Materials / Compare
Iron vs. PCB Laminate FR-4
Compare Iron vs. PCB Laminate FR-4 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 | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal | not given (tensile used) |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039) |
| Flexural strength | not sourced | 531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B) |
| Elongation at break | 38%sourcetypical, gauge 4D0 | not sourced |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2) |
| Density | 7,860kg/m³sourcetypical | 1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR |
| Strength to weight | 23.7kN·m/kg | 164kN·m/kg6.94x higher |
| Stiffness to weight | 26.3MN·m/kg2.12x higher | 12.4MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.171–0.177sourcetypical, in-plane: cross direction .. length direction |
| Shear modulus | 80.7GPa7.94x stiffer in shear | 10.2GPa |
| Bulk modulus | 158GPa | 12.2GPa |
| Speed of sound | 5,132m/s | 3,525m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C) |
| 100 mm part over a 50 °C swing | 68.5µm growth | 67.5µm growth1% less |
| Specific heat | 450J/kg·Ksourcetypical | 1,200–1,400J/kg·Ksourcetypical (ASTM E1461); another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR |
| Heats up and cools (diffusivity) | 20.7mm²/s129x faster | 0.16mm²/s |
| Thermal shock resistance | 3,447W/m10.7x more resistant | 324W/m |
| Melting point | 1,532°Csourcetypical | not sourced |
| Glass transition | not sourced | 180°Csourcetypical, DSC (IPC-TM-650 2.4.25C) |
| Max service temperature | not sourced | 130°CsourceUL Relative Thermal Index (UL 796) |
| Values for | Cleveland-Cliffs / AK Steel ARMCO Pure Iron Product Data Bulletin (07/2022): Table 1 typical physical properties, Table 2 typical mechanical properties after SRA/recrystallization anneal. | 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. |
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 Iron stronger than PCB Laminate FR-4?
PCB Laminate FR-4 is stronger: its tensile strength is 315 MPa against yield strength 186 MPa for Iron (1.7x).
Which is lighter, Iron or PCB Laminate FR-4?
PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or PCB Laminate FR-4?
Iron is stiffer: Young's modulus 207 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or PCB Laminate FR-4?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension); PCB Laminate FR-4 is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | PCB Laminate FR-4 |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 2.12x heavier |
| Stiff beam (bending) | 39% heavier | lighter |
| Stiff panel or plate | 1.99x heavier | lighter |
| Strong rod or tie | 6.94x heavier | lighter |
| Strong beam | 5.82x heavier | lighter |
| Strong panel or plate | 5.33x heavier | lighter |
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, Iron or PCB Laminate FR-4?
Iron conducts heat better: 73.2 W/m·K against 0.4 W/m·K for PCB Laminate FR-4.
Which expands less with temperature?
PCB Laminate FR-4 expands less: 13.5 µm/m·K against 13.7 µm/m·K for Iron.