Low Balls Research Articles

A Study of Low Temperature Solder on Microstructure and Reliability

Low temperature solder (LTS) dopped with low melting temperature metals on basis of the commonly used Sn category solder, has generated a low eutectic point and dropped its peak reflow temperature to the range of 130 °C to 200 °C. This lower operating temperature peculiarity has already made LTS shined in many next-generation markets, such as high warpage caused by larger package size, heterogeneous integrated packages with more complicated stack-ups, temperature sensitive photonics packages and so on. Among all the newly-developing LTS systems in microelectronic packaging, Sn-Bi alloys obtains the most widely application, because the melting point is lower than Sn-Ag-Cu (SAC) systems but higher than its In-type competitors, which harmoniously balanced the manufacturability and thermomechanical properties to acquired high performance devices. In this paper, two types of low temperature solder balls (Sn-Bi-Ag/Sn-Bi-Cu-Ni) were selected to study the microstructure and reliability on the most common Cu pad and Au pad. The test vehicle was designed as a large size chip to chip (C2C) structure, in order to observe the soldering behavior on large size packages, but extremely suppressed the interference of package warpage. Then the investigation can be focused on the intermetallic compounds (IMC) formation at different solder/pad interfaces during both the flip chip process and the TC/HTSL reliability tests. Through evaluating the corresponding microstructures, it further revealed the essential conditions how LTS can achieve high-reliable solder joints.

Quality Characteristics of Chicken Meat Balls Incorporated with Pearl Millet (Pennisetum glaucum)

Background: Pearl millet is rich in dietary fiber and micro-nutrients such as vitamins and minerals apart from the carbohydrates, protein and fat. This study was conducted to fortify low fat chicken meat balls with pearl millet (Pennisetum glaucum) as a dietary fibre source and to assess the physico-chemical, sensory and textural properties. Methods: Emulsion based low fat chicken meat balls were prepared with the addition of Pearl millet flour (PMF) at levels of 4%, 7% and 10%, over and above the amount of meat along with a control and analysed for physico-chemical, textural and sensory properties. Result: In the physico-chemical properties, Emulsion pH, product pH and emulsion stability were not affected by the addition of PMF. Product yield was significantly (P≤0.01) lowered at 4 per cent level of PMF, but increased at higher levels of PMF inclusion. In texture analyses, hardness and cohesiveness were not affected by inclusion of PMF up to 7%. In sensory evaluation, though the scores for texture, tenderness and overall acceptability of 4% treatment were comparable with that of control and significantly (P≤0.01) decreased with increase in the level of PMF, the scores for 7% treatment were above ‘Very acceptable’ level. It is concluded emulsion based functional low fat chicken meat balls could be fortified with pearl millet flour up to a level of 7% without affecting the quality characteristics.

Data-driven strength and conditioning, and technical training programs for goalkeeper’s diving save in football

ABSTRACT The goal of this study was to evaluate the technical and physical adaptations to a data-driven 12-weeks training programs that incorporated recent findings from biomechanical studies on the diving save. Three-dimensional kinematics and kinetics were collected and analysed from 11 goalkeepers diving to save high (190 cm) and low (30 cm) balls at three occasions: twice pre-training and once post-training. Intraclass correlation coefficients were found to be excellent (>.7) between the pre-training tests, and there were no learning effects between them. Three-way repeated measures ANOVAs were used to evaluate the effect of dive side, dive height and training programme (pre- vs post-training) on normalised dive time [s·m−1], average centre of mass (CoM) horizontal velocity [m·s−1] and total power [W] generated at contralateral and ipsilateral push-offs. Compared to pre-training, the post-training results revealed greater average CoM horizontal velocity (+.82 m·s−1, 95% CI = [.62, 1.02]) and power (+523 W, 95% CI = [313, 732]) at contralateral push-off. These adaptations caused a reduction in normalised dive time (- .008 s·m−1, 95% CI = [- .014, - .002]) at post-training compared to pre-training. This translates to 42 cm more goal area coverage in a penalty situation.

Pulled fly balls are harder to catch: a game analysis with a machine learning approach

Two hypotheses were tested: (1) the deflecting motion of fly balls caused by aerodynamic effects varies between the pull side and opposite side of the fair territory, and (2) the probability of flyout is lower on the pull side than the opposite side in Japan’s professional baseball games. From all radar-tracking outputs of official games in 2018–2019, fly balls that resulted in outs or base hits were selected for analysis (N = 25,413), and indices representing horizontal and vertical deflecting motions of fly balls were computed and compared between the pull side and opposite side. A machine learning algorithm was used to construct a model to predict the probability of flyout from the kinematic characteristics of fly balls. Flyout zones where the probability of flyout was > 0.6 were computed for a systematically constructed set of fly balls having identical distribution between the pull side and opposite side. The results showed that: (1) most fly balls landing on the opposite side deflected in the same direction whereas the pulled fly balls deflected to either direction, (2) the pulled low fly balls had greater variability in the deflecting motions than the opposite side counterpart, (3) overall probability of flyout of the low fly balls was lower in the pull side (0.41) than the opposite side (0.49), and (4) the flyout zone of an outfielder in the pull side (mean = 698 m2) for low fly balls was smaller than that of the others (≥ 779 m2). The hypotheses were supported. The pulled low fly balls had substantial variations in the direction and magnitude of deflections, which might have reduced the flyout zone on the pull side.

Contributed Session III: Global Luminance and Local Contrast Modulate Interocular Delay in Virtual Reality

Virtual reality (VR) systems take advantage of depth cues to create immersive environments that simulate a three-dimensional world. Most often these cues provide consistent information about depth, but on occasion, such cues conflict with each other to create compelling phenomena that illustrate the function of underlying mechanisms. Here we examine the interaction of depth produced by local contrast, global luminance, and interocular luminance differences (i.e., a Pulfrich effect). We measure depth perception with two adjustment tasks. 1: Two moving streams of balls, one upwards (the standard) and the other sideways; the observer adjusts the depth of the sideways stream to lie in the same plane as the upward stream. 2: Balls move sinusoidally back and forth in the frontal plane; if depth is perceived, the pattern appears as a rotating helix. The observer adjusts the helical path until the balls appear to move in a single depth plane. We report that at low luminance levels dark balls are more effective at creating depth than bright balls; at higher luminance levels the effectiveness of dark balls decreases but the effectiveness of bright balls remains constant. Based on these data, we demonstrate how changes in the luminance of the background (or balls) can lead to shifts in the apparent depth order and the apparent direction of helical rotation. The results suggest a method for investigating potentially conflicting contributions of contrast and Pulfrich depth information.

FUNCTIONAL LOW FAT CHICKEN MEAT BALLS ENRICHED WITH GRAPE (VITIS VINIFERA) POMACE POWDER

This study was conducted to prepare low fat chicken meat balls with incorporation of grape (Vitis vinifera) pomace powder and assess its proximate composition, physico-chemical, sensory and textural properties. Emulsion based low fat chicken meat balls were prepared with the addition of grape pomace powder (GPP) at levels of 2%, 4% and 6%, over and above the amount of meat along with a control. There was a significant (P≤0.05) increase in the crude fibre, total ash and gross energy levels of the meat balls at 4% and 6% level of inclusion of GPP. In the physico-chemical properties, the emulsion pH and product pH significantly (P≤0.05) decreased with increase in the GPP content. In sensory evaluation, the scores for appearance and colour, flavour, juiciness, tenderness and overall acceptability were significantly (P≤0.01) reduced for the 6% GPP treatment. Though the scores of 2% and 4% treatments were significantly (P≤0.05) lower than that of the control, the scores were above the acceptable level. The textural properties of the chicken meat balls significantly (P≤0.05) changed with the addition of GPP. It is concluded emulsion based functional low fat chicken meat balls could be enriched with an optimum level of 4% of grape pomace powder without much affecting the quality characteristics, thus enhancing the dietary fibre content and antioxidant efficacy of the chicken meat balls.

An Efficient Cooling Tower for a Stationary Engine

Cooling tower is a type of heat exchanger used to dissipate the unwanted heat from a medium into the atmosphere. A well-designed cooling tower provides prolong contact time for water with air and breaks down the water to have large surface area to promote the heat transfer rate. In the present work, an induced draft cooling tower is fabricated and used with a stationary IC Engine to minimize the overall usage of water. The performance of the tower with two different bed materials (Jute carpet & Polystyrene balls) with and without wire mesh at three different water flow rates viz., 12, 18 and 30 lpm are studied. The cooling tower parameters such as range, approach, efficiency, effectiveness, heat loss, windage losses, and evaporative losses are calculated from the experimental data. At higher flow rates, jute carpets with wire mesh provided optimal results for the parameters while at low flow rates polystyrene balls are found to provide better results. The experimental results showed that the efficiency of the cooling tower increased by 67% as the flow rate increased from 12 lpm to 30 lpm with jute carpet and wire mesh, whereas the efficiency decreases as the flow rate increases with polystyrene as the bed material. Also, the similar trend is observed for the effectiveness of cooling tower.

Thermal characteristics on melting/solidification of low temperature PCM balls packed bed with air charging/discharging

Melting and solidification phenomena of low-temperature phase change material (PCM) balls packed bed with air flowing during charging and discharging were tested and modeled by numerical enthalpy method. In this study, a commercial paraffin RT-42 (melting point 38°C-43 °C) contained in a set of celluloid balls each having 0.04 m diameter. The experiments were performed with various bed thicknesses, air mass flow rates, and inlet air temperatures. It could be found that the simulated results on the PCM temperature and the outlet air temperature of the PCM bed agreed well with those of the experimental data. With these data, correlations were developed in dimensionless terms which could be used to estimate the air temperature leaving the bed at any operating period and any PCM bed thickness for both melting and solidification processes.

Kinematic and kinetic analysis of the goalkeeper’s diving save in football

ABSTRACTKinetics and full body kinematics were measured in ten elite goalkeepers diving to save high and low balls at both sides of the goal, aiming to investigate their starting position, linear and angular momentum, and legs' contribution to end-performance. Our results showed that goalkeepers adopted a starting position with a stance width of 33 ± 1% of leg length, knee flexion angle of 62 ± 18° and hip flexion angle of 63 ± 18°. The contralateral leg contributed more than the ipsilateral leg to COM velocity (p < 0.01), both for the horizontal (2.7 ± 0.1 m·s−1 versus 1.2 ± 0.1 m·s−1) and for the vertical component (3.1 ± 0.3 m·s−1 versus 0.4 ± 0.2 m·s−1). Peak horizontal and peak angular momenta were significantly larger (p < 0.01) for low dives than for high dives with a mean difference of 55 kg·m·s−1 and 9 kg·m2·s−1, respectively. In addition, peak vertical momentum was significantly larger (p < 0.01) for high dives with a mean difference between dive heights of 113 kg·m·s−1. Coaches need to highlight horizontal lateral skills and exercises (e.g. sideward push-off, sideward jumps), with emphasis on pushing-off with the contralateral leg, when training and assessing goalkeeper’s physical performance.

Process variables influencing solder reinforced adhesive (SRA) performance

To improve peel strength of adhesively bonded joints, low melting point solder balls were added to adhesive as a means to bridge metallic substrates. This solder reinforced adhesive (SRA) has a potential to enhance the peel strength and energy absorption of adhesively bonded joints by bridging the two substrates via a metallurgical bond and thereby creating a mechanical obstacle to crack propagation in the adhesive layer. In a previous study, the effectiveness of SRA was demonstrated for joints fabricated with steel substrates in terms of cross tension strength and energy absorption however, the metallurgical connection between the solder balls and steel substrates was degraded owing to residual adhesive between the solder balls and substrates. In this paper, the effect of process variables, e.g., adhesive viscosity and solder ball size, on the residual adhesive layer was studied. Results showed that a low viscosity adhesive and larger solder balls help facilitate elimination of the residual adhesive layer. However, the cross tension strength of SRA joints dropped significantly because of low solder-substrate soldering strength. To enhance the bonding between the solder balls and substrates, the effect of flux and substrate material was investigated. It was found that flux could enhance energy absorption by 16.7% compared with pure adhesive bonding with a steel substrate though was unable to achieve the full theoretical potential because of severe pores in the adhesive layer resulting from the flux/substrate interaction. A switch to copper substrates resulted in an improvement of the joint strength and energy absorption by 10.7% and 36.9%, respectively, despite the existence of pores.

Efficacy of different variants of corn flour (Zea mays) and peanut flour (Arachis hypogea) on quality characteristics of designer low sodium fish (Pangasius pangasius) balls

The present study was undertaken to analyze the effect of incorporation of different combinations of corn flour (Zea mays) and peanut flour (Arachis hypogea) on quality characteristics of low sodium fish (Pangasius pangasius) balls. Replacement of 50% sodium chloride by 40% KCl, 30% citric acid and 30% sucrose was optimum for preparation of low sodium fish balls. Three different levels of corn flour with peanut flour viz. 25:75, 50:50 and 75:25 were incorporated for preparation of low sodium fish balls and were compared with fish balls prepared by incorporating 10% refined wheat flour (control). On the basis of physico-chemical and sensory evaluation, emulsion stability, cooking yield and overall acceptability were significantly (p&amp;lt;0.05) found to be higher with incorporation @75% corn flour and 25% peanut flour for preparation of low sodium fish balls. The FFA, TBA and all microbiological profile were found to be significantly (p&amp;lt;0.05) increasing with increase in days of storage. The pH, cooking yield, FFA, TBA, total plate count, pychrotropic count, yeast and mould count, overall acceptability were found to be 5.74 ±0.14, 87.06 ± 0.43, 0.36 ± 0.01, 0.72 ± 0.19, 4.43 ± 0.12,3.74 ± 0.2 ,2.60 ± 0.2 ,7.09±0.09 respectively on 21st day of refrigeration storage. The prepared designer low sodium fish balls were found to be fit for human consumption till 21st day of refrigeration storage (4±1°C).

Why low bounce balls exhibit high rolling resistance

A simple experiment is described to measure the coefficient of rolling friction for a low bounce ball rolling on a horizontal surface. As observed previously by others, the coefficient increased with rolling speed. The energy loss due to rolling friction can be explained in terms of the measured coefficient of restitution for the ball, meaning that low bounce balls have a higher coefficient of rolling friction than high bounce balls.

유성밀 프로세스와 밀링에너지

Milling is a core fabrication process in powder technology. Especially the high-energy milling technology is being frequently used in energy-intensive process like mechanical alloying, mechanical activation and mechanochemistry, etc. Planetary ball mill is a representative highenergy mill together with shaker mill, stirred mill and vibration mill. Since milling condition strongly affects the property of milled powder materials, it should be controlled by changing the milling balls, the milling vial, the geometry of mill, and the rotation speed etc. to obtain an end product with desired characteristics. Milling with large, high density balls and higher rotation speed seems to provide materials with higher impact energy in comparison with small, low density balls and lower rotation speed. It is important to have an understanding the relationship between the milling process variables and the characteristics of final powder products. Many researchers have reported already their results and theories in such aspects. Attempts to modeling the ball mill process have been done in the last decades [1-14]. Burgio et al. [1] has established the fundamentals of mathematic model for determining the impact velocity of the ball and the energy transferred to powder. Padella [6] reported the results from experiments in which the energy transfer was intentionally controlled to form either intermetallic compound or amorphous phase of Pd-Si system. Research works to establish a milling map have pointed out the importance of determining which milling parameters have to be employed in order to obtain a particular final product. This paper reviews the theories of milling energy in planetary ball mill process based on the collision model.

Effect of V-Ti on the Microstructure and Abrasive Wear Behavior of 6CrC Cast Steel Mill Balls

Iron-chromium cast alloys are basically abrasive wear resistant materials particularly employed in mining industry; these alloys are often utilized in the manufacture of milling balls. In particular, high Cr and high C cast alloys have been subjected of significant research; for instance, most reports have been addressed on analyzing the relation between microstructure and the abrasive wear behavior; however, there exist a reduced number of reports on relatively low Cr and low C cast alloys. In this research, five low Cr cast steels containing additions of V and Ti were melted in an open atmosphere induction furnace. Comparisons on the morphology, size, type and distribution of carbides were carried through optical microscopy, SEM and XRD. Hardness testing was employed at room temperature with the purpose of correlate to wear behavior. A laboratory pilotplant ball-mill set with a batch of ore was utilized in order to evaluate the abrasive wear resistance. According to microstructure observations, a martensitic primary matrix was revealed in all specimens. The fraction of M7C3 and M3C interdendritic eutectic carbides varied according to alloying level. Further results indicated that variations in the shape and size of M7C3 and M3C along with the presence of V and Ti carbides influenced on the abrasive wear behavior of low Cr cast steel mill balls.

The effect of pH, solid content, water chemistry and ore mineralogy on the galvanic interactions between chalcopyrite and pyrite and steel balls

The role of pH, solid content, water chemistry and ore mineralogy on the galvanic interactions between chalcopyrite and pyrite and low alloy steel balls were investigated in the grinding of Sarcheshmeh porphyry copper sulfide ore. All these factors strongly affect the galvanic current between the minerals and the steel during the grinding process. The galvanic current density decreased as the solution pH and percent solids increased. In addition, changing the water in the ball mill from tap to distilled water reduced the galvanic current between the minerals and the balls. Potentiodynamic polarization curves showed that pyrite and chalcopyrite demonstrated typical active-passive-transpassive anodic behavior in the grinding of copper ore. However, the nature of their transitions from the active to the passive state differed. This behavior was not seen in the grinding of pure minerals. In addition, an EDTA extraction technique was employed to quantify the amount of oxidized iron in the mill discharge. The amount of extractable iron was influenced by the same experimental factors and in the same way as the galvanic current.

Effect of Low-Compression Balls on Wheelchair Tennis Match-Play

The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low vs. standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20 min) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P<0.05), forward distance (P<0.05), and average speed (P<0.05) were higher for play using a low-compression ball. A lower percentage of total time was spent stationary (P<0.001), with significantly more time spent at speeds of 1-1.49 (P<0.05), 1.5-1.99 (P<0.05) and 2.0-2.49 (P<0.05) m ∙ sec(-1) when using the low-compression ball. Main effects for physiological variables were not significant. Greater total and forward distance, and higher average speeds are achieved using a low-compression ball. The absence of any difference in measured HR and estimated physiological responses would indicate that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development.

High-Speed Shear Test for Low Alpha Sn-1.0%Ag-0.5%Cu (SAC-105) Solder Ball of Sub-100-$\mu{\rm m}$ Dimension for Wafer Level Packaging

The issue of soft error in microelectronics packaging has necessitated the development of low alpha activity solders, as solders are found to be one of the major sources of radiation in electronic devices that causes soft error. Low alpha ray emitter Sn-1.0Ag-0.5Cu (SAC) solders were prepared and their alpha activity was measured using ultra-low background alpha particle counting systems. The solders are confirmed to be low alpha solders having activity less than 0.005 α h-1 cm-2. High-speed shear test is performed to assess the strength of low alpha SAC solder balls of sub-100-μm diameter for different pad finishes. Two types of fluxes, one rosin mildly activated (RMA) and the other water soluble (WS) types are used during soldering to investigate the effect of flux on solder joint strength. Fracture energy has proved to be better index than maximum shear force in interpreting the test results as the former correlates with the fracture mode better. The performance of WS flux is better than RMA flux across all pad finish and speed conditions and among the pad finish electroless nickel electroless palladium immersion gold (ENEPIG) is superior to electroless nickel immersion gold, which in turn is better than organic solder preservative. Clearly the best choice is ENEPIG pad finish with WS flux. Intermetallic compound composition and morphology has been found to have significant effect on strength of solder joint. The shear strength of low alpha SAC105 is found to be lower than the high-Ag containing SAC305 and SAC405 solders. However, the effect of removing radioactive impurities from SAC105 on its shear strength and fracture energy remains inconclusive and needs further investigations.

Low Temperature Flex‐on‐Flex Assembly Using Polyvinylidene Fluoride Nanofiber Incorporated Sn58Bi Solder Anisotropic Conductive Films and Vertical Ultrasonic Bonding

In this study, solder ball incorporated polyvinylidenefluoride (PVDF) nanofiber was added into the ACF system to overcome short circuit issues of fine pitch flex‐on‐flex (FOF) assembly. Also, in order to improve the thermal mismatch of the flexible substrate which can lead to electrode misalignment during the bonding process, low melting temperature Sn58Bi solder balls were used with vertical ultrasonic (U/S) bonding method. When performing FOF assembly using PVDF nanofiber/Sn58Bi solder ACF and vertical ultrasonic bonding, PVDF nanofiber/Sn58Bi solder ACFs showed 34% higher solder capture rate on an electrode compared to conventional Ni ACFs and conventional Sn58Bi solder ACFs. Additionally, PVDF nanofiber/Sn58Bisolder ACFs showed 100% insulation between neighboring electrodes where conventional Ni ACFs and conventional Sn58Bi solder ACFs showed 75% and 87.5% insulation. Other electrical properties such as contact resistance and current handling capability as well as reliability test of PVDF nanofiber/Sn58Bi solder ACFs showed improved results compared to those of conventional Ni ACFs, which proves the formation of stable solder joint of PVDF nanofiber/Sn58Bi solder ACFs.

230 野球の試合における投球されたボールの軌道(動作・設計)

The aim of this study was to describe, in detail, the trajectory of baseballs pitched under game conditions. In six games of a college baseball league, all balls thrown by the pitchers on each team were recorded by using two video cameras. The trajectories of pitched balls were calculated from the video data by a three-dimensional direct linear transformation method. The initial ball velocity, the variation of trajectories, and arrival position of pitched ball were calculated. The results were as follows. 1) Most pitchers threw types of pitches with two or three clearly different ball trajectories, but some pitchers did not. 2) Batters hit balls only in or near strike zone. When thrown a breaking ball, batters occasionally swung at balls below the strike zone. Batters must rapidly make an exact judge on the ball's trajectory, especially for low balls. 3) For some pitchers, the trajectory of fastballs was correlated with arrival position, which should be considered by batters 4) For some pitchers, the initial ball velocity or the vertical variation of trajectory decreased as the pitch count increased. However, this trend was not observed for pitchers who threw a complete game.

Rate Distortion and Denoising of Individual Data Using Kolmogorov Complexity

We examine the structure of families of distortion balls from the perspective of Kolmogorov complexity. Special attention is paid to the canonical rate-distortion function of a source word which returns the minimal Kolmogorov complexity of all distortion balls containing that word subject to a bound on their cardinality. This canonical rate-distortion function is related to the more standard algorithmic rate-distortion function for the given distortion measure. Examples are given of list distortion, Hamming distortion, and Euclidean distortion. The algorithmic rate-distortion function can behave differently from Shannon's rate-distortion function. To this end, we show that the canonical rate-distortion function can and does assume a wide class of shapes (unlike Shannon's); we relate low algorithmic mutual information to low Kolmogorov complexity (and consequently suggest that certain aspects of the mutual information formulation of Shannon's rate-distortion function behave differently than would an analogous formulation using algorithmic mutual information); we explore the notion that low Kolmogorov complexity distortion balls containing a given word capture the interesting properties of that word (which is hard to formalize in Shannon's theory) and this suggests an approach to denoising.