PCB Surface Finishes & the Cleaning Process – A Compatibility StudyAuthors: Umut Tosun, M.S.Ch.E., Naveen Ravindran, M.S.Ch.E.
Company: ZESTRON Americas
Date Published: 9/17/2017 Conference: SMTA International
This study was designed to investigate the effect of reflow and various cleaning agent types on ImSn, ImAg and ENIG surface finishes. Unpopulated test vehicles, with the appropriate surface finish, were used for all trials. In a previous study by the authors, the OSP surface finish was analyzed for integrity within an aqueous-based cleaning system and was therefore excluded from this study. An inline spray-in-air cleaning process was chosen to assess the surface finish integrity. Three (3) aqueous cleaning agent types were selected for use within this study. Two (2) alkaline cleaning agents, inhibited and uninhibited, as well as a pH neutral cleaning agent, were used. Cleaning system process variables were established and held constant for all trials.
Surface finish assessment following reflow and cleaning was conducted using visual inspection, adhesion test, copper test (ImAg and ImSn), nickel test (ENIG), and the X-Ray Fluorescence (XRF) test. Additionally, baseline tests were conducted on boards with all finish types without exposure to reflow or the cleaning process in order to assess the effect of the reflow process.
PCB surface finish, cleaning process, Surface test analysis, copper test, nickel test, adhesion test, XRF test
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