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Layout and Packaging
Published in Arjuna Marzuki, CMOS Analog and Mixed-Signal Circuit Design, 2020
Wire bonding (see Figure 10.24) is a method used to connect a fine wire between an on-chip pad and a substrate pad. This substrate may simply be the ceramic base of a package or another chip. The common materials used are gold and aluminum. The main advantage of wire bonding technology is its low cost; but it cannot provide large I/O counts, and it needs large bond pads to make connections. The connections have relatively poor electrical performance. The solder bump is another approach. This is shown in Figure 10.25. Solder bumps are small spheres of solder (solder balls) that are bonded to contact areas or pads of semiconductor devices and subsequently used for face-down bonding. The length of the electrical connections between the chip and the substrate can be minimized by placing solder bumps on the die, flipping the die over, aligning the solder bumps with the contact pads on the substrate, and re-flowing the solder balls in a furnace to establish the bonding between the die and the substrate. This technology provides electrical connections with minute parasitic inductances and capacitances. In addition, the contact pads are distributed over the entire chip surface rather than being confined to the periphery. As a result, the silicon area is used more efficiently, the maximum number of interconnects is increased, and signal interconnections are shortened. But this technique results in poor thermal conduction, difficult inspection of the solder bumps, and possible thermal expansion mismatch between the semiconductor chips and the substrate.
Deposition
Published in Sunipa Roy, Chandan Kumar Sarkar, MEMS and Nanotechnology for Gas Sensors, 2017
Sunipa Roy, Chandan Kumar Sarkar
Wire bonding is the final step of microelectronic fabrication and is used for electrical interconnection using thin (1 mil) wire (e.g. Au) and with the combined effect of heat, pressure and ultrasonic energy. It is analogous to welding in the subject of mechanical engineering and involves the joining of any two (or more) substances together to make the final device. The two surfaces are brought to intimate contact, and then inter-diffusion of atoms takes place. Heat is used to make this interatomic diffusion faster. So, the bonding time is reduced. Wire bonding is also used to connect different components on the same substrate, such as resistor and capacitor.
Interconnection Technologies
Published in Fred W. Kear, Hybrid Assemblies and Multichip Modules, 2020
This method of interconnection provides the designer with the opportunity to accomplish connections where very little space is available. At the same time, it requires expensive equipment, trained operators, and careful processing. Wire bonding is essentially a welding process and is widely used in the construction of hybrid assemblies and microcircuits. It has proven its reliability over many years of use and offers significant advantages for simplifying and improving the construction of hybrid assemblies.
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.
Testing process quality of wire bonding with multiple gold wires from viewpoint of producers
Published in International Journal of Production Research, 2019
Tsang-Chuan Chang, Kuen-Suan Chen
During IC packaging, wire bonding involves welding gold wires to the chip and the inner leads of the lead frame so that the IC is connected to the external circuit. This means that the gold wires are crucial media for power and signal transmission between the IC and the outside, thereby making wire bonding one of the most important processes in IC packaging. Poor-quality wire bonding can easily lead to poor connections or even disconnections between the gold wires and the chip or the lead frame, which in turn prevents the IC and the electronic product from functioning normally. According to Roy, Das, and Banerjee (2016), Yeh and Tsai (2014), Tsai (2014), Chauhan, Zhong, and Pecht (2013), Su and Yeh (2011), and Kinnaird and Khotanzad (1999), wire pull and ball shear are two significant quality characteristics used to evaluate the quality of wire bonding. In view of this, the means of assisting IC packaging companies in the assessment of the quality of wire bonding is an important topic. Thus, based on the viewpoints of both process and producers, we first present consistency analysis of process performance for wire bonding with multiple gold wires, and then employed the Six Sigma quality index (SSQI) proposed by Chen, Chen, and Chang (2017), which can directly reflect process quality level and yield, to evaluate the process quality of wire bonding and examine its relationship with process yield. In practice, the index value must be estimated based on sample data, but it is clear that sampling errors cause some uncertainty in the assessment of process quality. For this reason, based on the upper confidence limit (UCL) of index, we developed a statistical hypothesis testing model to assist IC packaging companies. This model allows companies to determine whether the quality of their wire bonding process reaches the level demanded by customers and ensures the quality and reliability of their electronic products.