Influence of debinding and sintering conditions on the composition and thermal conductivity of copper parts printed from highly loaded photocurable formulations
Abstract
Metal 3D printing based on the photopolymerization reaction (Digital Light Processing DLP) of an organic matrix in which metal particles are embedded is a developing technology. This technology requires a step of resin removal and densification by sintering to obtain a metal part. This process has been applied to copper. Photocurable formulations with a high loading rate of copper powder of 60 vol.% were developed and suitable for DLP printing with thicknesses>25 µm. Debinding and sintering cycles were investigated on specimens fast cured by gamma irradiation to save materials and time. A debinding in air at 400 °C and sintering in hydrogen lead to a C content of 0.018 wt.%, similar to the raw copper powder and slightly higher oxygen content. The low thermal conductivity of 250 W·m-1·K-1 highlighted the harmful effect of phosphorus from the powder and photoinitiators such as BAPO. The C and O contents and the thermal conductivity measured on copper parts printed by DLP confirm the results obtained on specimens cured by gamma irradiation.