G10 / FR4 (Glass-Epoxy) vs PEEK
G10/FR4 glass-epoxy laminate and PEEK are both high-performance engineering materials, but they target different jobs. G10/FR4 is a structural insulating laminate offering excellent electrical insulation, good strength, and low cost, with a temperature limit around 140 C. PEEK is a premium thermoplastic that handles higher temperatures (~250 C), chemicals, and wear, but costs far more. For electrical insulators, G10 usually wins on cost.
The verdict
Choose G10/FR4 for electrical insulators, standoffs, and structural laminate parts where cost and rigid insulation matter and temperatures stay below ~140 C. Choose PEEK when you need higher service temperature (~250 C), chemical resistance, wear performance, or a machinable thermoplastic, accepting its top-tier price.
Side-by-side data
| Property | G10 / FR4 (Glass-Epoxy) | PEEK |
|---|---|---|
| Category | Composite | Engineering Plastic |
| Density (g/cm³) | 1.85 | 1.32 |
| Tensile strength (MPa) | 280 | 100 |
| Yield strength (MPa) | 280 | 97 |
| Elongation (%) | 2 | 45 |
| Hardness | M110 | R126 |
| Max service temp (°C) | 140 | 250 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 0.29 | 0.25 |
| Typically used for | Electrical insulators & structural standoffs | High-temp, chemical & medical-grade parts |
Which should you choose?
Choose G10/FR4 when…
- Electrical insulation is the primary function (insulators, standoffs, PCB substrate)
- Cost matters: G10 rates 3.0/5 vs PEEK's 5.0/5
- High in-plane stiffness and strength from the glass laminate are needed (280 MPa)
- Service stays below ~140 C, within the laminate's limit
- You want a rigid, dimensionally stable structural board material
- Low elongation (2%) is acceptable because parts are stiff, not flexed
Choose PEEK when…
- Service runs hot: PEEK tolerates ~250 C vs G10's ~140 C
- Aggressive chemical resistance is required (PEEK rates 5/5)
- Wear, friction, or bearing performance is a design driver
- You need a machinable or injection-moldable thermoplastic, not a laminate
- Medical-grade or sterilizable parts are required
- The higher cost (5/5) is justified by temperature or chemical demands
Key differences that matter
- Temperature is the clearest split: PEEK (~250 C) nearly doubles G10/FR4's ~140 C limit.
- Cost favors G10/FR4 strongly (3.0/5 vs 5.0/5), the key reason it dominates electrical insulators.
- G10/FR4 has higher rated tensile strength (280 vs 100 MPa) from its continuous glass reinforcement.
- Both are excellent insulators and rate 5/5 for corrosion/chemical resistance, but PEEK handles harsher chemistries hot.
- G10/FR4 is a CNC-only laminate; PEEK can be CNC machined or injection molded for higher volumes.
- PEEK is the better choice for wear and bearing parts; G10 is brittle (2% elongation) and laminate-structured.
- Both have very low thermal conductivity (~0.25-0.29 W/m-K), confirming their role as thermal and electrical insulators.
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Open the Material SelectorGet a Quote →Frequently asked questions
Is G10/FR4 cheaper than PEEK?
Yes, substantially. G10/FR4 rates 3.0/5 on cost while PEEK rates 5.0/5, the top tier. For electrical insulators and structural standoffs that stay below about 140 C, G10 delivers excellent insulation and strength at a fraction of PEEK's price, which is why it remains the default for those parts.
Why choose PEEK over G10/FR4?
PEEK is the choice when temperature, chemicals, or wear exceed what the laminate can handle. It tolerates roughly 250 C versus G10's ~140 C, resists aggressive chemistries, and performs as a wear and bearing material. It is also moldable and machinable as a true thermoplastic, unlike the rigid laminate G10.
Which has the higher tensile strength?
G10/FR4 rates higher at about 280 MPa versus PEEK's 100 MPa, thanks to its continuous glass-fiber reinforcement. However, G10 is a brittle laminate with only 2% elongation, while PEEK is tougher and more impact tolerant. Pick based on whether you need laminate stiffness or thermoplastic toughness.
Are both materials good electrical insulators?
Yes, both are strong insulators with very low thermal conductivity (around 0.25-0.29 W/m-K). G10/FR4 is the classic structural insulator and PCB material, while PEEK also insulates well. For pure electrical insulation at moderate temperature and lower cost, G10/FR4 is typically preferred over the far pricier PEEK.
Property values are typical/nominal figures for early-stage guidance only and vary by temper, grade, supplier and heat treatment. Confirm critical specifications against a certified datasheet or with an mfgiq engineer before production.