Study On Time-frequency Characteristics Of Guided Wave In Ultrasonic Bonding Process And Visual Monitoring Of Hot-melt

Ultrasonic precision bonding technology is an emerging technology in polymer micro-assembly applications.It is widely used in the field of micro-device manufacturing and has many advantages such as fast bonding,high efficiency,and simple process.At present,the research on improving the controllability of the bonding process of polymer microdevices and the precision of the bonding effect has received great attention.During the ultrasonic bonding process,the propagation of ultrasonic waves will be changed due to the change of the physical state of the interfacial polymer.This paper focuses on the correlation between the ultrasonic guided wave and the melting behavior of the hot-melt interface.The vibration analysis method is used to extract the time-frequency information contained in the ultrasonic guided wave,and then a vibration algorithm is written to obtain the correlation characteristics of the three harmonics.The melting behavior of the polymer hot-melt interface is monitored in real time by online visual monitoring technology.The fusion behavior of the hot-melt interface and the time-frequency characteristics of the ultrasonic guided wave are analyzed and correlated,and it is proved that the ultrasonic guided wave is an effective parameter to monitor the fusion degree on-line.The influence of different control parameters of ultrasonic precision bonding on the fusion degree of the hot-melt interface was studied.Through the constant amplitude and constant pressure control experiments,it was proved that the hot-melt interface under different control parameters has different fusion processes,and the difference of the process is relatively high.The control parameters of ultrasonic precision bonding will affect the bonding time,the generation of melting zones,local fusion and cavitation.The three-stage variable-amplitude comparative control experiment was carried out,which proved that in the large-amplitude-medium-amplitude-small-amplitude control mode,the bonding quality of the polymer can be greatly improved,and the cavitation caused by the ultrasonic cavitation effect is also effectively reduced.The research based on the variable pressure self-feedback control method was carried out,the static pressure control parameters were used as the object to design the process and the variable pressure self-feedback control experiment was carried out to ensure that the pressure difference between the ultrasonic tool head and the interface to be bonded is adaptive.By analyzing the dynamic and static force change characteristic curves and the final fusion effect of the bonding interface,it is proved that the variable pressure self-feedback control method can not only avoid the boundary overflow problem in the bonding process,but also effectively reduce the generation of bubbles.An effective means to improve the quality and precision of polymer ultrasonic precision bonding.