The bonding tool, often referred to simply as a bonding tool, is used in ultrasonic wire bonding to transmit the vibrational motion to the wire. The tip of bonding tools is usually designed so that the wire is guided laterally. By applying a normal force, the wire is first pressed into the groove of the bonding tool and, during bonding, the vibrational motion is then transferred to the wire via frictional contact. In the process, the wire initially rubs against the substrate and, once bonded, some slippage occurs between the bonding tool and the wire. The applied normal force, the tangential force of the bonding tool (which can be transmitted depending on the geometry) and the ultrasonic motion have a significant influence on wire deformation and the formation of the bond.

Finite element simulations demonstrate the influence of the bonding tool’s geometry on the wire’s geometry. In addition to the opening angle, the groove width and depth have a direct influence on the resulting geometry of the wire. This gives rise to various approaches for optimisation. The force transmission between the bonding tool and the wire, and the contact area between the wire and the substrate, can be varied. This offers the potential to increase the efficiency of the bonding process for robust substrates or to reduce the stresses during bonding in order to protect sensitive substrates.