Laser printing of flip-chip interconnects for high frequency applications

We demonstrate flip-chip interconnects using laser-induced forward transfer (LIFT) of Ag nanopaste. To achieve this, Ag nanopaste interconnects were laser printed directly onto the bond pads of an RF switch. The devices were bonded to test fixtures via reflow processing, eliminating the need for thermocompression bonding. High frequency measurements were performed on both a switch with laser printed / reflow cured interconnects and a wire-bonded switch. After bonding, the RF switch with laser printed interconnects performed similar to a wirebonded switch, confirming the bonding process does not degrade high frequency performance. This result implies that laser printing directly onto device bond pads in combination with reflow processing offers a fast and efficient alternative to current flip-chip packaging techniques.