Nondestructive Evaluation of Thermal Phase Growth in Solder Ball Microjoints by Synchrotron Radiation X-Ray Microtomography

2007 ◽  
Vol 129 (4) ◽  
pp. 434-439 ◽  
Author(s):  
Hiroyuki Tsuritani ◽  
Toshihiko Sayama ◽  
Kentaro Uesugi ◽  
Takeshi Takayanagi ◽  
Takao Mori
Keyword(s):  
Synchrotron Radiation ◽  
Nondestructive Evaluation ◽  
Solder Ball ◽  
Printed Circuit Boards ◽  
Thermal Strain ◽  
Ct Images ◽  
Fourth Power ◽  
Phase Growth ◽  
Eutectic Solder ◽  
X Ray

In high-density packaging technology, one of the most important issues is the reliability of the microjoints connecting large scale integrated circuit chips to printed circuit boards electrically and mechanically. The development of nondestructive testing methods with high spatial resolution is expected to enhance reliability. An X-ray microtomography system called SP-μCT has been developed in Super Photon ring-8 GeV (SPring-8), the largest synchrotron radiation facility in Japan. In this work, SP-μCT was applied in the nondestructive evaluation of microstructure evolution, that is, the phase growth due to thermal cyclic loading in solder ball microjoints. Simulating solder microjoints used in a flip chip, specimens were fabricated by joining a Sn–Pb eutectic solder ball 100 μm in diameter to a steel pin in the usual reflow soldering process. The phase growth process was determined by observing the computed tomography (CT) images obtained consecutively at the fixed point of the target joining. In the reconstructed CT images, the distribution of the constituent phases in the Sn–Pb eutectic solder was identified based on the estimation value of the X-ray linear attenuation coefficient. Consequently, the microstructure images obtained nondestructively by SP-μCT provided us with the following useful information for evaluating the reliability of the solder microjoints. First, each phase involves not dispersing particles but a three-dimensional monolithic structure like a sponge. Second, the phase growth proceeds in such a way that the average phase size to the fourth power increases proportionally to the number of cycles. Finally, in the vicinity of the joining interface, more rapid phase growth occurs compared to the other regions because local thermal strain due to the mismatch of thermal expansion leads to a remarkable phase growth.

Nondestructive Evaluation of Thermal Phase Growth in Solder Ball Micro-Joints by Synchrotron Radiation X-Ray Micro-Tomography

2005 ◽  
Author(s):  
Toshihiko Sayama ◽  
Hiroyuki Tsuritani ◽  
Kentaro Uesugi ◽  
Akira Tsuchiyama ◽  
Tsukasa Nakano ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Solder Ball ◽  
Printed Circuit Boards ◽  
Thermal Strain ◽  
Ct Images ◽  
Linear Attenuation Coefficient ◽  
Phase Growth ◽  
Eutectic Solder ◽  
X Ray ◽  
Micro Tomography

In high-density packaging technology, one of the most important problems is reliability of the micro-joints connecting LSI (Large Scale Integrated Circuit) chips to PCBs (Printed Circuit Boards) electrically and mechanically. Development of nondestructive testing methods with high spatial resolution is expected to enhance the reliability. Our research group has developed an X-ray micro-tomography system called SP-μCT at the beamline BL47XU in SPring-8, the largest synchrotron radiation facility in Japan. In this work, SP-μCT was applied to three-dimensional evaluation of microstructure evolution; that is, phase growth due to thermal cyclic loading in solder ball micro-joints. Simulating solder micro-joints used in a flip chip, specimens were fabricated by joining a Sn-Pb eutectic solder ball 100 μm in diameter to a steel pin in the usual reflow soldering process. The phase growth process was determined by observation of the CT images obtained consecutively at the fixed point of the target joining. In the reconstructed CT images, the distribution of the constituent phases in Sn-Pb eutectic solder was identified based on the estimation value of the X-ray linear attenuation coefficient. The following results were obtained. First, each phase involves not dispersing particles but a three-dimensionally monolithic structure just like a sponge. Second, the phase growth proceeds in such a way that the average phase size to the 4th power increases proportionally to the number of cycles. Finally, in the vicinity of the joining interface, more rapid phase growth occurs in comparison to the other regions because local thermal strain due to the mismatch of thermal expansion leads to remarkable phase growth. Consequently, the microstructure images obtained by SP-μCT bring us useful information to evaluate the reliability of micro-joints.

Application of Synchrotron Radiation X-Ray Microtomography to Nondestructive Evaluation of Thermal Fatigue Process in Flip Chip Interconnects

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Hiroyuki Tsuritani ◽  
Toshihiko Sayama ◽  
Yoshiyuki Okamoto ◽  
Takeshi Takayanagi ◽  
Kentaro Uesugi ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Crack Propagation ◽  
Nondestructive Evaluation ◽  
Thermal Fatigue ◽  
Flip Chip ◽  
Fatigue Cracks ◽  
Nondestructive Inspection ◽  
Ct Images ◽  
Phase Growth ◽  
X Ray

New nondestructive inspection methods with high spatial resolution are expected to support the evaluation and enhancement of the reliability of microjoints on printed circuit boards. An X-ray microtomography system, the SP-μCT has been developed at the Super Photon ring-8 GeV (SPring-8), the largest synchrotron radiation facility in Japan. In this work, the SP-μCT was first applied to the nondestructive evaluation of thermal fatigue phenomena, namely microstructure evolution (i.e., phase growth) and microcrack propagation, appearing in actual solder microbumps of flip chip interconnects due to thermal cyclic loading. In addition, a refraction-contrast imaging technique was simultaneously applied to visualize the fatigue cracks with an actual opening of less than 100 nm. The observed specimen has a flip chip structure joined by Sn-37wt%Pb eutectic solder bumps 150 μm in diameter. Consequently, the process of phase growth and crack propagation was determined via observation of consecutive computed tomography (CT) images obtained in the same plane of the same specimen. As the thermal cycle proceeded, remarkable phase growth was clearly observed, followed by the appearance of fatigue cracks in the corners of the interfaces between the solder bump and Cu pad. Moreover, the CT images also enabled us to evaluate the fatigue lifetime of the bumps, as follows. The lifetime to fatigue crack initiation was estimated by quantifying the increase in the phase growth. The crack propagation lifetime to failure was then determined by measuring the average crack propagation rate. Such results have not been obtainable at all by X-ray CT systems for industrial use and demonstrate the possibility of nondestructive inspection by a synchrotron radiation X-ray microtomography system.

In situ x-ray CT under tensile loading using synchrotron radiation

1995 ◽  
Vol 10 (2) ◽  
pp. 381-386 ◽  
Author(s):  
T. Hirano ◽  
K. Usami ◽  
Y. Tanaka ◽  
C. Masuda
Keyword(s):  
Synchrotron Radiation ◽  
Tensile Loading ◽  
Ct Images ◽  
Matrix Cracking ◽  
Alloy Matrix ◽  
X Ray ◽  
Sic Fibers ◽  
Matrix Cracks ◽  
The Matrix

Internal damage in metal matrix composite (MMC) under static tensile loading was observed by in situ x-ray computed tomography based on synchrotron radiation (SR-CT). A tensile testing sample stage was developed to investigate the fracture process during the tensile test. Aluminum alloy matrix composites reinforced by long or short SiC fibers were used. The projection images obtained under tensile loading showed good performance of the sample stage, and matrix deformation and breaks of the long SiC fibers could be observed. In the CT images taken at the maximum stress just before failure, debondings of the short SiC fibers to the matrix, many pullouts of the fibers, and matrix cracking could be clearly observed. The in situ SR-CT allowed the observation of generation and growth of such defects under different tensile stress levels. The results from the nondestructive observation revealed that the MMC was broken by propagation of the matrix cracks which might be caused by stress concentration at the ends of the short fibers. A three-dimensional CT image reconstructed from many CT images provided easy understanding of the fiber arrangement, crack shape, and form of the void caused by fiber pullout. In situ SR-CT is a useful method for understanding failure mechanisms in advanced materials.

Application of Synchrotron Radiation X-Ray Micro-Tomography to Nondestructive Evaluation of Thermal Fatigue Damage in Flip Chip Interconnects

2007 ◽  
Author(s):  
Hiroyuki Tsuritani ◽  
Toshihiko Sayama ◽  
Yoshiyuki Okamoto ◽  
Takeshi Takayanagi ◽  
Kentaro Uesugi ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Thermal Cycle ◽  
Flip Chip ◽  
Solder Bump ◽  
Fatigue Cracks ◽  
Phase Growth ◽  
X Ray ◽  
Solder Bumps

A synchrotron radiation X-ray micro-tomography system called SP-μCT with a spatial resolution of about 1μm has been developed in SPring-8, the largest synchrotron radiation facility in Japan. In this work, SP-μCT was applied to the nondestructive evaluation of microstructure evolution; that is phase growth, and micro-crack propagation appearing as thermal fatigue damage in solder micro-bumps of flip chip interconnects. The observed specimens have a flip chip structure joined by Sn-37wt%Pb eutectic solder bumps 100μm in diameter. A thermal cycle test was carried out, and the specimens were picked up at any number of cycles. The solder bumps were observed by using SP-μCT at the beamlines BL47XU and BL20XU in SPring-8. An X-ray energy of 29.0 keV was selected to obtain absorption images with a high contrast between the Sn-rich and the Pb-rich phases. Additionally, a refraction-contrast imaging technique was applied to visualize fatigue cracks in the solder bumps. The obtained CT (Computed Tomography) images clearly show the process of phase growth and crack propagation due to the thermal cyclic loading of the same solder bump; such information has not been obtained at all by industrially-used X-ray CT systems. In the initial state, the Pb-rich phase was dispersed with characteristic shape, which appears in reflow soldering process. Remarkable phase growth was also observed clearly as the thermal cycle test proceeded. When the loading reached 300 cycles, fatigue cracks appeared in the corners of the interfaces between the solder bump and the Cu pad. The CT images enabled us to evaluate the lifetime of the bumps to the initiation of fatigue cracks by estimating the increase in a phase growth parameter, which corresponds to the accumulation of fatigue damage in the solder joints. The results showed that the estimated lifetime strongly agreed with the average value, which was determined by SEM (Scanning Electron Microscope) destructive observations. As the thermal cycle proceeded, the cracks propagated gradually to the inner region of the solder bump. From the CT images, the average propagation rate was calculated, and the mean of the total fatigue lifetime was estimated to be less than 1800 cycles. These results show the possibility that nondestructive testing by a synchrotron radiation X-ray micro CT system is useful for evaluating the thermal fatigue lifetime in micro-joints.

Segmentation of Synchrotron Radiation X-Ray µCT images using energy minimization via Graph Cuts for quantitative analysis

2011 ◽  
Author(s):  
Anderson Alvarenga de Moura Meneses ◽  
Alessandro Giusti ◽  
Andre Pereira de Almeida ◽  
Liebert Nogueira ◽  
Delson Braz ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Synchrotron Radiation ◽  
Energy Minimization ◽  
Graph Cuts ◽  
Ct Images ◽  
X Ray

Application of the X-Ray CT Technique for NDE of Wood in Field

2006 ◽  
Vol 321-323 ◽  
pp. 1172-1176 ◽  
Author(s):  
Sang Joon Lee ◽  
Kwang Mo Kim ◽  
Jun Jae Lee
Keyword(s):  
Nondestructive Evaluation ◽  
High Accuracy ◽  
Ct Images ◽  
Projection Data ◽  
X Ray ◽  
Ct Technique

NDE (Nondestructive Evaluation) of wood was performed using X-ray CT technique in order to determine the applicability of this technology to ancient wooden buildings in the field. Two main objectives were studied to consider applicability as well as accuracy. First, the most suitable number of radiographs for reconstructing proper X-ray CT images was determined. Secondly, X-ray CT images using SIRT were reconstructed using various numbers of radiographs in order to consider the possible effects of absent projection data in field applications. As a result of this study, 9 radiographs were determined to be the most suitable number for this application. Brown-rotted part in wood was also detected by X-ray CT images using 9 radiographs. It was concluded that even there exists some absent projection data, CT images can be reconstructed with high accuracy.

Sign in / Sign up

Export Citation Format

Share Document