Die Attach (also known as Die Mount or Die Bond) is the process of attaching the silicon chip to the die pad or die cavity of the support structure (e.g., the leadframe) of the semiconductor package. There are two common die attach processes, i.e., adhesive die attach and eutectic die attach. For high-powered applications, the die is usually eutectic bonded onto the package for good heat conduction. For low-cost, low-powered applications, the die is often glued directly onto a substrate using an epoxy adhesive.
Both of these processes use special die attach equipment and die attach tools to mount the die.
Adhesive die attach uses adhesives such as polyimide, epoxy and silver-filled glass as die attach material to mount the die on the die pad or cavity. The adhesive is first dispensed in controlled amounts on the die pad or cavity. The die for mounting is then ejected from the wafer by one or more ejector needles.
While being ejected, a pick-and-place tool commonly known as a 'collet' then retrieves the die from the wafer tape and positions it on the adhesive. All of the above steps are done by special die attach equipment or 'die bonders.
The mass of epoxy climbing the edges of the die is known as the die attach fillet. Excessive die attach fillet may lead to die attach contamination of the die surface. Too little of it may lead to die lifting or die cracking.
The attach materials and process will be specified by the customers.