Patent ID: 6244499
Filing Date: 2001-06-12
Classification: B23K,H01L

Abstract:
A method of forming a ball bump on a bonding pad of a chip for wire bonding, the method consisting of the following steps in the sequence set forth:providing a bonding tool having a capillary holding a wire with a ball formed on the end of the wire wherein the capillary has a feed hole for receiving the wire, a flat bottom face, and a chamfer with a height (h) surrounding the feed hole at the flat bottom face;moving the capillary downward to bring the ball in contact with the bonding pad of the chip and pressing the ball to form a ball bump on the end of the wire;moving the capillary upward vertically for a first distance substantially equal to the height (h) without breaking the wire;moving the capillary horizontally for a second distance substantially equal to 2/3-7/8 of the diameter of the wire without breaking the wire;moving the capillary upward for a predetermined distance such that a length of the wire is reserved for forming another ball; andclamping the wire in the bonding tool and raising the capillary to break the wire from the ball bump.