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Additive manufacturing of copper enables enhanced design freedom which allows for improved performance of components in thermal management and electrical applications. Joining via soldering provides ideal electrical and thermal connections, but the solderability of complex additively manufactured surfaces is poorly understood. In the present work, the solderability of nominally pure copper coupons manufactured by three additive manufacturing techniques (laser powder bed fusion, laser engineered net shaping, and bound powder extrusion) was experimentally assessed using the wetting balance technique and pin pull testing. Coupons produced by each method were tested as built and after surface modification by dry electropolishing. Contact angles and wetting times were calculated from wettability testing. Peak tensile loads required to remove pins soldered to coupons were also recorded for each surface condition. The dipped coupons and solder joint fracture surfaces were examined with optical and scanning electron microscopes. It was found that nonuniform wetting and excessive wicking of solder can result in weak joints, and surface modification positively affected overall solderability in all cases. All surfaces were shown to be wettable, but bound powder extrusion was found to produce the most solderable copper surfaces among the additive manufacturing methods tested. [ABSTRACT FROM AUTHOR]

Zr55Al10Ni5Cu30 metallic glass (bulk amorphous alloy) has unique properties, such as highly resistant to corrosion, high strength and elastic deformation over whole deformation range, so that it is expected to be the next-generation engineering materials. To develop further industrial applications, joining technology for the metallic glass is necessary. In this study, surface modification with Cu on Zr55Al10Ni5Cu30 metallic glass using laser cladding and the consequent solderability improvement were studied. As a result, the interface between Cu foil and Zr55Al10Ni5Cu30 metallic glass were continuously welded by the laser cladding. XRD showed that there are no crystalline and reaction layer in the weld interface. Furthermore, it was found, by XPS, that the Cu-modified layer on the Zr55Al10Ni5Cu30 metallic glass surface inhibited the formation of a strong oxide film. Consequently, the Cu-modified layer played an important role in improving the solderability to the Zr55Al10Ni5Cu30 metallic glass. [ABSTRACT FROM AUTHOR]

This study investigated the influence of Sb addition on the microstructure, thermal behavior, mechanical properties, and interfacial evolution of SAC305-2Bi-xSb/Cu solder joints. Compared with the SAC305-2Bi alloy, the melting temperature and pasty range slightly increased with the increasing of Sb content from 0.2 to 2.0 wt.%, while the undercooling temperature decreased. The research revealed that with the addition of Sb element, the grain size of β-Sn is refined. When the content of Sb is 0.5 wt.%, the grain size of β-Sn reached minimum (19.91 μm). Compared to the SAC305-2Bi alloy, the ultimate tensile strength of SAC305-2Bi–2Sb alloy is increased by 30.10%, contributed to the Sb solid solution strengthening effect and the refinement of β-Sn. With the addition of Sb, the thickness and growth rate of the interface is reduced gradually. The uniform solution of Sb and Sn can significantly inhibit the diffusion rate of Cu atoms and Sn atoms at the interface. The SAC305-2Bi-xSb alloy system has low melting temperature, superior mechanical properties, and reliable solder joints for service. Therefore, it is a potentially reliable lead-free solder for high-stability connections in automotive electronics, communications electronics, and medical devices.

This article presents Cu/diamond composite coatings produced by electrochemical reduction on steel substrates and a comparison of these coatings with a copper coating without diamond nanoparticles (<10 nm). Deposition was carried out using multicomponent electrolyte solutions at a current density of 3 A/dm2 and magnetic stirring speed of 100 rpm. Composite coatings were deposited from baths with different diamond concentrations (4, 6, 8, 10 g/dm3). This study presents the surface morphology and structure of the produced coatings. The surface roughness, coating thickness (XRF), mechanical properties (DSI), and adhesion of coatings to substrates (scratch tests) were also characterized. The coatings were also tested to assess their solderability, including their spreadability, wettability of the solder, durability of solder-coating bonds, and a microstructure study. [ABSTRACT FROM AUTHOR]

The concept of solderability is rigorously defined, accompanied by the proposal of quantitative criteria for its assessment. A comprehensive categorization of solderable materials into three distinct groups—namely, easily solderable, moderately solderable, and unsolderable—is proposed based on solderability parameters. Practical recommendations are given for the effective deployment of solderability testing methodologies across a spectrum of materials and electronic components. Detailed expositions are offered on the methods employed in the evaluation of solderability, encompassing solder immersion, measurement of solder spreading area, and assessment of capillary penetration into gaps. Schematic representations of these evaluation techniques, alongside descriptions of the requisite apparatus for their implementation, are presented. Furthermore, tabulated data on the solder spreading factors for diverse categories of chemical and electroplated coatings, including hot tinning, are given. Prolonged storage may lead to the formation of oxide films on the surface of coatings, thereby deteriorating solderability. To enhance the quality of electroplated coatings, it is recommended to employ periodic currents in nonstationary electrolysis modes during the deposition of electroplated coatings. [ABSTRACT FROM AUTHOR]

Determination of the physico-chemical interactions between liquid and solid substances is a key technological factor in many industrial processes in metallurgy, electronics or the aviation industry, where technological processes are based on soldering/brazing technologies. Understanding of the bonding process, reactions between materials and their dynamics enables to make research on new materials and joining technologies, as well as to optimise and compare the existing ones. The paper focuses on a wetting force measurement method and its practical implementation in industrial applications. Soldering simulation is a process in which simulation tools are used to model and simulate soldering processes. With simulation, different soldering methods and parameters can be tested to identify the best approach and minimize the risk of errors and failures in the real process. Soldering simulation can be used to optimize the soldering process and increase productivity, as well as to train personnel. [ABSTRACT FROM AUTHOR]

In this work, SnBiAg-xSb solder alloys (where x = 0, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, and 2.5 wt.%) were prepared by compression and annealing treatment following water cooling. The microstructure of the SnBiAg-xSb alloy became finer due to the addition of a small amount of Sb. When the Sb content exceeded 1.0 wt.%, the effect of grain refinement decreased, and the grain gradually became coarser with the addition of Sb. As the Sb content increased, the tensile strength of SnBiAg-xSb solder alloys gradually increased while elongation decreased, which was attributed to the solution strengthening of Sb and subsequent microstructural changes. SnBiAg-0.5Sb showed the best elongation at break, reaching a value of 119.12%. Sb increased the starting temperature of the solder during solidification and cooling, expanding the range of the mushy temperature zone. The addition of a small quantity of Sb had a minimal effect on the solder's wettability. The bonding performance of SnBiAg-xSb solder joints before and after aging was studied, and it was found that SnBiAg-2.0Sb solder joints had the strongest bonding strength. [ABSTRACT FROM AUTHOR]

The growing need to use low-power and high-frequency signals for the high-speed transmission of large-capacity data is driving the demand for suitable printed circuit boards. Most printed circuit boards use Cu as a conducting material and require a surface finish that forms an organic or a metallic protective layer on the Cu surface to prevent Cu diffusion/oxidation. Metallic protective layers typically have a higher resistivity than Cu, resulting in significant signal transmission losses in the high-frequency range. For example, electroless Ni/electroless Pd/immersion Au (ENEPIG), a surface finish that forms a metallic protective layer, sequentially forms Ni-P, Pd-P, and Au layers on a Cu surface. Among these, the Ni-P layer is the main cause of signal transmission loss owing to its high resistivity. In this study, we developed immersion Ag/immersion Pd/immersion Au (ISIPIG), a cost-effective surface finishing process that does not form a Ni-P layer. ISIPIG effectively prevented the diffusion/oxidation of Cu and improved solder wettability while exhibiting a lower insertion loss and higher antenna efficiency than ENEPIG. Our results suggest that ISIPIG is a promising surface finishing process for applications that require the high-speed transmission of large-capacity data using low-power and high-frequency signals. [ABSTRACT FROM AUTHOR]

This article presents Cu/diamond composite coatings produced by electrochemical reduction on steel substrates and a comparison of these coatings with a copper coating without diamond nanoparticles (2 and magnetic stirring speed of 100 rpm. Composite coatings were deposited from baths with different diamond concentrations (4, 6, 8, 10 g/dm3). This study presents the surface morphology and structure of the produced coatings. The surface roughness, coating thickness (XRF), mechanical properties (DSI), and adhesion of coatings to substrates (scratch tests) were also characterized. The coatings were also tested to assess their solderability, including their spreadability, wettability of the solder, durability of solder-coating bonds, and a microstructure study.

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although Sn3.0Ag0.5Cu solder (SAC305) has higher reliability, there are a large number of harmful voids in solder joints. Larger voids can reduce thermal conductivity of solder joints. However, as a microstructure growth inhibitor, the influences of Ag nanoparticles on voids growth are not clear at present. Herein, we prove that Ag nanoparticles can increase SAC305 solderability, but promote voids growth. Ag nanoparticles and SAC305 solder paste were mixed by mechanical stirring for 0.5 h. Next, SAC305- x Ag _P ( x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5 wt%) was obtained. The results indicated that solder solderability was improved increasingly with Ag nanoparticles addition. The lower the amount of nanoparticles added, the greater the final loss. After being aged at 100 °C for 150 h, the voids stopped growing. Due to the violent reaction between Ag nanoparticles and flux, the final voids growth rate became faster, and the average voids size changed from 14.34% to 24.91%.

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Determination of the physico-chemical interactions between liquid and solid substances is a key technological factor in many industrial processes in metallurgy, electronics or the aviation industry, where technological processes are based on soldering/brazing technologies. Understanding of the bonding process, reactions between materials and their dynamics enables to make research on new materials and joining technologies, as well as to optimise and compare the existing ones. The paper focuses on a wetting force measurement method and its practical implementation in industrial applications. Soldering simulation is a process in which simulation tools are used to model and simulate soldering processes. With simulation, different soldering methods and parameters can be tested to identify the best approach and minimize the risk of errors and failures in the real process. Soldering simulation can be used to optimize the soldering process and increase productivity, as well as to train personnel.

[Display omitted] • Effect of plasma treatment and six different fluxes on solder wetting was studied. • Copper samples treated by N 2 /H 2 plasma exhibited excellent wetting with any flux. • Even expired fluxes can be successfully used for soldering of plasma-treated connectors. • Flux cannot be omitted from soldering due to the remaining thin oxide/organic layer. • Plasma treatment allows much less active flux to be used in the soldering process. To enhance the solderability, highly active fluxes are commonly employed in lead-free soldering. However, there are industry-wide efforts to use less active fluxes to avoid possible issues associated with corrosion processes and minimize subsequent cleaning processes, thereby reducing potential environmentally harmful waste. Therefore, in this study, the effect of the plasma treatment (N 2 /H 2 97:3) on the wettability of the soldered surface (copper connectors) was investigated. Wettability measurements were conducted using SAC305 solder alloy and six different fluxes. The wetting balance test revealed a significant improvement in wetting for all tested fluxes, regardless of their composition. On the other hand, non-wetting occurred when no flux was applied to the plasma-treated surface, attributed to a thin residual oxide layer detected by X-ray photoelectron spectroscopy. Thus, the plasma treatment of the surface supports the flux effect, which cannot be entirely omitted from the soldering process. However, incorporating plasma treatment in the soldering process allows for the use of much less active or even expired fluxes. [ABSTRACT FROM AUTHOR]

In the present work, the effects of Bi addition on the microstructure, solderability, and mechanical properties of Sn-Zn-Cu lead-free solder were studied. The composition of Sn-Zn-Cu-Bi solder was designed by the cluster-plus-glue-atom (CPGA) model. The results reveal that with the increase of Bi content, the tensile strength of the alloy increased from 94.4 MPa to 131.3 MPa. Still, the elongation decreased, and the fracture mode changed from ductile to brittle, which was because the excessive hard and brittle Bi particles precipitated significantly reduce the ductility of solder. With increasing Bi content, the alloy wettability became better, and the spreading area increased from 52.92 mm2 to 59.09 mm2, which may be because the addition of Bi reduced the surface tension and melting point of the solder. Furthermore, the appropriate addition of Bi promoted the uniform and smooth growth of the intermetallic compound (IMC) layer at the Sn-Zn-Cu-Bi/Cu soldering interface, which was beneficial to improve the reliability of the soldering interface. Results demonstrate that Sn7.98Zn0.68Cu (wt.%) alloys with a Bi content of 2.2 wt.% exhibited better comprehensive properties. The findings have important implications for the development of a new Sn-Zn series low-temperature lead-free solder. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 °C. The solder consists of a tin matrix where the Ti6(Sb,Sn)5 and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33° was obtained in a vacuum at the temperature of 950 °C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi2 and Ti3Ni5Si6 phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni3Sn2 and Ni3Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 °C. [ABSTRACT FROM AUTHOR]

The role of flux activators in flux formulation is to remove oxides from metal surface and, hence, allow the formation of metallurgical bond between metal substrate and solder alloy. However, flux activator in the no-clean flux residue on printed circuit board assemblies (PCBAs) affects the climatic reliability due to its hygroscopic and ionic behavior under humidity exposure. Four amino acids-based wave flux was investigated using wetting balance test and microscopy inspection, and the humidity effects of four amino acids were analyzed using electrochemical impedance spectroscopy (EIS) and chronoamperometry under various testing conditions. Water absorption and thermal degradation were analyzed using gravimetric method and Fourier-transform infrared spectroscopy (FT-IR). Combined results indicate that glutamine-based model flux obtained superior solderability for 96.5Sn-3Ag-0.5Cu (SAC 305) alloy due to suitable melting and activation temperature of amino group for the oxides removal. The robust humidity reliability of amino acids was dependent upon relative high deliquescence point and low moisture absorption under harsh climatic conditions. [ABSTRACT FROM AUTHOR]

We report on structuring copper representing soldering pads of printed circuit boards by laser-induced periodic surface structures. Femtosecond laser radiation is used to generate low spatial frequency laser-induced surface structures, having a spatial period of 992 nm and a modulation depth of 120 nm, respectively. The slump of screen-printed solder paste is measured to compare the solder coverage on the pads after the solder process on a hot plate. A comparative study of the coverage of solder paste on a fresh polished pad, a pad stored for two weeks, and femtosecond laser-structured pads reveals the improved wettability of structured pads even after storage. In addition, leaded and lead-free solder pads are compared with the particular advantages of the solder-free pad when periodically laser structured. Our findings are attributed to two major effects: namely, the increase of the surface area and the improved surface chemical wettability. Overall, the application of laser-induced periodic surface structures helps to reduce the demand of lead-based solder in the electronic industry and provides a feasible method for a fast and spatial selective way of surface functionalization. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 °C. The solder consists of a tin matrix where the Ti6(Sb,Sn)5 and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33° was obtained in a vacuum at the temperature of 950 °C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi2 and Ti3Ni5Si6 phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni3Sn2 and Ni3Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 °C.

A novel high-temperature-resistant organic solderability preservative (OSP) applied to printed circuit board (PCB) was prepared. The effects of OSP composition, temperature, and treatment time on the thickness and uniformity of OSP film were studied, and the performance of the OSP in industrial application was evaluated. The OSP composition and operation conditions were optimized as follows: 2-(2,4-dichlorobenzyl)benzimidazole (bmz24) 2.5 g/L, formic acid 20 g/L, acetic acid 60 g/L, n-heptanoic acid 0.50 g/L, copper(II) acetate 2 g/L, pH 3.1, temperature 46 °C, and time 75 s. A high-temperature-resistant OSP film with uniform thickness could be formed under the said conditions. [ABSTRACT FROM AUTHOR]

The connection between diamond and other materials is always a key problem for its applications in microwave energy transmission windows. In this paper, a TiZrNbTa high-entropy alloys (HEAs) coating was prepared on single-crystal diamond (SCD) sheet by magnetron sputtering and post-annealing for enhancing the connection strength between diamond and Cu. Thereafter, the TiZrNbTa modified SCD was brazed onto a Cu sheet by vacuum brazing using Cu Sn Ti alloy as solder. The results showed that TiZrNbTa HEA coating with nanocrystalline structure and single orientation of (111) was formed after magnetron sputtering. The annealing treatment transformed the single (111) orientation to multi-orientations including (110), (200) and (211), and significantly enhanced the coating adhesion. The shear strength of the SCD/Cu joint with annealed TiZrNbTa HEA coating is about 102.6 MPa, which is about 49 % higher than that of the joints without HEA coating. The annealed TiZrNbTa coated joints mainly fracture in the deep inner of the solder. The fracture modes include the ductile fracture of Cu solid solution and the brittle fracture of CuSn 3 Ti 5 compounds. This is much better than the un-coated joints and the as-deposited TiZrNbTa coated joints, which mainly fracture at the SCD/solder interface (the un-coated joints), the TiZrNbTa/solder interface and in the solder close to the TiZrNbTa coating (the as-deposited TiZrNbTa coated joints). In conclusion, preparing TiZrNbTa HEA coating on the diamond surface by magnetron sputtering combined with post-annealing is very effective in improving the weldability of SCD. [Display omitted] [ABSTRACT FROM AUTHOR]

We report on structuring copper representing soldering pads of printed circuit boards by laser-induced periodic surface structures. Femtosecond laser radiation is used to generate low spatial frequency laser-induced surface structures, having a spatial period of 992 nm and a modulation depth of 120 nm, respectively. The slump of screen-printed solder paste is measured to compare the solder coverage on the pads after the solder process on a hot plate. A comparative study of the coverage of solder paste on a fresh polished pad, a pad stored for two weeks, and femtosecond laser-structured pads reveals the improved wettability of structured pads even after storage. In addition, leaded and lead-free solder pads are compared with the particular advantages of the solder-free pad when periodically laser structured. Our findings are attributed to two major effects: namely, the increase of the surface area and the improved surface chemical wettability. Overall, the application of laser-induced periodic surface structures helps to reduce the demand of lead-based solder in the electronic industry and provides a feasible method for a fast and spatial selective way of surface functionalization.

Attempts to improve the application performance of noncontact silver (Ag) screen-printing paste for crystalline silicon solar cells, especially in terms of solderability, depend heavily on controlling the properties of the glass additive therein. Taking PbO–B2O3–SiO2–RxOy glasses as an example, this work demonstrates an improvement in the Ag paste due to the RxOy (e.g., ZnO, Bi2O3, Al2O3, and MgO) component. The RxOy components were found to help improve the sintering compactness of the Ag paste. The inclusion of the different RxOy components resulted in obvious differences in the soldering state of the sintered Ag grid. Microscopic observations revealed that the soldering state was related to the covering of the solder on the Ag grid and the growth rate of the intermetallic compound Ag3Sn during soldering. Comparatively, the sintered Ag grid was soldered more firmly when the glass containing the Bi2O3 or Al2O3 component was used in the Ag paste. This is due to the higher coverage of solder on these Ag grids and the appropriate growth rate of Ag3Sn. Considering these findings, the functions of the RxOy components are discussed comprehensively. [ABSTRACT FROM AUTHOR]

There are numerous substrates that are electroplated in electronic industry to use in electronic devices. Nickel–Cobalt (Ni–Co) is one of the substrates that is used in the integrated circuits for telecommunication. The substrate is needed to prepare before electroplating of which pre-cleaning is of paramount importance. The substrate must be cleaned to remove grease, oil, etc. from the surface. Moreover, the gold contaminant on the surface of Ni–Co substrate is transformed to gold oxide during heat treatment, which is a prerequisite step before electroplating. It was observed that standard pre-cleaning procedure practiced in the electronic industry cannot remove the oxide contaminant. Fairly controlled uniform thickness can be achieved by proper control of electroplating parameters. However, the defects generated on plated substrate cannot be eliminated by controlling electroplating parameters. It was found that pre-cleaning of substrate played an important role to eliminate the contaminants. Poor adhesion of plating materials, blistering, skip plating, plate flakes, pitting are a few common plating defects which result in poor solderability. In this review, electroplating and its defects and minimisation of defects are discussed. Surface preparation before plating is crucial in this respect. Defect-free substrate results in efficient solderability, consequently reducing rejection rate of substrate and increasing the yield, thereby, making the process cost effective. [ABSTRACT FROM AUTHOR]

The present investigation explores the influence of Ni and Bi on the solderability of Sn-0.7Cu solder coatings. The minor addition of 0.05 wt.% Ni into the Sn-0.7Cu solder alloy results in an improvement in the wettability based on dipping tests. The solderability investigation using a globule mode shows the influence of Ni and Bi on the interfacial intermetallic compound (IMC). The addition of Ni to a Sn-0.7Cu solder coating resulted in a (Cu,Ni)6Sn5 interfacial IMC, which enhanced the solderability performance during the globule test. With an increasing amount of Bi in the Sn-0.7Cu-0.05Ni-xBi solder ball, the surface energy of the solder alloy can be reduced, and this improves the solderability. The synchrotron micro-XRF results indicate that Ni is found in a relatively high concentration in the interfacial layer. Additionally, Bi was found to be homogenously distributed in the bulk solder, which improved solderability. [ABSTRACT FROM AUTHOR]

Magnesium alloys are promising as light materials, while their high chemical reactivity makes them difficult to be soldered. In this study, the AZ31B alloy was pretreated by zincification and coated by an electrodeposited Cu layer, and then soldered with Sn-58Bi solder in air furnace. The microstructure and properties of the AZ31B/Cu(Zn)/SnBi solder joints were characterized to evaluate the solderability of the Cu-coated Mg alloy and the influence of soldering on the Cu coating. It was found that the Cu coating is dense, and little defect exists along the Cu(Zn)/AZ31B interface. The soldering process has little negative effect on the bonding between the Cu coating and the AZ31B substrate, and the AZ31B/Cu(Zn)/SnBi solder joints of high metallurgical quality were obtained. Tensile fracture of the solder joint occurs mainly in the solder, with no peeling of the Cu coating. Under shear loading, cracks initiate inside the SnBi solder and the final fracture of the joint occurs around the Cu6Sn5/solder interface or along the Cu(Zn)/AZ31B interface. The tensile and shear strength of the AZ31B/Cu(Zn)/SnBi solder joints are close to that of the SnBi/Cu solder joints. It is demonstrated that the Cu-coated Mg alloy shows superior solderability and can be soldered by the Sn-based low-melting solder in air. [ABSTRACT FROM AUTHOR]

In this paper, solderability, microstructure and hardness of SAC0705-xNi solder joints on Cu and graphene-coated Cu (G-Cu) substrates were studied. As Ni content increases in the solder, the solderability improves gradually on both the Cu and G-Cu substrates. The solderability of SAC0705-xNi is better on G-Cu substrate than that on Cu substrate. The increasing Ni content in the solder has a positive effect on the microstructure refinement of both the kinds of substrates. Such effect is more significant on G-Cu substrate than that on Cu substrate. With the increase of Ni content, the thickness of the interfacial intermetallic compound (IMC) shows an increasing trend first and then decreasing trend on the two kinds of substrates. Since the graphene layer works as a diffusion barrier, the IMC on G-Cu is thinner than that on Cu substrate. The addition of Ni leads to the strengthening of the microstructure and thus increases the hardness of the solder bulks. [ABSTRACT FROM AUTHOR]

Electroless-plating and electro-plating have been used to deposit Cu-Ni-Au coating on diamond/Cu composites. Before electroless copper plating, pretreatment should be applied to the surface of composites by means of boiled HNO 3 etching, sensitization with SnCl 2 and activation with PdCl 2 . The influence of pre-treatment on the electroless copper plating and electroplating Ni/Au is studied in this paper. Scanning electronic microscope, energy dispersive spectroscopy and optical microscope are used to examine microstructure and morphologies of coatings. Results indicated that the uniform and tight bonded Cu/Ni/Au coating have been successfully deposited on the diamond/Cu composites. Meanwhile, high temperature baking, solder wetting and the polarization curve tests are used to evaluate the adhesion strength, solderability and corrosion resistance of Cu/Ni/Au coatings in detail. Investigated results indicated that diamond/Cu covered with Cu-Ni-Au coatings exhibited excellent solderability and mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the effects of Ag, Ni and Bi additions on the melting, solidification, fluidity and wetting behavior of Sn-0.7Cu base solder alloy are studied. The addition of a small amount of Ni reduces the undercooling and improves the feeding distance (fluidity length); however, Ni does not improve the wetting and the spreading performance. The effect of Ni on the fluidity length of Ag-containing Sn-0.7Cu (SAC alloy) is marginal. Bi and Ag both improve wetting performance and also lower the melting temperature; however, they do not improve the fluidity; instead, they reduce the maximum length of fluidity. [ABSTRACT FROM AUTHOR]

The effects of the plating current density ( j ) on the electroplated Cu microstructure, impurity distribution, and the solderability of the electroplated Cu were investigated. Analyses of electron backscatter diffraction and transmission electron microscopy showed that the Cu grain size ( D ) decreased from microscale to submicron-scale, and the predominant crystallographic orientation translated from [111]||ND + [101]||ND into [101]||ND (ND: Cu deposition direction) with increasing j . Time-of-flight secondary ion mass spectrometry analysis showed that the impurity content in the Cu platings (especially the Cl content) increased as a function of j . These investigations showed that j posed a significant influence on the characteristics of the electroplated Cu. Two intermetallic compound (IMC) species (η-Cu 6 Sn 5 and Cu 3 Sn) accompanied with some material defects (e.g., nanovoids and microcracks) formed at the solder/Cu pillar interface after reflow. The IMC (Cu 6 Sn 5 ) growth morphology and orientation, and the defect distribution were also strongly j -dependent. These j -dependent interfacial microstructures were closely related to different D and impurity contents of the Cu platings. The results of this study advanced our understanding of the effects of j on electrochemical metal deposition, and they were helpful in the development of the high-speed Cu electrodeposition technology. [ABSTRACT FROM AUTHOR]

• A solderable conductive adhesive is developed for screen-printing conductive patterns on textiles. • The paste remains good flowability at high filler loading and shows a great conductivity without sintering. • The printed conductive patterns have a thermal endurance and possess great wettability to solder melt. • The conductive adhesive provides good shear strength and peel strength with intermetallic layer between solder. • Screen-printed patterns on textiles show good fidelity and electrical interconnectivity with solder joints. Background: In recent years, electronic textiles (e-textiles) have attracted widespread attention due to their versatility, but still lack a good packaging technique. Soldering, one of the electronic packaging technologies, has been widely used to provide electronic joints with good electrical and mechanical properties. However, direct soldering on e-textiles has to overcome several problems, such as melting at high soldering temperature and non-solderability of printed conductive patterns. Methods: The thermal stability and wettability of the resin were enhanced by adjusting the formulation to provide a base polymeric adhesive material. The formulated polymeric resin was then mixed with 85 wt% metal fillers to reach good conductivity after curing. A surfactant was also added to enhance particle dispersion and lowered the paste viscosity to screen print complicated conductive patterns on textile materials. Significant findings: The printed thin film showed good solderability with a low wetting angle for solder melt. A layer of intermetallic compound (Cu 6 Sn 5) was found between solder and solderable patterns, which provided a great adhesion strength and peel strength on fabrics. Solder joints on the printed conductive adhesive also showed great shear strength. The solderable paste was printed into a heating grid on textiles to show good electrical interconnectivity with solder joints. In summary, this study provides a general guideline for the preparation of solderable paste and can be extended for other packaging applications in electronic textiles. [Display omitted] [ABSTRACT FROM AUTHOR]

Diamond-Cu composites have been considered to be the next generation of electronic packing materials. One of the key stumbles for such an application is the joining problem between diamond-Cu composites and other materials due to the poor wettability of the diamond particles in the composites. In order to overcome this hurdle, pure Cu powder was thermally sprayed onto diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process. Microstructure and some fundamental properties of the coating obtained were systematically investigated, and morphologies of the single splat deposited on the diamond-Cu substrate were also observed. The splats obtained have good adhesion with the substrate as fine particles flattened sufficiently, while the coarse particles were significantly deformed. The coating was quite dense with porosity lower than 1%, oxygen content under 0.5% and thermal conductivity about 266 Wm K and still remained on the diamond-Cu substrate after 50 thermal shock cycles between 300 °C and water bath at room temperature. Meanwhile, the solderability of the coating was significantly improved. Therefore, Cu coating deposited on diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process can be beneficial in electronic industry assisting with soldering and improved wettability for joining of other materials. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)