effectiveness table, first row
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1285, 500 MHz E field
    value: 110
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1285
      frequency: 5.00e+8 Hz (500 MHz)
      field: E field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 110 dB' in the listing
    status: ground
    source: lp-chomerics-1285
    where: Shielding Effectiveness table, row at 5.00e+8 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1285, 100 MHz E field
    value: 115
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1285
      frequency: 1.00e+8 Hz (100 MHz)
      field: E field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 115 dB' in the listing
    status: ground
    source: lp-chomerics-1285
    where: Shielding Effectiveness table, row at 1.00e+8 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1285, 2 GHz plane wave
    value: 105
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1285
      frequency: 2.00e+9 Hz (2 GHz)
      field: plane wave
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 105 dB' in the listing
    status: ground
    source: lp-chomerics-1285
    where: Shielding Effectiveness table, row at 2.00e+9 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1285, 10 GHz plane wave
    value: 100
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1285
      frequency: 1.00e+10 Hz (10 GHz)
      field: plane wave
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 100 dB' in the listing
    status: ground
    source: lp-chomerics-1285
    where: Shielding Effectiveness table, row at 1.00e+10 Hz
  - benchmark: heat_aged_volume_resistivity
    label: Volume resistivity after heat ageing, CHO-SEAL 1285
    value: 0.01
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1285
      test: MIL-DTL-83528 Para. 4.6.15
      exposure: not printed on the page
    method: Maximum printed as '<0.01 ohm-cm' in the Descriptive Properties table
    status: ground
    source: lp-chomerics-1285
    where: Descriptive Properties table, Heat Aging row
  - benchmark: vibration_volume_resistivity
    label: Volume resistivity after vibration, CHO-SEAL 1285
    value: 0.008
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1285
      test: MIL-DTL-83528 Para. 4.6.13
      timing: after vibration
    method: Maximum printed as '<0.008 ohm-cm'
    status: ground
    source: lp-chomerics-1285
    where: Descriptive Properties table, Vibration Resistance, After row
  - benchmark: vibration_volume_resistivity
    label: Volume resistivity during vibration, CHO-SEAL 1285
    value: 0.012
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1285
      test: MIL-DTL-83528 Para. 4.6.13
      timing: during vibration
    method: Maximum printed as '<0.012 ohm-cm'
    status: ground
    source: lp-chomerics-1285
    where: Descriptive Properties table, Vibration Resistance, During row
  - benchmark: emp_survivability
    label: EMP survivability, CHO-SEAL 1285
    value: 0.9
    bound: lower
    unit: kA/in
    scope: material
    conditions:
      product: CHO-SEAL 1285
      test_method: not printed on the page
    method: Minimum printed as '>0.9 kA / in'
    status: ground
    source: lp-chomerics-1285
    where: Descriptive Properties table, EMP Survivability row
  - benchmark: density
    label: Specific gravity, CHO-SEAL 1287 (fluorosilicone binder)
    value: 1.75
    value_high: 2.25
    bound: range
    unit: g/cc
    scope: material
    conditions:
      product: CHO-SEAL 1287
      temperature: not printed on the page
    method: Range printed as specific gravity with test standard ASTM D792
    status: ground
    source: lp-chomerics-1287
    where: Physical Properties table, Specific Gravity row
  - benchmark: hardness_shore_a
    label: Hardness, Shore A, CHO-SEAL 1287
    value: 63
    value_high: 77
    bound: range
    unit: Shore A
    scope: material
    conditions:
      product: CHO-SEAL 1287
      scale: Shore A
    method: Range printed with test method ASTM D2240
    status: ground
    source: lp-chomerics-1287
    where: Mechanical Properties table, Hardness, Shore A row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at break, CHO-SEAL 1287
    value: 1.24
    bound: lower
    unit: MPa
    scope: material
    conditions:
      product: CHO-SEAL 1287
      printed_as: 1.24 MPa or more (180 psi or more)
      test: ASTM D412
    method: Minimum printed with test method ASTM D412
    status: ground
    source: lp-chomerics-1287
    where: Mechanical Properties table, Tensile Strength at Break row
  - benchmark: elongation
    label: Elongation at break, CHO-SEAL 1287
    value: 60
    value_high: 260
    bound: range
    unit: '%'
    scope: material
    conditions:
      product: CHO-SEAL 1287
      test: ASTM D412
    method: Range printed with test method ASTM D412
    status: ground
    source: lp-chomerics-1287
    where: Mechanical Properties table, Elongation at Break row
  - benchmark: tear_strength
    label: Tear strength, CHO-SEAL 1287
    value: 6.13
    unit: kN/m
    scope: material
    conditions:
      product: CHO-SEAL 1287
      printed_alongside: 35.0 pli
    method: Typical value printed with test method ASTM D624
    status: ground
    source: lp-chomerics-1287
    where: Mechanical Properties table, Tear Strength row
  - benchmark: compression_set
    label: Compression set, CHO-SEAL 1287
    value: 30
    bound: upper
    unit: '%'
    scope: material
    conditions:
      product: CHO-SEAL 1287
      temperature: 100 °C
      time: 252000 sec (70.0 hours as printed at 212 °F)
      test: ASTM D395 Method B
    method: Maximum printed with test method ASTM D395 Method B
    status: ground
    source: lp-chomerics-1287
    where: Mechanical Properties table, Compression Set rows
  - benchmark: max_service_temp
    label: Maximum service temperature in air, CHO-SEAL 1287
    value: 200
    unit: °C
    scope: material
    conditions:
      product: CHO-SEAL 1287
      environment: air
    method: Value printed; no test method given on the page
    status: ground
    source: lp-chomerics-1287
    where: Thermal Properties table, Maximum Service Temperature, Air row
  - benchmark: min_service_temp
    label: Minimum service temperature in air, CHO-SEAL 1287
    value: -55
    unit: °C
    scope: material
    conditions:
      product: CHO-SEAL 1287
      environment: air
      test: Flex TR10; ASTM D1329
    method: Value printed with test method Flex TR10; ASTM D1329
    status: ground
    source: lp-chomerics-1287
    where: Thermal Properties table, Minimum Service Temperature, Air row
  - benchmark: electrical_resistivity
    label: Volume resistivity, CHO-SEAL 1287
    value: 0.012
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1287
      state: without pressure-sensitive adhesive
      test: MIL-DTL-83528
    method: Value printed with the test named in the conditions
    status: ground
    source: lp-chomerics-1287
    where: Electrical Properties table, Volume Resistivity row (first)
  - benchmark: electrical_resistivity
    label: Volume resistivity after tensile set, CHO-SEAL 1287
    value: 0.015
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1287
      state: post tensile set
      test: MIL-DTL-83528 Para. 4.6.9 as printed
    method: Value printed for the post-tensile-set condition; the page prints the standard as MIL-G-83528
    status: ground
    note: The page prints the standard reference as MIL-G-83528 in this row and MIL-DTL-83528 elsewhere.
    source: lp-chomerics-1287
    where: Electrical Properties table, Volume Resistivity row (second)
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 200 kHz H field
    value: 55
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 200 kHz
      field: H field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 55 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, first row
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 500 MHz E field
    value: 100
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 5.00e+8 Hz (500 MHz)
      field: E field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 100 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, row at 5.00e+8 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 100 MHz E field
    value: 110
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 1.00e+8 Hz (100 MHz)
      field: E field
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 110 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, row at 1.00e+8 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 2 GHz plane wave
    value: 95
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 2.00e+9 Hz (2 GHz)
      field: plane wave
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 95 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, row at 2.00e+9 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 10 GHz plane wave
    value: 90
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 1.00e+10 Hz (10 GHz)
      field: plane wave
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 90 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, row at 1.00e+10 Hz
  - benchmark: shielding_effectiveness
    label: Shielding effectiveness, CHO-SEAL 1287, 40 GHz plane wave
    value: 75
    bound: lower
    unit: dB
    scope: material
    conditions:
      product: CHO-SEAL 1287
      frequency: 4.00e+10 Hz (40 GHz)
      field: plane wave
      standard: MIL-DTL-83528 Para. 4.6.12
    method: Minimum printed as '>= 75 dB' in the listing
    status: ground
    source: lp-chomerics-1287
    where: Shielding Effectiveness table, row at 4.00e+10 Hz
  - benchmark: heat_aged_volume_resistivity
    label: Volume resistivity after heat ageing, CHO-SEAL 1287
    value: 0.015
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1287
      test: MIL-DTL-83528 Para. 4.6.15
      exposure: not printed on the page
    method: Maximum printed as '<0.015 ohm-cm'
    status: ground
    source: lp-chomerics-1287
    where: Descriptive Properties table, Heat Aging row
  - benchmark: vibration_volume_resistivity
    label: Volume resistivity after vibration, CHO-SEAL 1287
    value: 0.012
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1287
      test: MIL-DTL-83528 Para. 4.6.13
      timing: after vibration
    method: Maximum printed as '<0.012 ohm-cm'
    status: ground
    source: lp-chomerics-1287
    where: Descriptive Properties table, Vibration Resistance, After row
  - benchmark: vibration_volume_resistivity
    label: Volume resistivity during vibration, CHO-SEAL 1287
    value: 0.015
    bound: upper
    unit: ohm-cm
    scope: material
    conditions:
      product: CHO-SEAL 1287
      test: MIL-DTL-83528 Para. 4.6.13
      timing: during vibration
    method: Maximum printed as '<0.015 ohm-cm'
    status: ground
    source: lp-chomerics-1287
    where: Descriptive Properties table, Vibration Resistance, During row
  - benchmark: emp_survivability
    label: EMP survivability, CHO-SEAL 1287
    value: 0.9
    bound: lower
    unit: kA/in
    scope: material
    conditions:
      product: CHO-SEAL 1287
      test: MIL-DTL-83528 Para. 4.6.16
    method: Minimum printed as '>0.9 kA / in' with the test paragraph named on the page
    status: ground
    source: lp-chomerics-1287
    where: Descriptive Properties table, EMP Survivability row
corrosion:
  - environment: Silver/aluminium filler in contact with aluminium housings (galvanic exposure)
    headline: Silver/aluminium fillers pair well with aluminium housings and reduce galvanic risk, according to a Modus Advanced guide on space-qualified EMI gaskets.
    effect: The guide's filler table rates silver/aluminium as good with aluminium housings, and its galvanic section says the filler reduces galvanic risk. It also says plating the housing with nickel or tin improves galvanic compatibility. No corrosion test on CHO-SEAL 1285 or 1287 was read.
    rating: low
    conditions:
      basis: general vendor guidance, no test condition, exposure time or product named
      housing: aluminium
    source: modus-emi-guide
    where: Filler Comparison table; Galvanic Compatibility section; Designing for Manufacturability section
  - environment: Thermal cycling combined with galvanic exposure over a mission
    headline: The Modus guide says thermal cycling and galvanic effects together can reduce shielding by several dB over a mission.
    effect: The guide states that the combination of thermal cycling and galvanic effects can reduce shielding effectiveness by several dB over the life of a mission, and that wrong filler and housing pairings can increase contact resistance over time. The guide gives no dB figure or time for this loss.
    rating: moderate
    conditions:
      basis: vendor statement, no mission duration or dB figure given
      product: silver/aluminium filled gaskets in general
    source: modus-emi-guide
    where: Thermal Cycling section; Galvanic Compatibility section
  - environment: Heat ageing at the MIL-DTL-83528 test condition
    headline: After heat ageing, the listed volume resistivity stays below 0.01 ohm-cm for CHO-SEAL 1285 and below 0.015 ohm-cm for CHO-SEAL 1287.
    effect: The Descriptive Properties tables of both Chomerics listings print a heat-ageing resistivity limit under MIL-DTL-83528 Para. 4.6.15. The exposure temperature and time are not printed on the pages, so the limit cannot be tied to a service life.
    rating: low
    conditions:
      basis: maximum limits as printed; exposure temperature and time not printed
      standard: MIL-DTL-83528 Para. 4.6.15
    source: lp-chomerics-1285
    where: Descriptive Properties table, Heat Aging row (1285); the 1287 page gives the 1287 row
  - environment: Corrosion resistance claim on the CHO-SEAL 1285 listing
    headline: The CHO-SEAL 1285 listing describes the material as having improved corrosion resistance but gives no test figure for it.
    effect: The listing's Material Notes say 'Conductive Elastomer with Improved Corrosion Resistance'. The page does not name the comparison material, the test or the result, so the claim is recorded as printed and not rated.
    rating: unknown
    conditions:
      basis: manufacturer claim as printed on a reseller listing
      comparison: not stated
    source: lp-chomerics-1285
    where: Material Notes
risks:
  hazards:
    - text: 'Silver, as the plating on the filler particles (bare metal, powder or nano form): PubChem''s EU entries give ''Very toxic to aquatic life with long lasting effects'' and ''Very toxic to aquatic life'' with signal word ''Warning'' and the environmental hazard pictogram. Japanese NITE entries list ''May cause an allergic skin reaction'' and ''Causes eye irritation'' with signal word ''Danger''. These are GHS data for the bare metal, not for the gasket.'
      ghs:
        - H410
        - H400
        - H317
        - H320
      source: pubchem-silver
      where: Safety and Hazards, GHS Classification (CID 23954)
    - text: 'Aluminium, as the base metal of the filler particles (powder form): PubChem''s ECHA aggregate and most EU entries give ''In contact with water releases flammable gas'' with signal word ''Danger'' and the flammable pictogram. Stabilised aluminium powder is listed as ''Flammable solid'', and a pyrophoric powder entry as ''Catches fire spontaneously if exposed to air''. Japanese NITE-CMC entries add ''Causes damage to organs'' and ''Causes damage to organs through prolonged or repeated exposure''. These are GHS data for the bare powder, not for the gasket.'
      ghs:
        - H261
        - H228
        - H250
        - H370
        - H372
      source: pubchem-aluminium
      where: Safety and Hazards, GHS Classification (CID 5359268)
  failure_risks:
    - mode: Galvanic corrosion at the gasket-to-housing interface
      trigger: Silver/aluminium filler in contact with a housing that is not plated or otherwise matched, in a humid or thermally cycled environment
      consequence: The Modus guide says wrong filler and housing pairings can lead to increased contact resistance over time, which reduces shielding.
      severity: moderate
      source: modus-emi-guide
      where: Galvanic Compatibility section
    - mode: Shielding loss from thermal cycling over a mission
      trigger: Repeated thermal cycling of a gasket seam over the life of a mission
      consequence: The guide says the combined effects can reduce shielding effectiveness by several dB over the life of a mission. No dB value or time is given.
      severity: moderate
      source: modus-emi-guide
      where: Thermal Cycling section
  side_effects: []
  handling: []
  mitigations:
    - text: Plate aluminium housings with nickel or tin to improve galvanic compatibility, as the Modus guide recommends for silver/aluminium gaskets.
      source: modus-emi-guide
      where: Designing for Manufacturability section
uses:
  - application: electronics-and-chips
    device: EMI gasket on enclosure flanges and covers in military electronics (MIL-DTL-83528 scope)
    example: The MIL-DTL-83528 specification covers conductive elastomeric shielding gaskets that give low interface resistance between enclosure flanges or covers and provide environmental sealing. CHO-SEAL 1285 is listed as a Military-Aerospace Type B material to that specification.
    source: everyspec-mil-83528
    where: Scope summary; CHO-SEAL 1285 page, Grade and Type fields
  - application: electronics-and-chips
    device: EMI gasket for satellite electronics enclosures (vendor guidance, no flight result read)
    example: A Modus Advanced guide on space-qualified EMI gaskets for satellite shielding discusses silver/aluminium fillers for this use. The guide gives no flight result for CHO-SEAL 1285 or 1287.
    source: modus-emi-guide
    where: Page title; FAQ heading 'Which conductive filler is best for satellite applications?'
supply:
  - subject: Silver (filler metal)
    abundance: Not read in this run. The USGS silver chapter was read for production, reserves and recycling only.
    producers:
      - country: Mexico
        share_percent: 24.2
        year: 2025
      - country: Peru
        share_percent: 13.8
        year: 2025
      - country: China
        share_percent: 13.1
        year: 2025
      - country: Bolivia
        share_percent: 5.8
        year: 2025
      - country: Chile
        share_percent: 5.4
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in the United States in 2025, about 11% of apparent consumption.'
    substitutes:
      - 'USGS: aluminum and rhodium may replace silver in mirrors and reflecting surfaces. The chapter names no substitute for silver in conductive elastomers.'
    source: usgs-mcs2026-silver
    where: 'Domestic Production and Use; Recycling; World Mine Production and Reserves table (2025e: Mexico 6,300, Peru 3,600, China 3,400, Bolivia 1,500, Chile 1,400 of a 26,000 world total); Substitutes. Shares calculated by Space Mushroom against the printed world total.'
  - subject: Aluminium (filler base metal)
    abundance: Not read in this run.
    producers:
      - country: China
        share_percent: 60.8
        year: 2025
      - country: India
        share_percent: 5.7
        year: 2025
      - country: Russia
        share_percent: 5.3
        year: 2025
      - country: Canada
        share_percent: 4.5
        year: 2025
      - country: United Arab Emirates
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS: about 3.6 million tons of aluminum was recovered from purchased scrap in the United States in 2025, equivalent to about 28% of apparent consumption from old scrap.'
    substitutes:
      - 'USGS: copper can replace aluminum in electrical and heat-exchange applications.'
    source: usgs-mcs2026-aluminum
    where: 'World Smelter Production and Capacity table (2025e: China 45,000 of a 74,000 world total, India 4,200, Russia 3,900, Canada 3,300, United Arab Emirates 2,700); Recycling; Substitutes. Shares calculated by Space Mushroom against the printed world total (rounded). Smelter output, not mine output.'
    note: The USGS table is smelter production of primary aluminium; it is not bauxite mine production.
documents:
  - title: Parker Chomerics CHO-SEAL 1285 listing (lookpolymers.com, data attributed to Chomerics)
    type: datasheet
    url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1285-Conductive-Elastomer.php
  - title: Parker Chomerics CHO-SEAL 1287 listing (lookpolymers.com, data attributed to Chomerics)
    type: datasheet
    url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1287-Conductive-Elastomer.php
  - title: MIL-DTL-83528E, Gaskets, Electrically Conductive Elastomeric, Shielding (EverySpec summary page)
    type: standard
    url: https://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-83528E_52081/
    year: 2012
  - title: 'USGS Mineral Commodity Summaries 2026: Silver'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: PubChem compound record for Silver (CID 23954), GHS Classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
  - title: PubChem compound record for Aluminum (CID 5359268), GHS Classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
gaps:
  - 'No Parker Chomerics datasheet or product page could be opened in this run: the Parker selector guide, the NASA outgassing PDF, the CHO-TM-TP09 test procedure and the ph.parker.com product pages returned HTTP 403, and the Mouser listing timed out. All CHO-SEAL values come from two reseller pages that state the information is provided by Chomerics.'
  - Outgassing (ASTM E595 total mass loss and CVCM) for CHO-SEAL 1285 or 1287 was not read on a fetched page. A search summary mentioned Parker outgassing figures, but they were not opened and are not recorded here.
  - No flight, space-environment or vacuum result for CHO-SEAL 1285 or 1287 was read. The space use in the uses section is vendor guidance, not a flight record.
  - The MIL-DTL-83528 per-type plane-wave shielding table was not read. The EverySpec page shows only the scope and revision list, and the PDF returned HTTP 404.
  - The revision of MIL-DTL-83528 that governs CHO-SEAL 1285 and 1287 is not confirmed. The EverySpec page shows Rev. E dated 2012 with later revisions F and G listed; the revision letter cited by each Chomerics listing is not printed.
  - No safety data sheet for CHO-SEAL 1285 or 1287 was read. The hazards entries use PubChem GHS data for the constituent silver and aluminium metals in powder form, not for the gasket, so the gasket's own hazard classification is not recorded. A search returned SDSs only for other silver-aluminium or nickel-graphite products, which were not used.
  - Binder and filler mass shares, and the composition of the silver-plated aluminium particles, are not printed in any source read.
  - Thermal conductivity is printed for CHO-SEAL 1285 only; the CHO-SEAL 1287 listing prints none.
  - Chemical resistance, salt-fog or humidity corrosion data, and galvanic test data for CHO-SEAL 1285 or 1287 were not found in any source read. The corrosion-resistance claim on the 1285 listing has no figure.
  - Hardness (Shore A), tear strength, compression set, heat-ageing and vibration resistivity, and EMP survivability are not in the properties canon; they use short snake_case names (hardness_shore_a, tear_strength, compression_set, heat_aged_volume_resistivity, vibration_volume_resistivity, emp_survivability).
  - Shielding effectiveness values are the listing's minimum values for two grades, not measured data on a stated gasket size or seam. The conditions for the seam, compression and mounting are not printed.
  - Abundance (crustal) of silver and aluminium and the EU critical raw materials list were not read in this run.
  - No comparison with other shielding profiles in this collection was made; their values were not read for this profile.
sources:
  lp-chomerics-1285:
    title: Parker Chomerics CHO-SEAL 1285 Conductive Elastomer (product listing on lookpolymers.com; information provided by Chomerics)
    id: CHO-SEAL 1285; Military-Aerospace Grade B; MIL-DTL-83528 Type B
    url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1285-Conductive-Elastomer.php
    year: 2026
    kind: web
    license: reseller listing, linked not reproduced
  lp-chomerics-1287:
    title: Parker Chomerics CHO-SEAL 1287 Conductive Elastomer (product listing on lookpolymers.com; information provided by Chomerics)
    id: CHO-SEAL 1287; Military-Aerospace Type D; MIL-DTL-83528 Type D
    url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1287-Conductive-Elastomer.php
    year: 2026
    kind: web
    license: reseller listing, linked not reproduced
  everyspec-mil-83528:
    title: MIL-DTL-83528E, Gaskets, Electrically Conductive Elastomeric, Shielding (summary page)
    id: MIL-DTL-83528E, dated 13-AUG-2012 (Rev. E listed as 08-2012)
    url: https://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-83528E_52081/
    year: 2012
    kind: standard
    license: standard summary, linked not reproduced
  ssp-mil-83528-guide:
    title: 'Military Gaskets for EMI Shielding: What are MIL-DTL-83528 and QPL 83528? (Specialty Silicone Products)'
    id: SSP web article on MIL-DTL-83528 sections A, B, C, D and K
    url: https://sspinc.com/?p=11006
    kind: web
    license: vendor article, linked not reproduced
  modus-emi-guide:
    title: 'Space-Qualified EMI Gasket Selection: A Material Guide for Satellite Shielding (Modus Advanced)'
    id: Modus Advanced blog guide
    url: https://www.modusadvanced.com/resources/blog/space-qualified-emi-gasket-selection-a-material-guide-for-satellite-shielding-1
    kind: web
    license: vendor article, linked not reproduced
  usgs-mcs2026-silver:
    title: Mineral Commodity Summaries 2026, Silver
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-aluminum:
    title: Mineral Commodity Summaries 2026, Aluminum
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  pubchem-silver:
    title: PubChem compound record for Silver (CID 23954), GHS Classification
    id: PubChem CID 23954
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
    kind: database
    license: public domain (NCBI PubChem), linked not reproduced
  pubchem-aluminium:
    title: PubChem compound record for Aluminum (CID 5359268), GHS Classification
    id: PubChem CID 5359268
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
    kind: database
    license: public domain (NCBI PubChem), linked not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 40
  unreachable: 5
  caveats: 5
  note: 'Read by an AI assistant on 2026-11-01. All CHO-SEAL values come from two reseller listings that attribute the data to Chomerics; the Parker pages, the NASA outgassing PDF and the MIL-DTL-83528 PDF could not be opened. Unreachable: Parker selector guide, Parker product page, Parker CHO-TM-TP09 procedure, Parker NASA outgassing PDF (all HTTP 403), and the MIL-DTL-83528 PDF (HTTP 404). Caveats: values are typical or minimum listing figures; the shielding minima are for one test set-up; the 1287 resistivity row cites MIL-G-83528; the specific gravity is not a density.'
story:
  recipe:
    line: 'CHO-SEAL gaskets are a conductive elastomer: a cured silicone or fluorosilicone binder filled with silver-plated aluminium particles, printed as Ag/Al. The binder gives the rubber sealing and resilience; the filler gives the electrical conductivity. Shares of binder and filler are not printed in any source read.'
    parts:
      - name: Silicone or fluorosilicone elastomer binder
        role: The rubber matrix. It gives the gasket its hardness, elongation and sealing; CHO-SEAL 1285 uses a silicone binder and CHO-SEAL 1287 a fluorosilicone binder.
        share_note: Mass share not printed in the sources read
      - name: Silver-plated aluminium particles (Ag/Al)
        role: The conductive filler. Silver on aluminium particles provides the electrical path that gives the shielding and the low volume resistivity.
        share_note: Mass share not printed in the sources read
  risk_groups:
    - title: For people
      lead: No safety data sheet for CHO-SEAL 1285 or 1287 was read in this run, so their own hazard classification is not recorded. PubChem GHS data for the constituent silver and aluminium metals is in the hazards section.
      level: 0
      verdict: Not checked
      points:
        - label: Hazard data
          line: The sources read give no hazard classification for these two gasket grades. Read the supplier's safety data sheet for the exact part before handling.
    - title: If it fails
      lead: 'The failure routes in the sources read are electrical: loss of shielding and contact resistance over time.'
      points:
        - label: Galvanic and thermal
          line: The Modus guide says wrong filler and housing pairings can raise contact resistance over time, and that thermal cycling plus galvanic effects can reduce shielding by several dB over a mission. It gives no time or dB figure.
  why: Conductive elastomer EMI gaskets seal an enclosure seam and carry its shielding current across the joint. CHO-SEAL 1285 and CHO-SEAL 1287 are Parker Chomerics silver-aluminium filled gaskets built to the MIL-DTL-83528 specification. The 1285 has a silicone binder and is listed as Type B, with at least 100 dB of plane-wave shielding at 10 GHz. The 1287 has a fluorosilicone binder and is listed as Type D, with at least 90 dB at 10 GHz. The choice between them depends on the binder and the shielding frequency needed.
  uses:
    - where: Military and aerospace electronics
      line: The MIL-DTL-83528 specification covers electrically conductive elastomeric shielding gaskets that give low interface resistance between enclosure flanges or covers and also provide environmental sealing. CHO-SEAL 1285 is listed as a Type B material to that specification.
    - where: Satellite electronics (vendor guidance only)
      line: A Modus Advanced guide on space-qualified EMI gaskets for satellite shielding discusses silver/aluminium fillers for this use. The guide does not give a flight result for these two grades.
  can_do:
    - label: Shielding
      benchmark: shielding_effectiveness
      value: At least 100 dB at 10 GHz
      line: Per the CHO-SEAL 1285 listing, the minimum plane-wave shielding effectiveness is 100 dB at 10 GHz (1.00e+10 Hz) and 110 dB at 500 MHz for the E field. The 1287 listing gives 90 dB at 10 GHz and 100 dB at 500 MHz for the E field.
    - label: Conductivity
      benchmark: electrical_resistivity
      value: 0.0080 ohm-cm
      line: The 1285 listing prints a volume resistivity of 0.0080 ohm-cm without pressure-sensitive adhesive, and 0.015 ohm-cm after tensile set. The 1287 listing prints 0.012 ohm-cm and 0.015 ohm-cm.
    - label: Temperature
      benchmark: max_service_temp
      value: 200 °C in air
      line: Both listings print a maximum service temperature in air of 200 °C. The 1285 minimum is -65 °C and the 1287 minimum is -55 °C, both per the Flex TR10 and ASTM D1329 test named on the pages.
  compare: 'This profile compares two grades from one manufacturer rather than other shielding materials. CHO-SEAL 1285 (silicone, Type B) lists at least 100 dB at 10 GHz and 0.0080 ohm-cm volume resistivity. CHO-SEAL 1287 (fluorosilicone, Type D) lists at least 90 dB at 10 GHz and 0.012 ohm-cm. The two grades are not interchangeable: the binder changes the shielding minima and the resistivity as printed.'
  compare_rows:
    - label: Specific gravity
      benchmark: density
    - label: Volume resistivity
      benchmark: electrical_resistivity
    - label: Shielding effectiveness
      benchmark: shielding_effectiveness
  handling:
    - No handling source was read for CHO-SEAL 1285 or 1287. Check the supplier's safety data sheet for the exact part.
    - The listed service range is -65 °C to 200 °C in air for CHO-SEAL 1285 and -55 °C to 200 °C for CHO-SEAL 1287.
    - Specify the grade by name, since the binder and the minimum temperature differ between 1285 and 1287.
  good_for:
    - Enclosure seams that need a conductive gasket to MIL-DTL-83528. CHO-SEAL 1285 is listed as Type B with at least 100 dB at 10 GHz.
    - 'Seams that must stay conductive through vibration: volume resistivity after vibration is printed as below 0.008 ohm-cm for CHO-SEAL 1285.'
  watch_out:
    - 'Galvanic pairing: the Modus guide says the filler suits aluminium housings but the pairing still needs plating or matching to avoid contact-resistance rise over time.'
    - 'Thermal cycling: the guide says shielding can fall by several dB over a mission. No time or dB figure is given.'
    - 'Outgassing and flight data: none were read for these two grades, so their suitability for vacuum use is not established by these sources.'
  verdict: 'CHO-SEAL 1285 and 1287 are MIL-DTL-83528 silver-aluminium gaskets with printed shielding minima and volume resistivity. The sources read give listing values only: no Parker datasheet, outgassing, hazard or flight data could be checked in this run.'