Research On Ultrasonic Precision Bonding Technology Based On Online Filtering And Physical State Control

Ultrasonic bonding is a rapid packaging technology with local heating,high efficiency and no pretreatment.With the introduction of ultrasonic sealing technology into the packaging field of polymer micro-nano devices,the key technology of packaging is to improve the control accuracy and consistency of bonding behavior.This paper aims at the process control of the application of the ultrasonic detection function in the ultrasonic bonding of the polymer,and conducts related researches on the connection between the vibration transfer characteristics in the ultrasonic bonding and the transition of the interface state of the polymer.In order to study the transmission characteristics of vibrations in polymer micro-devices in ultrasonic bonding,finite element analysis was performed on the bonding of polymethyl methacrylate(PMMA)micro-connected tubes and substrates.Firstly,an ultrasonic bonding simulation analysis model was established to set the parameters of the welding layer material,and a three-step simulation experiment process was designed.The contact force between the substrate and the base in the simulation model is set as the output,and the vibration transmission curve corresponding to the interface temperature is obtained with the temperature of the fusion layer as an independent variable,and the variation rule of the vibration transfer curve is analyzed in combination with the mechanical characteristics of the polymer material.Through the optimal design of the ultrasonic bonding test bench,a real-time dynamic pressure acquisition system and an on-line temperature detection and detection platform are constructed.In the ultrasonic bonding of PMMA,the interface temperature of vibration transmission and bonding was measured.Wavelet packet analysis was used to decompose the waveform of vibration transmission.The energy share of each node was calculated,and the frequency band of energy distribution was reconstructed by single node of wavelet packet.Combining with the online temperature change curve and the mechanical properties of polymer materials,the characteristic wavelet bands reflecting the change of polymer state were extracted.For the polymer ultrasonic bonding process,a filtering system based on FIR filtering for online feature band extraction is designed.A three-phase feedback control process is proposed based on the continuous increase or decrease of the relative change rate of the characteristic wavelet amplitude.In the initial stage of ultrasonic loading,the control process for the continuous attenuation of the relative change rate of the amplitude is designed in the first characteristic stage;the amplitude in the phase of the transition feature increases.During the period,design the control process where the amplitude relative change rate continuously decays and then increase;for the second feature phase change characteristics,use the time point at which the transition feature phase judges to stop as the initial time,and design a control method based on the continuous attenuation of the relative amplitude change rate.The three-stage feedback control condition is used as the parameter to control ultrasonic loading,and the ratio of fusion at each characteristic point is calculated,and the quantitative relationship between the characteristic wavelet and the fusion degree of interface is analyzed.The selective control of interface fusion degree in ultrasonic fine sealing of microdevices is realized.