Materials / Compare
PCB Laminate FR-4 vs. Stainless Steel 304
Compare PCB Laminate FR-4 vs. Stainless Steel 304 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) | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | 246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039) | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Flexural strength | 531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B) | not sourced |
| Elongation at break | not sourced | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2) | 193GPasourcetypical, in tension |
| Density | 1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR | 8,030kg/m³sourcetypical |
| Strength to weight | 164kN·m/kg5.47x higher | 30kN·m/kg |
| Stiffness to weight | 12.4MN·m/kg | 24MN·m/kg1.93x higher |
| Poisson's ratio | 0.171–0.177sourcetypical, in-plane: cross direction .. length direction | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 10.2GPa | 74.2GPa7.3x stiffer in shear |
| Bulk modulus | 12.2GPa | 161GPa |
| Speed of sound | 3,525m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C) | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 67.5µm growth25% less | 84.5µm 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 | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | 0.16mm²/s | 4.03mm²/s25.2x faster |
| Thermal shock resistance | 324W/m | 838W/m2.59x more resistant |
| Melting point | not sourced | 1,399–1,454°Csourcemelting range |
| Glass transition | 180°Csourcetypical, DSC (IPC-TM-650 2.4.25C) | not sourced |
| Max service temperature | 130°CsourceUL Relative Thermal Index (UL 796) | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| 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. | Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 Stainless Steel 304?
PCB Laminate FR-4 is stronger: its tensile strength is 315 MPa against yield strength 241 MPa for Stainless Steel 304 (31%).
Which is lighter, PCB Laminate FR-4 or Stainless Steel 304?
PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 8,030 kg/m³ for Stainless Steel 304.
Which is stiffer, PCB Laminate FR-4 or Stainless Steel 304?
Stainless Steel 304 is stiffer: Young's modulus 193 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Stainless Steel 304 deflects less under the same load.
Which is lighter for the same job, PCB Laminate FR-4 or Stainless Steel 304?
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; Stainless Steel 304 is lighter for a stiff rod or tie (tension).
| Part that must be | PCB Laminate FR-4 | Stainless Steel 304 |
|---|---|---|
| Stiff rod or tie (tension) | 1.93x heavier | lighter |
| Stiff beam (bending) | lighter | 47% heavier |
| Stiff panel or plate | lighter | 2.08x heavier |
| Strong rod or tie | lighter | 5.47x heavier |
| Strong beam | lighter | 5x heavier |
| Strong panel or plate | lighter | 4.78x 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 Stainless Steel 304?
Stainless Steel 304 conducts heat better: 16.2 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 16.9 µm/m·K for Stainless Steel 304.