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

A method to combine additively manufactured substrates or foils and multilayer inkjet printing for the fabrication of sensor devices is presented. First, three substrates (acrylate, ceramics, and copper) are prepared. To determine the resulting material properties of these substrates, profilometer, contact angle, scanning electron microscope (SEM), and focused ion beam (FIB) measurements are done. The achievable printing resolution and suitable drop volume for each substrate are, then, found through the drop size tests. Then, layers of insulating and conductive ink are inkjet printed alternately to fabricate the target sensor structures. After each printing step, the respective layers are individually treated by photonic curing. The parameters used for the curing of each layer are adapted depending on the printed ink, as well as on the surface properties of the respective substrate. To confirm the resulting conductivity and to determine the quality of the printed surface, four-point probe and profilometer measurements are done. Finally, a measurement set-up and results achieved by such an all-printed sensor system are shown to demonstrate the achievable quality.

Hybrid Printing for the Fabrication of Smart Sensors

A great deal of attention has been attracted to the additive manufacturing technique of 3D printing in rapid prototyping of electronic packages. This technique enables fast and reliable production of complex structures with arbitrary configurations and possesses several advantages over the conventional manufacturing methods, such as mechanical machining and laser cutting. In addition, 3D printed packages can be considered as a try-out for the assessment of customized design prior to mass production, which will significantly reduce the expensive machining costs and material waste. This study proposes an innovative approach to construct simple radio frequency identification (RFID) package by integrating a surface acoustic wave (SAW) transponder in a 3D printed housing. On that account, an acrylate-type plastic SAW transponder housing was 3D-printed, and the corresponding wireless antenna and contact pads were produced via ink-jet printing with a silver nanoparticle (NP) ink. The proper functionality of the silver tracks was obtained by sintering the printed NPs using a photonic curing device. A flip-chip configuration has been pursued for connecting the chip pads to the corresponding pads on the housing. The performance of the package has been tested with a wireless reading unit via antenna-bridge for SAW transponders.

Printed SAW transponder package for rapid prototyping of electronic packages

Glass frit bonding is a widely used technology to cap and seal micro-electromechanical systems on the wafer level using a low melting point glass. Screen printing is the main method to apply glass frit paste on wafers. Screen printing of glass frit paste is usually performed on less sensitive, less critical wafers, normally the capping wafer, because screen printing is a rough process involving the mechanical contact of the screen printing mesh and the wafer. However, for some applications in which contactless patterning of glass frit materials on the device wafers are preferred (e.g., 3D topographies, micro-lens and optics integration) jet dispensing could be a promising approach. Consequently, in this study, wafer-level jetting of glass frit materials on silicon wafers was proposed and investigated. The jetting parameters such as jetting distance, power and temperature were optimized for a glass frit paste. Additionally, the effect of jetted pitch size on the bond-line thickness was assessed. The wafers with jetted glass frit pastes were conclusively bonded in low vacuum and characterized. As a single-step (non-contact) additive approach, the jet printing of glass frit was revealed to be a straightforward, cost-effective and flexible approach with several implications for hermetic packaging.

/pdf/glass-frit-jetting-for-advanced-wafer-level-hermetic-3v3hwdp6.pdf

Glass Frit Jetting for Advanced Wafer-Level Hermetic Packaging

Copper sinter paste has been recently established as a robust die-attach material for high -power electronic packaging. This paper proposes and studies the implementation of copper sinter paste materials to create top-side interconnects, which can substitute wire bonds in power packages. Here, copper sinter paste was exploited as a fully printed interconnect and, additionally, as a copper clip-attach. The electrical and thermal performances of the copper-sinter paste interconnections (“sinterconnects”) were compared to a system with wire bonds. The results indicate comparable characteristics of the sinterconnect structures to the wire-bonded ones. Moreover, the performance of copper sinterconnects in a power module was further quantified at higher load currents via finite element analysis. It was identified that the full-area thermal and electrical contact facilitated by the planar sinterconnects can reduce ohmic losses and enhance the thermal management of the power packages.

https://www.mdpi.com/1996-1073/14/8/2176/pdf

Sinterconnects: All-Copper Top-Side Interconnects Based on Copper Sinter Paste for Power Module Packaging

\n The trend toward heterogeneous integration of optoelectronic, electronic, and micromechanical components favors three-dimensional (3D) integration in which the components are not arranged side-by-side but rather in vertical stacks. This presents a particular challenge due to the fact that the stacked components have different geometric dimensions, and their contact surfaces are also dissimilar. Therefore, an intermediate substrate, the so-called interposer, with different formats (i.e., flip-chip, wire-bond, and hybrid flip-chip/wire bond) comes into play. Currently, the interposers are mainly made of silicon or glass, which incur huge additional costs to the packaged components. In this study, the unique advantages of additive manufacturing (AM) are exploited to realize organic interposers. The proposed interposers provide easy signal probing and flexible die-to-board integration in lower costs without any lithography process, drilling, plating, or any waste. Accordingly, the two state-of-the-art 3D printers (i.e., a monomaterial 3D printer and a bimaterial 3D printer) were utilized for the manufacturing of the interposer parts. The complementary circuitry for vias and through-holes was facilitated by also additive technologies, i.e., 2D-inkjet printing and microdispensing. Moreover, and to manifest the unique possibilities within AM for the next generation of interposers, two examples for 3D-printed interposers with incorporated added-features, i.e., pillars for flip-chip bonding and cavities for face-up die-attachment were realized. The assemblies were consequently assessed by electrical examinations. Conclusively, the main opportunities and challenges toward the full implementation of AM technology for the fabrication of organic interposers with added-features such as integrated multipurpose vias were discussed. Based on the results obtained from this study, it was found that bimaterial 3D printer was more efficient and powerful for the construction of interposers.

Ali Roshanghias

Papers

Hybrid Printing for the Fabrication of Smart Sensors

Printed SAW transponder package for rapid prototyping of electronic packages

Glass Frit Jetting for Advanced Wafer-Level Hermetic Packaging

Sinterconnects: All-Copper Top-Side Interconnects Based on Copper Sinter Paste for Power Module Packaging

Additive-Manufactured Organic Interposers