Laser cuts increase the reliability of heavy-wire bonds and enable on-line process control using thermography

The active thermal cycling lifetime of heavy wire bonds decreases significantly with increasing wire diameter. This paper presents an innovative method for shaping the wire bond in the bonding region such that the thermo-mechanical load on the interface region between wire bond and semiconductor metallization is significantly reduced. The efficiency of the approach has been validated using finite element simulations and power cycling experiments. Moreover, the method can be used as a 'non-destructive' in-situ measurement technique, in which crack growth can be determined based on thermography measurements of the trenches, which act as magnifiers for the thermography camera and eliminate preconditioning such as using black colouring.