Wire sweep during molding of integrated circuits

The conditions that lead to wire sweep during transfer molding of plastic packages are examined. The parameters investigated include the material flow properties, the mold cavity/leadframe aspect ratio, the wire modulus, and the wire bond configuration (e.g. diameter, length, and orientation). Flow visualization with a clear silicone fluid and actual molding with an epoxy compound were carried out in order to quantify sweep conditions. A 14-lead bipolar device attached to a recessed copper leadframe and bonded with gold wires was the test vehicle. A functional relationship between the wire sweep behavior and the various processing parameters is presented.<
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