LaVern Mullet asked for the Thermal Conductivity of FR-4.
I'd like to reinforce Frank Hinojos' point that be careful to include the contribution of
copper to total thermal conductivity. Manno and Kurita provide the following numbers
for copper clad laminates:
Board Cu Thickness Effective x-y conductivity
Plain epoxy 0.0 meters 0.26 Watt/moC
1 oz Double clad 0.000035 meters 1.14 Watt/moC
2 oz Double clad 0.000070 meters 35.9 Watt/moC
Note what a nonlinear effect the copper has! I've often wondered if post-lamination
warpage is more noticeable than warpage at other processing steps because of a lack of
copper vertically through the PWB structure, allowing higher thermal gradients to exist
through the PWB than are possible once there are high conduction paths (PTHs &
PTVs).
Anyway, some other figures for good measure:
Barker uses 0.157 W/moC for FR-4 and 398 W/moC for copper. These figures are
widely used.
Prakash and Knadle suggest 0.342-0.366 Watt/moC for Epoxy resin and laminate.
Their value for copper is 401.6
Hope it helps,
Cheers,
Andy
Refs:
Barker, D., Pecht, M., Dasgupta, A., Naqvi, "Transient Thermal Stress Analysis of a
Plated Through Hole Subjected to Wave Soldering," Journal of Electronic Packaging,
Vol. 113, No. 2, 1991, pp.149-155.
Prakash, V. and Knadle, K., "Analysis of Transient Thermal Strains in a Plated Through
Hole Using Current Induced Heating and Transient Moire Interferometry", EEP-Vol.
13/AMD-Vol.214, Applications of Experimental Mechanics to Electronic Packaging,
ASME 1995, pp.53-60.
Manno, Vincent P. , Kurita, Nadine R., and Azar, Kaveh, "Experimental Characterization
of Board Conduction Effects", Ninth IEEE SEMI-THERM Symposium, Austin, TX 2-4
Feb. 1993. pp. 127- 135.
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