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

Emerging from 2D printed electronics, 3D printed electronics promise a break-through in additive manufacturing and prototyping of electronics. However, transferring the know-how from 2D flexible electronics to 3D parts with complex structures (e.g. internal vias and external interconnects) might not be a straightforward approach. As an example, the variation of light intensity with respect to the distance and angle of incidence casts doubt on the efficiency of the intense pulsed laser (IPL) as a robust sintering method for metallic traces in 3D printed bulk structures, whereas IPL is currently by far the most prevailing sintering technique for 2D printed flexible electronics. Sintering of metallic traces in 3D printed parts can be executed either as a sequential layer-by-layer printing and processing step (LP) or as a bulk post-processing step (BP). In the current study, a survey on the most common sintering strategies for inkjet printed silver nanoparticles was conducted, while the compatibility to 3D printed structures was brought into the focal point. To discover the capabilities and limitations of six sintering methods (i. e. IPL, ohmic curing, thermal heating, laser, atmospheric plasma and microwave sintering) for 3D printed electronics, a comparative study utilizing the same materials and diagnostic methods was pursued. The results revealed that for 3D functional parts, some of the sintering techniques can be considered as complementary methods for each other, whereas a few showed readily the potential to be adapted in 3D printed electronics production.

https://iopscience.iop.org/article/10.1088/2058-8585/aa8ed8/pdf

Sintering strategies for inkjet printed metallic traces in 3D printed electronics

To date, additions of different oxide nanoparticles is one of the most widespread procedures to improve the mechanical properties of metals and metal alloys. This research deals with the effect of minor ceramic nanoparticle additions (SiO2, TiO2 and ZrO2) on the microstructure and mechanical properties of Cu/solder/Cu joints. The reinforced Sn3.0Ag0.5Cu (SAC305) solder alloy with 0.5 wt.% and 1.0 wt.% of ceramic nanoparticles was prepared through mechanically stirring. The microstructure of as-solidified Cu/solder/Cu joints was studied using scanning electron microscopy. The additions of ceramic nanoparticles suppressed the growth of the intermetallic compound layer Cu6Sn5 at the interface solder/Cu and improved the microstructure of the joints. Furthermore, measurements of mechanical properties showed improved shear strength of Cu/composite solder/Cu joints compared to joints with unreinforced solder. This fact related to all investigated ceramic nanoinclusions and should be attributed to the adsorption of nanoparticles on the grain surface during solidification. However, this effect is less pronounced on increasing the nanoinclusion content from 0.5 wt.% to 1.0 wt.% due to agglomeration of nanoparticles. Moreover, a comparison analysis showed that the most beneficial influence was obtained by minor additions of SiO2 nanoparticles into the SAC305 solder alloy.

/pdf/morphology-and-shear-strength-of-lead-free-solder-joints-2oswvlztqr.pdf

Morphology and Shear Strength of Lead-Free Solder Joints with Sn3.0Ag0.5Cu Solder Paste Reinforced with Ceramic Nanoparticles

Impedance analysis for condition monitoring of single lap CNT-epoxy adhesive joint

https://iopscience.iop.org/article/10.1088/2058-8585/ab0cea/pdf

Inkjet printing and characterisation of a resistive temperature sensor on paper substrate

Melting temperatures of Sn–Ag–Cu (SAC) alloys in the Sn-rich corner are of interest for lead-free soldering. At the same time, nanoparticle solders with depressed melting temperatures close to the Sn–Pb eutectic temperature have received increasing attention. Recently, the phase stability of nanoparticles has been the subject of plenty of theoretical and empirical investigations. In the present study, SAC nanoparticles of various sizes have been synthesized via chemical reduction and the size dependent melting point depression of these particles has been specified experimentally. The liquidus projection in the Sn-rich corner of the ternary SAC system has also been calculated as a function of particle size, based on the CALPHAD-approach. The calculated melting temperatures were compared with those obtained experimentally and with values reported in the literature, which revealed good agreement. The model also predicts that with decreasing particle size, the eutectic composition shifts towards the Sn-rich corner.

Ali Roshanghias

Papers

Sintering strategies for inkjet printed metallic traces in 3D printed electronics

Morphology and Shear Strength of Lead-Free Solder Joints with Sn3.0Ag0.5Cu Solder Paste Reinforced with Ceramic Nanoparticles

Impedance analysis for condition monitoring of single lap CNT-epoxy adhesive joint

Inkjet printing and characterisation of a resistive temperature sensor on paper substrate

Sn–Ag–Cu nanosolders: Melting behavior and phase diagram prediction in the Sn-rich corner of the ternary system