Aluminum 7050-T7451 vs. PCB Laminate FR-4

Compare Aluminum 7050-T7451 vs. PCB Laminate FR-4 strength, stiffness, weight and thermal properties.

Mechanical	Aluminum 7050-T7451	PCB Laminate FR-4
Yield strength	469MPa1	not given (tensile used)
Ultimate tensile strength	524MPa1	246–385MPa2
Flexural strength	not sourced	531–621MPa2
Elongation at break	11%1	not sourced
Young's modulus (stiffness)	70.3GPa1	21.9–25.8GPa2
Density	2,830kg/m³1	1,920kg/m³347% lighter
Strength to weight	166kN·m/kg	164kN·m/kg
Stiffness to weight	24.8MN·m/kg2x higher	12.4MN·m/kg
Poisson's ratio	0.334	0.171–0.1772
Shear modulus	26.4GPa2.6x stiffer in shear	10.2GPa
Bulk modulus	68.9GPa5.65x higher	12.2GPa
Speed of sound	4,984m/s41% faster	3,525m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Aluminum 7050-T7451	PCB Laminate FR-4
Thermal conductivity	157W/m·K1393x more heat through a fin	0.4W/m·K2
Thermal expansion	23.5µm/m·K1	13–14µm/m·K2
100 mm part over a 50 °C swing	118µm growth	67.5µm growth1.74x less
Specific heat	860J/kg·K1	1,200–1,400J/kg·K3
Heats up and cools (diffusivity)	64.5mm²/s403x faster	0.16mm²/s
Thermal shock resistance	29,862W/m92.3x more resistant	324W/m
Melting point	melting range524–635°C1	not sourced
Glass transition	not sourced	180°C2
Max service temperature	not sourced	130°C2

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

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Sources4 documents: Kaiser Aluminum, Isola, Park Electrochemical (Nelco), U.S. Department of Defense

Aluminum 7050-T7451: 7050-T7451 plate, Kaiser Aluminum sheet, coil & plate typical datasheet (longitudinal); Poisson from MIL-HDBK-5J
PCB Laminate FR-4: 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.

1
Alloy 7050 Sheet, Coil & Plate Technical DataKaiser Aluminumarchived copyAluminum 7050-T7451 · Yield strength: typical, longitudinal, 0.2% offsetAluminum 7050-T7451 · Ultimate tensile strength: typical, longitudinalAluminum 7050-T7451 · Elongation at break: typical, longitudinalAluminum 7050-T7451 · Young's modulus (stiffness): typicalAluminum 7050-T7451 · Density: nominalAluminum 7050-T7451 · Thermal conductivity: typical, 20 °CAluminum 7050-T7451 · Thermal expansion: typical, mean 20-100 °CAluminum 7050-T7451 · Specific heat: typical, at 100 °CAluminum 7050-T7451 · Melting point: melting range
2
370HR Laminate and Prepreg Data SheetIsolaarchived copyPCB Laminate FR-4 · Ultimate tensile strength: typical, in-plane: cross direction .. length direction (ASTM D3039)PCB Laminate FR-4 · Flexural strength: typical: cross direction .. length direction (IPC-TM-650 2.4.4B)PCB Laminate FR-4 · Young's modulus (stiffness): typical, in-plane: cross direction .. length direction (ASTM D790-15e2)PCB Laminate FR-4 · Poisson's ratio: typical, in-plane: cross direction .. length directionPCB Laminate FR-4 · Thermal conductivity: typical (ASTM E1952); direction not stated by the sheetPCB Laminate FR-4 · Thermal expansion: typical, in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C)PCB Laminate FR-4 · Glass transition: typical, DSC (IPC-TM-650 2.4.25C)PCB Laminate FR-4 · Max service temperature: UL Relative Thermal Index (UL 796)
3
N4000-6 Laminate Data Sheet (2006)Park Electrochemical (Nelco)archived copyPCB Laminate FR-4 · Density: typical, 50% resin content; another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HRPCB Laminate FR-4 · Specific heat: typical (ASTM E1461); another FR-4 producer: Park Nelco N4000-6 (high-Tg multifunctional epoxy), not Isola 370HR
4
MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseAluminum 7050-T7451 · Poisson's ratio: typical (handbook physical constant)

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Is Aluminum 7050-T7451 stronger than PCB Laminate FR-4?

Aluminum 7050-T7451 is stronger: its yield strength is 469 MPa against tensile strength 315 MPa for PCB Laminate FR-4 (49%).

Which is lighter, Aluminum 7050-T7451 or PCB Laminate FR-4?

PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 2,830 kg/m³ for Aluminum 7050-T7451.

Which is stiffer, Aluminum 7050-T7451 or PCB Laminate FR-4?

Aluminum 7050-T7451 is stiffer: Young's modulus 70.3 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Aluminum 7050-T7451 deflects less under the same load.

Which is lighter for the same job, Aluminum 7050-T7451 or PCB Laminate FR-4?

For the same stiffness or strength: Aluminum 7050-T7451 is lighter for a stiff rod or tie (tension), stiff beam (bending); PCB Laminate FR-4 is lighter for a stiff panel or plate, strong beam, strong panel or plate.

Part that must be	Aluminum 7050-T7451	PCB Laminate FR-4
Stiff rod or tie (tension)	lighter	2x heavier
Stiff beam (bending)	lighter	16% heavier
Stiff panel or plate	3% heavier	lighter
Strong rod or tie	about equal	about equal
Strong beam	13% heavier	lighter
Strong panel or plate	21% heavier	lighter

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).

Thermal

Which conducts heat better, Aluminum 7050-T7451 or PCB Laminate FR-4?

Aluminum 7050-T7451 conducts heat better: 157 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 23.5 µm/m·K for Aluminum 7050-T7451.