Die attach or die bonding is the process of attaching a semiconductor die to a package, a substrate such as a PCB board or another die. The die attach process is fundamental to multiple types of packaging.
CMOS overlay with the MZM
Stack of solid state batteries
The four common types of die attach processes offer differing bond properties and use either distinct workflow procedures or different materials.
Adhesive die attach makes use of adhesives such as epoxy and polyimide to form a bond between a die and a package/substrate/another die.
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.
Die is attached using a solder/solder paste.
Flip chip is a die attach method where the electrical connections between the chip and package/substrate are made directly by inverting the die face-down onto the substrate/package.
Die bonding processes are application specific where the operating conditions, environment and reliability requirements for the electronic device are considered. Forming a bond/joint between the die and the package, substrate or another die and its precise placement is a multifunctional process which aims to achieve the following:
A bonding material such as adhesive, eutectic preform or solder paste is deposited on a specific area of the substrate/package. The bonding material may be dispensed or dip coated on a substrate/package. In case of flip chip, gold balls/bumps are deposited first on the die.
At the Advanced Packaging Facility, we have used all the die attach processes. The facility contains a Tresky 3002 FC1-XP semi-automatic die bonder which has an integrated precise pick and place function. It has a heated work stage for eutectic bonding, an integrated dip coating needle and epoxy dispenser for adhesive and solder die attach options. The die bonder allows picking a die from a pre-sawn wafer using an additional die ejection vacuum tool to separates the bare die from the wafer backing tape. We also have a high precision Finetech FINEPLACER lambda flip-chip bonding machine which has a placement accuracy of up to 0.5 µm.