다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

A review : On the development of low melting temperature Pb-free solders

Composite lead-free solders, containing micro and nano particles, have been widely studied. Due to grain boundary drag or Zener drag, these particles can refrain the solder microstructure from coarsening in services, especially for Cu6Sn5, Ag3Sn intermetallic compounds and the β-Sn phases. Due to dispersion hardening or dislocation drag, the mechanical properties of the composite solder alloys were enhanced significantly. Moreover, these particles can influence the rate of interfacial reactions, and some particles can transform into a layer of intermetallic compound. Wettability, creep resistance, and hardness properties were affected by these particles. A systematic review of the development of these lead-free composite solders is given here, which hopefully may find applications in microbumps to be used in the future 3D IC technology.

Structure and properties of lead-free solders bearing micro and nano particles

Considerable researches have been focused on zinc–iron (Zn–Fe) alloy coatings due to their superior characteristics among zinc alloy electrodeposits in recent years. The corrosion behavior of these coatings depends on the phase structure and morphology of the Zn–Fe deposits. In this work the effects of pulse plating variables such as current density, off-time, frequency and pulse modes on the morphology and phase structure of Zn–Fe deposits was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) analysis. The corrosion behavior of these coatings was measured by means of polarization curves and Neutral salt spray tests. It was shown that pulse reverse coatings exhibit excellent resistance to corrosion in comparison with normal pulse and direct current conditions.

The effects of pulse plating variables on morphology and corrosion behavior of Zn–Fe alloy coatings

The application of inkjet printing technology to electronic packaging has spurred intense interest since inkjet printing promises superior precision in dispensing of interconnects in a digital and non-contact manner at relatively high speed. Correspondingly, in this study, the advantages and challenges of employing inkjet printing as a means for dispensing die-attach materials for advanced electronic packaging applications are discussed. Recently Ag sinter paste has emerged as an attractive substitute for solders, especially for high-temperature applications. As an alternative to Ag paste, the feasibility of employing an inkjet-printable Ag ink as a novel die-attach material was investigated. Inkjet-printable Ag inks contain a lower amount of Ag in comparison to Ag pastes, enabling a jetting process due to a lower viscosity. Ag particle size and its configuration in an ink are also different from a paste. Consequently, the sinter bonding of the printed Ag die-attach at different temperatures (up to 400 °C) and pressures (up to 20 MPa) was studied. It was revealed that a consistent and crack-free bond-line was produced by inkjet printing. The mechanical properties of the assemblies were subsequently assessed by shear strength analysis.

https://link.springer.com/content/pdf/10.1007/s10854-018-9234-6.pdf

Sinter bonding of inkjet-printed Ag die-attach as an alternative to Ag paste

The increasing demand for miniaturization of electronic packages and assemblies necessitates tighter tolerances in dispensing interconnects and robotic control for placement In fact, due to increasing requirements in regards to cycle time and accuracy of interconnects (ie surface mount adhesives), contactless dispensing is constantly gaining acceptance In this study, inkjet printing of adhesives is proposed as a promising contactless methodology, in which a precise volume control of dispensed material is applicable Exploiting the drop-on-demand (DOD) process of inkjet printing, the deposition of non-conductive adhesives (NCA) by means of inkjet printer equipped with an industrial inkjet print-head were investigated Correspondingly, individual droplets of different kinds of NCA were jetted from small diameter vessels directly to a specified position on the substrate to create the bonding patterns for die-attachment The resulting die-attach was subsequently characterized, in terms of uniformity, thickness and flatness

Digital micro-dispension of non-conductive adhesives (NCA) by inkjet printer

In the quest of low-stress M(O)EMS packaging, in this study, low-temperature adhesive bonding methodologies facilitated by inkjet printing technology were investigated. M(O)EMS devices contain fragile components and are very susceptible to external damages as well as thermal stresses. As to alleviate these stresses, integration of M(O)EMS devices at low processing temperature have been one of the critical requirements in the development of MOEMS packages. Given that, room or low-temperature die-attachments by using UV-curing for transparent substrates or UV-assisted hybrid approaches such as B-staging and shadow curing for opaque substrates are gaining significance. Inkjet printing of these adhesives is proposed here as a promising technique for M(O)EMS die-attachment; while controlled amount of adhesives jetted by a digital printer can mitigate several bonding-induced defects. Bond-line engineering of M(O)EMS die-attachments via inkjet printing is also introduced and further discussed.

Inkjet printed adhesives for advanced M(O)EMS packaging

In this study the cross-sectional nanoindentation (CSN) technique has been employed to investigate the adhesion behavior of Titanium-Tungsten (TiW) thin films in various thicknesses on silicon substrate. Furthermore, the nanoindentation-induced blister (NIB) technique has been implemented on the same samples to evaluate the adhesion energy of the films with a different approach. The adhesion energy release rate of these thin films, derived by these two techniques, revealed a good agreement. Accordingly, the results show that as the thickness of the TiW layer increases, the adhesion toughness of the film decreases. It was suggested that three factors might be responsible for the superior adhesion strength of thin films with lower thicknesses: higher surface energy due to the smaller mean grain size; higher constraint from the substrate, which causes inferior fracture toughness of the coating and facilitates crack deflection from interface to surface; and, energy dissipation due to decohesion. The thickness dependency of the transition between delamination and decohesion mechanism in thin films has also been discussed and modelled.

https://iopscience.iop.org/article/10.1088/0022-3727/48/3/035301/pdf

Ali Roshanghias

Papers

The effects of pulse plating variables on morphology and corrosion behavior of Zn–Fe alloy coatings

Sinter bonding of inkjet-printed Ag die-attach as an alternative to Ag paste

Digital micro-dispension of non-conductive adhesives (NCA) by inkjet printer

Inkjet printed adhesives for advanced M(O)EMS packaging

Cross-sectional nanoindentation (CSN) studies on the effect of thickness on adhesion strength of thin films