Materials / Compare
PCB Laminate FR-4 vs. Plastic PEEK
Compare PCB Laminate FR-4 vs. Plastic PEEK strength, stiffness, weight and thermal properties.
| Try it on a partA sample part to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | not given (tensile used) | 98MPasourcetypical, tensile yield |
| Ultimate tensile strength | 246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039) | not sourced |
| Compressive strength | not sourced | 125MPasourcetypical, 23 C |
| Flexural strength | 531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B) | 165MPasourcetypical, flexural stress at yield, 23 C |
| Elongation at break | not sourced | 25%sourcetypical, at break |
| Young's modulus (stiffness) | 21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2) | 4GPasourcetypical (nominal) |
| Density | 1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR | 1,300kg/m³sourcetypical (crystalline) |
| Strength to weight | 164kN·m/kg2.18x higher | 75.4kN·m/kg |
| Stiffness to weight | 12.4MN·m/kg4.04x higher | 3.08MN·m/kg |
| Poisson's ratio | 0.171–0.177sourcetypical, in-plane: cross direction .. length direction | 0.38sourcetypical |
| Shear modulus | 10.2GPa7.01x stiffer in shear | 1.45GPa |
| Bulk modulus | 12.2GPa | 5.56GPa |
| Speed of sound | 3,525m/s | 1,754m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet | 0.29W/m·Ksourcetypical, average, 23 C |
| Thermal expansion | 13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C) | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) |
| 100 mm part over a 50 °C swing | 67.5µm growth4.07x less | 275µm growth |
| Specific heat | 1,200–1,400J/kg·Ksourcetypical (ASTM E1461); another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) |
| Heats up and cools (diffusivity) | 0.16mm²/s1.58x faster | 0.101mm²/s |
| Thermal shock resistance | 324W/m4.04x more resistant | 80.1W/m |
| Melting point | not sourced | 343°Csourcetypical, DSC |
| Glass transition | 180°Csourcetypical, DSC (IPC-TM-650 2.4.25C) | 143°Csourceonset (midpoint 150 C) |
| Max service temperature | 130°CsourceUL Relative Thermal Index (UL 796) | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) |
| Values for | Isola 370HR FR-4 laminate (Polyclad PCL-FR-370HR, 180 C Tg multifunctional epoxy, E-glass fabric), copper removed; Isola data sheet Revision C, last updated April 15, 2021. Woven-glass laminate: the sheet gives in-plane values per weave direction (length / cross) and the Z-axis CTE separately; the solver is isotropic per material. | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Is PCB Laminate FR-4 stronger than Plastic PEEK?
PCB Laminate FR-4 is stronger: its tensile strength is 315 MPa against yield strength 98 MPa for Plastic PEEK (3.22x).
Which is lighter, PCB Laminate FR-4 or Plastic PEEK?
Plastic PEEK is lighter: 1,300 kg/m³ against 1,920 kg/m³ for PCB Laminate FR-4.
Which is stiffer, PCB Laminate FR-4 or Plastic PEEK?
PCB Laminate FR-4 is stiffer: Young's modulus 23.9 GPa against 4 GPa for Plastic PEEK, so the same part in PCB Laminate FR-4 deflects less under the same load.
Which is lighter for the same job, PCB Laminate FR-4 or Plastic PEEK?
For the same stiffness or strength: PCB Laminate FR-4 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | PCB Laminate FR-4 | Plastic PEEK |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 4.04x heavier |
| Stiff beam (bending) | lighter | 1.65x heavier |
| Stiff panel or plate | lighter | 23% heavier |
| Strong rod or tie | lighter | 2.18x heavier |
| Strong beam | lighter | 48% heavier |
| Strong panel or plate | lighter | 21% heavier |
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which conducts heat better, PCB Laminate FR-4 or Plastic PEEK?
PCB Laminate FR-4 conducts heat better: 0.4 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
PCB Laminate FR-4 expands less: 13.5 µm/m·K against 55 µm/m·K for Plastic PEEK.