Patent ID: 6677229
Filing Date: 2004-01-13
Classification: H01L,H05K

Abstract:
A method for producing a solder bump transfer sheet, comprising the steps of:forming on the surface of a stainless steel sheet a chromium oxide layer as an outermost surface wherein the chromium oxide layer contains substantially no iron oxide formed during formation of the bromium oxide layer; and forming a plurality of solder bumps placed in a predetermined pattern on said chromium oxide layer, wherein said stainless steel sheet has a conductive surface, said chromium oxide layer being formed on said conductive surface, and said plurality of solder bumps are formed by electroplating, said chromium oxide layer is formed by a process including a step of thermally oxidizing the conductive surface of said stainless steel sheet, and said step of forming a plurality of solder bumps comprises the steps of: forming a resist layer on said chromium oxide layer, the resist layer having a plurality of openings formed in said predetermined pattern; depositing solder on portions of said chromium oxide layer exposed in said plurality of openings of said resist layer by electroplating; and prior to said step of depositing solder by electroplating, washing the outermost surface of said stainless steel sheet with an acid aqueous solution.