Suppression of electro chemical migration generation through forming parylene coating and improving adhesion strength between polyphthalamide substrate used for molded interconnection device and coated film

Abstract

Because of a decrease in the bonding area, the problem in adhesion strength on the joint area is generated. At the same time, misgivings to the breakdown of electronic equipment due to ECM(electro chemical migration) phenomenon has risen along with making more fine pitched wiring on PPA substrate. Infiltration of moisture and existing ion were considered as an accelerating factor of ECM. In this research, the infiltration of moisture and the movement of the metallic ion can be controlled through improving adhesion strength between the PPA substrate and coated resin. Therefore in this paper, the surface treatment of the PPA substrate is conducted for improving adhesion strength with coated resin. For the surface treatment method, the atmospheric pressure plasma processing was employed. These processing can improve adhesion strength through removing an organic contaminant and changing chemical bonding state. In addition, because this processing can be conducted under the atmospheric pressure condition, this method can be built into in-line manufacturing process. The effect of the surface treatments were evaluated by the contact-angle of the surface of polyimide substrate. Then, it was also evaluated by adhesion strength between epoxy resin and PPA substrate. These characteristics were evaluated with passage of time. Moreover, THB test for examining ECM resistance was conducted by using PPA substrate with surface treatments. As a result, adhesion strength was able to be improved, and also expected to improve long life ECM resistance.