Effect of PI film surface on printing of Pd(II) catalytic ink for electroless copper plating in the printed electronics

Pd(II) catalytic ink was synthesized by the hydrolysis of PdCl2, followed by treatment with a small amount of stabilizing agent. The Pd(II) ink has excellent storage stability and the same low viscosity and surface tension as water. Polyimide film was used as a substrate for inkjet printing of the Pd(II) ink, while various characteristic changes of the printing were observed according to the contact angle on the substrate surface. The contact angle was affected by the concentration of KOH solution, and a surface condition suitable for composing Copper circuit was obtained by printing Pd(II) catalyst ink and electroless plating when it was treated in 1 M KOH solution for 10 min. The physical properties of Pd(II) ink were analyzed using a surface tension meter, viscometer, pH meter and UV–visible spectrophotometer, whereas the surface properties of polyimide film were analyzed using a contact angle instrument, FTIR-ATR, video microscope, XPS, FESEM and AFM. The physical properties of Pd(0) particles were analyzed by XPS and AFM, while the characteristics of electroless copper plating were analyzed by video microscope and XPS.