Abstract
Flip chip technology has been widely used in various fields. As the density of the solder balls in flip chip technology is increasing, the pitch among solder balls is narrowing, and the size effect is more significant. Therefore, the micro defects of the solder balls are more difficult to detect. In order to ensure the reliability of the flip chip, it is very important to detect and evaluate the micro defects of solder balls. High-frequency ultrasonic testing technology is an effective micro-defect detection method. In this paper, the interaction mechanism between high-frequency ultrasonic pulse and micro defects is analyzed by finite element simulation. A transient simulation model for the whole process of ultrasonic scanning of micro defects is established to simulate scanning in acoustic microscopy imaging. The acoustic propagation path map is obtained for analyzing acoustic energy transmission during detection, and the edge blurring effect in micro-defect imaging detection is clarified. The processing method of the time-domain signal and cross-section image signal of micro defects based on sparse reconstruction is studied, which can effectively improve the accuracy of detection and the signal-to-noise ratio.
Highlights
Flip chip technology, which uses the solder balls to achieve electrical and mechanical interconnection between the chip and the substrate, has been widely used in many fields of high-density microelectronic packaging due to its advantages of improving the speed of signal transmission and processing as well as reducing stray capacitance and parasitic inductance [1,2]
Can be seen that the and size of micro defects intuitively, the sparse reconstruction of time-domain echo signals and the accuracy of detecting the size and the location of defects in the ultrasonic testing process depends on cross-section signals obtained by simulation is carried out to solve the effect of edge blurring in the imaging detection of micro defects [22,23]
In order to analyze the propagation mechanism of an ultrasonic wave in a complex chip and the energy distribution of an ultrasonic wave acting on a chip micro defect more intuitively, the ultrasonic detection of flip chip is simulated by the “Acoustic-Solid Interaction, Transient” in COMSOL
Summary
Flip chip technology, which uses the solder balls to achieve electrical and mechanical interconnection between the chip and the substrate, has been widely used in many fields of high-density microelectronic packaging due to its advantages of improving the speed of signal transmission and processing as well as reducing stray capacitance and parasitic inductance [1,2]. High-frequency ultrasound for micro-defects diagnosis technology refers to acoustic micro imaging technology, which has been effectively applied to the detection of typical defects such as voids, cracks, and ball missing [18]. Can and detect the position andofsize micro defects in the by comparing and defect-free solder realized the defect ballofmissing diagnosis andobject recognition Active and analyzing both the time domain and frequency domain of a single point and the whole process infrared thermal detection technology has a better effect on detecting flip chip with a larger solder echosize, signal out of through the ball signal processing. Sparse reconstruction of time-domain echo signals such as voids, cracks, andintuitively, ball missing It uses the high-frequency ultrasound emittedand by the cross-section signals obtained byThe simulation is carried out to solveinto the the effect of edgesample blurring in the high-frequency focusing probe. We can detect the position and size of micro defects in the object by comparing
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