Surface Modification of PTFE Using Low Energy Nitrogen Ion Irradiation:—Improvement in Adhesive Strength on Modification of Deep Modifying Layer—

Polytetrafluoroethylene PTFE has the best properties as a material of high-frequency PC board. However, it has low adhesion force for using cabling material. In order to improve adhesion force, we studied on surface modification of PTFE by using nitrogen ion irradiation. As a result, peel strengths of PTFE improved up to 900 N/m to amount of treatment time. On the other hand, surface energy did not increase. From here onward, improved peel strengths on modified surface could be forecasted because of a change that is binding state of modified layer. The compositions of surface on samples after peel test were analyzed so as to prove the hypothesis. As a result, adhesive/PTFE system occurred to destruction in deep portion of modified layer. Moreover, binding of oxygen could be existed with long treatment time. Therefore, it was suggested that the brittle layer of deep modifying layer needs to be modified for the improvement of adhesive strength.