246–385MPasourcethe bare laminate's (fr4-370hr), in-plane: cross direction .. length direction (ASTM D3039)
41.4MPasourcemodulus of rupture (no direct tensile value)
Flexural strength
not sourced
41.4MPasourcestatic bending MOR (Douglas-fir); range 33.72-42.61 across species
Elongation at break
not sourced
not sourced
Young's modulus (stiffness)
21.9–25.8GPasourcethe bare laminate's (fr4-370hr), in-plane: cross direction .. length direction (ASTM D790-15e2); the copper planes are left out
7.45GPasourcestatic bending MOE of the panel (Douglas-fir); range 6.96-8.55 across species
Density
not sourced
not sourced
Strength to weight
not sourced
not sourced
Stiffness to weight
not sourced
not sourced
Poisson's ratio
0.171–0.177sourcethe bare laminate's (fr4-370hr), in-plane: cross direction .. length direction
not sourced
Shear modulus
10.2GPa
not sourced
Bulk modulus
12.2GPa
not sourced
Speed of sound
not sourced
not sourced
Thermal
Thermal conductivity
not sourced
0.12W/m·KsourceAPA-recommended design value (Douglas-fir plywood), as reported by FPL/ORNL
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·Ksourcebase material: solid wood parallel to grain, ovendry, 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·Ksourcebase material: solid wood (all species), 12% MC, 27 C
Heats up and cools (diffusivity)
not sourced
not sourced
Thermal shock resistance
not sourced
not sourced
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.
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 Plywood?
PCB Board FR-4, 2 copper planes is stronger: its tensile strength is 315 MPa against 41.4 MPa for Plywood (7.62x).
Which is stiffer, PCB Board FR-4, 2 copper planes or Plywood?
PCB Board FR-4, 2 copper planes is stiffer: Young's modulus 23.9 GPa against 7.45 GPa for Plywood, so the same part in PCB Board FR-4, 2 copper planes deflects less under the same load.
Which expands less with temperature?
Plywood expands less: 3.8 µm/m·K against 13.5 µm/m·K for PCB Board FR-4, 2 copper planes.