Direct Ink Printing of Cavities in DPC Ceramic Substrates With Kaolin Pastes for Hermetic Packaging

Fabrication of three-dimensional cavities containing kaolin pastes to be used as direct plated copper (3DPC) substrates ceramics is a very important advancement for electronic packaging of hermetic and ultraviolet light emitting diodes. This work demonstrates usage of pastes consisting of 32–40 wt% of kaolin clay and polyacrylic acid for direct ink printing (DIP) of 3DPC. Rheological and zeta potential tests were performed to determine printability and stability, respectively, of these kaolin pastes. Kaolin content variation had minimum effect on absolute values of the zeta potentials. All pastes had enough stability with the absolute values larger than 30 mV. 40 wt% kaolin solids mass paste was the optimal for DIP due to its excellent shear thinning and viscoelastic properties. Cured 40 wt% kaolin solids mass paste had superior compressive, flexural and bonding strengths. DIP using pastes containing 40 wt% of kaolin is promising for electronic chip integrated hermetic packaging.