Die Bonding

First Level Interconnects

Die bonding, or die attach, is the process of attaching a semiconductor die (chip) to a substrate or package and common techniques include epoxy, eutectic, and silver sintering. Each method has its advantages. Epoxy die bonding, using both conductive and non-conductive epoxies cured at 80°C to 150°C, is a common method, while eutectic die bonding, suitable for high-reliability applications like advanced packaging and power electronics, uses eutectic alloys. Commonly used solder alloys for eutectic die bonding are 100In, SAC305, 80Au20Sn, and 88Au12Ge preforms; these materials are usually vacuum reflow at temperatures up to 450C. Silver Sintering, a process using silver paste, is a reliable alternative to traditional soldering for power modules and RF assembly, offering superior thermal and electrical conductivity, and high-temperature stability.

Epoxy die bonding is a popular die attach method due to its cost-effectiveness and speed, with epoxy being dispensed in various ways like line, dot, or through epoxy stamping processes.

Eutectic die bonding is a common die attach process for power electronics and RF assembly, using specific solder alloys like 100In, SAC305, 80Au20Sn and 88Au12Ge where the die is placed onto the preform and heated to the alloy’s melting point, forming a strong, reliable bond with excellent thermal and electrical conductivity.

Silver sintering die bonding is a pressure-less silver sintering process that offers thermal and electrical conductivity comparable to solder die bonding, while retaining benefits of epoxy bonding and avoiding issues like voiding, flux, and high temperatures associated with soldering.