PCB Laminate FR-4 vs. Plastic Polycarbonate

Compare PCB Laminate FR-4 vs. Plastic Polycarbonate strength, stiffness, weight and thermal properties.

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Plastic PolycarbonateBulk polymer (molded or machined)

Mechanical
Try it on a partA sample part to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	not given (tensile used)	65MPasourcetypical, tensile yield
Ultimate tensile strength	246–385MPasourcetypical, in-plane: cross direction .. length direction (ASTM D3039)	65MPasourcetypical, stress at break
Flexural strength	531–621MPasourcetypical: cross direction .. length direction (IPC-TM-650 2.4.4B)	97MPasourcetypical, flexural strength
Elongation at break	not sourced	125%sourcetypical, strain at break
Young's modulus (stiffness)	21.9–25.8GPasourcetypical, in-plane: cross direction .. length direction (ASTM D790-15e2)	2.4GPasourcetypical
Density	1,920kg/m³sourcetypical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR	1,200kg/m³sourcetypical
Strength to weight	164kN·m/kg3.03x higher	54.2kN·m/kg
Stiffness to weight	12.4MN·m/kg6.21x higher	2MN·m/kg
Poisson's ratio	0.171–0.177sourcetypical, in-plane: cross direction .. length direction	0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1)
Shear modulus	10.2GPa11.7x stiffer in shear	0.87GPa
Bulk modulus	12.2GPa	3.33GPa
Speed of sound	3,525m/s	1,414m/s
Thermal
Thermal conductivity	0.4W/m·Ksourcetypical (ASTM E1952); direction not stated by the sheet	0.2W/m·Ksourcetypical, through-plane, 23 C
Thermal expansion	13–14µm/m·Ksourcetypical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C)	65µm/m·Ksourcetypical, 23-55 C, parallel and normal
100 mm part over a 50 °C swing	67.5µm growth4.81x less	325µm 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	1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766
Heats up and cools (diffusivity)	0.16mm²/s13% faster	0.142mm²/s
Thermal shock resistance	324W/m6.26x more resistant	51.7W/m
Glass transition	180°Csourcetypical, DSC (IPC-TM-650 2.4.25C)	144°Csourcetypical, DSC 10 C/min
Max service temperature	130°CsourceUL Relative Thermal Index (UL 796)	125°CsourceUL 746B RTI, tensile strength, 1.5 mm
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.	Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values

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 Plastic Polycarbonate?

PCB Laminate FR-4 is stronger: its tensile strength is 315 MPa against yield strength 65 MPa for Plastic Polycarbonate (4.85x).

Which is lighter, PCB Laminate FR-4 or Plastic Polycarbonate?

Plastic Polycarbonate is lighter: 1,200 kg/m³ against 1,920 kg/m³ for PCB Laminate FR-4.

Which is stiffer, PCB Laminate FR-4 or Plastic Polycarbonate?

PCB Laminate FR-4 is stiffer: Young's modulus 23.9 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in PCB Laminate FR-4 deflects less under the same load.

Which is lighter for the same job, PCB Laminate FR-4 or Plastic Polycarbonate?

For the same stiffness or strength: PCB Laminate FR-4 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	PCB Laminate FR-4	Plastic Polycarbonate
Stiff rod or tie (tension)	lighter	6.21x heavier
Stiff beam (bending)	lighter	1.97x heavier
Stiff panel or plate	lighter	34% heavier
Strong rod or tie	lighter	3.03x heavier
Strong beam	lighter	1.79x heavier
Strong panel or plate	lighter	38% 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 Plastic Polycarbonate?

PCB Laminate FR-4 conducts heat better: 0.4 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.

Which expands less with temperature?

PCB Laminate FR-4 expands less: 13.5 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.

Among 72 materials

Stiffness against density

Strength against density