Materials / Compare
PCB Laminate FR-4 vs. Steel AISI 1045
Compare PCB Laminate FR-4 vs. Steel AISI 1045 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) | 531MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | 246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039) | 627MPasourceproducer-stated, cold drawn |
| Flexural strength | 531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B) | not sourced |
| Elongation at break | not sourced | 12%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2) | 210GPasourcetypical |
| Density | 1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR | 7,800kg/m³sourcetypical |
| Strength to weight | 164kN·m/kg2.41x higher | 68.1kN·m/kg |
| Stiffness to weight | 12.4MN·m/kg | 26.9MN·m/kg2.17x higher |
| Poisson's ratio | 0.171–0.177sourcetypical, in-plane: cross direction .. length direction | 0.3sourcetypical |
| Shear modulus | 10.2GPa | 80.8GPa7.95x stiffer in shear |
| Bulk modulus | 12.2GPa | 175GPa |
| Speed of sound | 3,525m/s | 5,189m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet | 40–45W/m·Ksourcetypical range, ambient |
| Thermal expansion | 13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C) | 12µm/m·Ksourcetypical, mean 20-300 °C |
| 100 mm part over a 50 °C swing | 67.5µm growth | 60µm growth12% less |
| 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 | 460–480J/kg·Ksourcetypical range, 50/100 °C |
| Heats up and cools (diffusivity) | 0.16mm²/s | 11.6mm²/s72.3x faster |
| Thermal shock resistance | 324W/m | 6,269W/m19.4x more resistant |
| Glass transition | 180°Csourcetypical, DSC (IPC-TM-650 2.4.25C) | not sourced |
| Max service temperature | 130°CsourceUL Relative Thermal Index (UL 796) | not sourced |
| 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. | AISI 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants |
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 Steel AISI 1045?
Steel AISI 1045 is stronger: its yield strength is 531 MPa against tensile strength 315 MPa for PCB Laminate FR-4 (1.68x).
Which is lighter, PCB Laminate FR-4 or Steel AISI 1045?
PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.
Which is stiffer, PCB Laminate FR-4 or Steel AISI 1045?
Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Steel AISI 1045 deflects less under the same load.
Which is lighter for the same job, PCB Laminate FR-4 or Steel AISI 1045?
For the same stiffness or strength: 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; Steel AISI 1045 is lighter for a stiff rod or tie (tension).
| Part that must be | PCB Laminate FR-4 | Steel AISI 1045 |
|---|---|---|
| Stiff rod or tie (tension) | 2.17x heavier | lighter |
| Stiff beam (bending) | lighter | 37% heavier |
| Stiff panel or plate | lighter | 1.97x heavier |
| Strong rod or tie | lighter | 2.41x heavier |
| Strong beam | lighter | 2.87x heavier |
| Strong panel or plate | lighter | 3.13x 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 Steel AISI 1045?
Steel AISI 1045 conducts heat better: 42.5 W/m·K against 0.4 W/m·K for PCB Laminate FR-4.
Which expands less with temperature?
Steel AISI 1045 expands less: 12 µm/m·K against 13.5 µm/m·K for PCB Laminate FR-4.