Materials / Compare
PCB Laminate FR-4 vs. Steel
Compare PCB Laminate FR-4 vs. Steel 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) | 385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC |
| Ultimate tensile strength | 246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039) | 505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey) |
| Flexural strength | 531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B) | not sourced |
| Elongation at break | not sourced | not sourced |
| Young's modulus (stiffness) | 21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2) | 200GPasourcedesign value (AISC 360-16) |
| Density | 1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR | 7,850kg/m³sourcenominal (constructional data) |
| Strength to weight | 164kN·m/kg3.35x higher | 49kN·m/kg |
| Stiffness to weight | 12.4MN·m/kg | 25.5MN·m/kg2.05x higher |
| Poisson's ratio | 0.171–0.177sourcetypical, in-plane: cross direction .. length direction | 0.3sourcedesign value (AISC 360-16 Commentary) |
| Shear modulus | 10.2GPa | 76.9GPa7.57x stiffer in shear |
| Bulk modulus | 12.2GPa | 167GPa |
| Speed of sound | 3,525m/s | 5,048m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet | 48W/m·Ksourcenominal at 20 °C |
| Thermal expansion | 13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C) | 12µm/m·Ksourcenominal (constructional data, no temperature range stated) |
| 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·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C |
| Heats up and cools (diffusivity) | 0.16mm²/s | 13mm²/s81.2x faster |
| Thermal shock resistance | 324W/m | 5,390W/m16.7x 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. | Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards. |
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?
Steel is stronger: its yield strength is 385 MPa against tensile strength 315 MPa for PCB Laminate FR-4 (22%).
Which is lighter, PCB Laminate FR-4 or Steel?
PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 7,850 kg/m³ for Steel.
Which is stiffer, PCB Laminate FR-4 or Steel?
Steel is stiffer: Young's modulus 200 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Steel deflects less under the same load.
Which is lighter for the same job, PCB Laminate FR-4 or Steel?
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 is lighter for a stiff rod or tie (tension).
| Part that must be | PCB Laminate FR-4 | Steel |
|---|---|---|
| Stiff rod or tie (tension) | 2.05x heavier | lighter |
| Stiff beam (bending) | lighter | 41% heavier |
| Stiff panel or plate | lighter | 2.01x heavier |
| Strong rod or tie | lighter | 3.35x heavier |
| Strong beam | lighter | 3.58x heavier |
| Strong panel or plate | lighter | 3.7x 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?
Steel conducts heat better: 48 W/m·K against 0.4 W/m·K for PCB Laminate FR-4.
Which expands less with temperature?
Steel expands less: 12 µm/m·K against 13.5 µm/m·K for PCB Laminate FR-4.