Flexible polyimide interposer for CSP preparation

Chip size packaging (CSP) is a promising approach in packaging and interconnect technologies in order to solve the increasing demands in microelectronics and microsystems. The application of bare dies to produce electrical components is considered as the major advantage of this packaging concept. In this study, an interposer consisting of a polyimide film is attached by a pre-deposited adhesive at the active side of the chip. Photolithography for patterning the conductor lines in a semiadditive processing sequence was employed. Bond wire techniques were used to connect the bond pads at the interposer and the die. The detailed description of the technology focuses on the adhesive deposition, the fabrication of the conductor pattern and the attachment of the pre-fabricated assembly to the board by soldering techniques.