Thermal conductivity of sintered copper samples prepared using 3D printing-compatible polymer composite filaments

Metal-filled polymers containing micro-powders of highly conductive metals can serve as a starting material to fabricate complex metal structures using economic filament extrusion-based 3D printing and molding methods. We report our measurements of the thermal conductivity of copper samples prepared using these methods before and after a thermal treatment process. Sintering the samples at 980 degrees C leads to an order of magnitude improvement in thermal conductivity when compared with as-printed or as-molded samples. Thermal conductivity values of approximately 30 W/mK are achieved using commercially available polymer-copper composite filaments with a copper volume fraction of 0.4. Over-sintering the samples at 1080 degrees C further enhances the thermal conductivity by more than two folds, but it leads to uncontrolled shrinkage of the samples. The measured thermal conductivities show a modest decrease with increasing temperatures due to increased electron-phonon scattering rates. The experimental data agree well with the thermal conductivity models previously reported for sintered porous metal samples. The measured electrical conductivity, Young's modulus and yield strength of the present sintered samples are also reported.