US Patent 7909228 Ribbon bonding tool and process

An ultrasonic bond is formed using a bond tool foot having a waffle shape of thin protrusions and gaps between the protrusions. The tool is brought in contact with the ribbon to a depth to create depressions in a ribbon approximately 150 μm or less from the underlying bonding surface. The tool is then brought down further into the ribbon to contact the portions of the ribbon between the depressions, such as an additional 25 to 50 μm. The result is lightly bonded regions underneath the groove portions and highly bonded regions underneath the protrusions and around the perimeter of the bond. In another embodiment, an ultrasonic bond is formed along a partial width of a ribbon.