Enhancing adhesion strength of photonic sintered screen-printed Ag circuit by atmospheric pressure plasma

Intense pulsed light sintering of printed metallic circuits on polymer substrates is an attractive technique. However it still does not yield the mechanical quality required for industrial applications. This technology must improve adhesion and flexibility to produce highly reliable flexible electronic devices. The effects of atmospheric pressure oxygen plasma and acrylic acid polymerization treatments upon the adhesion and flexibility properties were investigated. Modified polyimide surfaces were characterized by surface free energy measurements, and adhesion and flexibility properties were evaluated by means of roll-type 90 degrees peel tests and IPC sliding tests. The strength of adhesion with oxygen-treated and acrylic acid polymerized samples increased about 17- and 20-fold compared with that of untreated samples, and the flexibility was improved by about 2 fold, respectively. The evident improvements in surface free energy, adhesion and flexibility were attributed to the creation of oxygen functional groups on the polyimide surface after atmospheric pressure plasma treatment.