0.18W/m·Ksourceacross grain, 12% MC (Table 4-7, approximate)
Thermal expansion
13–14µm/m·Ksourcethe bare laminate's (fr4-370hr), in-plane X/Y-axis, below Tg (IPC-TM-650 2.4.24C)
3.1–4.5µm/m·Ksourceparallel to grain, ovendry wood, range across species
100 mm part over a 50 °C swing
67.5µm growth
19µm growth3.55x less
Specific heat
not sourced
1,700J/kg·Ksourcesolid wood (all species), 12% MC, 27 C
Heats up and cools (diffusivity)
not sourced
not sourced
Thermal shock resistance
not sourced
244W/m
Values for
A whole circuit board read as one orthotropic plate: the JEDEC high-K thermal test board (JESD51-7, "2s2p"), 0.062 in (1.575 mm) thick with two internal solid copper planes 0.0014 in (1 oz) thick, as Texas Instruments SZZA017A Table 1 gives it. Copper C110 and the Isola 370HR laminate from this library; the layers conduct in parallel along the board and in series through it (boardStackup.ts). Its two 0.0028 in trace layers cover little of the board and are left out; vias are ignored. Mechanical values are the bare laminate's.
Northern red oak (Quercus rubra), clear straight-grained specimens at 12% MC, parallel to grain unless stated; USDA FPL Wood Handbook FPL-GTR-282 (2021) Ch. 4 and Ch. 5
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 Board FR-4, 2 copper planes stronger than Wood?
PCB Board FR-4, 2 copper planes is stronger: its tensile strength is 315 MPa against 99 MPa for Wood (3.19x).
Which is stiffer, PCB Board FR-4, 2 copper planes or Wood?
PCB Board FR-4, 2 copper planes is stiffer: Young's modulus 23.9 GPa against 12.5 GPa for Wood, so the same part in PCB Board FR-4, 2 copper planes deflects less under the same load.
Which expands less with temperature?
Wood expands less: 3.8 µm/m·K against 13.5 µm/m·K for PCB Board FR-4, 2 copper planes.