Direct ink writing of 3D cavities for direct plated copper ceramic substrates with kaolin suspensions

The development of three-dimensional kaolin-based materials cavities for direct plated copper (3DPC) ceramic substrates has great promising in hermetic and ultraviolet light emitting diodes electronic packaging field. In this study, suspensions with kaolin clay solids content of 24-32 vol% and polyacrylic acid were used for direct ink writing (DIW) technique to fabricate 3DPC. Experiments results showed that the stability and extrudability of kaolin suspensions related to their zeta potential and rheological properties, respectively. The zeta potential absolute values had little variation with the increase of kaolin solids content and characterized that kaolin particles were dispersed adequately in colloidal suspensions. Rheological and thixotropic tests showed that the 32 vol% kaolin solids content suspension with good fluidity and viscoelastic properties was suitable for DIW. The 3DPC prepared using this suspension can maintain basically primal appearance with little slumping. Mechanical properties such as compression, flexural and bonding strengths of the cured 32 vol% kaolin solids content suspension were also conducted. Processing kaolin suspensions via DIW presents opportunity for integrated packaging of electronics chips.