Thermosonic bonding

[2][3] Owing to the well proven reliability of thermosonic bonds, it is extensively used to connect the central processing units (CPUs), which are encapsulated silicon integrated circuits that serve as the "brains" of today's computers.

As a result of Coucoulas introducing thermosonic bonding lead wires in the early 1960s, its applications and scientific investigations by researchers throughout the world have grown.

[6] These two independent softening mechanisms eliminated the incidence of cracking in the fragile and costly silicon chip which was observed by Coucoulas when using earlier commercially available solid-state bonding machines.

The improvement occurs because pre-heating and ultrasonic softening of the lead-wire dramatically eases deformation as to produce the required contact area using a relatively low set of bonding parameters.

The proven reliability of thermosonic bonding has made it the process of choice, since such potential failure modes could be costly whether they occur during the manufacturing stage or detected later, during an operational field-failure of a chip which had been connected inside a computer or a myriad of other microelectronic devices.

In this case, other bonding methods would degrade or even destroy YBaCuO7 microstructures, such as microbridges, Josephson junctions and superconducting interference devices[8] (DC SQUID).