Cyanate Ester BT (BT resin)
Finish state
Workhorse blend for IC-substrate and high-Tg PCB laminates: better toughness and processability than neat CE at slightly higher loss.
Values for the BT condition
Other Cyanate Ester grades and fills
Cyanate Ester is listed in 8 conditions; see the grade overview at Cyanate Ester.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Fused-silica / mineral-filled CE | Choose for chip encapsulation and low-CTE tooling where dimensional match to silicon/ceramic is required. | — | 70 | 0.8 | — |
Flame-retardant grade | For laminates and enclosures needing certified V-0 with low smoke; phosphorus modification slightly raises Df and lowers Tg. | — | 72 | 2 | 89 Shore D |
Toughened cyanate ester | Pick when microcracking resistance under thermal cycling matters (space structures, thick laminates); costs ~30–50 °C of Tg. | — | 78 | 4.5 | — |
NEATDefault Neat / unfilled cast cyanate ester | Baseline unmodified resin: highest Tg and lowest dielectric loss, but brittle — use for castings, adhesives and as a matrix reference. | — | 80 | 2.6 | 89 Shore D |
Epoxy-blended cyanate ester (cost-reduced, easier cure) | Use when full CE performance is not needed — lower cost and lower cure temperature, at reduced Tg and higher dielectric loss. | — | 82 | 3.2 | 88 Shore D |
BTThis page BT resin | Workhorse blend for IC-substrate and high-Tg PCB laminates: better toughness and processability than neat CE at slightly higher loss. | — | 85 | 2 | 90 Shore D |
E-glass fabric / CE laminate | Standard form for high-speed copper-clad laminates and radomes needing stable Dk/Df to microwave frequencies. | — | 400 | 2 | — |
Carbon-fiber / CE composite | Primary space-structure form — near-zero CTE laminates, very low moisture-induced dimensional drift and low outgassing. | — | 1,900 | 1.4 | — |
What is Cyanate Ester BT?
Cyanate Ester BT is Cyanate Ester supplied in the BT condition — workhorse blend for IC-substrate and high-Tg PCB laminates: better toughness and processability than neat CE at slightly higher loss. Cyanate Ester BT has a tensile strength of 85 MPa (12.3 ksi), stronger than 85% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.5 GPa (0.508 Msi). Cyanate Ester BT has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is 200°C (392 °F). NEAT is the default condition FabDigit quotes; BT is available on request or by drawing note.
Advantages
- High service temperature — 180°C (356 °F), better than 85% of polymer grades
- Stiff — 3.5 GPa (0.508 Msi), better than 83% of polymer grades
Limitations
- Low fracture toughness — 0.55 MPa·√m (0.501 ksi·√in), worse than 98% of polymer grades
- Difficult to weld — 0/100, worse than 98% of polymer grades
- Limited ductility — 2%, worse than 95% of polymer grades
- Limited formability — 5/100, worse than 95% of polymer grades
- High embodied carbon — 9.5 kg CO₂/kg, worse than 89% of polymer grades
Cyanate Ester BT properties
Typical room-temperature values for Cyanate Ester BT; 26 are specific to this condition. Other listed values are Cyanate Ester reference data and may not represent this condition. Bars are the position among polymer grades.
Physical5
Cyanate Ester BT has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is 200°C (392 °F).
Mechanical15
Cyanate Ester BT has a tensile strength of 85 MPa (12.3 ksi), stronger than 85% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.5 GPa (0.508 Msi).
Thermal10
Cyanate Ester BT is rated for continuous service to 180°C (356 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 72% of polymer grades. Thermal expansion is 55 µm/m·K (30.6 µin/in·°F).
Electrical7
Cyanate Ester BT is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 52% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of Cyanate Ester BT takes about 185 MJ of energy and emits 9.5 kg of CO₂ — more than 88% of polymer grades. Typical recycled content is 0%.
Manufacturability7
Cyanate Ester BT's machinability is fair (50/100, worse than 73% of polymer grades); weldability not recommended (0/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Cyanate Ester BT
Is Cyanate Ester easy to machine?
Machine fully post-cured parts with sharp PCD/diamond tooling, light feed and dust extraction — the neat resin is brittle and glass/carbon-filled laminates are highly abrasive.
Can Cyanate Ester be welded?
Thermoset — cannot be welded; join by co-cure, secondary CE/epoxy film adhesive bonding or mechanical fasteners.
Can Cyanate Ester be formed, bent or molded?
Processed as prepreg (autoclave/oven, 177–200 °C cure with 220–250 °C free-standing post-cure), RTM/VARTM or casting; keep resin and reinforcement dry — moisture and amine/phenol contamination form carbamates that depress Tg and cause voids.
What surface finishes work on Cyanate Ester?
Post-cure before machining, seal or paint/UV-coat exposed surfaces since aromatic triazine networks yellow and chalk in sunlight; copper foil bonds well in laminate pressing without an adhesive tie layer.
Cyanate Ester chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| transition-metal catalyst (Cu/Zn/Mn carbcyclotrimerization catalyst package | 0.05 – 2 | 0.4 |
| toughener (thermoplastic or core-shell rtoughened variants only | 0 – 20 | 0 |
| filler / reinforcement (fused silica, E-filled and composite variants only | 0 – 70 | 0 |
| bisphenol-A dicyanate ester monomer/prepmay be replaced/blended with novolac (PT-type), dicyclopentadiene (XU-71787) or bisphenol-E (LECy) dicyanates | ≥ 95 (balance) | — |
Cyanate Ester BT — frequently asked
What is Cyanate Ester BT used for?
Cyanate Ester BT is typically used for satellite composite structures, high-frequency RF PCB substrates and radome composites. In short: lowest dielectric loss thermoset; space-grade low outgassing; costlier than BMI.
What is the tensile strength of Cyanate Ester BT?
Cyanate Ester BT has a typical tensile strength of 85 MPa (12.3 ksi) — stronger than 85% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is Cyanate Ester BT easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 73% of polymer grades). Machine fully post-cured parts with sharp PCD/diamond tooling, light feed and dust extraction — the neat resin is brittle and glass/carbon-filled laminates are highly abrasive.
Can Cyanate Ester BT be welded?
Not readily — weldability is rated not recommended (0/100). Thermoset — cannot be welded; join by co-cure, secondary CE/epoxy film adhesive bonding or mechanical fasteners.
What surface finishes work on Cyanate Ester BT?
Post-cure before machining, seal or paint/UV-coat exposed surfaces since aromatic triazine networks yellow and chalk in sunlight; copper foil bonds well in laminate pressing without an adhesive tie layer.
Can Cyanate Ester BT be formed, bent or molded?
Processed as prepreg (autoclave/oven, 177–200 °C cure with 220–250 °C free-standing post-cure), RTM/VARTM or casting; keep resin and reinforcement dry — moisture and amine/phenol contamination form carbamates that depress Tg and cause voids.
What is the maximum service temperature of Cyanate Ester BT?
Cyanate Ester BT is rated for continuous use to about 180°C (356 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Primaset cyanate ester monomers technical data — Lonza (2019)
- AroCy cyanate ester resin data sheets (B-10, L-10, XU-71787) — Huntsman / Ciba (2005)
- Cyanate ester prepreg systems (EX-1515, RS-3, CE toughened grades) — Solvay / Tencate Advanced Composites (2021)
- Engineered Materials Handbook Vol.3: Adhesives and Sealants / Vol.1 Composites — cyanate ester chemistry — ASM International (1990)
- Chemistry and Technology of Cyanate Ester Resins — Blackie / Springer (I. Hamerton, ed.) (1994)
- Outgassing Data for Selecting Spacecraft Materials (ASTM E595 results) — NASA GSFC (2023)
- IPC-4101 laminate specification sheets (BT/CE high-Tg, low-loss classes) — IPC (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.