Is there any method to estimate specific heat capacity, latent heat of fusion of a mixture of metals and polymers (e.g. printed circuit board)?
The specific heat capacity will vary with the mass fraction of the component materials.
If you have A kg of substance a, and B kg of substance b, the average heat capacity per unit kg is:
(c_a * A + c_B * B) / (A+B)
The latent heat is less clear - how are you applying the heat?
(the materials will melt or sublimate at different temperatures, and you may well have gradients depending on the heating method)