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Interconnections and Connectors
Published in Michael Pecht, Handbook of Electronic Package Design, 2018
Ball bonding is a process in which a small ball is formed on the end of the wire by severing the wire with a flame and deformed under pressure against the pad area on the silicon chip (Figure 5.3). The lead wire is perpendicular to the silicon chip as it leaves the bond area. The number of steps in this bonding operation is small and the strength of the bond obtained is strong. Aluminum wire cannot be used because of its inability to form a ball when severed with a flame. However, gold wire is an excellent electric conductor, is more ductile than aluminum, and is chemically inert. For ball bonding, hard gold wire may be used since the balling process determines the ductility of the gold to be deformed. A disadvantage of ball bonding is that a relatively large bond pad is required.
Deposition
Published in Sunipa Roy, Chandan Kumar Sarkar, MEMS and Nanotechnology for Gas Sensors, 2017
Sunipa Roy, Chandan Kumar Sarkar
Ball bonding is again of two types, thermocompression (T/C) and thermosonic (T/S). T/C utilizes pressure and temperature to form a bond, and in T/S, bonding is the amalgamated effect of thermocompression (T/C) and thermosonic (T/S) and also ultrasonic energy in the process. Ball bonding is generally performed with pure gold wire (typically for 1 mil gold wire) drawn out from a gold wire bobbin as it can be easily deformed with applied pressure. In both methods, the end of the bond wire is transformed into a ball shape by the application of an electronic flame off. The ball is then positioned by a mechanical shaft, just above the bond pad which lies on the substrate, and contact is made by any of the earlier two methods. Aluminium is much more susceptible to oxidation, that is why it is not used in ball bonding. The presence of heat at the time of ball formation can create oxides that will positively obstruct the joining process.
A data-driven method for enhancing the image-based automatic inspection of IC wire bonding defects
Published in International Journal of Production Research, 2021
Junlong Chen, Zijun Zhang, Feng Wu
Integrated circuits (IC) are core components in numerous electronic products including smart phones, personal computers, industrial robots, autonomous vehicles, etc. In IC manufacturing, the IC packaging and testing are two critical sub-processes which need to be well managed (Park, Ahn, and Hur 2018). The IC packaging process is composed of a number of major steps which might influence the performance of ICs (Chang and Chen 2019). One of the most important steps in IC packaging is the wire bonding since it connects chips and the substrate via metal wires as well as it determines the quality and reliability of the power and signal transmission. However, a variety of defects might appear in the wire bonding process, such as defects and failures in the ball bonding and wire bonding. In addition, identifying causes of wire bonding defects is challenging because different factors including the human errors, equipment, materials, and methods (Gong et al. 2017) are involved. To facilitate IC manufacturing to achieve a high yield ratio, it is of great importance to inspect the IC wire bonding quality after packaging. As ICs are mass-produced nowadays, an accurate technique for rapidly and automatically inspecting wire bonding defects is extremely valuable to the IC quality control and is of great interests to the industry.