Brown Oxide Treatment (BOT)

Brown oxide treatment is a generic term to describe a chemical process applied to copper lead frame as adhesion promoter. This treatment was originally developed for enhancing adhesion between copper circuity and laminated material in PCB substrate. However, field evaluations reported that the typical process recommended by chemical suppliers did improve adhesion but at the same time deteriorating the wire bonding performance, specifically non-stick-on-lead (NSOL). Our chemical experts were called for a solution and finally developed a modified brown oxide treatment fitting for lead frame application: on one hand improving its adhesion to Encapsulation Molding Compound (EMC); while on the other hand ensuring no deterioration on wire bonding performance. This lead frame BOT uses both mechanical and chemical mechanisms to enhance its adhesion with encapsulation molding compound (EMC), with quantitative measure of Brown Oxide thickness at angstrom scale.