Eutectic bonding refers to attaching a die to a package or a substrate using a metal alloy as an intermediate layer to form a continuous bond.
A eutectic bond is formed when the metal alloy in the melted state forms atomic contact with the die and the substrate.
The alloy metals diffuse into the surface layers of the die and the substrate to form a continuous bond.
The bonding process is normally assisted by application of mechanical force on the die when the alloy is in the liquid form.
It may also be assisted by a scrubbing motion of the die on the substrate/package.
Eutectic bond is highly suitable for applications which require high thermal conductivity and reliability.
It is specifically crucial for communication devices which require high data rates and low noise signals.
RF amplifiers and power devices are examples which make use of eutectic bonding.
Eutectic bonding offers the following advantage over other die attach processes.
- It offers better thermal conduction compared to the epoxies and other fluid bonding solutions.
- The bonded die is instantly fixed which eliminates any chances of unwanted repositioning.
- Does not require any curing operations which reduces processing requirements.
- Does not produce any gas which could adversely affect the strength of the bond.
The following are the important eutectic bonding parameters.
The mechanical force: It is the force applied on the die head to hold the die during the bonding process.
Initial temperature and the increased temperature: The initial temperature is the temperature just below the eutectic temperature and the increased temperature is the temperature above the eutectic temperature at which the die is bonded.
The bonding time: The time duration of application of mechanical force and the increased temperature during the bonding process.
Inert gas flow: The rate of flow of the hot inert gas affects the rate at which the preform melts and flows.
The advanced packaging facility is equipped with a semi-automatic Tresky 3002 FC1-XP die bonder which is capable of making eutectic bonds. In addition to the pick and place, the die bonder has a heated stage, a temperature control unit, a eutectic gas unit and a scrubbing head. The pick and place is used for placing the die and the eutectic preform on precise locations of a substrate. The heated stage and the temperature control unit can control the temperature to appropriately melt the eutectic preform. The eutectic gas unit allows the eutectic bonding process to take place in an inert gas environment to prevent oxidation of the metal surfaces. The scrubbing head can be used to make void free bonds. The facility also has access to plasma cleaning and a range of cleaning solvents for pre-treatment of the surfaces to be bonded.
Contact us to discuss your applications or requirements. We have a dedicated packaging facility with a range of equipment to provide you comprehensive packaging services.