spore: profile
id: fr-4
spore_version: 0.2
family: glass-and-composites
name: FR-4 glass-fibre epoxy laminate
abbreviation: FR-4
role: rigid circuit-board substrate, woven glass cloth bonded with epoxy resin
category: electronics
type: circuit-board-laminates
summary: |
  FR-4 is a NEMA grade of rigid laminate made of woven glass cloth bonded with epoxy resin, self-extinguishing and used as the substrate of almost all printed circuit boards. This profile reads the Isola 370HR FR-4 product page, a standard-loss, thermally robust epoxy laminate with a glass transition of 180 °C by DSC, a decomposition temperature of 340 °C at 5 % weight loss, and a dielectric constant of 4.17 at 1 GHz. No space flight data for FR-4 was read in this run.
best_for: 'Standard printed circuit boards: 180 °C Tg and 60 min T260 for multilayer boards, as printed for Isola 370HR'
weakest_at: 'Loss at high frequency and expansion above Tg: a Z-axis CTE of 230 ppm/°C above Tg, and a dissipation factor of 0.0210 at 2 GHz'
identity:
  formula: Woven E-glass cloth impregnated with an epoxy resin binder; laminate of glass fibre and epoxy, flame-retardant grade
  cas: ''
  source: wikipedia-fr4
  where: Lead section (FR-4 is a NEMA-designated composite of woven glass cloth bonded with an epoxy resin binder)
tags:
  environments: []
  stresses: []
  applications:
    - electronics-and-chips
properties:
  - benchmark: tg
    label: Glass transition temperature (DSC), Isola 370HR
    value: 180
    unit: °C
    scope: material
    conditions:
      method_as_printed: DSC, IPC-TM-650 2.4.25C
    method: Typical value printed on the Isola product page, Typical Values table
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Glass Transition Temperature (Tg) by DSC row
  - benchmark: decomposition_temperature
    label: Decomposition temperature (TGA, 5 % weight loss), Isola 370HR
    value: 340
    unit: °C
    scope: material
    conditions:
      method_as_printed: TGA at 5 % weight loss, IPC-TM-650 2.4.24.6
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Decomposition Temperature (Td) row
  - benchmark: time_to_delamination
    label: Time to delaminate by TMA at 260 °C (T260), Isola 370HR, copper removed
    value: 60
    unit: min
    scope: material
    conditions:
      temperature: 260 °C
      copper: removed
      method_as_printed: TMA, IPC-TM-650 2.4.24.1
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Time to Delaminate by TMA, sub-row A. T260
  - benchmark: time_to_delamination
    label: Time to delaminate by TMA at 288 °C (T288), Isola 370HR, copper removed
    value: 30
    unit: min
    scope: material
    conditions:
      temperature: 288 °C
      copper: removed
      method_as_printed: TMA, IPC-TM-650 2.4.24.1
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Time to Delaminate by TMA, sub-row B. T288
  - benchmark: cte
    label: Z-axis CTE, pre-Tg, Isola 370HR
    value: 45
    unit: ppm/°C
    scope: material
    conditions:
      range: below Tg
      method_as_printed: IPC-TM-650 2.4.24C
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Z-Axis CTE, sub-row A. Pre-Tg
  - benchmark: cte
    label: Z-axis CTE, post-Tg, Isola 370HR
    value: 230
    unit: ppm/°C
    scope: material
    conditions:
      range: above Tg
      method_as_printed: IPC-TM-650 2.4.24C
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Z-Axis CTE, sub-row B. Post-Tg
  - benchmark: cte
    label: Z-axis total expansion, 50 to 260 °C, Isola 370HR
    value: 2.8
    unit: '%'
    scope: material
    conditions:
      range: 50 to 260 °C
      method_as_printed: IPC-TM-650 2.4.24C
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Z-Axis CTE, sub-row C. 50 to 260°C (Total Expansion)
  - benchmark: cte
    label: X-axis CTE, pre-Tg, Isola 370HR
    value: 13
    unit: ppm/°C
    scope: material
    conditions:
      range: below Tg
      axis: X
      method_as_printed: IPC-TM-650 2.4.24C
    method: Typical value printed on the Isola product page, printed as 13/14 for X/Y
    status: ground
    source: isola-370hr-page
    where: Typical Values table, X/Y-Axis CTE row, first figure
  - benchmark: cte
    label: Y-axis CTE, pre-Tg, Isola 370HR
    value: 14
    unit: ppm/°C
    scope: material
    conditions:
      range: below Tg
      axis: 'Y'
      method_as_printed: IPC-TM-650 2.4.24C
    method: Typical value printed on the Isola product page, printed as 13/14 for X/Y
    status: ground
    source: isola-370hr-page
    where: Typical Values table, X/Y-Axis CTE row, second figure
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Isola 370HR
    value: 0.4
    unit: W/m·K
    scope: material
    conditions:
      method_as_printed: ASTM E1952
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Thermal Conductivity row
  - benchmark: dielectric_constant
    label: Dielectric constant (permittivity) at 1 GHz, Isola 370HR
    value: 4.17
    unit: '-'
    scope: material
    conditions:
      frequency: 1 GHz
      method_as_printed: IPC-TM-650 2.5.5.9
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Dk Permittivity, sub-row B. @ 1 GHz
  - benchmark: dielectric_constant
    label: Dielectric constant (permittivity) at 2 GHz, Isola 370HR
    value: 4.04
    unit: '-'
    scope: material
    conditions:
      frequency: 2 GHz
      method_as_printed: Bereskin stripline
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Dk Permittivity, sub-row C. @ 2 GHz
  - benchmark: dissipation_factor
    label: Dissipation factor (loss tangent) at 1 GHz, Isola 370HR
    value: 0.0161
    unit: '-'
    scope: material
    conditions:
      frequency: 1 GHz
      method_as_printed: IPC-TM-650 2.5.5.9
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Df Loss Tangent, sub-row B. @ 1 GHz
  - benchmark: dissipation_factor
    label: Dissipation factor (loss tangent) at 2 GHz, Isola 370HR
    value: 0.021
    unit: '-'
    scope: material
    conditions:
      frequency: 2 GHz
      method_as_printed: Bereskin stripline
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Df Loss Tangent, sub-row C. @ 2 GHz
  - benchmark: peel_strength
    label: Peel strength, standard profile copper, at 125 °C, Isola 370HR
    value: 1.25
    unit: N/mm
    scope: material
    conditions:
      temperature: 125 °C
      copper: standard profile
      method_as_printed: IPC-TM-650 2.4.8.3
    method: Typical value printed on the Isola product page; 7.0 lb/inch printed alongside
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Peel Strength, sub-row B. at 125ºC
  - benchmark: flexural_strength
    label: Flexural strength, length direction, Isola 370HR
    value: 620
    unit: MPa
    scope: material
    conditions:
      direction: length
      method_as_printed: IPC-TM-650 2.4.4B
    method: Typical value printed on the Isola product page; 90.0 kpsi printed alongside
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Flexural Strength, sub-row A. Length direction
  - benchmark: moisture_absorption
    label: Moisture absorption, Isola 370HR
    value: 0.15
    unit: '%'
    scope: material
    conditions:
      method_as_printed: IPC-TM-650 2.6.2.1A
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Moisture Absorption row
  - benchmark: electric_strength
    label: Electric strength, laminate and laminated prepreg, Isola 370HR
    value: 54
    unit: kV/mm
    scope: material
    conditions:
      method_as_printed: IPC-TM-650 2.5.6.2A
    method: Typical value printed on the Isola product page; 1350 V/mil printed alongside
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Electric Strength row
  - benchmark: volume_resistivity
    label: Volume resistivity after moisture resistance, Isola 370HR
    value: 300000000
    unit: MΩ-cm
    scope: material
    conditions:
      state: after moisture resistance
      method_as_printed: IPC-TM-650 2.5.17.1
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Volume Resistivity, sub-row A. After moisture resistance
  - benchmark: relative_thermal_index
    label: Relative thermal index, Isola 370HR
    value: 130
    unit: °C
    scope: material
    conditions:
      method_as_printed: UL 796
    method: Typical value printed on the Isola product page
    status: ground
    source: isola-370hr-page
    where: Typical Values table, Relative Thermal Index (RTI) row
  - benchmark: tg
    label: Glass transition temperature (DSC), Shengyi S1000-2M
    value: 180
    unit: °C
    scope: material
    conditions:
      method_as_printed: IPC-TM-650 2.4.25D, DSC
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, Tg row, DSC
  - benchmark: tg
    label: Glass transition temperature (DMA), Shengyi S1000-2M
    value: 185
    unit: °C
    scope: material
    conditions:
      method_as_printed: IPC-TM-650 2.4.24.2, DMA
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, Tg row, DMA
  - benchmark: decomposition_temperature
    label: Decomposition temperature (TGA, 5 % weight loss), Shengyi S1000-2M
    value: 355
    unit: °C
    scope: material
    conditions:
      method_as_printed: IPC-TM-650 2.4.24.6, TGA at 5 % weight loss
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, Td row
  - benchmark: cte
    label: Z-axis CTE, pre-Tg, Shengyi S1000-2M
    value: 41
    unit: ppm/°C
    scope: material
    conditions:
      range: below Tg
      method_as_printed: IPC-TM-650 2.4.24
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, CTE (Z-axis) before Tg row
  - benchmark: cte
    label: Z-axis CTE, post-Tg, Shengyi S1000-2M
    value: 208
    unit: ppm/°C
    scope: material
    conditions:
      range: above Tg
      method_as_printed: IPC-TM-650 2.4.24
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, CTE (Z-axis) after Tg row
  - benchmark: dielectric_constant
    label: Dielectric constant (permittivity) at 1 GHz, Shengyi S1000-2M
    value: 4.6
    unit: '-'
    scope: material
    conditions:
      frequency: 1 GHz
      method_as_printed: IPC-TM-650 2.5.5.9, C-24/23/50
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, Permittivity (1GHz) row
  - benchmark: dissipation_factor
    label: Dissipation factor (loss tangent) at 1 GHz, Shengyi S1000-2M
    value: 0.018
    unit: '-'
    scope: material
    conditions:
      frequency: 1 GHz
      method_as_printed: IPC-TM-650 2.5.5.9, C-24/23/50
    method: Typical value printed on the Shengyi datasheet
    status: ground
    source: shengyi-s1000-2m
    where: General Properties table, Loss Tangent (1GHz) row
  - benchmark: resin_content
    label: Prepreg resin content by glass style, Shengyi S1000-2MB
    value: 44
    value_high: 77
    unit: '%'
    scope: material
    conditions:
      basis: nominal prepreg resin content, range across glass styles 106 to 7628
    method: Range across the glass styles in the Shengyi prepreg table, minimum and maximum as printed
    status: ground
    source: shengyi-s1000-2m
    where: PREPREG PARAMETERS table, Resin content column
corrosion:
  - environment: Humidity with a DC voltage across adjacent vias (CAF test)
    headline: Copper salt filaments grow along the epoxy-glass interface and can short adjacent vias or planes.
    effect: In the NPL CAF test, laminate was held at 85 °C and 85 % RH for up to 1000 hours with a DC voltage across vias. Vias closer together fail sooner, anodic vias fail faster than cathodic ones, and higher voltage shortens time to failure. CAF-resistant DICY-free resins reduce the risk, and identically specified laminates from different suppliers performed differently.
    rating: severe
    conditions:
      temperature: 85 °C
      humidity: 85 % RH
      duration: up to 1000 h
    source: npl-caf-matc155
    where: Abstract (test method), and section 6, Conclusions
  - environment: Moisture before and during use
    headline: Moisture starts the leakage path, and BT resin has the best CAF record of the materials compared.
    effect: Turbini describes CAF as a copper hydroxy chloride salt that grows from anode to cathode along the epoxy-glass interface, and as enhanced by high humidity, high voltage gradient, multiple thermal cycles and higher lead-free processing temperatures. In the comparison Turbini cites, bismaleimide triazine (BT) was the most CAF-resistant material, attributed to its low moisture absorption.
    rating: moderate
    conditions: {}
    source: turbini-caf-history
    where: Introduction paragraphs, and the comparison of FR-4, G-10, polyimide, triazine and MC-2 substrates
  - environment: Reflow and lead-free soldering
    headline: A 250 °C reflow peak is potentially harmful to CAF performance.
    effect: NPL lists peak reflow temperatures of 250 °C as potentially harmful to the CAF performance of a laminate. Its conclusions also say the board house's own processing gives laminates different CAF performance, so the laminate must be tested as built.
    rating: moderate
    conditions:
      peak: 250 °C
    source: npl-caf-matc155
    where: Section 6, Conclusions, Reflow conditions and Manufacturing
  - environment: Thermal stress at soldering temperatures
    headline: Shengyi S1000-2M withstands 288 °C solder dip for over 100 s and gives T260 above 60 min.
    effect: Shengyi prints by TMA (IPC-TM-650 2.4.24.1) a T260 above 60 min, a T288 of 30 min and a T300 of 15 min, and a solder-dip thermal stress at 288 °C of over 100 s. These show delamination time falls quickly above 260 °C, which matches the Isola 370HR figures recorded above.
    rating: low
    conditions:
      temperature: 260 to 300 °C
    source: shengyi-s1000-2m
    where: General Properties table, rows T260, T288, T300 and Thermal Stress
risks:
  hazards:
    - text: 'PubChem record for tetrabromobisphenol A (CID 6618), formula C15H12Br4O2 and molar mass 543.9 g/mol, aggregated GHS: H350 may cause cancer, H400 and H410 very toxic to aquatic life, and H351 suspected of causing cancer in 21.2 percent of notifications. This describes the additive, not the cured laminate. No safety data sheet for an FR-4 laminate was read.'
      ghs:
        - H350
        - H351
        - H400
        - H410
      source: pubchem-tbbpa
      where: Safety and Hazards, GHS Classification (aggregated)
  failure_risks:
    - mode: Expansion through thickness above Tg
      trigger: Heating a board above its glass transition, where the Z-axis CTE rises from 45 to 230 ppm/°C
      consequence: Plated-through-hole and copper stress as the board expands; the page prints a 2.8 % total Z-axis expansion from 50 to 260 °C
      severity: moderate
      source: isola-370hr-page
      where: Typical Values table, Z-Axis CTE rows A to C
    - mode: CAF short between vias or planes
      trigger: Humidity with a DC voltage across adjacent vias, with anodic vias failing first
      consequence: A copper-salt filament grows along the epoxy-glass interface and causes an electrical short; the NPL test ran at 85 °C and 85 % RH for up to 1000 hours
      severity: critical
      source: npl-caf-matc155
      where: Abstract, and section 6, Conclusions
  side_effects: []
  handling:
    - text: Shengyi prepreg keeps 3 months below 23 °C and under 50 % RH, or 6 months below 5 °C, in damp-proof wrap. It should normalise at room temperature for at least 4 h before use, since moisture uptake weakens bonding strength.
      source: shengyi-s1000-2m
      where: Prepreg, Storage Condition
  mitigations:
    - text: Specify a CAF-resistant laminate, such as a DICY-free resin, but test the board as the board house builds it, because processing changes CAF results (NPL).
      source: npl-caf-matc155
      where: Section 6, Conclusions
    - text: Stagger vias at 45 degrees to the weave, since NPL found this resists CAF better than vias aligned with warp or weft at the same gap.
      source: npl-caf-matc155
      where: Section 6, Conclusions, Alignment to reinforcement
    - text: Limit reflow peaks; NPL calls 250 °C potentially harmful to CAF performance.
      source: npl-caf-matc155
      where: Section 6, Conclusions, Reflow conditions
uses:
  - application: electronics-and-chips
    device: Printed circuit board substrate
    example: Isola 370HR, a standard-loss, thermally robust epoxy laminate with a 180 °C Tg and a 1 GHz dielectric constant of 4.17, as printed on the product page.
    source: isola-370hr-page
    where: Product page summary and Typical Values table
  - application: electronics-and-chips
    device: Computers and communication equipment
    example: Shengyi S1000-2M, a high-Tg FR-4 with anti-CAF capability, lists computer, communication and automotive electronics as applications.
    source: shengyi-s1000-2m
    where: Features and Applications box, first page of the datasheet
  - application: electronics-and-chips
    device: Printed circuit boards in general
    example: FR-4 glass epoxy is described as the most common insulating substrate for printed circuit boards.
    source: wiki-pcb
    where: Printed circuit board article, substrate paragraph
supply:
  - subject: Copper foil
    abundance: 'Mine production in 2025e, thousand metric tons of copper content: Chile 5,300, Congo (Kinshasa) 3,200, Peru 2,700, China 1,800, United States 1,000. China leads refinery output at 14,000. The US net import reliance was 57 percent of apparent consumption in 2025e. Electrical and electronic products took 23 percent of copper use, per the Copper Development Association.'
    producers: []
    critical_lists: []
    recycling: Not sourced.
    substitutes: []
    source: usgs-mcs2026-copper
    where: World Mine and Refinery Production and Reserves table, Salient Statistics, Domestic Production and Use paragraph
  - subject: Laminate producers
    abundance: No production volume or country share for FR-4 laminate was printed on the pages read.
    producers:
      - name: Isola Group
        note: Makes the 370HR laminate and prepreg read here
        country: Isola Group
      - name: Shengyi Technology Co., Ltd.
        note: Issues the S1000-2M and S1000-2MB datasheet (CN-TDS-1901-03) and refers buyers to the company for detail
        country: Shengyi Technology Co., Ltd.
      - name: Panasonic
        note: Makes MEGTRON 6 (R-5775), a low-loss, high-speed grade rather than a standard FR-4
        country: Panasonic
    critical_lists: []
    recycling: Not sourced.
    substitutes:
      - Bismaleimide triazine (BT) resin was the most CAF-resistant material in the comparison Turbini cites, attributed to its low moisture absorption.
    source: shengyi-s1000-2m
    where: Datasheet footer and copyright line; Isola 370HR product page
documents:
  - title: Isola 370HR Industry Leading Epoxy Laminate and Prepreg, product page (typical values)
    type: datasheet
    url: https://www.isola-group.com/pcb-laminates-prepreg/370hr-laminate-prepreg/
  - title: Shengyi S1000-2M and S1000-2MB technical datasheet (CN-TDS-1901-03)
    type: datasheet
    url: https://www.eurotronics.be/wp-content/uploads/2021/11/Shengyi-S1000-2M-S1000-2MB-datasheet.pdf
  - title: Panasonic MEGTRON 6 R-5775, product page (general properties)
    type: datasheet
    url: https://industrial.panasonic.com/ww/products/pt/megtron/megtron6
  - title: NPL Report MATC(A)155, Susceptibility of glass-reinforced epoxy laminates to conductive anodic filamentation
    type: report
    url: https://eprintspublications.npl.co.uk/3017/1/MATC155.pdf
  - title: 'Turbini, Conductive Anodic Filament (CAF) Formation: An Historic Perspective'
    type: paper
    url: https://www.electronics.org/system/files/technical_resource/E17&S02-3.pdf
  - title: USGS Mineral Commodity Summaries 2026, Copper
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
  - title: PubChem, Tetrabromobisphenol A (CID 6618), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/6618
gaps:
  - 'Isola 370HR PDF datasheet could not be read: WebFetch returned only compressed PDF streams, so its values were taken from the product page instead.'
  - Isola FR408HR product page returned HTTP 404, so no second FR-4 type from Isola was read.
  - Ventec VT-4 product page redirected and returned HTTP 404, so no Ventec values were read.
  - The Panasonic MEGTRON 6 page was read, but it is a low-loss grade rather than a standard FR-4, and no Panasonic FR-4 grade was read. Its Dk and Df are at 13 GHz and are not compared with the 1 GHz values here.
  - everythingrf 370HR page returned HTTP 403.
  - Dielectric values differ between sources and test methods, so Dk and Df are recorded only at the frequencies and methods printed on the Isola page.
  - No IPC-4101 grade limits were read in this run. IPC-4101/126 is named only on the Shengyi datasheet, and the IPC standard is named on the Wikipedia IPC article.
  - Glass cloth (E-glass) and epoxy resin supply shares, producers and abundance were not found in the pages read, so the supply section covers copper foil and laminate makers only.
  - 'No NASA source for FR-4 outgassing was read: the NTRS PDF tried in this run returned HTTP 404.'
  - The resin_content property uses a short snake_case name because it is not in the canonical list.
  - The Shengyi S1000-2M datasheet line-up page is dated July 2018 and marks its Dk and Df values as not guaranteed. Its values appear in the story text only, not as properties, and the current Shengyi datasheet was not read.
  - Consumer devices such as phones and laptops are not named in any source read here, so the uses list names computers and communication equipment only.
  - No space flight, outgassing, atomic oxygen, or radiation data for FR-4 was read in this run.
  - Peel strength values at 125 °C and after thermal stress come from the Isola page layout; the row pairing was read from extracted text and is the page's best reading.
  - Dielectric breakdown, arc resistance, CTI and flammability (UL 94 V-0) are printed on the Isola page but are not recorded because they are ratings or lower-bound values, not single numbers.
sources:
  isola-370hr-page:
    title: Isola 370HR Industry Leading Epoxy Laminate and Prepreg, product page, Typical Values table
    id: Isola Group product page, 370HR laminate and prepreg
    url: https://www.isola-group.com/pcb-laminates-prepreg/370hr-laminate-prepreg/
    year: 2026
    kind: datasheet
    license: manufacturer web page, linked not reproduced
  wikipedia-fr4:
    title: FR-4, Wikipedia
    id: Wikipedia article FR-4, lead section and Properties table
    url: https://en.wikipedia.org/wiki/FR-4
    year: 2026
    kind: web
    license: CC BY-SA, linked not reproduced
  shengyi-s1000-2m:
    title: Shengyi S1000-2M and S1000-2MB technical datasheet (CN-TDS-1901-03), with prepreg and line-up tables
    url: https://www.eurotronics.be/wp-content/uploads/2021/11/Shengyi-S1000-2M-S1000-2MB-datasheet.pdf
    year: 2018
    kind: datasheet
    license: manufacturer datasheet, linked not reproduced
  panasonic-megtron6:
    title: Panasonic MEGTRON 6 R-5775, product page, general properties table
    url: https://industrial.panasonic.com/ww/products/pt/megtron/megtron6
    kind: web
    license: manufacturer web page, linked not reproduced
  npl-caf-matc155:
    title: NPL Report MATC(A)155, Susceptibility of Glass-Reinforced Epoxy Laminates to Conductive Anodic Filamentation
    url: https://eprintspublications.npl.co.uk/3017/1/MATC155.pdf
    year: 2004
    kind: report
    license: Crown copyright, extracts reproduced with source given; linked not reproduced
  turbini-caf-history:
    title: 'Conductive Anodic Filament (CAF) Formation: An Historic Perspective, Turbini, ECWC 10 and APEX 2005'
    url: https://www.electronics.org/system/files/technical_resource/E17&S02-3.pdf
    year: 2005
    kind: paper
    license: conference paper, linked not reproduced
  usgs-mcs2026-copper:
    title: USGS Mineral Commodity Summaries 2026, Copper
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: US government work, linked not reproduced
  pubchem-tbbpa:
    title: PubChem, Tetrabromobisphenol A (CID 6618), Safety and Hazards
    url: https://pubchem.ncbi.nlm.nih.gov/compound/6618
    year: 2026
    kind: database
    license: public database, linked not reproduced
  wiki-tbbpa:
    title: Tetrabromobisphenol A, Wikipedia, Production and use
    url: https://en.wikipedia.org/wiki/Tetrabromobisphenol_A
    year: 2026
    kind: web
    license: CC BY-SA, linked not reproduced
  wiki-pcb:
    title: Printed circuit board, Wikipedia, substrate and laminate type
    url: https://en.wikipedia.org/wiki/Printed_circuit_board
    year: 2026
    kind: web
    license: CC BY-SA, linked not reproduced
  wiki-ipc:
    title: IPC (electronics), Wikipedia, standards list
    url: https://en.wikipedia.org/wiki/IPC_(electronics)
    year: 2026
    kind: web
    license: CC BY-SA, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-19'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 5
  caveats: 6
  note: 'Deepen pass on 2026-10-19 by an AI assistant. Kept the 20 existing properties and 2 existing sources. Added 8 properties for the second FR-4 grade, Shengyi S1000-2M (Tg by DSC and DMA, Td, Z-axis CTE before and after Tg, Dk and Df at 1 GHz, and prepreg resin content). Added recipe, supply, corrosion (ageing), uses, hazards, failure risks, handling, mitigations and story sections, and 9 sources: Shengyi S1000-2M datasheet (read as a PDF via curl and pdftotext), Panasonic MEGTRON 6 product page (second laminate maker, read through WebFetch), NPL MATC(A)155 and Turbini CAF papers (text read via pdftotext), USGS Copper MCS 2026 (PDF), PubChem CID 6618 (TBBPA GHS), and Wikipedia PCB, TBBPA and IPC articles. Unreachable in this run: Isola 370HR PDF (binary only), Isola FR408HR page (404), Ventec VT-4 page (404), everythingrf page (403), NASA NTRS PDF (404). Caveats: the numeric properties still come from one product page; Dk and Df differ by source and frequency; the Shengyi and Panasonic values appear in the story text, not as properties; the TBBPA hazard describes the additive, not the cured laminate.'
story:
  recipe:
    line: FR-4 is woven glass cloth impregnated with an epoxy resin binder, then hot-pressed into laminate. The cloth type, the resin and the cloth-to-resin ratio set the laminate's type designation (Wikipedia, PCB article). The resin is a brominated epoxy, using tetrabromobisphenol A as the flame retardant (Wikipedia, TBBPA article). Shengyi cures its prepreg with a hot-pressing cycle of more than 60 min at 185 to 195 °C. The laminate and prepreg standard is IPC-4101, and Shengyi cites specification sheet IPC-4101/126.
    parts:
      - name: E-glass woven cloth
        symbol: glass
        share_note: Resin content by glass style is printed in the Shengyi prepreg table; the range is recorded as the resin_content property
        role: Woven reinforcement. The glass style sets the resin content and cured thickness.
        source: shengyi-s1000-2m
      - name: Epoxy resin binder
        symbol: epoxy
        share_note: Share not printed on the pages read
        role: Binds the glass cloth into a rigid laminate. The resin system sets the glass transition and the thermal stress limits.
        source: wiki-fr4
      - name: Tetrabromobisphenol A
        symbol: TBBPA
        share_note: Share not printed on the pages read; atoms C15H12Br4O2
        role: Brominated flame retardant built into the epoxy. A lower grade of TBBPA is used to prepare epoxy resins for printed circuit boards (Wikipedia). PubChem gives its formula and molar mass.
        source: wiki-tbbpa
      - name: Copper foil
        symbol: Cu
        share_note: Foil thickness is printed in the Shengyi purchasing table, laminated to the board surface
        role: Conductor layer on the surface of the board.
        source: shengyi-s1000-2m
  risk_groups:
    - title: For people
      lead: No safety data sheet for an FR-4 laminate was read. The hazard data below is for TBBPA, the flame-retardant additive in the resin.
      level: 1
      verdict: Additive hazards only
      points:
        - label: Additive
          line: 'PubChem aggregated GHS for TBBPA: H350 may cause cancer, H351 in 21.2 percent of notifications, and H400 and H410 for aquatic toxicity.'
        - label: Handling
          line: Shengyi prepreg keeps 3 months below 23 °C and under 50 % RH, and must be normalised for at least 4 h before use.
    - title: If it fails
      lead: The failure route in the source is thermal expansion through the board thickness above Tg.
      points:
        - label: Z-axis expansion
          line: The Isola 370HR page prints a Z-axis CTE of 45 ppm/°C below Tg and 230 ppm/°C above Tg, with 2.8 % total expansion from 50 to 260 °C.
  uses:
    - where: Computers and communication equipment
      line: Shengyi lists computer, communication and automotive electronics as applications for the S1000-2M grade.
    - where: Printed circuit boards
      line: Wikipedia describes FR-4 glass epoxy as the most common insulating substrate for printed circuit boards.
  why: FR-4 is a woven glass cloth bonded with epoxy resin, flame retardant and self-extinguishing. It is the default substrate for printed circuit boards. The Isola 370HR grade prints a glass transition of 180 °C, a decomposition temperature of 340 °C, and a dielectric constant of 4.17 at 1 GHz.
  can_do:
    - label: Survive thermal stress
      value: 60 min T260
      benchmark: time_to_delamination
      line: The 370HR page prints 60 minutes to delaminate by TMA at 260 °C with copper removed, and 30 minutes at 288 °C.
    - label: Hold a stable board
      value: 13 ppm/°C X-axis CTE
      benchmark: cte
      line: Below Tg the X and Y CTE are printed as 13 and 14 ppm/°C, close to copper, so plated holes stay under less stress.
    - label: Stay insulating
      value: 54 kV/mm
      benchmark: electric_strength
      line: After moisture resistance the volume resistivity is printed in MΩ-cm, and the electric strength as 54 kV/mm.
  compare: Isola 370HR and Shengyi S1000-2M are both high-Tg FR-4 grades. The 370HR page prints a glass transition of 180 °C by DSC, a decomposition temperature of 340 °C and a Z-axis CTE of 45 ppm/°C below Tg. Shengyi prints 180 °C by DSC and 185 °C by DMA, a decomposition temperature of 355 °C and a Z-axis CTE of 41 ppm/°C below Tg, with anti-CAF capability. At 1 GHz Shengyi prints a permittivity of 4.6 and a loss tangent of 0.018, against 4.17 and 0.0161 for the 370HR, so the 370HR is the lower-loss grade at 1 GHz. Panasonic MEGTRON 6 R-5775 is a different class, a low-loss, high-speed laminate rather than a standard FR-4 grade. Its values are read from the Panasonic product page but are not compared here, because they are taken at a different frequency and for a different product.
  compare_rows:
    - scope: material
      label: Tg
      benchmark: tg
    - scope: material
      label: Dielectric constant
      benchmark: dielectric_constant
    - scope: material
      label: Dissipation factor
      benchmark: dissipation_factor
  handling:
    - Check the grade and the test frequency before comparing dielectric values, since Dk and Df vary with frequency and method.
    - Use the supplier datasheet for each grade, since the values here are typical values from one product page.
  good_for:
    - 'Standard printed circuit boards: 180 °C Tg and 340 °C Td on the Isola 370HR page.'
    - 'Multilayer boards that need a high T260: 60 minutes at 260 °C with copper removed.'
  watch_out:
    - Dissipation factor rises with frequency, from 0.0161 at 1 GHz to 0.0210 at 2 GHz on the same page.
    - Z-axis expansion above Tg is 230 ppm/°C, so boards should stay below Tg in service.
    - No space or outgassing data for FR-4 was read, so it is not recorded for orbit use.
    - Humid conditions with a DC voltage can grow CAF shorts between vias. NPL found closer vias and anodic vias fail sooner, and higher voltage shortens time to failure.
  verdict: FR-4 is the standard circuit-board substrate. The Isola 370HR grade read here has a Tg of 180 °C, a Td of 340 °C, a dielectric constant of 4.17 at 1 GHz and a dissipation factor of 0.0161 at 1 GHz. Its high-frequency loss and Z-axis expansion above Tg are the limits, and no space-flight data was read.