Copper Balls Research Articles

GC-MSによる芋焼酎揮発性硫黄化合物の測定とガス臭物質の特定

Volatile sulfuric compounds such as hydrogen sulfide were thought to be the source of off-flavor be-cause a sulfur-like odor was detected from just distilled sweet potato shochu. A highly sensitive purge and cold trap GC-MS method equipped with an ethanol removal system to analyze volatile sulfuric compounds was developed to demonstrate the above idea. Unblended sweet potato shochu A which exuded a strong off-flavor was analyzed with this method and the concentrations of hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethy disulfide were 0.10mg/L, 0.070mg/L, 0006mg/L, and 0.002mg/L respectively. It was confirmed that the hydrogen sulfide and methyl mercaptan having strong off-flavors were detected at higher concentrations compared to the other two sulfuric compounds.In order to confirm that the off-flavor is caused by hydrogen sulfide and methyl mercaptan, the column（φ14mm × 40mm）of copper balls（φ1 ∼ 2mm）was used to remove these two volatile sulfuric compounds. A total of 4000mL of unblended sweet potato shochu B which exuded a very strong off-flavor was passed through the column at a flow speed of 20mL/minute. It was found that hydrogen sulfide and methyl mercaptan were eliminated completely by the column and the off-flavor also disappeared at the same time. Hydrogen sulfide and methyl mercaptan were confirmed as the sources of the off-flavor.

Friction Behaviors of the Hot Filament Chemical Vapor Deposition Diamond Film under Ambient Air and Water Lubricating Conditions

The friction behavior of the hot filament chemical vapor deposition(HFCVD) diamond film plays a critical role on its applications in mechanical fields and largely depends on the environment. Studies on the tribological properties of HFCVD diamond films coated on Co-cemented tungsten carbide (WC-Co) substrates are rarely reported in available literatures, especially in the water lubricating conditions. In this paper, conventional microcrystalline diamond(MCD) and fine-grained diamond(FGD) films are deposited on WC-Co substrates and their friction properties are evaluated on a reciprocating ball-on-plate tribometer, where they are brought to slide against ball-bearing steel and copper balls in dry and water lubricating conditions. Scanning electron microscopy(SEM), atomic force microscopy(AFM), surface profilometer and Raman spectroscopy are adopted to characterize as-deposited diamond films; SEM and energy dispersive X-ray(EDX) are used to investigate the worn region on the surfaces of both counterface balls and diamond films. The research results show that the friction coefficient of HFCVD diamond films always starts with a high initial value, and then gradually transits to a relative stable state. For a given counterface and a sliding condition, the FGD film presents lower stable friction coefficients by 0.02-0.03 than MCD film. The transferred materials adhered on sliding interface are supposed to have predominate effect on the friction behaviors of HFCVD diamond films. Furthermore, the effect of water lubricating on reducing friction coefficient is significant. For a given counterpart, the stable friction coefficients of MCD or FGD films reduce by about 0.07-0.08 while sliding in the water lubricating condition, relative to in dry sliding condition. This study is beneficial for widespread applications of HFCVD diamond coated mechanical components and adopting water lubricating system, replacing of oil lubricating, in a variety of mechanical processing fields to implement the green production process.

Detailed investigation of ultrasonic Al–Cu wire-bonds: I. Intermetallic formation in the as-bonded state

Scanning and transmission electron microscopy were used to study intermetallic formation and the interface morphology in copper wire-bonds. The ends of copper wires were melted in air and in a protective environment to form wire-balls. The protective environment enabled formation of symmetrical and relatively defect-free copper balls, together with a smaller heat affected zone (in comparison with wires melted in air). Detailed morphological and compositional characterization of the Al–Cu as-bonded interface was conducted using scanning and transmission electron microscopy, on specimens prepared by focused ion beam milling. Discontinuous and non-uniform intermetallics were found in regions where high localized stress was introduced during the wire-bonding process. The main intermetallic phase was found to be Al2Cu.

Study of factors affecting the hardness of ball bonds in copper wire bonding

Copper wire bonding has gained popularity due to its economic advantage and superior electrical performance. However, copper is harder than gold, and replacing gold wire with copper wire introduces hardness related issues. This article reports investigations of the properties including microhardness of the copper balls bonded using ϕ25.4-μm copper wire and different combinations of electronic-flame-off (EFO) current and firing time settings with forming gas (5%H 2 and 95%N 2) as the inert cover gas. FABs with an identical diameter, obtained under different EFO firing conditions, were ball bonded with the same wire bonding parameters established using design of experiments. Microhardness tests were then performed on the cross-section of the bonded balls. The study revealed that ultrasonic generator current is the most significant factor to increase the bonded mashed ball diameter, ball shear and shear per unit area and to decrease the ball height. The microhardness of bonded copper balls is related to the EFO parameters, with FABs obtained by higher EFO current being softer. The lower hardness is attributed to the higher maximum temperature during the FAB melting state.

Optimum MoS2–Cr coating for sliding against copper, steel and ceramic balls

Abstract The chromium doping in MoS2–Crx% coatings improves their mechanical properties, adhesion strength and tribological properties. An investigation of the coating system MoS2–Crx% with varying chromium contents deposited on tungsten carbide disks by unbalanced magnetron sputtering was carried out. The results of hardness, elastic modulus, scratch adhesion and tribological properties of these coatings were reported. The tribological properties of the coatings against copper, AISI 52100 steel and Si3N4 ceramic balls were investigated by using an oscillation sliding test machine with a point-contact wear mode under dry condition. A Cr metal atomic percentage at 8% in the MoS2–Crx% coating was found to possess the optimum wear resistance and durability when paired with a copper, steel and ceramic ball.

The effect of vibration on rotation on boiling heat transfer in heating tank with different grooved pattern on its base and copper balls enclosed inside

The effect of either vertical vibration or reciprocating rotation on boiling heat transfer in cylindrical heating tank with different grooved pattern on its base and with copper balls enclosed inside was studied experimentally. The experimental model consists of seven aluminum cylindrical tanks with different grooved pattern on their base and copper balls enclosed in the heating section and a vertical vibration disc or a reciprocating rotation disc attached to the bottom of the cylindrical tank base. By utilizing the vibrating and rotating test on the heating tank base with different grooved pattern, the effect on boiling heat transfer was investigated. The working fluid is distilled water. Besides the effect of different grooved pattern in heating tank, different frequency of vertical vibration and reciprocating rotation on boiling heat transfer was studied, the effects of the diameter and quantity of enclosed copper balls on boiling heat transfer was also investigated in this experiment. The result shows that the boiling heat transfer was reduced and converged to a constant as the frequency of reciprocating rotating disc increases after copper balls were enclosed inside the heating tank. There is an optimum frequency of vertical vibrating disc for boiling heat transfer. 15% increment of boiling heat transfer can be obtained with proper grooved pattern on aluminum heating tank base and with proper volume of copper balls enclosed inside aluminum cylindrical tank.

Influência do material do destilador na composição química das aguardentes de cana: parte II

The quantitative chemical analysis of the Brazilian sugar cane spirit distilled from glass column packaged with copper, stainless steel, aluminum sponge, or porcelain balls is described. The main chemical compounds determined by gas chromatography coupled with flame ionization (FID) and flame photometric (FPD) detectors and liquid chromatography coupled with diode array detector are aldehydes, ketones, carboxylic acids, alcohols, esters and dimethylsulfite (DMS). The spirits produced either in columns filled with copper or aluminum pot still exhibits the lowest DMS contents but the higher sulfate and methanol contents, whereas spirits produced in stainless steel or porcelain showed higher DMS concentration and lower teors of sulfate ion and methanol. These observations are coherent with DMS oxidation to sulfate, with methanol as by product, in the presence of either copper or aluminum.

Development of PCM for Recovering High Temperature Waste Heat and Utilization for Producing Hydrogen by Reforming Reaction of Methane.

For efficient heat-recovery of high temperature waste gas such as LDG in the form of latent heat, the utilization technology of phase change material, PCM, was experimentally studied. Copper balls as the PCM were encapsulated by nickel film with/without an insertion of carbon or ruthenium as an inhibition layer, based on an electro-plating method. Then, the effect of the film thickness on the strength of capsules was experimentally examined. As a result, the obtained PCM had enough strength by increasing the film thickness and showed an excellent catalytic property for reforming reaction from methane to hydrogen. In conclusion, the copper PCM with the thick film of nickel and an inactive layer between nickel and copper was available for producing hydrogen by recovering high-temperature waste heat efficiently.

Influence of ball-forming conditions on the hardness of copper balls

Effect of ball-forming conditions on the microstructure and the hardness of balls has been investigated in order to obtain soft balls suitable for a reliable ball-bonding process using copper wire. Copper balls formed in a room-temperature shield gas are found to be harder by 6 Hv than fully annealed copper wires of the same purity. This is caused by many dislocation loops which are generated in balls due to inclusion of gaseous impurities from the atmosphere and due to rapid solidification. On the other hand, copper balls formed in a shield gas heated above 175 °C are found to be softer by the amount of 4.5 Hv than balls formed in a room-temperature shield gas. This is due to disappearance of dislocation loops caused by the reduction of solidification rate and by elimination of gaseous impurities from the balls during solidification. Impurities, especially oxygen, are found to have a strong influence on the hardening of copper balls. From these results, we conclude that copper balls formed in a shield gas heated at 175 °C are suitable for mass production.

Development of copper wire bonding application technology

The continuous forming of oxide-free, stable, spherical copper balls which has been realized by blowing a reducing gas over the copper wire during copper ball formation (sparkling) is described. The prevention of chip damage resulting from hard copper wire, including underpad cracking and silicon cratering, by the double-load wire bonding technology is discussed; this technology can minimize chip damage from wire bonding stress because the bonding load is decreased during ultrasonic power oscillation. It was confirmed that copper wires have a reliability equivalent to that of gold wires. The double-load wire bonding technology makes it possible to use copper wires in MOS LSI devices on a commercial basis. >

An experimental study of ball formation processes with aluminum and copper

In integrated circuits, bond pads on the semiconductor chip and terminals on the supporting lead frame are usually interconnected by a wire on which a ball has been formed at the end by heating from an electric discharge to melt a length of wire. Results are given of an experimental investigations of the ball formation processes using high-speed photography and methods of metallographic examination. The electrical discharges are in air or argon. High-speed photography at 500–1000 frames/s has revealed details of the wire melting characteristics, ball surface motion, neck formation at the ball-wire junction, material ejection from the ball, and the characteristics of the electrical discharge. Where present, the necking above the ball occurs after the arc is extinguished. The electrical discharge is found to be more stable in argon than in air. Aluminum and copper balls have also been sectioned and examined under the optical microscope. The examinations reveal the presence and type of porisity in the balls, solidification patterns, melting into the wire above the ball-wire junction, and the presence of cracks. Porosity in aluminum balls ranges from very large void(s) in the “balloon” balls to small distributed pores in the “slow-melt” balls. For similar discharge conditions, the copper balls are substantially solid (very little porosity). Large voids in the balloon balls may be attributed to the vaporization of aluminum in the interior. The porosity in the slow-melt aluminum balls may be explained in terms of density change during solidification, aluminum oxidation, and changes in the solubility of hydrogen in aluminum during melting and solidification. Slow-melt balls formed in argon are less porous than those formed in air.

Diffusion bonding of silver balls to a copper substrate and vice versa

Small balls of pure silver (copper) placed on a single crystal substrate of copper (silver), as well as pairs of silver and copper balls kept in contact by gravity, were annealed at temperatures close to the eutectic temperature. Some aspects of the Ag Cu interphase boundaries which form were examined and 105 relative orientations of both phases were measured from Laue back reflection or Kossel patterns. These orientations are classified conveniently in terms of disorientations of the silver lattice with respect to the copper lattice. The disorientations are treated firstly in terms of a random distribution of the relative orientations of both lattices, and secondly in terms of a model where the lattices are oriented in such a manner that they have non-primitive near-coincident cells. The model allows the computation of theoretical disorientations corresponding to such relative orientations and gives results in agreement with some of the experimental disorientations.