Surface treatment of tape substrates using atmospheric pressure low temperature plasma

Abstract

Surface treatment of tape substrates such as TCP (tape carrier package), COF (chip on flex) using atmospheric pressure low temperature plasma has been reported. Reliability issues of tape substrates, one of constituents of display devices, are getting more attention as device size get smaller and functions more complex. Resin pottability and ink printability of the tape substrates are improved by surface modification using ejection type plasma and the surfaces are analyzed by XPS and FE-SEM. XPS analysis showed that surfaces covered with hydrophobic material, PDMS(polydimethylsiloxane), were modified to hydrophilic by atmospheric pressure low temperature plasma treatment. Plasma treatment system is designed to activate the surfaces of TCP and COF for further processing. In contrast to conventional wet methods, higher wettability of the surfaces provides higher adhesion strength of potting resin and marking ink thus enhanced reliability and quality of the treated substrates. Moreover it produces no damage and discoloration to the substrates. Shelf life of 2 months gives more flexibility in operating the equipment and also arranging the production schedule. The plasma treatment system works under atmospheric conditions and well qualified reel-to-reel process speed up to 6 m/min results in higher production capability. It produces no harmful liquid wastes and is environment-friendly.