An improved method for inspection of solder joints using X-ray laminography and X-ray microtomography

2002 ◽  
Author(s):  
A.R. Kalukin ◽  
V. Sankaran ◽  
B. Chartrand ◽  
D.L. Millard ◽  
R.P. Kraft ◽  
...  
Keyword(s):  
Solder Joints ◽  
Improved Method ◽  
X Ray

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

Improved Method of Measuring X‐Ray Tube Focus

1967 ◽  
Vol 38 (12) ◽  
pp. 1779-1782 ◽  
Author(s):  
William Parrish
Keyword(s):  
Improved Method ◽  
X Ray

Investigation of Stress Evolution Induced by Electromigration in Sn-Ag-Cu Solder Joints Based on an X-Ray Diffraction Technique

2011 ◽  
Vol 41 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Limin Ma ◽  
Fu Guo ◽  
Guangchen Xu ◽  
Xitao Wang ◽  
Hongwen He ◽  
...  
Keyword(s):  
Solder Joints ◽  
Stress Evolution ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Head-on-Pillow Defect Detection: X-Ray Inspection Limitations

2019 ◽  
Vol 16 (2) ◽  
pp. 91-102
Author(s):  
Lars Bruno ◽  
Benny Gustafson
Keyword(s):  
Solder Joints ◽  
Solder Paste ◽  
Wafer Level ◽  
Reflow Soldering ◽  
X Ray ◽  
Soldering Process ◽  
Irregular Shapes ◽  
Fine Pitch ◽  
Solder Balls ◽  
Ball Grid Array Packages

Abstract Both the number and the variants of ball grid array packages (BGAs) are tending to increase on network printed board assemblies with sizes ranging from a few millimeter die size wafer level packages with low ball count to large multidie system-in-package (SiP) BGAs with 60–70 mm side lengths and thousands of I/Os. One big challenge, especially for large BGAs, SiPs, and for thin fine-pitch BGA assemblies, is the dynamic warpage during the reflow soldering process. This warpage could lead to solder balls losing contact with the solder paste and its flux during parts of the soldering process, and this may result in solder joints with irregular shapes, indicating poor or no coalescence between the added solder and the BGA balls. This defect is called head-on-pillow (HoP) and is a failure type that is difficult to determine. In this study, x-ray inspection was used as a first step to find deliberately induced HoP defects, followed by prying off of the BGAs to verify real HoP defects and the fault detection correlation between the two methods. The result clearly shows that many of the solder joints classified as potential HoP defects in the x-ray analysis have no evidence at all of HoP after pry-off. This illustrates the difficulty of determining where to draw the line between pass and fail for HoP defects when using x-ray inspection.

SAC–xTiO2 nano-reinforced lead-free solder joint characterizations in ultra-fine package assembly

2018 ◽  
Vol 30 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Fakhrozi Che Ani ◽  
Azman Jalar ◽  
Abdullah Aziz Saad ◽  
Chu Yee Khor ◽  
Roslina Ismail ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Solder Joint ◽  
Solder Joints ◽  
Ion Beam ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Content Type ◽  
X Ray ◽  
Free Solder

Purpose This paper aims to investigate the characteristics of ultra-fine lead-free solder joints reinforced with TiO2 nanoparticles in an electronic assembly. Design/methodology/approach This study focused on the microstructure and quality of solder joints. Various percentages of TiO2 nanoparticles were mixed with a lead-free Sn-3.5Ag-0.7Cu solder paste. This new form of nano-reinforced lead-free solder paste was used to assemble a miniature package consisting of an ultra-fine capacitor on a printed circuit board by means of a reflow soldering process. The microstructure and the fillet height were investigated using a focused ion beam, a high-resolution transmission electron microscope system equipped with an energy dispersive X-ray spectrometer (EDS), and a field emission scanning electron microscope coupled with an EDS and X-ray diffraction machine. Findings The experimental results revealed that the intermetallic compound with the lowest thickness was produced by the nano-reinforced solder with a TiO2 content of 0.05 Wt.%. Increasing the TiO2 content to 0.15 Wt.% led to an improvement in the fillet height. The characteristics of the solder joint fulfilled the reliability requirements of the IPC standards. Practical implications This study provides engineers with a profound understanding of the characteristics of ultra-fine nano-reinforced solder joint packages in the microelectronics industry. Originality/value The findings are expected to provide proper guidelines and references with regard to the manufacture of miniaturized electronic packages. This study also explored the effects of TiO2 on the microstructure and the fillet height of ultra-fine capacitors.

Nondestructive Observation of Thermal Fatigue Crack Propagation in FBGA and Die Attached Solder Joints by Synchrotron Radiation X-Ray Laminography

2015 ◽  
Author(s):  
Hiroyuki Tsuritani ◽  
Toshihiko Sayama ◽  
Yoshiyuki Okamoto ◽  
Takeshi Takayanagi ◽  
Masato Hoshino ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Synchrotron Radiation ◽  
Crack Propagation ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Fatigue Cracks ◽  
Three Dimensional ◽  
X Ray ◽  
Micro Cracks ◽  
Solder Bumps

The reliability of solder joints on printed circuit boards (PCBs) is significantly affected by thermal fatigue processes due to downsizing and high density packaging in electronic components. Accordingly, there is a strong desire in related industries for development of a new nondestructive inspection technology to detect fatigue cracks appearing in these joints. The authors have applied the SP-μCT, a synchrotron radiation X-ray microtomography system, to the nondestructive observation of such cracks. However, for planar objects such as PCB substrates, reconstruction of CT images is difficult due to insufficient X-ray transmission along the parallel axis of the substrate. In order to solve this problem, a synchrotron radiation X-ray laminography system was developed to overcome the size limits of such specimens. In this work, this system was applied to the three-dimensional, nondestructive observation of thermal fatigue cracks in solder joints, for which X-ray CT inspection has been extremely difficult. The observed specimens included two typical joint structures formed using Sn-3.0Ag-0.5Cu solder: (1) a fine pitch ball grid array (FBGA) joint specimen in which an LSI package is connected to a substrate by solder bumps 360 μm in diameter, and (2) a die-attached specimen in which a 3 mm square ceramic chip is mounted on a substrate. The optical system developed for use in X-ray laminography was constructed to provide a rotation axis with a 30° tilt from the right angle to the X-ray beam, and to obtain X-ray projection images via the beam monitor. The same solder joints were observed successively using the laminography system at beamline BL20XU at SPring-8, the largest synchrotron radiation facility in Japan. In the FBGA type specimen, fatigue cracks were clearly observed to appear at the periphery of the joint interface, and to propagate gradually to the inner regions of the solder bumps as thermal cycling proceeded. In contrast, in the die-attached joint specimen, micro-cracks were observed to appear and propagate through the thin solder layer. An important observation was that these micro-cracks become interconnected prior to propagation of the main fatigue crack. The fatigue crack propagation lifetime was also estimated in both specimens by measuring the crack surface area and calculating the average crack propagation rate through the three-dimensional images. Consequently, the sectional images obtained by the laminography system clearly show the process of crack propagation due to thermal cyclic loading.

An Improved Method to Extract Crystalline Cellulose from Alternatives Sources

2017 ◽  
Vol 371 ◽  
pp. 128-130
Author(s):  
M. Sánchez ◽  
Mauro Cesar Terence ◽  
Juan Alfredo Guevara Carrió
Keyword(s):  
Diffraction Method ◽  
Crystallinity Index ◽  
Crystalline Cellulose ◽  
Cellulose Crystallinity ◽  
Improved Method ◽  
X Ray Diffraction ◽  
Waste Wood ◽  
X Ray ◽  
Alternative Sources ◽  
High Cellulose

Crystalline cellulose can be obtained from alternative sources like waste wood by hydrolysis with hydrochloric or sulfuric acid. In this study we report a process for producing crystals with high cellulose crystallinity index of approximately 82%. We chose to work with eucalyptus FSC certified as a way to ensure the reproducibility of experiments. Said wood samples were subjected to acid hydrolysis with nitric acid. The resulting mass was dried out and measured by the X-ray diffraction method.

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