This paper investigates the thermal properties, including the thermal conductivity and linear thermal expansion coefficient, of isotropic conductive adhesives (ICA) containing Cu filler particles. For randomly dispersed filler particles, it was shown that the thermal conductivity of the ICA agrees with that given by Kanari's equation, which is derived from Bruggeman's equation by generalizing the shape parameter of the filler particles. Furthermore, the effect of voids can be taken account into the theoretical analysis of the thermal conductivity by additionally applying Bruggeman's equation or Kanari's equation for a composite structure composed of a void and filler/adhesive matrix approximated as a mean-field. The linear thermal expansion coefficient of the ICA was characterized using a rule of mixture proposed by Schapery. The thermal expansion coefficient of ICA with a low volume fraction of filler particles agrees well with Schapery's upper limit. As the volume fraction of filler particles increases, the linear thermal expansion coefficient tends to approach Schapery's lower limit.