985 research outputs found
Modeling with structure of resins in electonic compornents
In recent years, interfacial fracture becomes one of the most important
problems in the assessment of reliability of electronics packaging. Especially,
underfill resin is used with solder joints in flip chip packaging for
preventing the thermal fatigue fracture in solder joints. In general, the
interfacial strength has been evaluated on the basis of interfacial fracture
mechanics concept. However, as the size of devices decrease, it is difficult to
evaluate the interfacial strength quantitatively. Most of researches in the
interfacial fracture were conducted on the basis of the assumption of the
perfectly bonding condition though the interface has the micro-scale structure
and the bonding is often imperfect. In this study, the mechanical model of the
interfacial structure of resin in electronic components was proposed.
Bimaterial model with the imperfect bonding condition was examined by using a
finite element analysis (FEA). Stress field in the vicinity of interface
depends on the interfacial structure with the imperfect bonding. In the front
of interfacial crack tip, the behavior of process zone is affected by
interfacial structure. However, the instability of fracture for macroscopic
crack which means the fracture toughness is governed by the stress intensity
factor based on the fracture mechanics concept.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Effect of the coastal conservation due to beach nourishment of Totori sand dune coast
Tottori Sand Dune Coast located at western part of Japan is a sandy beach with a length about 8km facing Sea of Japan. The coast has been eroded starting around 1940s and the beach nourishment project has been carried out to restore the shoreline since 2005 at Tottori Sand Dune Coast. In the project, the deposition sands at port and river mouth were transported to the erosional area and injected in the region of the offshore erosional area and the backshore area and the total volumes of the sand are about 400,000m3 from 2005 to2011. However the effects of the project are not clarified and the detailed examination is not performed. The purpose of this study is to investigate the movement of the injected sand and the effect of the beach nourishment. In this study, using the bottom sounding data from 2002 to 2011, the sand volumes were estimated and the shoreline changes were investigated. Also, at the Tottori Port adjacent to the Coast, the amount of the sediment is estimated as well as Tottori Sand Dune Coast. From these analyses, the beach nourishment are effective and the large amount of the sediment placed at land area restored the shoreline quickly
Reliability Evaluation Method for Electronic Device BGA Package Considering the Interaction Between Design Factors
The recent development of electric and electronic devices has been
remarkable. The miniaturization of electronic devices and high integration are
progressing by advances in mounting technology. As a result, the reliability of
fatigue life has been prioritized as an important concern, since the thermal
expansion difference between a package and printed circuit board causes thermal
fatigue. It is demanded a long-life product which has short development time.
However, it is difficult because of interaction between each design factor. The
authors have investigated the influence of various design factors on the
reliability of soldered joints in BGA model by using response surface method
and cluster analysis. By using these techniques, the interaction of all design
factors was clarified. Based upon the analytical results, design engineers can
rate each factor's effect on reliability and assess the reliability of their
basic design plan at the concept design stage.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
New Reliability Assessment Method for Solder Joints in BGA Package by Considering the Interaction between Design Factors
As the integration and the miniaturization of electronics devices, design
space become narrower and interactions between design factors affect their
reliability. This paper presents a methodology of quantifying the interaction
of each design factor in electronics devices. Thermal fatigue reliability of
BGA assembly was assessed with the consideration of the interaction between
design factors. Sensitivity analysis shows the influence of each design factor
to inelastic strain range of a solder joint characterizing the thermal fatigue
life if no interaction occurs. However, there is the interaction in BGA
assembly since inelastic strain range depends on not only a mismatch in CTE but
also a warpage of components. Clustering can help engineers to clarify the
relation between design factors. The variation in the influence was taken to
quantify the interaction of each design factor. Based on the interaction,
simple evaluating approach of inelastic strain range for the BGA assembly was
also developed. BGA package was simplified into a homogeneous component and
equivalent CTE wascalculated from the warpage of BGA and PCB. The estimated
equation was derived by using the response surface method as a function of
design factors. Based upon these analytical results, design engineers can rate
each factor's effect on reliability and assess the reliability of their basic
design plan at the concept design stage.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Swelling of acetylated wood in organic liquids
To investigate the affinity of acetylated wood for organic liquids, Yezo
spruce wood specimens were acetylated with acetic anhydride, and their swelling
in various liquids were compared to those of untreated specimens. The
acetylated wood was rapidly and remarkably swollen in aprotic organic liquids
such as benzene and toluene in which the untreated wood was swollen only
slightly and/or very slowly. On the other hand, the swelling of wood in water,
ethylene glycol and alcohols remained unchanged or decreased by the
acetylation. Consequently the maximum volume of wood swollen in organic liquids
was always larger than that in water. The effect of acetylation on the maximum
swollen volume of wood was greater in liquids having smaller solubility
parameters. The easier penetration of aprotic organic liquids into the
acetylated wood was considered to be due to the scission of hydrogen bonds
among the amorphous wood constituents by the substitution of hydroxyl groups
with hydrophobic acetyl groups.Comment: to be published in J Wood Science (Japanese wood research society
Electrochemical supercapacitor behavior of nanoparticulate rutile-type Ru1-xVxO2
ArticleJournal of Power Sources. 160(2):1480-1486 (2006)journal articl
Rbf1-independent termination of E2f1-target gene expression during early Drosophila embryogenesis
The initiation and maintenance of G1 cell cycle arrest is a key feature of animal development. In th
Evaluation Technique for The Failure Life Scatter of Lead-Free Solder Joints in Electronic Device
Recently, the electronic device equipment using a semiconductor is widespread to all industrial fields. Solder is used to mount electronic parts, such as resistors and capacitors, on printed-circuit boards in almost all electronic devices. However, since in many cases the thermal expansion coefficients of electronic parts and PCBs are different, cyclic thermal stress and strain causes solder fatigue and device failure. Especially in the power electronic module and car electric module, the evaluation of thermal fatigue life is important. It is understood that the fatigue life of some electronic devices shows large scatter in the thermal cycle test, even if their design is the same. The dispersion of design factors such as shape, size and material properties of solder joints is thought as one of these reasons. Moreover, in the case of chip components, it is thought that the interacting effect by the structural asymmetry due to the unbalance solder joints would influence reliability. At the same time, the changeover from eutectic Sn-Pb solder to lead-free solder has been driven by environmental concerns. Therefore, it cannot be disregard as the main factor of the reliability evaluation in the solder joints. In this study, how the dispersion of design factors and the interacting effect between the design factors influences the fatigue life in lead-free solder joint was investigated by the analytical approach. It is understood that the thermal fatigue life of solder joints can be estimated by the inelastic strain range obtained from the FEM analysis. Recently, it is demanded to evaluate the final failure life of electronic components. So, it is necessary to evaluate not only crack initiation but also crack propagation. In this study, crack propagation analysis was carried out by using a new approach and the failure life was evaluated on the basis of Manson-Coffin's law and Miner's rule. Moreover, sensitivity analyses were carried out to study the main effect of the dispersion of each factor on solder joints. And then, the interacting effect between the factors on the reliability was studied by considering the structural asymmetry due to the unbalanced solder joints. As a result, a practical evaluating technique for the failure life scatter of solder joints was proposed
K-ras mutation in the endometrium of tamoxifen-treated breast cancer patients, with a comparison of tamoxifen and toremifene
The putative presence of a mutation in codon 12 of the K-ras gene was investigated in the endometrium of tamoxifen (TAM) and toremifene (TOR)-treated breast cancer patients. DNA was extracted from fresh cytologic samples of the endometrium in 86 TAM and 21 TOR-treated breast cancer patients. Mutations were detected by enriched PCR and an enzyme-linked mini-sequence assay (ELMA). K-ras mutation was found in 35 TAM-treated endometrial samples, and in only one TOR-treated endometrium (P<0.003). In 24 premenopausal patients, K-ras mutation was found in seven (43.8%) of 16 patients with less than 47 months of TAM treatment, while none was found in eight patients with more than 48 months of TAM treatment (P<0.03). In 62 postmenopausal-amenorrheic patients, K-ras mutation was found in three (15.8%) of 19 patients with less than 23 months of TAM treatment, while it was found in 16 (61.5%) of 26 patients with 24–47 months of TAM treatment and nine (52.9%) of 17 patients with more than 48 months of TAM treatment (P=0.002). The presence of K-ras mutation is significantly influenced by the duration of TAM treatment and menstrual status of the patients. TOR may have a lower potential genotoxicity than TAM
Techniques of disinformation: constructing and communicating "soft facts" after terrorism
Informed by social media data collected following four terror attacks in the UK in 2017, this article delineates a series of “techniques of disinformation” used by different actors to try and influence how the events were publicly defined and understood. By studying the causes and consequences of misleading information following terror attacks, the article contributes empirically to the neglected topic of social reactions to terrorism. It also advances scholarship on the workings of disinforming communications, by focusing on a domain other than political elections, which has been the empirical focus for most studies of disinformation to date. Theoretically, the analysis is framed by drawing an analogy with Gresham Sykes and David Matza's (1957) account of the role of “techniques of neutralization” originally published in the American Sociological Review. The connection being that where they studied deviant behaviour, a similar analytic lens can usefully be applied to disinformation cast as “deviant” information
- …