FLIP-CHIP INTERCONNECTION TO VARIOUS SUBSTRATES USING ANISOTROPIC CONDUCTIVE ADHESIVE FILMS

Flip-chip interconnection to various substrates using ACF was investig ated. It was demonstrated that the interconnection resistance of the j oints made between gold bumps of the chip and Ni/Au coated pads on FR- 4 boards was lower than 10 m Ohm depending upon the kinds of conductin g particles, although the interconnection was due to the mechanical co ntact between conducting particles and conductor surfaces. The current -voltage characteristics of the interconnection exhibited an ohmic beh avior up to currents of 2000 mA per bump. In attaching bumpless chips to various substrates, the interconnection resistance strongly depende d on the kinds of conducting particles and substrates. It was demonstr ated that Ni particles were favorable for making good electrical conta cts between Al pads of the bumpless chip and substrate electrodes. It was also demonstrated that low interconnection resistance in the range of 2 m Ohm to 7 m Ohm was obtained as well as with bumped chips, when FR-4 boards with Ni/Au bumped pads were used as substrates for interc onnecting bumpless chips.