Copper-phosphorus Alloys Research Articles

INVESTIGATION OF WAYS TO REMOVE OXIDE FILM FROM THE SURFACE OF METALS AND SOLDER MATERIALS IN THE SOLDERING PROCESS UNDER DIFFERENT CONDITIONS

The article considers important to study the issues of removal of oxide films from the surface of metals and solder materials and the increase of homogeneity of the space in the process of soldering under the active gas and vacuum conditions. Theoretical and experimental studies have shown that the process of self-fluxing is mainly associated with the reduction of adsorption forces, dispersion of oxide films and solubility in solder. Keywords: steel unit, copper-phosphorus alloy, active gas-vacuum, melting temperature, cracking, wetting, oxide film, self-fluxing, microstructure, hardening.

Influence of antimony on structure and mechanical properties of pre-eutectic copper-phosphorus alloys

Influence of antimony on structure and mechanical properties of pre-eutectic copper-phosphorus alloys

A reaction mechanism of atmospheric sintering for copper–phosphorus alloy electrode

In this study, we propose a reaction mechanism for atmospherically sintered copper-phosphorus (Cu–P) alloy electrodes which are expected to replace silver (Ag) electrodes. Structural analysis using transmission electron microscopy (TEM) has revealed that not only copper phosphide (Cu3P) but also copper phosphates of Cu2P2O7, Cu3(PO4)2 and Cu2PO4 distributed mainly at the P-concentrated region of the metallic part, where Cu3P distributed before sintering. In addition, the ordered superstructures which have a period based on the specific lattice spacing of Cu3P {002} were newly discovered. From structural analysis, we estimated the mechanisms comprised of the decomposition of Cu3P accompanied by a lack of Cu and P, then formation of metastable phases involving structural vacancies, and eventual transition to the copper phosphates. We also discussed another manner of forming the copper phosphates by the thermo-dynamical approach. Our results may provide a way to reduce the electrical resistivity of Cu-P alloy electrodes by controlling the structures including the deoxidized Cu.

Composition, Properties, Application, and Manufacturing Features of Binary Copper–Phosphorus Solders

The field of application is given for binary copper–phosphorus alloys in the metallurgical industry. Features of copper–phosphorus alloy structure are described. Binary copper–phosphorus solders produced in Russia and abroad are analyzed. Processing properties are provided for binary copper–phosphorus solders in relation to phosphorus content. Features of soldering with binary copper–phosphorus solders are provided. Characteristics of copper–phosphorus solder manufacture by domestic producers in the form of ribbon, bar, and wire are given. It is shown that during hot extrusion of copper–phosphorus alloys they develop superplastic flow. A mechanism is described for increasing the ductility of some copper–phosphorus alloys after thorough hot extrusion.

Analysis of the Production of Ribbons of Copper-Phosphorus Solder by the Lateral Flow of a Melt onto a Rotating Roller Mold

Copper-phosphorus solders in the form of ribbons with a phosphorus content of 5–8%, thickness of 0.2–1 mm, and width of 10–20 mm are widely used to secure windings and contacts in electrical machinery. Certain alloys which are based on the copper–phosphorus system and contain a nickel addition are made in the form of ribbons that are in the amorphous state and are less than 100 μm thick. They are used to solder copper alloys in high-precision assembly work. Since the processing properties of copper-phosphorus solders are usually equivalent to those of solders that contain silver, they are used in place of silver-bearing solders as long as the finished joints have the required service characteristics. One serious drawback of copper-phosphorus solders is the difficulty in shaping them, which is due to the presence of brittle copper phosphide in the structure (this phosphide can account for up to 50% of the volume of the solder in some cases). Some factories fill their own needs for solder by turning heated cylindrical ingots on a lathe to make chip-shaped ribbons thinner than 1 mm. Such a technology is obviously unsuited for industrial use. Thus, in international practice copper-phosphorus alloys are made either by hot deformation or by casting a melt on a rotating mold. To more thoroughly investigate copper-phosphorus solders and the entire process of making them by feeding a melt laterally onto a rotating roller mold, tests were performed with the use of different speeds of rotation of the mold. The speed of the mold affects the geometric parameters and structure of ribbons based on alloy PMF7. The results of the tests are reported in this article.

Effect of Glass Frits Amount on Atmospheric Sintering Behavior and Characteristics of Electrode Produced by Copper–Phosphorus Alloy

In this study, we evaluate the atmospheric sintering behavior and characteristics of electrodes produced by copper–phosphorus (Cu–P) alloy paste containing various amounts of B2O3–Bi 2O3–SiO2 glass frits. We demonstrate the need for a certain extent of glass frits to expand the applicable temperature for use of Cu–P alloy paste shifted to the higher temperature side, where commercial pastes for crystalline silicon (Si) photovoltaics are sintered, although the minimum electrical resistivity of the Cu–P alloy electrode increased by increasing the amount of glass frits. Based on the characteristics of the Cu–P alloy electrode, the need to expand the Cu crystal network and prevent the oxidization of generated Cu has emerged to reduce electrical resistivity. A crystalline BiPO4 was formed in the sintered Cu–P alloy electrode, which suggests a reaction between partially crystallized glass frits and P2O5 generated from Cu–P–O glass derived from the Cu–P alloy that has occurred. Subsequently, the sintering behavior of Cu–P alloy paste, including the glass frits, was discussed based on the results of X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy energy-dispersive X-ray spectroscopy, and electron energy loss spectroscopy.

Experimental Research Regarding the Development of Ecological CuSnP Powder

The paper presents research made to achieve environmental powder precursors from a CuSnP alloy, used in the manufacturing process of brazing materials, such as coated rods. The innovation of the paper consists in the elemental participation of the components in the new alloys, procedure that takes place in the alloying process, through coat conditions of the addition materials and by simultaneous obtaining the new precursors that fulfill high friability and deoxidation conditions of the participants in the brazing process. Developing the copper alloy batches is conditioned by a good protection to oxidation and gas absorption from the melting oven atmosphere. In order to protect the melt from the above mentioned phenomena’s we developed a slagging flux, boron-cryolithe type, which has melting proprieties below those of the copper phosphorus alloy, approx. 700°C. The load calculation was made based on the technical characteristics of the industrial base materials that were used, taking into account the loss coefficient of 5%. The melting, casting and cooling of the samples, dimensioned so they will be friable, was accomplished through classic procedures. The grinding of the sample, including the moistening thermic treatments, was achieved by experimental research, followed by calculations, based on the criteria of maximum yield for grinding. Estimating the sample friability, in the preliminary phase of the experimental determinations, was needed in order to restrain the testing domain, through structural and hardness analyses. The chemical composition of the samples was spectral determined on the copper and copper phosphorus programs.

Development of Innovative Application Films for Silicon Solar Cells Using a Copper–Phosphorus Alloy by an Atmospheric Sintering Process

In this paper we aim to develop copper (Cu)-based backside soldering tabs/pads for crystalline silicon (Si) solar cells using atmospheric sintering. In our previous study, we found that a Cu network can be formed in an application film (AF) by self-deoxidization when the AF consisting of copper-phosphorus (Cu-P) alloy paste is sintered in an atmospheric environment, and the Cu AF showed low electrical resistivity that satisfied the criteria for backside soldering tabs/pads. In this study, Si solar cells using Cu AF for front-side contacts were evaluated to confirm that Cu AF is applicable to Si solar cells in principle. The Cu-P alloy paste using Cu-7 mass%P particles was printed on an Si wafer and, finally, sintered at 640 °C in atmosphere. The resulting AF showed low electrical resistivity of 2.96 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> Ωcm. The solar cell using the Cu AF and conductive glass layer had conversion efficiency (η) of 6.6%. We demonstrated the need for a barrier layer to prevent the formation of Cu 3Si compound on the Si wafer surface when applying it to Cu AF on the solar cells. Our results may improve the potential for the widespread use of an atmospheric sintered Cu AF as backside soldering tabs/pads for Si solar cells.

Effects of Copper Powder Bearing Material Composition on Working Characteristics

Effects have been established for phosphorus and lead on the working characteristics of tinned bronze with high-speed operation (up to 20000 rpm or up to 2 m/sec) at low pressures (up to 2.0 MPa). It has been found that Cu - Sn - Pb - CP powder bearing material, where CP is a copper-phosphorus alloy, under such conditions has a lower coefficient of friction than does tinned bronze and a much higher wear resistance, while sliding bearings based on it have high working life. A microheterogeneous structure is formed in this material: an α-solid solution of tin in copper, along the boundaries of which there is uniformly distributed a strengthening phase (network of copper phosphide Cu3P with inclusions of the phosphide eutectic Cu3P + Cu3Sn + (Cu - Sn), and there are lead inclusions at the grain boundaries intersections. This material has very good tribotechnical characteristics at high rotation speeds and low pressures and also low coefficient of friction, low wear, and consequently long working life of bearings made of it.

A thermodynamic study of dephosphorization using BaO-BaF2, CaO-CaF2, and BaO-CaO-CaF2 systems

Phosphorus partition ratios between BaO-BaF2 fluxes and copper-phosphorus alloys have been measured as a function of slag composition at 1400 °C. A molybdenum sleeve has been used to avoid contact between the slag and the crucible in order to prevent the absorption of slag by the graphite crucible. The effects of additions of BaO to the CaO-CaF2 system have been investigated by measuring the phosphorus partition ratios between these fluxes and Fe-Csat-P alloy as a function of slag composition at 1400 °C. Also, the activity of BaO as a function of slag composition at 1400 °C has been determined by equilibrating a silver-barium alloy with the BaO-CaO-CaF2 fluxes and CO in a graphite crucible. The results indicate that phosphorus partition ratios with carbon-saturated iron, LP, for the BaO-BaF2 system are relatively high, going up to 400, even for oxygen partial pressure as low as 7.8 × 10−16 atm. The phosphate capacity and the activity coefficient of PO2.5 for this system were calculated from the experimental results using the available thermodynamic data. No effects of barium oxide addition in lime-based fluxes were observed for BaO contents less than 40 pct. One of the reasons for this phenomenon is that BaO activity in a lime-based flux is very small for BaO content less than 46 pct. However, for high BaO contents,\(C_{PO4^{3 - } } \) increases significantly, as does the activity of BaO.

Microstructure and properties of some extruded copper–phosphorus alloys

Abstract Five Cu-P alloys have been produced by extruding cast and heat treated billets. This paper reports the effects of the extrusion variables on the resultant structure and properties. It is shown that the recrystallized structure observed in the α phase is produced by dynamic recrystallization occurring during the deformation process. The α grain size is determined by the processing parameters, but considerably modified in the two phase alloys by the Cu3P phase such that it may be quantified only by expressing it as a function of both extrusion ratio and temperature compensated strain rate. The deformation process is considerably affected by the large volume of second phase: the Cu3P being either broken or elongated during the extrusion process. The mechanical properties are influenced by the extrusion conditions and may be further modified by an annealing process which causes precipitation in the α phase and coalescence of the Cu3P phase. The mechanism of fracture during tensile testing is also rep...

Corrosion of Soldered and Brazed Joints in Tap Water

Three test rigs of copper pipes joined with nine different solders or brazing alloys have been exposed to hot tap water in Copenhagen, Gothenburg and Oslo for 18 months under normal service conditions. The alloys investigated were the silver brazing alloys (hard solders) L–Ag55Sn, L–Ag34Sn and L–Ag18Sn, the copper–phosphorus brazing alloys (hard solders) L–Ag15P, L–Ag5P and L–CuP6, and the soft solders L–Sn5Ag and L–SnCu3.In spite of the considerable differences in water analysis in the three cities, there were no major differences in the degree of corrosion of the joints. Nearly all the joints were noticeably corroded but the form varied with the solder or brazing alloy type.In all three silver brazing alloys, selective corrosion resulted in deep corrosion attack of up to 3 mm/year. There was a wide variation in corrosion depth and some alloy/water combinations were completely free from corrosion. In all cases the copper–phosphorus alloys were not corroded but the copper adjacent to the joint in samples exposed in Copenhagen and Oslo was corroded up to 0·2mm/year. The soft solders all behaved similarly, irrespective of alloy or water quality: they suffered general corrosion of up to 0·3mm/year. The corrosion products, containing small, unattacked grains of one of the solder phases, remained attached to the solder surface.The rapid corrosion rate indicates that attention should be paid to the contribution of corrosion to the failure of soldered and brazedjoints in tap water. It should be noted that, although the joints were prepared under good workshop conditions, they did contain some cavities.

Determination of phosphorus in copper-phosphorus alloys, by GLC technique

A simple, sensitive, accurate and rapid gas chromatographic method for the quantitative determination of phosphorus in copper-phosphorus alloys is described. The method is based on the chlorination of the sample with carbon tetrachloride in a sealed glass capsule at 550°C. The volatile products are introduced into the gas chromatograph after crushing the capsule in a special device.

A study of the nucleation of recrystallization using HVEM

Direct observations have been made of recrystallization in copper and a copper-phosphorus alloy by annealing specimens of the cold worked materials inside the high voltage electron microscope (HVEM). Nucleation of recrystallised grains was observed to occur by growth from suitable long subgrains by bulging out of their boundaries. In addition, it was observed that growing recrystallised grains could sometimes ‘catalyse’ nucleation of other grains when they impinged upon certain subgrains. These and other observations are discussed in the light of current theories of nucleation.