A lamination technique of LCP/Cu for electronic packaging

Liquid crystalline polymer (LCP) is expected to be used for the lamination of electronic circuit boards because of its excellent mechanical and electric properties, such as a low dielectric constant and dimensional stability. However, it has not been widely used yet due to the weak interaction between LCP and Cu. Roughened surfaces of Cu foil that could deteriorate the electrical property are being used in conventional lamination process in order to improve the bonding strength. Surface activated bonding (SAB) of Cu/LCP based on a surface cleaning process by physical bombardment in vacuum has been performed to achieve the strong bonding. A peel strength of 800/spl sim/900 g/cm of the laminate prepared by SAB process is achieved, and the surface roughness of the interface between LCP and Cu is controlled to be less than 100 nm. In this experiment, additional treatment including Cu deposition on LCP and annealing after bonding is applied in order to obtain strong bonding. The effects of these treatments are investigated with the discussion of bonding mechanism.