The effect of PVAc in silver ink for adhesion and conductivity of conductive pattern

The adhesion with substrate and conductivity of silver (Ag) conductive pattern are critical for practical applications of flexible electronic devices. Polymer vinyl acetate (PVAc) as an important solvent in Ag ink might largely improve the conductive pattern's adhesion property. However, the addition of PVAc in Ag ink also result in decreasing the patterns conductivity to about 210 ± 2 μΩ cm after infrared sintering at air atmosphere. Here, we found a facial method to eliminate the effect of the addition of PVAc for Ag conductive pattern. In this method, the thickness of PVAc layer coated on Ag particles surface was decreased via a washing treatment by ethanol mixed with acetone. After post-sintering treatment of ethanol brushing, a stable and conductive pattern was achieved. Owing to these treatments, compared with the blank sample, the adhesion of patterns was improved by the scratch test with higher damage force from 1 to 3.8 N. Meanwhile, the resistivity of the formed Ag pattern gradually decreased to 22 ± 0.5 μΩ cm after post-sintering treatment for 50 times, and this value did not change after bending 6000 times. The mechanism was given and confirmed by energy dispersive spectroscopy (EDS) analysis, indicating that the residual organic coatings on patterns had been taken away by the evaporation of alcohol molecular. LEDs pasted in the electronic circuit of our university badge were illuminated, indicating their wide application in the field of flexible electronic devices.