Adhesion Test for Dry Film Photoresist on Copper by the Peeling Method

Abstract

This study describes a peel test to quantitatively measure the adhesion of dry film photoresist on copper. Using this peeling method, the adhesion effects of: (a) the copper surface treatments, (b) the UV radiation of a laminated resist, and (c) the baking of a resist laminated coupon were measured. Adhesive tape with rectangular or wedge‐shaped openings was placed between the photoresist and copper surfaces with the adhesive side facing the resist. The openings in the tape allowed for contact between the copper surface and the resist, and the opening dimensions determined the width and length of contact. With the aid of the adhesive tape, a better grip of the resist was obtained during the peeling. The results of this study led to the following conclusions: A tin‐silane (SNS) treated copper surface with a peeling strength of 4–7 lbs/in. was the most effective surface treatment. A UV radiation dose below or equal to 32 mJ/cm2 produces an adhesion of the resist with micro‐etched copper of 38±03 lbs/in; above this dose, adhesion increases. Thermal baking improves adhesion; the calculated activation energy of a micro‐etched copper surface with the resist is 65 kcal/mole.