Adhesion effect of polyimide passivation layer on lead-on-chip die attachment

Adequate die-to-lead frame adhesion is necessary for lead-on-chip (LOC) pac kage integrity during and after the manufacturing process. Inadequate adhes ion may result in a variety of defects such as die adhesion failure, margin al wire bond, broken wire, and bent leads, which ultimately lead to electri cal failure [Mallik, US Patent No. 4,835,120 (May 1989); M. Amagai and E. K awasaki, Mater. Res. Symp. Proc. 338, 185 (1994)]. Adhesion between the LOC tape and the polyimide passivation is affected by the surface properties o f both materials. Understanding the relationships between these properties helps engineers eliminate inadequate adhesion at die attach and continuousl y improve the manufacturing process. To this end, die that exhibit inadequa te adhesion at die attach are analyzed and compared with die that exhibit a dequate adhesion characteristics. To focus on the surface chemistry and phy sical properties of the passivation layer, x-ray photoelectron spectroscopy , Fourier-transform infrared spectroscopy, atomic force microscopy (AFM), a nd surface energy are used. Molecular concentrations and orientations are i nvestigated and related to inadequate adhesion at die attach. (C) 2000 Amer ican Vacuum Society. [S0734-2101(00)12104-9].