Materials / Compare
Plastic Polycarbonate vs. Silicon
Compare Plastic Polycarbonate vs. Silicon 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 | 65MPasourcetypical, tensile yield | not given (tensile used) |
| Ultimate tensile strength | 65MPasourcetypical, stress at break | 130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point |
| Flexural strength | 97MPasourcetypical, flexural strength | 130MPasourcemodulus of rupture |
| Elongation at break | 125%sourcetypical, strain at break | not sourced |
| Young's modulus (stiffness) | 2.4GPasourcetypical | 131GPasourcetypical (single quoted value of an anisotropic crystal) |
| Density | 1,200kg/m³sourcetypical1.94x lighter | 2,329kg/m³sourcetypical |
| Strength to weight | 54.2kN·m/kg | 55.8kN·m/kg3% higher |
| Stiffness to weight | 2MN·m/kg | 56.2MN·m/kg28.1x higher |
| Poisson's ratio | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) | 0.221sourcetypical |
| Shear modulus | 0.87GPa | 53.6GPa61.7x stiffer in shear |
| Bulk modulus | 3.33GPa | 78.3GPa |
| Speed of sound | 1,414m/s | 7,500m/s |
| Thermal | ||
| Thermal conductivity | 0.2W/m·Ksourcetypical, through-plane, 23 C | 163W/m·Ksourcetypical at 313 K (40 °C) |
| Thermal expansion | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal | 2.62µm/m·Ksourcetypical at 300 K |
| 100 mm part over a 50 °C swing | 325µm growth | 13.1µm growth24.8x less |
| Specific heat | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 | 732J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.142mm²/s | 95.6mm²/s672x faster |
| Thermal shock resistance | 51.7W/m | 48,095W/m931x more resistant |
| Melting point | not sourced | 1,412°Csourcetypical |
| Glass transition | 144°Csourcetypical, DSC 10 C/min | not sourced |
| Max service temperature | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm | 300°Csourceproducer's maximum application temperature (optical components) |
| Values for | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values | Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic. |
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 Plastic Polycarbonate stronger than Silicon?
Silicon is stronger: its tensile strength is 130 MPa against yield strength 65 MPa for Plastic Polycarbonate (2x).
Which is lighter, Plastic Polycarbonate or Silicon?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 2,329 kg/m³ for Silicon.
Which is stiffer, Plastic Polycarbonate or Silicon?
Silicon is stiffer: Young's modulus 131 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Plastic Polycarbonate or Silicon?
For the same stiffness or strength: Plastic Polycarbonate is lighter for a strong beam, strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie.
| Part that must be | Plastic Polycarbonate | Silicon |
|---|---|---|
| Stiff rod or tie (tension) | 28.1x heavier | lighter |
| Stiff beam (bending) | 3.81x heavier | lighter |
| Stiff panel or plate | 1.95x heavier | lighter |
| Strong rod or tie | 3% heavier | lighter |
| Strong beam | lighter | 22% heavier |
| Strong panel or plate | lighter | 37% 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, Plastic Polycarbonate or Silicon?
Silicon conducts heat better: 163 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.