In the processing and packaging of semiconductor devices, wire bonding continues to be the primary method of providing electrical interconnection between two locations within a package (e.g., between a die pad of a semiconductor die and a lead of a leadframe). More specifically, using a wire bonder (also known as a wire bonding machine), wire loops are formed between respective locations to be electrically interconnected.
An exemplary conventional wire bonding sequence includes: (1) forming a free air ball on an end of a wire extending from a bonding tool; (2) forming a first bond on a die pad of a semiconductor die using the free air ball; (3) extending a length of wire in a desired shape between the die pad and a lead of a leadframe; (4) stitch bonding the wire to the lead of the leadframe; and (5) severing the wire. In forming the bonds between (a) the ends of the wire loop and (b) the bond site (e.g., a die pad, a lead, etc.), varying types of bonding energy may be used including, for example, ultrasonic energy, thermosonic energy, thermocompressive energy, amongst others.
In conventional wire bonding systems, certain looping parameters are input into the wire bonding machine by an operator (e.g., through a user interface screen or the like), whereby a trajectory of the bonding tool is defined based on these looping parameters. Exemplary looping parameters include the neck height portion after first bond, kink positions to form kinks in the wire, the top of loop position, amongst others. The trajectory is the path followed by the bonding tool when the length of wire is extended between the first bond and the second bond position.
The process of manually inputting the looping parameters into the machine invariably involves a level of guesswork. After a wire loop is formed, the wire loop may be taken offline and examined. For example, manual measurements may be taken of the wire loop to determine if the wire loop meets certain specifications. The operator can then manually alter the parameters to change the resultant wire loop. This process is inherently time consuming and prone to error.
Thus, it would be desirable to provide improved systems and methods of optimizing the trajectory of a wire loop.