Research For The Effect Of Ultrasonic Power And Bonding Force On Gold Thermosonic Bonding Quality

As a main microelectronics packaging technology nowadays, Wire bonding refers to the technology of welding the metal wire(Al, Pt, Au) With the substrate pad by way of thermal, pressure, ultrasonic energy, etc. and thus to ensure the electrical interconnection between the chips and substrate pad, and the information exchange among chips, Which is one of the force welding technologies.According to the different requirements for microelectronic packaging in different fields, there are usually three wire bonding positioning platform technologies adopted in industry, namely thermal force wire bonding, ultrasonic Wire bonding, and thermosonic Wire bonding, among which thermosonic boning process, on the basis of ultrasonic bonding, is to enhance the atomic interdiffusion force in the original interface of metals by heating the station, so as to ensure the welding quality of wires. It combines the advantages of thermos-force process and ultrasonic process, Which has become the boning mainstream due to its merits of low heating temperature, high bonding strength, device reliability and etc.Based on the in-depth understanding of bonding mechanism, the existing need, and the reality, the subjects of this thesis are the ultrasonic power and bonding force parameters in the 25μm gold thermal ultrasonic wedge bonding process and the 25μm gold Wire ball thermosonic bonding process. The main content is as follows:1. Analyze the mechanism of bonding and explain the similarities and differences between wedge bonding process and ball bonding process. On the basis of theoretical analysis, it can be proved that ultrasonic power and bonding force are the main factors affecting the chip bonding quality in this company.2. On the platform of HYBOND626 thermosonic wire bonding machine, prepare the single factor test samples of 25μm gold Wire ball bonding and the 25μm gold wire wedge bonding respectively on the same chip and substrate pad. The software Matlab is adopted to deal with the test results and carry out the quadratic function fitting, Which can result in the effect trend of single factor on bonding strength for different bonding modes.3.Design the orthogonal factors table according to the single factor test and con--duct the orthogonal test; range analysis is conducted as for the test results; the following conclusion is proved: In different bonding modes, the effect of ultrasonic power and bonding force on bonding quality at the first and second welding point is weak:As for the wedge bonding, at the first Welding point, the impact of ultrasonic power on bonding quality is greater than that of bonding force, but not obvious; at the second Welding point, the impact of bonding force on bonding quality is far greater than that of ultrasonic power. As for the ball bonding, at the first welding point, the impact of ultrasonic power on the bonding quality is greater than that of bonding force, and it’s obvious; at the second welding point, the impact of both processes on the bonding quality is the same. During the test, an optimized parameters combination is achieved, Which contribute to realize the test goals and complete this study.