TREATMENT OF COPPER CIRCUIT ON INNER LAYER CIRCUIT BOARD

摘要

PURPOSE:To improve adhesion between a copper circuit and prepreg resin and prevent the development of a halo phenomenon by removing an oxide coating on the surface of the copper circuit with an alkaline solution after performing oxidation treatment of the copper circuit which is provided on an inner layer circuit board. CONSTITUTION:After electric circuits are formed on the surface and rear of a laminated board which is a glass cloth base material-epoxy resin laminated board clad with copper foils on the both sides of the above board, both faces are made to become slightly rough by a belt sander. Then the solution of alkaline sodium chlorite is prepared at a temperature of 90 deg.C and an inner layer circuit board is immersed in the above solution for 10min. Then its circuit face is made to become rough still more by performing oxidation treatment of the surface of the copper circuit and a cupric oxide film is formed as well. Subsequently, this circuit board is immersed in a 15% of aqueous ammonium for 30min. at a temperature of 30 deg.C to dissolve the cupric oxide film. Then its cupric oxide film is removed and the above board is washed with water and is dried. Thus surface treatment of the copper circuit not only improves adhesion between the copper circuit and prepreg region but also prevents the development of a halo phenomenon.