Thermal conductivity against densityHigher and further left: spreads more heat for its weightThermal 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 6061-T6
6061-T6/T651, Kaiser Aluminum typical properties; 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 6061 Sheet, Coil & Plate Technical DataKaiser Aluminumarchived copyAluminum 6061-T6 · Yield strength: typical, 0.2% offset, .500 in dia specimenAluminum 6061-T6 · Ultimate tensile strength: typicalAluminum 6061-T6 · Elongation at break: typical, in 4D, 0.500 in dia specimenAluminum 6061-T6 · Young's modulus (stiffness): typicalAluminum 6061-T6 · Density: nominalAluminum 6061-T6 · Thermal conductivity: typical, 20 °CAluminum 6061-T6 · Thermal expansion: typical, mean 20-100 °CAluminum 6061-T6 · Specific heat: typical, at 100 °CAluminum 6061-T6 · Melting point: solidus-liquidus
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 6061-T6 · 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 6061-T6 stronger than PCB Laminate FR-4?
PCB Laminate FR-4 is stronger: its tensile strength is 315 MPa against yield strength 276 MPa for Aluminum 6061-T6 (14%).
Which is lighter, Aluminum 6061-T6 or PCB Laminate FR-4?
PCB Laminate FR-4 is lighter: 1,920 kg/m³ against 2,700 kg/m³ for Aluminum 6061-T6.
Which is stiffer, Aluminum 6061-T6 or PCB Laminate FR-4?
Aluminum 6061-T6 is stiffer: Young's modulus 68.3 GPa against 23.9 GPa for PCB Laminate FR-4, so the same part in Aluminum 6061-T6 deflects less under the same load.
Which is lighter for the same job, Aluminum 6061-T6 or PCB Laminate FR-4?
For the same stiffness or strength: Aluminum 6061-T6 is lighter for a stiff rod or tie (tension), stiff beam (bending); PCB Laminate FR-4 is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Aluminum 6061-T6
PCB Laminate FR-4
Stiff rod or tie (tension)
lighter
2.04x heavier
Stiff beam (bending)
lighter
20% heavier
Stiff panel or plate
about equal
about equal
Strong rod or tie
1.61x heavier
lighter
Strong beam
1.54x heavier
lighter
Strong panel or plate
1.5x 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 6061-T6 or PCB Laminate FR-4?
Aluminum 6061-T6 conducts heat better: 167 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 23.6 µm/m·K for Aluminum 6061-T6.