Development And Application Of High Frequency Ultrasound Scanning System

In the process of industrial production,it is often necessary to perform non-destructive testing on the production workpiece to check the performance of the workpiece.Ultrasonic microscopic inspection technology can use the propagation characteristics of ultrasonic waves to display the defect or delamination information on the surface and inside of the sample,which is an effective way of non-destructive inspection.With the rapid development of device miniaturization,the size of defects to be detected is getting smaller and smaller,and the resolution of ultrasonic nondestructive testing also needs to be continuously improved.In order to realize the ultrasonic non-destructive testing of micron-scale defects,a set of high-precision and high-resolution ultrasonic scanning microscopy system is developed in this paper.The main research work of this paper is as follows:(1)The hardware construction and software design of the ultrasound scanning imaging system are realized.The hardware components of the imaging system include motion controller,precision motion platform,high-frequency pulse transmitter/receiver and highspeed signal acquisition module.The scanning range of the precision motion platform is 500 mm×300 mm,the scanning resolution is 0.1μm,and the maximum scanning speed is 2000 mm/s.The bandwidth of the sampling module is 500 MHz,the maximum sampling rate is 2.5 Gsps,and the sampling resolution is 10 bits.The motion control system is used as a slave computer,and the software design realizes the precise motion control of the motion axis and the triggering of the position synchronization signal by using the C#programming language.The software design of the main control computer realizes high-speed data acquisition,segmented data storage and transmission,real-time display of A-mode waveform and ultrasound B/C/X scanning imaging through Lab VIEW programming language.Through the A-mode sampling of the echo signal of the ultrasonic transducer with a center frequency of 100 MHz,it is verified that the system can work normally at the sampling rates of 312.5 Msps,625 Msps,1.25 Gsps and 2.5 Gsps,and can meet the requirements below 500 MHz Nondestructive testing imaging requirements of high-frequency ultrasound transducers.(2)The surface tracking and autofocus algorithm based on V(z)curve are proposed and implemented.By setting the synchronization position and the synchronization threshold,the primary echo reflected by the surface of the tested sample is identified,and the full-wave data at the position is synchronized to realize the automatic tracking of the sample surface,and the experimental verification is given.By measuring the relationship between the peakto-peak value of the primary echo and the defocus coordinate when the spherical pressure focused ultrasonic transducer is in the defocused position,the V(z)curve of the ultrasonic transducer is drawn.The actual focus position of the ultrasonic transducer is obtained by using the coordinates of the maximum value of the V(z)curve,so as to realize the automatic and precise focusing of the ultrasonic transducer.(3)High-precision,high-resolution ultrasonic NDT imaging(100 MHz)is realized.First,the zebrafish eye and the sound field of the ultrasound transducer were imaged by ultrasound B-scan,and the internal structure of the zebrafish eye was successfully observed and the lateral resolution of different ultrasound transducers was verified.Secondly,using a highfrequency ultrasonic scanning microscope to perform ultrasonic C-scan imaging of the surface and internal structure of the integrated circuit package chip,and successfully identify the fonts marked on the surface of the chip and the internal lead structure.Finally,ultrasonic X-scan was performed on the bonding layer between the flexible circuit and the piezoelectric array using a high-frequency ultrasonic scanning microscope,and a layer with a thickness of about 169 μm was successfully identified.The experimental results show that the highfrequency ultrasonic scanning microscope system developed in this paper has high working frequency and high scanning resolution,and can meet the application of high-frequency ultrasonic nondestructive testing of various target requirements.