Showing papers on "Contact area published in 1987"

The abrasive wear behaviour of continuous fibre polymer composites

Abstract: The dry abrasive-dominant wear behaviour of several composite materials consisting of uni-directional continuous fibres and polymer matrices was investigated. Seven materials were examined: neat epoxy (3501-6), carbon fibre epoxy (AS4/3501-6), glass fibre/epoxy (E-glass/ 3501-6), aramid fibre/epoxy (K49/3501-6), neat polyetheretherketone (PEEK), carbon fibre/PEEK (APC2) and aramid fibre/PEEK (K49/PEEK). The wear behaviour of the materials was characterized by experimentally determining the friction coefficients and wear rates with a pin on-flat test apparatus. First, the effects of the operation variables apparent normal pressure, sliding velocity and apparent contact area were observed. The dimensionless wear rate increased linearly as the apparent normal pressure increased and decreased as the apparent contact area increased. Second, through microscopic observations of the worn surfaces and subsurface regions, basic wear mechanisms were identified as a function of fibre orientation. Observations of fibre-abrasive particle interactions allowed for the differentiation of the dominating wear mechanisms. Finally, a network of data was compiled on the wear behaviour in terms of the three material parameters: fibre orientation, fibre material and matrix material. This enabled the systematic selection of an ideal low wear composite material which would consist of a PEEK matrix reinforced with aramid fibres oriented normal to the contacting surface and carbon fibres oriented parallel to the contacting surface.

IMPROVED LOW CONTACT RESISTANCE IN HIGH-T//c Y-Ba-Cu-O CERAMIC SUPERCONDUCTORS

Abstract: One of the important problems for electrical applications of high-temperature superconductors is the contact resistance between the superconductor and a normal metallic wire. In this paper, the authors report a simple method of contact preparation for high-T//c copper-oxide materials (Y-Ba-Cu-O). Based on high-temperature metallization, it reduces the contact resistance from typically 1 OMEGA mm** minus **2 down to APP 1STH 10 mu OMEGA mm** minus **2 (77 K), and makes it possible to measure the critical current of a bulk sample, with current densities in the contact area in excess of 2000 A cm** minus **2.

Dental ultrasonic endodontic unit

Abstract: A readily manipulatable fastening for a dental endodontic file and tip assembly for operation by ultrasonic vibrations. The fastening is compatible with a wide range of handpieces of different domestic and foreign manufacturers of dental instruments, and may be used interchangeably with ultrasonically operated scaling tips of various shapes and configurations, also catheters and other dental cleaning and scraping tools. A simple and rugged two-part unit consisting of a flow-through tip fastened to the outlet end of the vibratory stack and a completely enclosed housing for the outer end of the tip, other than a single small aperture therein, preferably bored at a small obtuse angle to the longitudinal axis of the tip for the shank of the file, permits a rapidly executed secure fastening or release of the shank from between the end of the tip and the internal end wall of the housing. Preferably, the end wall of the housing and the outer end of the tip are specially contoured to provide a large contact area for the fastening, to transmit the vibratory energy from the transducer to the file with maximum effectiveness and accurate control, with minimum possibility of breakage.

Solar cell having improved front surface metallization

Abstract: A gallium arsenide solar cell (6) having an aluminum gallium arsenide window layer (20) in which fine metallic contact lines (40) extend through the aluminum gallium arsenide window (20) to electrically contact the emitter layer (14), and a plurality of metallic grid lines (50) disposed on the window layer (23) cross the contact lines, thereby making electrical contact to the metallic contact lines (40). A flat metallic strip (60) extending along one of the edges of the solar cell electrically couples the grid lines (50) to one another. Consequently, two separate metals can be used, one with good ohmic contact properties for the metallic contact lines (40) and another with good adhesion and current conducting properties for the metallic grid lines (50). Additionally, the metallic contact lines (46) can be made very narrow to reduce the contact area to the emitter (14) thereby reducing the recombination current in the emitter.

Growth of contact area between rough surfaces under normal stress

Abstract: The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

Ultrasonic welding technique, particularly for welding contact tab to battery electrode

Abstract: At least one of the two contacting metal areas to be welded are in the form of void-containing disseminated units, such as a bundle of wires, the strands of a wire mesh, the fibres of a metallic fibre mat, or the component elements of a metal foam or sponge. This ensure that the necessary vibration can take place whereby frictional engagement at a multiplicity of points gives rise to heat and fusion with good mechanical and electrical connection. In one example (Fig. 1a) a bundle of wires (3) has a flattened contact area (4) of separated wires ultrasonically welded to a prepared electrode (1). In another example (Fig. 2b) a metal tab (10) is ultrasonically welded to a compressed zone (8) of a fibrous mat electrode (7) utilizing additionally a wire mesh element (9) whose area corresponds to that of the compressed zone (8). The electrode (7) may be a nickel fibre mat.

A highly reliable interconnection for a BF + 2 -implanted junction utilizing a TiN/Ti barrier metal system

Abstract: A submicrometer-rule interconnection structure of the Al-Si layer to the BF 2 +-implanted Si region is described. The contact resistance of Al-Si to BF 2 +-implanted Si increases more than those to B+- or As+-implanted Si, as contact hole size is scaled down to around 1 µ2. Through SEM and TEM analyses, it is found that solid phase epitaxial growth of Si takes place on the contact interfaces, where crystalline defects induced by BF 2 +implantation act as seeds. Thus, the effective metal contact area to Si is reduced very much. In order to realize a stable metallization system, a TiN/Ti barrier metal structure is introduced. The TiN/Ti structure is optimized in terms of contact resistance and contact barriers, and its feasibility for submicrometer-rule CMOS VLSI's is clarified.

Method of making fully self-aligned bipolar transistor involving a polysilicon collector contact formed in a slot with an oxide sidewall

Abstract: An improved method of making a bipolar transistor is disclosed which comprises forming one or more mask layers over a silicon substrate, etching at least one of said one or more masking layers to define a base contact area and a spaced apart collector contact area with an unetched emitter contact area defined in-between, forming a collector slot in a substrate of an integrated circuit structure through the collector contact area defined in the one or more mask layers, oxidizing the sidewall of the collector slot, filling the collector slot and the base and collector contact regions with polysilicon, removing one or more of the mask layers between the polysilicon base and collector contacts, oxidizing the exposed sidewalls of the polysilicon base and collector contacts, forming an emitter contact region between said collector and base contact regions insulated from the base and collector contacts by the sidewall oxidation thereon, and forming a base region in said substrate spaced from the collector slot by the oxide formed on the sidewall of the collector slot.

High-density contact area electrical connectors

Abstract: An improved electrical connector for making electrical connections between electronic components. The improved electrical connector includes an insulating board interposed between metalized contact areas on the electronic components. The insulating board has openings at positions corresponding to the contact areas of the electronic components, with electrical connections between the contact areas established with conductive connector elements positioned in the openings of the insulating board. The connector elements are preferably each formed from a strand of metal wire, each strand being wadded together to form a nearly cylindrical "button" of material having a density of between twenty and thirty percent. The improved electrical connector provides high density contact areas, easy engagement and disengagement of the electronic components, and minimum electrical resistance between the contact areas.

Charge Transfer between a Single Polymer Particle and a Metal Plate due to Impact

Abstract: This paper describes an experimental investigation of the charge acquired by a single particle when striking a metal plate. The particle was projected from a pneumatic gun onto the metal plate. The initial charge carried on the particle before impact and the impact charge were measured under various conditions of impact velocity, v0 (7-18m/s) and angle, θ (0°-60°).The charge transfer is dependent not only upon the impact conditions but also upon the initial charge of the particle. The impact charge almost decreases proportionally to the increase in the initial charge. There is a particular value of this charge which results in no net transfer and which is independent of the impact conditions. This special point can be utilized to estimate the effective work function of insulating particles. While a larger impact velocity leads to a larger charge transfer because of the increase in the contact area, the data cannot be arranged with the maximum contact area derived from the normal component of the impact velocity, v0cosθ. A much larger enhancement of the charge transfer is caused by the tangential component of the velocity, v0sinθ. This fact is extremely different from the previous works (Refs. 2, 4) which describe that the tangential component had no effect on the charge transfer by collision.

Paper VIII(i) A 3-dimensional method of studying 3-body contact geometry and stress on real rough surfaces

Abstract: Synopsis A technique for three-dimensional surface contact analysis is described in detail with examples of results obtained on contact area and stress distribution presented for several typical engineering surface finishes. Other aspects such as the influence of third bodies within the contact and plasticity are examined in terms of their significance to the Hertzian type non-conforming contacts existing in rolling element bearings and gears.

Solar battery device

Abstract: PURPOSE:To obtain a high open voltage by a method wherein a reflection preventing film, 1st electrode layer and 2nd electrode layer are formed on a substrate in this order and the 1st electrode layer is made of material which provides excellent electrical contact with the substrate piercing through the reflection preventing film and the 2nd electrode layer is made of material which does not provide such excellent electrical contact. CONSTITUTION:As silver pastes for forming the surface electrodes of a solar battery device 10, a paste which can pierce through a reflection preventing film and can provide excellent electrical contact with a silicon substrate 11 and a paste which can not provide excellent electrical contact are employed together. Therefore, the contact area between the surface electrodes and the silicon substrate 11 can be reduced, the surface recombination speed at the electrode part can be reduced and a high open voltage can be obtained. Moreover, as silver paste layers 17, which are main electrodes, have an effect which does not degrade a curve factor, the conversion efficiency of the solar battery device 10 can be improved significantly.

Flat body, especially for use as a heat sink for electronic power components

Abstract: The body consists of a ceramic plate (1) which is covered by metal plates (2, 3) on both sides, which metal plates (2, 3) are firmly connected over their entire contact area, to be precise especially without use of any intermediate layer, to a ceramic plate (1), and have edge strips (5) of reduced thickness.

New flange correction formula applied to interfacial resistance measurements of ohmic contacts to GaAs

Abstract: A quasi-two-dimensional analytical model is developed to account for vertical and horizontal current flow in and adjacent to a square ohmic contact between a metal and a thin semiconducting strip which is wider than the contact. The model includes side taps to the contact area for voltage probing and relates the "apparent" interfacial resistivity to the (true) interfacial resistivity, the sheet resistance of the semiconducting layer, the contact size, and the width of the "flange" around the contact. This relation is checked against numerical simulations. With the help of the model, interfacial resistivities of ohmic contacts to GaAs were extracted and found independent of contact size in the range of 1.5-10 µm.

Thermocouple for measuring temperature

Abstract: PURPOSE: To obtain a thermocouple simply mounted on an object to be measured and having a wide contact area and good response, by fixing two thermocouple strands to the interior of a small metal container through an insulating agent and fixing the small metal container to a thin metal plate. CONSTITUTION: Two thermocouple strands 3, 3 composed of different kinds of metals are fixed to a metal sheath pipe 1 through an electric insulating agent 4 and the sheath pipe 1 is shaped into a semicylindrical shape in order to be closely brought into contact with a specimen. The hot contact 5 of the thermocouple is formed in the state welded to the pipe wall of the lower part of the sheath pipe 1 on the side of the specimen and, further, the sheath pipe 1 is held between thin nickel plates 2, 2 to be mounted by welding. By this constitution, since the thin plates 2, 2 are closely brought into contact with a boiler tube 7 along the curved surface thereof when the thin plates 2 are mounted to the surface of the tube 7 by spot-welding 6, the contact surface of the thermocouple is wide and, since the sheath pipe 1 is low in heat capacity, response is good and accurate temp. can be measured. COPYRIGHT: (C)1989,JPO&Japio

The effect of contact area shape and pressure distribution on multilayer systems response

Abstract: Numerical analysis of stresses, strains, and displacements in multilayer systems for any shape of contact area and pressure distribution is presented. The scheme developed for microcomputers is made of two programs: one for evaluating the stresses and deformations under a point load and the second for performing the numerical integration of the point load solution. Results obtained by using the scheme for the uniformly distributed pressure, Boussinesq, and three-layer system cases were compared to those of analytical and other numerical solutions. They were revealed to be in excellent agreement. Results for a rectangular contact area and nonuniform pressure distribution are presented. The effect of the contact area and pressure distribution shapes on the design strains is illustrated and discussed. The scheme presented is preferable to the 3-D finite element analyses. It dispenses with the use of mainframe computers and is highly accurate.

On inverse analysis technique to obtain contact stress distributions.

Abstract: In this paper, a computer technique to analyze the contact stress distributions between two elastic bodies is proposed. The technique is the inverse analysis method using the information, which is forces or stresses measured by experimental techniques, on the surface of elastic body distant from the contact area. The finite element method is used to formulate the method. Under the assumed contact area the stresses of one of the elastic bodies in contact, of which the experimental information is used in calculation, are analyzed. Furthermore, by minimizing the square sum of stresses at the contact area the reasonable contact area and the stress distribution are obtained. The validity of this technique is proved numerically by the analysis of two-dimensional contact problem.

Contact-pins arrangement for the electrical contacting of a test device with circular contact surfaces of a test sample

Abstract: The contact pin arrangement exhibits below an embedment of the contact pins (2) in a plastic compound, a stack (1, 1a) of perforated plates through which the contact pins extend. The stack of perforated plates consists of two types of perforated plates. The first one is formed by the lowermost perforated plates (1a). They exhibit round or square holes which ensure a perpendicular placement of the contact pins on the contact areas (4) of the test specimen (5). The perforated plates (1) of the second type exhibit nothing but elongated holes, rectangular, square, circular, elliptic or trapezoidal holes (3). Of in each case three perforated plates of the second type stacked on top of one another, the centre one is offset with respect to the other two which are aligned with one another, in such a manner that each contact pin is enclosed by a part of the lower edge of the hole of the top and a part of the upper edge of the hole of the centre and by a part of the lower edge of the hole of the centre and a part of the upper edge of the hole of the lower perforated plate. As a result, the contact pin can bend at the most to the part of the hole wall limiting its maximum bending with an axial load. This ensures a sufficiently low contact resistance between the contact pin and the contact area of the test specimen. The contact pins can be adapted to differences in the height of the contact areas of the test specimen due to unevennesses of the surface of the test specimen by a correspondingly selected number of perforated plates of the second type.

Ultrasonic wire bonder and method of manufacturing a semiconductor therewith

Abstract: The bonder is provided with a single bonding head 10 which has two bonding wedges and grooves for location of wires W1, W2 under the wedges and two guides through a tongue 10A at the rear of the bonding head. It is used to perform the simultaneous bonding of two connecting wires on the contact area 2 of a semiconductor device 3 and on a conductor 5 associated with the contact area. The bonding time required for two wires of a given diameter is the same as that required to bond a single wire of the same diameter, thus twin connecting wires may be provided in half the bonding cycle time and the wire spacing is accurately determined without operator intervention. The bonder is of particular use in the manufacture of triac devices where the wires can be accurately spaced one over a first sector, the other over a second sector of the triac structure, on a contact area common to both sectors of the triac.

Scanned electron beam alloyed ohmic contacts to n-GaAs

Abstract: Scanned electron beam (SEB) is used for the alloying of evaporated AuGe-Ni metallisation on n -type GaAs so as to realise high quality ohmic contacts to n -GaAs. The contact quality is studied for various incident beam energy, scanning time and metallisation thickness. The electrical properties of the contacts are characterised by contact resistivity measurements and it is found that the contact resistivity for SEB alloyed contacts is lower than furnace alloyed contacts and it is independent of metallisation thickness. The optical and Scanning Electron Microscopic observation of surface and subsurface morphology establishes that SEB alloyed contacts have smooth and uniform morphology compared to furnace alloyed contacts. The electron microprobe analysis confirms that the contact constituents are uniformly distributed over the entire contact area. Penetration depth of gold in GaAs is studied by Rutherford Backscattering Techniques which shows that the penetration of gold for SEB contact is far less than furnace alloyed contacts and is independent of metallisation thickness. High temperature ageing tests confirm that SEB alloyed contacts undergo less ageing degradation compared to furnace alloyed contacts.

Ultrasonic measuring method for contact stress of hose joint

Abstract: PURPOSE:To take a measurement quantitatively and precisely in real time by making an ultrasonic wave (transverse wave) incident on a contact surface from the outer periphery of a tube, reflecting the lateral wave in the tube through the contact surface, and measuring the sound pressure of the reflected wave CONSTITUTION:The transverse wave from an oblique probe 5 is made incident on the contact surface 4 between a steel tube 1 and a hose 2 from the outer peripheral surface 1a of the steel tube 1 to sound pressure P0 The incident transverse wave is propagated to an end surface 1c while reflected repeatedly between the inner periph eral surface 1b and outer peripheral surface 1a At this time, part of the wave is transmitted into the hose 2 because of the difference in acoustic impedance between the steel tube 1 and hose 2 on the contact surface 4, so the lateral wave is attenuated and reaches the end surface 1c and further reflected, so that the wave is received by the probe 5 with sound pressure Pn The contact part in the contact area 4 with air between becomes smaller as the contact stress on the contact surface 4 increases, so the transmission amount of the lateral wave on the contact surface 4 increases Therefore, the contact stress on the contact surface 4 can be measured from the correla tion between variation in the contact stress and variation in echo height

トロイダル形無段変速機に関する研究 : 第1報,速度伝達効率とトルク伝達効率

Abstract: A continuously variable transmission (CVT) will contribute to improve the fuel economy of automotive propulsion systems The half toroidal traction drive is a rolling element type CVT with a feature of low spin in contact area. In this report, a theoretical estimation method of speed and torque transmission efficiencies is shown by making a shear model of traction fluid in EHL contact area. Theoretical results are compared to test results of a prototype of nominal input torque capacity of 120 N·m, rotational speed of 5000 rpm and maximum speed ratio of 6.25.