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Molybdenum (Mo) coating was deposited on the diamond surface by vacuum micro-vapor deposition. Effects of deposition parameters on the formation of Mo coating on the diamond different crystal face was investigated. The mechanism of diamond metallization evolution, fracture mode and thermal conductivity of diamond/copper composites were discussed. It is shown that the coating of diamond particles is starting with point-like particles grew up to be continuous, dense spherical coating, and the compactness of the coating on diamond <100> facet always takes precedence over diamond <111> facet. The Mo coating on the diamond surface deposited at 1050 °C for 50 min shows the best quality. The fracture modes of Mo-coated diamond/copper composites are composed of diamond debonding from copper matrix, diamond transgranular fracture and copper ductile fracture, but some pores existed at the interfere, it concludes that the Mo2C prepare a Cu/Mo/diamondinterlayer between the diamond and copper matrix could improve the bonding between diamond and copper matrix, but the effect of Mo2C coating on strengthen the interfacial bonding is limited. The highest thermal conductivity of the composites achieved the value of 329 W/(m K). [ABSTRACT FROM AUTHOR]

Common 3-axis CNC milling machines are generally equipped with 2D tool radius compensation (2D-TRC), which can realize TRC function for the contours in three basic planes when flat end mills are used. The 2D-TRC function makes engineers to program according to the actual contour of a part, and avoids over-cut phenomenon. Unfortunately, the 2D-TRC is unsuitable for ball end mills (BEMs), especially in the situation of milling complex curves or surfaces. In this work, a new TRC named BEM-TRC is used for milling NURBS curve swept surfaces using BEMs based on 3-axis CNC milling machines. In BEM-TRC, the TRC of a BEM involves radial and axial compensation. The cutting point (CP), which is the tangent point between a BEM and a NURBS curve, is considered as a calculation basis point. After obtaining a CP on a NURBS curve using the equi-arc length bisection interpolation method, the cutter center point of a BEM is calculated through offsetting the CP the radius (r) distance of the BEM along its normal vector. Then the cutter location point of the BEM can be obtained according to the cutter center point. The CNC finishing program corresponding to the cutter location point can be obtained using Matlab software. The simulation based on VERICUT and machining based on a 3-axis milling machine verifies the effectiveness of the BEM-TRC. The over-cut phenomenon is avoided successfully when the BEM-TRC is used. [ABSTRACT FROM AUTHOR]

In order to extend the 2D-TRC (tool radius compensation) function of 3-axis CNC milling machines to ball end mills (BEMs), a new TRC named BEM-TRC is proposed to achieve successful milling of complex surfaces without over-cut. The implementation of the BEM-TRC for complex surfaces depicted in NURBS model is divided into three steps. The first one is to search the cutting point (CP) on a NURBS surface using equi-arc length interpolation in u or v direction. The second one is to accomplish BEM-TRC at the CP through offsetting the CP to the cutter center point (CCP) of a BEM along the normal vector at CP. The third one is to compute the cutter location point (CLP) of the BEM according to the BEM-CCP. The simulation and experiment verifies that the BEM-TRC is feasible and effective, and can avoid over-cut phenomenon successfully. The BEM-TRC extends the ability of the traditional 2D-TRC function, and makes 3-axis CNC milling machines to accomplish the milling process of complex NURBS surfaces. [ABSTRACT FROM AUTHOR]

ZnS ceramic has been extensively used in various optical applications, e.g., full-wave band infrared window. The attractiveness of this material is explained by its wider transmission radiation range and higher infrared transmittance. An infrared window has often to be bonded to the protective metal frame due to high risk of involving demanding operational conditions, e.g., a vibration. So, an innovative joining technique must be necessarily uncovered. The objective of this work was designed to use a low-temperature glass powder to directly solder/braze ZnS ceramics during the temperature range between 400 and 450 °C. Our hypothesis was that the mechanical strength between ZnS glass and PbO–B2O3–ZnO powder would be significantly enhanced by doping the solder/braze by PbTiO3 particles. The formed interfacial reaction layer consists of PbS and the uniformly dispersed PbTiO3 particles. A heuristic explanation of the bonding mechanism is offered, and it is found that the use of sintering remelting can reduce defects within the glass joints. Owning to the second-phase diffusion strengthening of PbTiO3 particles and an interfacial chemical bonding in the joint, the mechanical properties are enhanced. [ABSTRACT FROM AUTHOR]

It is commonly believed that silver nanowires transparent electrode is one of the promising substitutions of indium tin oxide. Silver nanowires transparent electrode has two important properties including high transparency and high conductivity. There are several articles reporting they have successfully fabricated high performance of nanowires electrode with high transmittance and high conductivity, however, those transparent electrodes usually have a poor uniformity, which limits the application of silver nanowires. This paper brings out a simple method to fabricate electrode, which has a high uniformity using Mayer rod coating, and dynamic heating, leading to 24 Ω/sq sheet resistance, 91% light transmittance. The research of this subject can expand the application range of silver nanowires electrode and further promote the development of flexible electronic devices. [ABSTRACT FROM AUTHOR]

ZnS has been widely used as infrared windows in defense applications and the ZnS glass with high purity has shown high transmittance in mid-infrared and near-infrared lights. The fabrication temperature of the ZnS ceramic was suggested to be reduced to avoid phase transformation of ZnS and sacrifice its good transparency. Similarly, the joining process of ZnS should be at a lower temperature. Traditionally, mechanical assembly and spicing techniques were used to assembly ZnS transparent windows with metal frames at the aircraft. Nevertheless, the assembly strength was still too low and might increase the risk for the safety of aircraft. Recently, low temperature bonding or soldering process has gradually become an opinion to reduce the safety risk. In this study, we utilized a pre-metallization method coating Ni–P on ZnS transparent ceramics and soldered with Sn–3Ag–0.5Cu at a low temperature. In this paper, we evaluated the solder wettability, bonding temperature, holding time and coating thickness of Ni–P layer in terms of the interfacial morphology and joining mechanism. Finally, the most failures of mechanical tests happened at Ni–P/ZnS interface due to long time reaction and weak interface coating forces between Ni–P/ZnS. [ABSTRACT FROM AUTHOR]

ZnS has been widely used as a material for windows in optical systems. This is because it has a good transmittance in both mid-infrared and far-infrared bands, a stable chemical performance, a moderate linear thermal expansion coefficient and an adequate mechanical strength. ZnS windows need the so-called splice technology implementation to satisfy the integrity of large size applications or special surface structures. Traditional ZnS light windows are mechanically assembled with metal frames. However, the strength of the large-size ZnS formed by mechanical assembly is low. Consequently, an adequate joining technology is needed to overcome the low splice strength and improve the mechanical strength of the assembly. In this paper, we proposed a pre-metallization method by using an electroless plating of Ni on ZnS surface. Subsequently, a low temperature joining by using a Sn63Pb37 solder was completed. By a study of the process and the corresponding mechanism of the electroless nickel plating, a Ni–P layer with a controllable P content and thickness has been formed, and a smooth surface and a good combination with ZnS has been obtained. The microstructure of the Sn63Pb37 and Ni–P/ZnS was analyzed, and the phase composition and element distribution within the joint were determined. The influences of process parameters on the microstructures of the joints have been explored, including the brazing temperature, the time of thermal energy preservation and the thickness of the coating. Finally, the shear strengths of joints under different imposed parameters were optimized leading to the peak soldering temperature of 250 °C and the dwell at the peak of 1 min. The fractures were along Ni–P/ZnS ceramic interface, therefore, a successfully low temperature joining process on ZnS ceramics using Ni–P plating and Sn63Pb37 solder had been performed. [ABSTRACT FROM AUTHOR]

In recent years, Moore's law had a remarkable effect on predicting the development of semiconductor technology. As the size of devices shrinks to micro scale or nano scale, Intel's newest 10-nm logic technology is scheduled to start product shipments before the end of 2017. Moore's law will not die out, as the research scale reaches the atomic scale, "new devices" and new interconnection methods are urgently needed. In this paper, based on emerging interconnection requirement, the contribution to the advanced electronic packaging containing novel nano-materials, such as the carbon nanotubes, nanoparticles sintering, interconnection of nano-solder, nano-silver and surface plasma nano-welding are discussed. For the next 5–10 years, two new types of interconnect solutions are gaining attentions: solder joint alternatives and Cu electrode alternatives. The former uses new materials such as graphene, carbon nanotubes and nanowires to replace traditional solder joints. The latter uses optical media to replace the traditional Cu metal. In general, advanced materials will make more and more outstanding contributions in the development of electronic packaging in the next 10–20 years. [ABSTRACT FROM AUTHOR]

Electrically conductive adhesives (ECAs) are mainly used in IC packaging, LED packaging and other electronic industry to replace the traditional soldering and lead-free solders, therefore, there is a constant need to improve the electrical conductive and mechanical property of ECAs. In this study, the electrical resistivity and shear strength of the modified nano-Ag coated Cu particles in ECA was investigated and compromised, in terms of filler contents, curing temperature and curing time. The conductive mechanism of the modified nano-Ag coated Cu particles in ECA was discussed as the filler content increased. Finally, the filler content was optimized by 23.5 vol% and 170 °C 100 min curing condition was selected to obtain the compromised property (5.159 × 10−6 Ω cm 6.121 MPa), which is better than the previous one (4.99 × 10−6 Ω cm, 4.406 MPa) at 200 °C. The tested data, as well as the failure mode and fracture interfaces, were carried out in this study. [ABSTRACT FROM AUTHOR]

The BiO-BO-SiO-ZnO glass system with addition of network modifier (BaO, CaO and FeO) were synthesized using the conventional melt quenching method. The effect of chemical compositions on the glass network structure, thermal properties, crystallization characteristics and electrical properties were systematically investigated. With rising the BiO content, the number of [BiO] and [BiO] units increases and a new bridging of Bi-O-B bond forms. Moreover, either the increase of BiO content or the decrease of SiO content induce a progressive conversion of [BO] into the [BO] unit. However, the influence of a network modifier on the conversion of [BO] to [BO] unit depends on the composition. An addition of network modifier helps stabilize the glass structure against a crystallization. A high content of BiO and ZnO promotes the formation of Bi-rich and Zn-rich crystals during heat-treated process, respectively. The Bi content of Bi-rich crystal increases and the Zn-rich crystal decomposes with increasing the heat-treated temperature. Both of the glass network structure and the formation of Bi-rich crystal in glass matrixes during testing process combine to determine the change rule of the CTEs (coefficients of thermal expansion). The variation of the T (glass transition temperature) only depends on the glass network structure. The dielectric constant of glasses without network modifier decreases with decreasing the BiO content. Moreover, an addition of network modifier could decrease the dielectric constant. Each glass offers a dielectric loss tangent below 0.005 and an electrical resistivity above 10 Ω cm. [ABSTRACT FROM AUTHOR]

The influence of the chemical composition of BiO-BO-SiO-ZnO glass brazes on (i) the microstructure, (ii) the mechanical and (iii) the dielectric properties of Li-Ti ferrite joints was systematically investigated. The Bi(TiFe)O whisker and a white block phase consisting of BiSiO and BiBO were observed in the joints of Li-Ti ferrite/Bi25-Ba and Li-Ti ferrite/glass brazes, respectively, containing a higher content of BiO. No crystalline phase was detected in the Li-Ti ferrite/Bi25 and Li-Ti ferrite/Bi20 joints. The joint strength reached the maximum of 48 MPa in the Li-Ti ferrite/Bi25-Ba couples. It is assumed that this is mainly due to the strengthening effect of Bi(TiFe)O whiskers. The bonding temperature (700°C) had little effect on the dielectric properties of Li-Ti ferrite. Moreover, compared to the Bi25-Ba glass brazes, the Bi25 and Bi20 glass brazes had a less pronounced influence on the dielectric properties of joints. Different glass brazes can be tailored to different requirements depending on specific application and joint property requirements. [ABSTRACT FROM AUTHOR]

Tin-bismuth solder has emerged as a promising lead-free alternative to tin-lead solder, especially for low-temperature packaging applications. However, the intrinsic brittleness of tin-bismuth solder alloy, aggravated by the coarse bismuth-rich phase and the thick interfacial intermetallic layer, notably limits the mechanical performance of the bonded joints. In this work, the microstructure and mechanical performance of solder joints were improved by adding 3.2 vol.% aluminum borate whiskers to the tin-bismuth solder alloy. This whisker-reinforced composite solder was fabricated through a simple process. Typically, 25- μm to 75- μm tin-bismuth particles were mixed with a small amount of aluminum borate whiskers with diameter of 0.5 μm to 1.5 μm and length of 5 μm to 15 μm. The addition of whiskers restrained the formation of coarse brittle bismuth-rich phase and decreased the lamellar spacing from 0.84 μm to 7.94 μm to the range of 0.22 μm to 1.80 μm. Moreover, the growth rate of the interfacial intermetallic layer during the remelting treatment decreased as well. The joint shear strength increased from 19.4 MPa to 24.7 MPa, and only declined by 4.9% (average, −5.9% to 15.8%) after the tenth remelting, while the shear strength of the joint without whiskers declined by 31.5% (average, 10.1-44.1%). The solder alloy was reinforced because of their high strength and high modulus and also the refinement effect on the solder alloy microstructure. [ABSTRACT FROM AUTHOR]