A Study of Plasma-Cleaned Ag-Plated Cu Leadframe Surfaces

摘要

In this study, an Ar plasma was employed to remove the antitarnish layer on Ag-plated Cu leadframe surfaces using various process powers and times. Measurements of the contact angle, field-emission scanning electron microscopy, x-ray photoelectron spectroscopy, and time-of-flight secondary-ion mass spectrometry were employed to characterize both the Ag and Cu surfaces before and after plasma cleaning. The antitarnish layer on the leadframe surfaces was determined to be benzotriazole and/or its derivatives. Low-power and short-duration plasma treatments did not significantly change the Ag and Cu surfaces in terms of their surface morphologies, and such treatments were not able to totally remove the antitarnish layer. In contrast, a high-power and long-duration plasma treatment made the surfaces slightly smoother and was able to remove the antitarnish layer on both Ag and Cu surfaces. However, cross-contaminations were also detected between the Ag and Cu surfaces during the plasma cleaning process. This cross-contamination is due to redeposition of Ag and Cu atoms during the plasma treatment.