Synthesis and characterization of water-soluble polymeric adhesion promoter for epoxy resin/copper joints

Abstract

Nobel polymeric adhesion promoter soluble in water was synthesized to improve the adhesion strength of copper lead frame/epoxy molding compound (EMC) joints. N-(4-phenolyl)-(benzotriazole-5-carboxylic)amide (PBCA) was synthesized by reacting benzotriazole-5-carboxylic acid (CBTA) with 4-aminophenol. Poly[acrylic-co-4(5-benzotriazole)amido phenyl acrylate] (PAB) was synthesized by reacting poly acryloyl chloride with PBCA. The adhesion strength of PAB-treated copper lead frame/epoxy resin joints increased with the increase of PBCA content in PAB by forming more Cu-triazole complex. The adhesion strength of PAB-treated copper lead frame/epoxy resin joints having high PBCA content in PAB (more than 0.3 of mole ratio) is comparable to that of polybenzimidazole (PBI)-treated copper lead frame/epoxy resin joints. However, the adhesion strength of PAB-treated copper/epoxy resin joints decreased with the increase of PAB treatment time since Cu-triazole complex particles were formed on PAB-treated copper surface and acted as defects. The initial adhesion strength was maintained by suppressing the formation of Cu-triazole complex particles using PAB having low PBCA contents (0.003 mole ratio of PBCA). The solubility of PAB in water was dependent on the mole ratio of carboxylic acid to PBCA in PAB. The increase of carboxylic acid content in PAB improved the solubility of PAB in water but decreased the adhesion strength with copper. PAB containing 0.03 mole ratio of PBCA was soluble in water. (C) 2002 Wiley Periodicals, Inc.