For extremely low loop profile of about <50um wire bonding application, the ball stitch on ball (BSOB) is an alternative choice. The process is a two-step one cycle; the first is to form a stud ball bump into the bond pad; and then a reverse bonding (the ball bond is bonded into the lead frame, and stitch on top of the ball bump). The general design rule for the capillary selection for BSOB bonding follows the basic wire bonding fundamentals. 8° face angle is recommended to improve the stitch bondability.
Capillary Part Number Selection Guide
The capillary design selection guide is always based on specific device & package configuration, wire type, and wire bonder. The selection of capillary part number process is simplified as follows:
Capillary Tip The selection of capillary tip design is determined by the device and metallization, bond pad pitch, bond pad opening, wire size, target mashed ball diameter, and critical loop height to derive the hole diameter(HD), chamfer diameter (CD), chamfer angle (CA), tip diameter (T) and face angle (FA).
Shank Style The shank style selection is characterized by geometrical design of the capillary bonding tool as dictated by specific device and / or package configuration.
Surface Finish The selection of a particular capillary tip surface finish hinges on whether the application is for gold or copper wire bonding.
Material Capillary material selection for optimum tool life performance for a given bonding application.
Wire Type The proper selection of capillary design is a resultant of the various wire bonding considerations.
Fine Pitch Part Number Selection
UT NON-FINE PITCH CAPILLARIES
QFN PACKAGE COPPER & GOLD WIRE BONDING CAPILLARY
COPPER WIRE BONDING CAPILLARY
ENHANCED STITCH BONDABILITY
ADVANCED BONDING APPLICATIONS
AZR LONG LIFE MATERIAL FOR CU WIRE BONDING
INFINITY 3X LONGER TOOL LIFE