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There are various wire bonding techniques (thermosonic bonding, ultrasonic bonding, thermocompression bonding) and types of wire bonds (ball bonding, wedge bonding) that affect susceptibility to manufacturing defects and reliability issues. Certain materials and wire diameters are more practical for fine pitch or complex layouts.
In beam-lead technology, the metallized pads that would be used for wire bonding connections in a conventional chip are thickened and extended to allow external connections to the circuit. Assemblies using "bare" chips have additional packaging or filling with epoxy to protect the devices from moisture.
Components such as thin fine-pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead-frame, wire bond damage, die damage, and internal cracks. Most of this ...
Tape-automated bonding (TAB) is a process that places bare semiconductor chips (dies) like integrated circuits onto a flexible circuit board (FPC) by attaching them to fine conductors in a polyamide or polyimide (like trade names Kapton or UPILEX) film carrier. This FPC with the die(s) (TAB inner lead bonding, ILB) can be mounted on the system ...
The advantage of wedge bonding is a finer pitch is possible. Wedge bonding also accommodates the use of metal ribbon instead of wire for bonding. Thermocompression Bonding (TCB): The technique uses heat and pressure to create a bond between a thin wire (typically aluminum or gold) and the bonding pads. As heat softens the wire, pressure is ...
In "wire bonding", the chip is attached to the board with an adhesive. Each pad on the device is connected with a fine wire lead that is welded to the pad and to the circuit board. This is similar to the way that an integrated circuit is connected to its lead frame, but instead the chip is wire-bonded directly to the circuit board. [3]
During the compliant bonding cycle the bond pressure is uniquely controlled by the inherent flow properties of the aluminum compliant tape (Figure 3). Therefore, if higher bond pressures are needed to increase the final deformation (flatness) of a compliant bonded gold wire, a higher yielding alloy of aluminum could be employed.
The resulting weld is quite different in appearance from the ball bond, and is referred to as the wedge bond, tail bond, or simply as the second bond. In the final step the machine pays out a small length of wire and tears the wire from the surface using a set of clamps. This leaves a small tail of wire hanging from the end of the capillary ...