Machinery and Electronics Research Institute

Toyama-shi, Japan

Machinery and Electronics Research Institute

Toyama-shi, Japan
SEARCH FILTERS
Time filter
Source Type

Nabesawa H.,Machinery and Electronics Research Institute | Hitobo T.,Tateyama Machine Co. | Asaji T.,National Institute of Technology, Toyama College | Abe T.,Niigata University | Seki M.,Chiba University
Journal of the Vacuum Society of Japan | Year: 2017

The etching characteristics of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA) bulk plates were studied in a magnetron enhanced reactive ion etching (M-RIE) system. The etch rates of the plates for oxygen plasma were investigated under the pressure range 0.1-2.0 Pa, and were found to strongly correlate with the self-bias voltage. The plates presented smooth surface in the 0.1-1.0 Pa pressure range, and rough surfaces at 1.5 Pa and 2.0 Pa. The roughness was introduced by a micromask sputtered from the chamber material. The titanium etching mask exhibited lower etch rates for oxygen plasma than aluminum and silicon dioxide. Finally, using the dry-etched titanium mask in low-pressure oxygen plasma, we fabricated a 5-μm pitch line-and-space structure on a PTFE plate and a 4-μm square pillar array on a PFA plate.


Tsuritani H.,Machinery and Electronics Research Institute | Sayama T.,Machinery and Electronics Research Institute | Okamoto Y.,Cosel Co. | Takayanagi T.,Cosel Co. | And 2 more authors.
ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, InterPACK 2011 | Year: 2011

The reliability or lifetime of micro-joints on printed circuit boards (PCBs) is significantly affected by fatigue processes, including fatigue crack initiation and propagation to failure. Accordingly, the industries producing electronic devices and components strongly desire a new nondestructive inspection technology, which detects micro-cracks appearing as thermal fatigue fractures in the joints. In this investigation, we applied a synchrotron radiation X-ray micro-tomography system called the SP-μCT to three-dimensionally and nondestructively evaluate the fatigue crack propagation process in complex-shaped solder joints. The observed specimens have a typical joint structure in which chip type resistors 1.0 mm in length and 0.5 mm in width are mounted on an FR-4 substrate by joining with Sn-3.0Ag-0.5Cu solder. A thermal cycle test was carried out, and specimens were collected at fixed cycle numbers. The same solder joints were observed successively using the SP-μCT at beamline BL20XU at SPring-8, the largest synchrotron radiation facility in Japan. An X-ray energy of 29.0 keV was selected to obtain computed tomography (CT) images with high contrast among some components, and a refraction-contrast imaging technique was also applied to the visualization of fatigue cracks in the solder joints. The following results were obtained. At the early stage in the fatigue process of normal joints, the main fatigue cracks were clearly observed to initiate from the region around the solder joint tip and the vicinity of the chip corner. Additionally, many micro-cracks roughly 5 to 10 μm in length also formed in the thin solder layer between the chip and substrate. The important observed fact is that these micro-cracks deform, grow, and connect to each other due to the thermal cyclic loading, prior to main crack propagation. On the other hand, in case of solder joints which included relatively larger initial voids, the voids deformed, and the fatigue cracks initiated and propagated from the surface of the voids. Furthermore, by employing the three-dimensional crack images, the crack dimensions were quantified straightforwardly by measuring the surface area of the fatigue crack, and the fatigue crack propagation process was also accurately evaluated via the average crack propagation rate. Consequently, the obtained CT images clearly illustrate the process of crack propagation due to the thermal cyclic loading of a solder joint. In contrast, such information has not been obtained in any form by industrially employed X-ray CT systems or finite element analyses. © 2011 by ASME.


Tsuritani H.,Machinery and Electronics Research Institute | Sayama T.,Machinery and Electronics Research Institute | Okamoto Y.,Cosel Co. | Takayanagi T.,Cosel Co. | And 3 more authors.
ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2013 | Year: 2013

The reliability and lifetime of micro-joints on printed circuit boards (PCBs) is significantly affected by fatigue processes, including fatigue crack initiation and propagation to failure. Accordingly, the industries producing electronic devices and components strongly desire the development of a new nondestructive inspection technology, which detects micro-cracks appearing as thermal fatigue fractures in these joints. Accordingly, the authors have demonstrated that the micro-cracks in the micro-solder joints can be observed using the SP-μCT synchrotron X-ray micro tomography system. However, in order for such solder joint micro-cracks to be observable by SP-μCT, the observation object must have a diameter of less than roughly 1 mm. In this investigation, we applied a synchrotron radiation X-ray laminography system to three-dimensionally and nondestructively evaluate the fatigue crack propagation process in flip chip solder micro-joints. X-ray laminography is a technique for nondestructively observing planar objects. The optical system developed for use in X-ray laminography was constructed to provide the rotation stage with a 20° tilt from the horizontally incident X-ray beam. For this reason, X-rays were sufficiently transmitted through the planar object, in all directions. The observed specimens had a flip chip structure, in which a 10.04 mm square LSI chip is connected to a 52.55 mm (length) × 30.0 mm (width) FR-4 substrate by 120 μm diameter Sn-3.0wt%Ag-0.5wt%Cu leadfree solder bumps. A thermal cycle test was carried out, and specimens were collected at fixed cycle numbers. The same solder joints were observed successively using the synchrotron radiation X-ray laminography system at beamline BL20XU at SPring-8, the largest synchrotron radiation facility in Japan. An X-ray beam energy of 29.0 keV was selected to obtain laminography images with high contrast among component. The obtained laminography images clearly show the evolution of cracks, voids, and the Ag3Sn phase due to the thermal cyclic loading of the solder joints. In addition, the surface area of the same fatigue cracks was also measured, to quantify the crack propagation process. However, the surface area change measured by laminography differed from the crack propagation results obtained by standard SP-μCT. This difference may be due to an inability to observe some micro-cracks, due to crack closure to beneath than the detection limit of synchrotron radiation X-ray laminography. Consequently, these results demonstrate the possibility that nondestructive observation of fatigue cracks in the solder bumps on a large size electronic substrate by synchrotron radiation X-ray laminography, although its detection ability for narrow cracks may be limited, compared to SP-μCT. Copyright © 2013 by ASME.


Tsuritani H.,Machinery and Electronics Research Institute | Sayama T.,Machinery and Electronics Research Institute | Okamoto Y.,Cosel Co. | Takayanagi T.,Cosel Co. | And 4 more authors.
ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels | Year: 2015

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 dieattached 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. © Copyright 2015 by ASME.


Tsuritani H.,Machinery and Electronics Research Institute | Sayama T.,Machinery and Electronics Research Institute | Okamoto Y.,Cosel Co. | Takayanagi T.,Cosel Co. | And 2 more authors.
Journal of Electronic Packaging, Transactions of the ASME | Year: 2011

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-37wtPb eutectic solder bumps 150 m 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. © 2011 American Society of Mechanical Engineers.


Tsuritani H.,Machinery and Electronics Research Institute | Sayama T.,Machinery and Electronics Research Institute | Uesugi K.,Japan Synchrotron Radiation Research Institute | Okamoto Y.,Cosel Co. | And 2 more authors.
ICSJ 2013 - IEEE CPMT Symposium Japan | Year: 2013

A synchrotron radiation X-ray micro-tomography system was applied to nondestructive visualization and evaluation of micro-crack propagation appearing as thermal fatigue damage in some solder joints. T he fatigue crack propagation lifetime was accurately estimated on the basis of the three-dimensional crack images. © 2013 IEEE.


Takei S.,Toyama Prefectural University | Takei S.,Osaka University | Murakami G.,Richell Co. | Mori Y.,Toyama Prefectural University | And 7 more authors.
Journal of Micro/Nanolithography, MEMS, and MOEMS | Year: 2013

Nanopatterning of an ecofriendly antiglare film derived from biomass using an ultraviolet curing nanoimprint lithography is reported. Developed sugar-related organic compounds with liquid glucose and trehalose derivatives derived from biomass produced high-quality imprint images of pillar patterns with a 230-nm diameter. Ecofriendly antiglare film with liquid glucose and trehalose derivatives derived from biomass was indicated to achieve the real refraction index of 1.45 to 1.53 at 350 to 800 nm, low imaginary refractive index of <0.005 and low volumetric shrinkage of 4.8% during ultraviolet irradiation. A distinctive bulky glucose structure in glucose and trehalose derivatives was considered to be effective for minimizing the volumetric shrinkage of resist film during ultraviolet irradiation, in addition to suitable optical properties for high-definition display. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.


Takegami Y.,University of Toyama | Yokoyama Y.,Machinery and Electronics Research Institute | Norisugi O.,University of Toyama | Nagatsuma M.,University of Toyama | And 7 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2011

Poly(N-isopropylacrylamide) (PNIPAAm) is the most popular thermosensitive polymer, and exhibits a low critical solution temperature of approximately 32°C. This study aimed to examine the usefulness of new cooling sheets, which are manufactured using a thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) material. We prepared cooling-hydrogel sheets containing PNIPAAm (PNIPAAm sheet). We measured the skin temperature on the arms of the subjects using a thermograph and compared the usefulness of the PNIPAAm sheet and a control cooling-hydrogel sheet that did not contain the PNIPAAm mixture. Thermographic measurements obtained 40 min after the treatment with the cooling sheets showed the skin temperature of the subjects treated with the 3.% (w/w) PNIPAAm sheets to be significantly lower than that of the subjects treated with the control cooling-hydrogel sheet (p < 0.005). Compared with the control sheet, the cooling effect of the new PNIPAAm sheet also persisted for a longer duration (up to 100 min). The PNIPAAm sheets exhibited excellent cooling effects. This sheet may therefore be useful for lowering the body temperature of patients with high-grade fever, such as fever due to influenza infection. © 2011 Wiley Periodicals, Inc.


Sayama T.,Machinery and Electronics Research Institute | Tsuritani H.,Machinery and Electronics Research Institute | Okamoto Y.,Cosel Co. | Kinoshita M.,Toyama Prefectural University | Mori T.,Toyama Prefectural University
ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels | Year: 2015

Fatigue damage in solder joints is one of the most significant factors in the failure of electronic components. Accordingly, many research studies on the fatigue lifetime evaluation of solder joints have been undertaken to improve the reliability of the components. The authors have devised a lapjoint specimen with high stiffness fixtures in order to carry out shear fatigue testing on thin solder joints, which have thickness of a few hundred μm and are manufactured via a reflow process similar to that used in actual printed circuit boards (PCBs). In this work, using the developed lap-joint specimen, the fatigue properties, including crack initiation and propagation of Sn- 3.0Ag-0.5Cu solder joints were evaluated under low cycle shear loading conditions with creep deformation. The lap-joint specimen was fabricated by the reflow soldering of two copper adherend, and was assembled with high stiffness loading fixtures. The dimensions of the solder joint are 4 mm (length) × 2 mm (width), with a thickness ranging from 100 to 400 μm. In the shear fatigue test, under the assumption of thermal loading conditions of actual PCBs, the inelastic strain amplitude and total strain rate were set to from 0.5 to 1.2 % and 1×10-4 s-1, respectively. In addition, the fatigue crack initiation lifetime is defined as the number of cycles N20% at which the load amplitude has decreased by 20 % from the initial value. As the first study result, the experimental relations between the fatigue crack initiation lifetime and the inelastic strain range were obtained. Next, in order to apply the experimental data to the evaluation of fatigue crack initiation in actual solder joints via finite element analyses, the lifetime data were related to the calculated inelastic strain at the interface corners of the solder joint of the specimen, where fatigue cracks initiate due to strain concentration. Finally, assuming that the reduction of the load amplitude corresponds linearly to the fatigue crack length, the experimental relations between the fatigue crack propagation rate and J-integral range were also obtained. The experimental data are regarded to be valid, given a comparison to other crack propagation curves for solder obtained by tensile cyclic loading of a flat specimen with a center crack. Consequently, the developed lap-joint specimen with high rigidity is effective for acquiring the material properties regarding fatigue crack initiation and propagation in actual thin solder joints. © Copyright 2015 by ASME.


Okamoto Y.,COSEL Co. | Takayanagi T.,COSEL Co. | Sayama T.,Machinery and Electronics Research Institute | Ejiri Y.,Toyama Prefectural University | And 2 more authors.
Proceedings of the ASME InterPack Conference 2009, IPACK2009 | Year: 2010

Thermal fatigue damage of solder joints is believed to be closely related to microstructure evolution, that is phase growth. In the previous researches, the authors have obtained the following results. The phase growth is characterized by phase growth parameter S, which is defined as average phase size to the 4th power, and proceeds such that S increases proportional to the number of thermal cycles. And a simple power low relation was found between average number of cycles to thermal fatigue crack initiation lifetime and average increase in the phase growth parameter per cycle ΔS. In this paper, in order to apply the relation to the evaluation of the crack initiation lifetime in actual solder joints, thermal cycle tests were carried out by using fabricated printed circuit board (PCB) on which chip resistors were mounted by Sn-3.0Ag-0.5Cu solder. Periodically, the specimen was taken out from thermal shock chamber and the phase growth of the β Sn phase in the solder joints was observed by scanning electron microscope (SEM). The following results were obtained. The microstructure observation showed that the lifetime prediction based on the phase growth parameter measured by the data in low cycles of 20 to 100, was within the range of 90% confidence limits of the experimentally determined lifetime. Therefore, the estimation method by the phase growth parameter can be applied to the lifetime prediction of solder joint with sufficient accuracy. Copyright © 2009 by ASME.

Loading Machinery and Electronics Research Institute collaborators
Loading Machinery and Electronics Research Institute collaborators