Pick-and-Place Silver Sintering Die Attach of Small-Area Chips

A method for high-temperature-stable die attaches based on sintering of micro and nano silver particles is described. A low-temperature (200°C) and low-pressure (3 N/mm²) process was established to ensure compatibility with conventional adhesive die attach and to avoid surface damage on the dice, respectively. A modified flip-chip bonder providing high placement accuracy (2 μm) is used for a precise pick-and-place die attach. A thermal finite element modeling simulation was performed to analyze the bonding process. Additionally, the influence of the surface properties on the adhesion of sintered silver layers was investigated. The area-selective sintering method allows combination with other standard processes for die attach. It is now possible to establish pressure-assisted silver sintering for the series production of hybrid electronic circuits, which is an option requested by the industry to expand the operation range of sensors and electronics in harsh environments (e.g., measurement while drilling).