An automated ultrasonic inspection approach for flip chip solder joint assessment

Yang, Ryan S.H.; Braden, Derek R.; Zhang, Guangming; Harvey, David M.

doi:10.1016/j.microrel.2012.07.018

Cited by 17 publications

(15 citation statements)

References 13 publications

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“…Acoustic micro imaging (AMI) is effective at detecting discontinuities inside a test sample, which makes it ideal of non destructive evaluation of solder bump discontinuities [4][5][6][7]. Edge effect [8] is a physical phenomenon in acoustic imaging of microelectronic packages where sample edges scatter acoustic energy leading to dark annular regions around the solder bump.…”

Section: Introductionmentioning

confidence: 99%

Characterization of micro-crack propagation through analysis of edge effect in acoustic microimaging of microelectronic packages

Lee

Zhang

Harvey

et al. 2016

NDT & E International

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Section: Introductionmentioning

confidence: 99%

Characterization of micro-crack propagation through analysis of edge effect in acoustic microimaging of microelectronic packages

Lee

Zhang

Harvey

et al. 2016

NDT & E International

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“…Acoustic micro imaging relies on the acoustic impedance differences of various material interfaces, and is particularly sensitive to gap type defects such as voids, cracks and delaminations as small as ~0.1µm [1]. A focused transducer emits an acoustic pulse into the test sample and receives the reflected echoes while mechanically scanning the transducer across the sample.…”

Section: Introductionmentioning

confidence: 99%

Finite element modelling for the investigation of edge effect in acoustic micro imaging of microelectronic packages

Lee¹,

Zhang²,

Harvey³

et al. 2016

Meas. Sci. Technol.

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In acoustic micro imaging of microelectronic packages, edge effect is often presented as artifacts of C-scan images, which may potentially obscure the detection of defects such as cracks and voids in the solder joints. The cause of edge effect is debatable. In this paper, a two-dimensional finite element model is developed on the basis of acoustic micro imaging of a flip-chip package using a 230 MHz focused transducer to investigate acoustic propagation inside the package in attempt to elucidate the fundamental mechanism that causes the edge effect. A virtual transducer is designed in the finite element model to reduce the coupling fluid domain, and its performance is characterised against the physical transducer specification. The numerical results showed that the Under Bump Metallization (UBM) structure inside the package has a significant impact on the edge effect. Simulated wavefields also showed that the edge effect is mainly attributed to the horizontal scatter, which is observed in the interface of silicon die-to-the outer radius of solder bump. The horizontal scatter occurs even for a flip-chip package without the UBM structure.

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“…AMI has strong penetration capabilities and is very effective at detecting discontinuities within materials and interconnects [1][2][3]. In practical AMI systems, the sample is normally submerged in water to reduce acoustic impedance mismatch.…”

Section: Introductionmentioning

confidence: 99%

“…Fig. 1 shows a C-scan image of the silicon die-solder bump interface obtained from the inspection of a flip-chip package soldered on a PCB board [3]. The flip chip packages contained 109 solder joints positioned at the periphery of the package.…”

Section: Introductionmentioning

confidence: 99%

“…2, indicating that most if not all of the incident acoustic energy has been angularly-reflected by the curvature of the solder ball geometry. The dark annular region can obscure the detection of defects such as cracks and voids inside the solder bump [2][3][4]. Consequently, the interpretation of C-scan images and defect detection of solder joints becomes difficult.…”

Section: Introductionmentioning

confidence: 99%

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Development of C-Line plot technique for the characterization of edge effects in acoustic imaging: A case study using flip chip package geometry

Lee

Zhang

Harvey

et al. 2015

Microelectronics Reliability

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Edge effect is a common phenomenon observed in Acoustic micro imaging of microelectronic packages. In this paper, using flip chip package geometry as a test vehicle, finite element modelling is carried out to study the fundamental mechanism of the edge effect phenomenon. C-line plot technique is developed for characterisation of edge effects in acoustic C-scan images, in particular solder joint C-scan images. Simulated results are compared to experimental results. Results reveal that edge effect generation is mainly attributed to the under-bump-metallisation structure. In addition, through analysis of the CLine profile of edge effects, the impact of the transducer focal point and the spot size on the edge effect is investigated. Results show that slight off-focus can reduce the severity of the edge effect in which image sharpness is a trade-off.

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An automated ultrasonic inspection approach for flip chip solder joint assessment

Cited by 17 publications

References 13 publications

Characterization of micro-crack propagation through analysis of edge effect in acoustic microimaging of microelectronic packages

Characterization of micro-crack propagation through analysis of edge effect in acoustic microimaging of microelectronic packages

Finite element modelling for the investigation of edge effect in acoustic micro imaging of microelectronic packages

Development of C-Line plot technique for the characterization of edge effects in acoustic imaging: A case study using flip chip package geometry

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