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Wire bonding is a method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Wire bonding can also be used to connect an IC to other electronics or to connect from one printed circuit board (PCB) to another, although these are less common. Wire ...
This process is known as the Kirkendall voiding, which leads to both increased electrical resistance and mechanical weakening of the wire bond. When the voids forms along the diffusion front, this process is aided by contaminants present in the lattice, and is known as the Horsting voiding, which is a similar process to the Kirkendall voiding.
Gold or copper wire can be used, though gold is more common because its oxide is not as problematic in making a weld. If copper wire is used, nitrogen must be used as a cover gas to prevent the copper oxides from forming during the wire bonding process. Copper is also harder than gold, which makes damage to the surface of the chip more likely.
The chip is then wire bonded and protected from mechanical damage and contamination by an epoxy "glob-top". Chip-on-flex (COF), a variation of COB, where a chip is mounted directly to a flex circuit. Tape-automated bonding process is also a chip-on-flex process as well.
If wire connections is the method of choice to form these connections, thermosonic bonding gold wires directly to the silicon chip has been the process most widely used because of its proven reliability as a result of the low bonding parameters of force, temperature, and time needed to form the bond.
The die is glued or soldered to the die pad inside the lead frame, and then bond wires are attached between the die and the bond pads to connect the die to the leads in a process called wire bonding. In a process called encapsulation, a plastic case is moulded around the lead frame and die, exposing only the leads.
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]
The following operations are performed at the packaging stage, as broken down into bonding, encapsulation, and wafer bonding steps. Note that this list is not all-inclusive and not all of these operations are performed for every package, as the process is highly dependent on the package type. IC bonding. Wire bonding; Thermosonic Bonding; Down ...