Synthesis of Pd(II) Ink and Surface Treatment of the Polyimide Film for Inkjet Printing

By hydrolyzing PdCl2 with NH4Cl and then by adding a stabilizing agent to it, the Pd(II) catalyst ink with the excellent storage stability, and as a low viscosity and surface tension as water was synthesized. Polyimide (PI) film was used as a substrate for manufacturing a printed circuit by inkjet printing of the Pd(II) catalyst ink, while various characteristic changes of the printing were observed depending on the contact angle on the substrate surface. The contact angle was affected by the concentration of KOH solution and by the duration of surface treatment, and a surface condition suitable for composing Cu circuit was obtained by printing Pd(II) catalyst ink and electroless plating when it was treated in 1–3 M KOH solution for 10 min. The physical properties of the Pd(II) catalyst ink were analyzed using a surface tension meter, viscometer, pH meter and ultraviolet–visible (UV–vis) spectrophotometer, whereas the surface properties of the PI film were analyzed using a contact angle instrument, fourier transform infrared–attenuated total reflectance (FTIR–ATR), video microscope, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The physical properties of Pd(0) particles were analyzed by XPS, FESEM, and AFM, while the characteristics of electroless plating were analyzed by video microscope and XPS.