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60 Mechanical Sensor Packaging
Platform
Flatpack
Monolithic
TO
Figure 4.1 Common metal packages.
Figure 4.2 Photo of typical metal, ceramic, and plastic packages.
4.3.1 Electrical Interconnects
4.3.1.1 Wire Bonding [3]
Wire bonding uses thin wire to connect the bond pads on the die to the packaging
interconnects. The attachment of the wire is achieved by using a combination of
heat, pressure, and/or ultrasonic energy. The wire is brought into intimate contact
with the surface of the pad, and the bonding process results in a solid phase weld via
electron sharing or diffusion of atoms. The bonding pressure ensures intimate
contact and aids the breakup of any surface contamination or oxidation, and this is
further enhanced by the application of ultrasonic energy. Heat can be applied to
accelerate atomic diffusion and therefore the bond formation. There are two
wire bonding processes employed: ball and wedge bonding. These processes, and
