What is Bonding Time
Bonding time is the duration involved in the ball bonding process. This process entails the joining of a wire and a pad surface through a solid phase welding technique. During ball bonding, a wire is passed through a hollow capillary, and an Electronic Flame-Off (EFO) system is used to melt a small portion of the wire extending outside. The molten wire forms a ball due to surface tension before solidifying. Subsequently, the ball is pressed onto the pad with sufficient force, causing plastic deformation and resulting in a strong and intimate bond between the wire and the bond pad surface.
The bonding time specifically refers to the time interval starting from the moment the hot-bar makes contact with the lead and pad until the solder joint is completed. This duration is critical as it determines the quality and reliability of the bond. After the bonding process, bond evaluation can be conducted through visual inspection or mechanical tests to ensure the integrity of the bond. Visual evaluation involves the use of scanning electron microscopes, optical microscopes, and similar instruments, while automated testing methods listed in the MIL-STD-883: test method standard can also be employed. These methods include delay measurements, ball bond shear tests, random vibration tests, internal visual inspections, stabilization bake tests, and more. By assessing the bond patterns, manufacturers can ensure the overall effectiveness of the bonding process and the resulting electrical interconnections.