Toward a Random Operation of Networks
Wire bonding is eliminated in the assembly of microelectronic devices, by a process involving the direct bonding of circuit electrodes to an unsupported metallic sheet-frame member having a plurality of inwardly extending leads. A single-step vibratory pressure welding technique is employed for the simultaneous bonding of all leads to a semiconductor integrated circuit chip. Lateral confinement of the leads during the bonding steps causes a buckling action to introduce a small but critical loop in each lead to ensure clearance between the lead fingers and the perimeter of the semiconductor chip, whereby electrical shorting is avoided. The loop also provides a structural flexibility in the leads, which tends to protect the bonding sites from excessive stresses. Subsequently, the first frame member including the bonded circuit is attached, preferably by resistance welding, to a second lead frame member of heavier gage and increased dimensions, suitable for connection with external circuitry. Excess portions of the first frame member are then removed, providing a completed assembly for packaging; e.g., plastic encapsulation or hermetic sealing, as in a ceramic-glass flat package.