Small Pads Research Articles

Gold Stud Bump on Sn Based Solders

When thick gold and tin come into contact the intermetallic formed is not one for long term reliability. AuSn intermetallics can lead to void formation, increased resistance and a very brittle joint that will fail in time. Such intermetallic formations occur when gold stud bumps are brought into contact with Sn based allows. Fine pitched devices, such as optical, typically use gold studs due to the tight pitch and small pad sizes. By transforming the gold to a less benign state the gold stud bumps allow assembly using standard Sn based solders. Such a process is beneficial when cheapers solders can be used as well as standard flip chip assembly equipment. This paper will provide cross sections of gold stud bumps with SAC305 solder after 3X reflow. The 3X reflow is required to demonstrate the capability and reliability of the modified solder joint. Rozalia/Ron ok move from 2.5/3D to FC/WLP 12-21-11.

A multi-pad electrode based functional electrical stimulation system for restoration of grasp

BackgroundFunctional electrical stimulation (FES) applied via transcutaneous electrodes is a common rehabilitation technique for assisting grasp in patients with central nervous system lesions. To improve the stimulation effectiveness of conventional FES, we introduce multi-pad electrodes and a new stimulation paradigm.MethodsThe new FES system comprises an electrode composed of small pads that can be activated individually. This electrode allows the targeting of motoneurons that activate synergistic muscles and produce a functional movement. The new stimulation paradigm allows asynchronous activation of motoneurons and provides controlled spatial distribution of the electrical charge that is delivered to the motoneurons. We developed an automated technique for the determination of the preferred electrode based on a cost function that considers the required movement of the fingers and the stabilization of the wrist joint. The data used within the cost function come from a sensorized garment that is easy to implement and does not require calibration. The design of the system also includes the possibility for fine-tuning and adaptation with a manually controllable interface.ResultsThe device was tested on three stroke patients. The results show that the multi-pad electrodes provide the desired level of selectivity and can be used for generating a functional grasp. The results also show that the procedure, when performed on a specific user, results in the preferred electrode configuration characteristics for that patient. The findings from this study are of importance for the application of transcutaneous stimulation in the clinical and home environments.

Tissue Distribution and Deposition of Clofazimine in Mice Following Oral Administration with or without Isoniazid

Tissue distribution and deposition of clofazimine (CAS 2030-63-9) in mice were investigated following administration of clofazimine with or without isoniazid (CAS 54-85-3). Balb/c mice were administered clofazimine suspension in mustard oil orally at a daily dose of 20 mg/kg body weight either alone or along with isoniazid (10 mg/kg body weight) for 15 or 30 days. Various tissues (liver, lung, spleen, small intestine, heart, kidneys, mesentric fat, foot pad and nerve) and pooled plasma were analysed for clofazimine in all the treated groups. High levels of clofazimine were observed in tissues having reticulo-endothelial components (53-263 microg/g wet tissue). In other tissues the levels of the drug were relatively lower (8.1-42.8 microg/g of wet tissue). There was a significant amount of the drug in foot pads and pooled nerve tissue showed detectable amount of the drug. The plasma concentrations in all treated groups were in the range of 0.5-0.8 microg/ml. Tissue levels were found to be increased in selective tissues with the length of drug administration. Concomitant administration of isoniazid reduced clofazimine levels significantly in tissues like small intestine, spleen, and foot pad and resulted in an increase in plasma levels.

Measuring single-cell gene expression dynamics in bacteria using fluorescence time-lapse microscopy

Quantitative single-cell time-lapse microscopy is a powerful method for analyzing gene circuit dynamics and heterogeneous cell behavior. We describe the application of this method to imaging bacteria by using an automated microscopy system. This protocol has been used to analyze sporulation and competence differentiation in Bacillus subtilis, and to quantify gene regulation and its fluctuations in individual Escherichia coli cells. The protocol involves seeding and growing bacteria on small agarose pads and imaging the resulting microcolonies. Images are then reviewed and analyzed using our laboratory's custom MATLAB analysis code, which segments and tracks cells in a frame-to-frame method. This process yields quantitative expression data on cell lineages, which can illustrate dynamic expression profiles and facilitate mathematical models of gene circuits. With fast-growing bacteria, such as E. coli or B. subtilis, image acquisition can be completed in 1 d, with an additional 1-2 d for progressing through the analysis procedure.

Termination of parental care in male giant waterbugs, Belostoma flumineum Say (Heteroptera: Belostomatidae) is associated with breeding season, egg pad size, and presence of females

Reproductive effort and/or success sometimes increase with the age of a parent. We found that reproductive effort was greatest in older egg-brooding male giant waterbugs, Belostoma flumineum Say. Consistent with previous studies, males with large egg pads were unlikely to discard them unhatched under any condition. However, males with small egg pads were significantly more likely to discard the eggs unhatched in the autumn (when breeding adults are young) than in the spring. By brooding smaller pads, older males invested more heavily in each offspring. Males bearing small egg pads were also significantly less likely to discard them in the presence of females. Three kinds of hypotheses have previously been proposed to explain why reproductive investment and/or success might increase with age: selection hypotheses predict differential survival of better parents; experience hypotheses predict that more experienced parents achieve greater success without additional cost per offspring; and residual reproduction hypotheses predict that older parents invest more per offspring. It is difficult to experimentally untangle these hypotheses, but the results of this study provide cautious support for a residual reproduction hypothesis that older males with few remaining reproductive opportunities invest more heavily per offspring by retaining small egg pads.

Intraoperative real-time continuous facial nerve monitoring in acoustic neuroma surgery

Dear Editor: We were very pleased to read the letter to the editor from Acioly et al. They estimated the intraoperative continuous monitoring of evoked facial nerve electromyograms we reported [1] as "a new device for an old concept," and we agree with their assessment. Because the first step for starting continuous monitoring of the facial nerve is to identify the root exit zone (REZ), the authors expressed concern about a case in which a large acoustic neuroma obstructed the REZ of the facial nerve because of anatomical distortion of the brainstem. In Kohno's experience, there have been only four cases (0.7%) out of 550 surgically treated patients with acoustic neuromas, in which he could not identify the REZ of the facial nerve, a very low percentage despite the fact that large tumors (Koos 3 and 4) account for 84% of cases. For a large tumor, internal decompression of the tumor is necessary to find the REZ of the facial nerve. Until we start continuous monitoring, we can notice that the facial nerve is mechanically stimulated by the free-running spontaneous facial electromyography. Therefore, we do not consider the possibility of facial nerve impairment before starting continuous monitoring. An important part of developing new surgical methodologies is to keep them simple, effective and easy to perform. For a new method to become popular and widely used over time, however, certain techniques and tips are required for every operation in the neurosurgical field. In particular with acoustic neuroma surgery, all neurosurgeons know that individual technique and experience must be considered. The authors express concern about movement of the electrode for continuous stimulation; however, we actually replace it at most twice or three times in a surgery, with minimum adjustment within a minute. To be sure, there are tips for stabilizing the electrode to prevent movement. As we described in our paper, we use a small cotton pad to fix the electrode in place. The authors also refer to the necessity of placing recording needle electrodes on three muscles (frontalis, orbicularis oculi and oris). Actually, electromyograms from three muscles vary in initial voltages and intraoperative changes, and there is the possibility that problems with a needle electrode or an electrical cord might occur. Therefore, we believe that setting recording electrodes on all of these three muscles is effective and necessary. The monitoring by transcranial facial motor-evoked potentials (FMEP), which is recommended by Alcioly et al., is surely effective, particularly until the surgeon finds the REZ of the facial nerve. However, body movement at electrical stimulation is considered a problem. In FMEP, as they point out, it is necessary to stop microsurgical procedures to record electromyograms from the viewpoint of safety. We consider FMEP to be a different type of monitoring compared to our method, which allows us to assess the condition of the facial nerve continuously during the process of dissecting the tumor from the facial nerve in real-time without stopping microsurgical procedures. M. Kohno (*) Department of Neurosurgery & Stroke Center, Tokyo Metropolitan Police Hospital, 4-22-1, Nakano, Nakano-Ku, Tokyo 164-0001, Japan e-mail: mkouno-nsu@umin.ac.jp

Fast micro Hall effect measurements on small pads

Sheet resistance, carrier mobility, and sheet carrier density are important parameters in semiconductor production, and it is therefore important to be able to rapidly and accurately measure these parameters even on small samples or pads. The interpretation of four-point probe measurements on small pads is non-trivial. In this paper we discuss how conformal mapping can be used to evaluate theoretically expected measurement values on small pads. Theoretical values calculated from analytical mappings of simple geometries are compared to the values found from the numerical conformal mapping of a square onto the infinite half-plane, where well-established solutions are known. Hall effect measurements are performed to show, experimentally, that it is possible to measure Hall mobility in less than one minute on squares as small as 70 × 70 μm2 with a deviation of ±6.5% on a 1σ level from accurate reference measurements, when only small sheet resistance variations are present. For samples with a sheet resistance variation of more than 5%, a more time consuming method must be used. Here, the theoretically expected measurement values are computed based on the sheet resistance variation using a finite element method. This more accurate method has an experimental repeatability of ±1.6% even on inhomogeneous samples.

Air Bearing Features on Discrete Track Media

This paper studies the air bearing features on discrete track media by very small mesh size. The mesh size is only 5 nm, and it allows to study the air bearing characteristics of a small square pad flying on discrete track media with sub-micrometer groove pitch. The air bearing spikes and the flying height loss are calculated and discussed. It is observed that the air bearing spikes exist mainly on discrete track media with groove pitches of micrometer level. When the groove pitch is smaller than 0.3 μm, the air bearing cannot “see” the grooves clearly, and the air bearing pressure profile is smooth generally. For groove pitch of micrometer level, the surface with a larger groove pitch provides a stronger air bearing force, if the groove depth and the groove ratio are fixed. For sub-micrometer groove pitches, the air bearing force is approximately independent of the pitch size.

Diametral compression test: validation using finite element analysis

The validation of the diametral disk compression test with a small flat ground and soft pad utilization has been established. The stress distribution was determined by the finite element analysis for a range of loading conditions. The results showed that for the case of a point load, the fracture is due to shear and compressive stresses at the loading point. The application of the diametral disk test for a flat ground, as well as the use of soft pads at loading regions were proposed and tested. The results showed that both grounds, flat areas and soft pads, have a significant effect on the stress distribution patterns and values in the compression disk test. The stress distributions obtained in both cases, as loading continued, are found to deviate immediately from the assumed ideal point load condition. The obtained results and data, particularly at the disk center, were manipulated in order to obtain a correction equation. Thus, the maximum tensile stress variations, at the center, with the different loading conditions over a wide range ratio of the width of the loading area to the diameter of 0.5 were recorded. Consequently, the stress differences from the ideal case (i.e., the point loading condition) were calculated and fitted with a correction equation. The use of this correction equation can be used to obtain accurate results of the diametral compression test.

Analysis of Failure Rate by Column Distribution in Magnetically Aligned Anisotropic Conductive Adhesive

Characteristics of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -axis interconnects using magnetically aligned anisotropic conductive adhesives (ACAs) are analyzed for their applicability for small pad sizes. In order to evaluate the performance of ACAs, a statistical estimation of the failure rate of interconnects was carried out using top-view images of assembled samples. Through a column mapping process, the failure rate is calculated as a function of pad size. The calculated and measured results indicate that the location of the formed columns is the predominant effect determining interconnect failure. The developed failure estimation approach is effective in demonstrating the effects of scaling to smaller particles in ACAs.

Scanning Electron Microscopic Study of the Human Fungiform Papillae

Human lingual mucosa reveals a highly differentiated papillary organization. The fungiform papillae are grouped as gustatory papillae as they contain taste buds and function as sensory end organs. Taste pores, the surface openings of the taste buds, play important roles both in preneural and neural phases of taste perception by receiving external chemical stimuli and its transduction. Scanning electron microscopy [SEM] of the dorsal lingual surface was used to study the morphology and ultrastructure of the fungiform papillae in human. The lingual samples were prepared from 20 unfixed cadavers at Burdwan Medical College and after proper processing they were examined under SEM at the University of Burdwan. The results demonstrated that these gustatory structures were dome shaped with round base and their diameters were approximately 300 – 800 µm. They were surrounded by shallow circular furrow with small mucosal pad encircling the furrow. The study verified that the covering epithelium of the fungiform papillae is stratified squamous type and frequent desquamation of lining cells was also noticed. Elevated cell margin with distinct intercellular borders were evident in the lining epithelium. Single or multiple circular taste bud pores opened on the upper surface of some of these papillae while in others taste pores were absent. Taste bud pores had diameter of about 3-6 µm. On higher magnification SEM images established the presence of lattice patterned microridges over the epithelial cell surfaces. Within these microridges microgrooves or mucous pits were observed. These observations were related with specific mechanical and gustatory roles.

Part 6: Electrical Therapies

The recommendations for electrical therapies described in this section are designed to improve survival from SCA and life-threatening arrhythmias. Whenever defibrillation is attempted, rescuers must coordinate high-quality CPR with defibrillation to minimize interruptions in chest compressions and to ensure immediate resumption of chest compressions after shock delivery. The high first-shock efficacy of newer biphasic defibrillators led to the recommendation of single shocks plus immediate CPR instead of 3-shock sequences that were recommended prior to 2005 to treat VF. Further data are needed to refine recommendations for energy levels for defibrillation and cardioversion using biphasic waveforms.

Efficacy of Clean Intermittent Catheterization for Urinary Incontinence in Children with Neurogenic Bladder Dysfunction Secondary to Myelodysplasia.

To evaluate the efficacy of clean intermittent catheterization for urinary incontinence in myelodysplastic children. The cohort comprised of 38 children (19 boys and 19 girls, aged between 10 months to 16 years) with neurogenic bladder secondary to myelodysplasia. Group A included 16 children who had dilated upper urinary tract or vesicoureteral reflux when clean intermittent catheterization was introduced. The remaining 22 children with normal upper urinary tract were enrolled to group B. In the present study, we defined socially acceptable continence as having completely dry or slight stress incontinence that patients can manage with several small pads. Of the 16 group A patients, 9 obtained socially acceptable continence by conservative management. Of the 22 group B patients, 11 reported socially acceptable continence by conservative management. Vesical compliance was significantly higher in cases who reported socially acceptable continence than in those with incontinence persistent regarding all participants (10 ± 7.2 vs 6.8 ± 6.2 mL/cmH2 O, P = 0.0347) and group A (9.1 ± 6.7 vs 3.7 ± 1.4 mL/cmH2 O, P = 0.0350). Leak point pressure was significantly higher in patients who obtained socially acceptable continence than in those having persistent incontinence regarding all participants (50 ± 17.2 vs 25 ± 6.6 mL/cmH2 O, P = 0.0003), group A (51 ± 21.4 vs 26 ± 7.2 mL/cmH2 O, P = 0.0348) and also, group B (49 ± 12.8 vs 23.7 ± 6.3 mL/cmH2 O, P = 0.0043). In our series, socially acceptable continence was obtained in only 20 patients (52%) by conservative management. The present study suggests that the limitation of conservative treatment seems to be apparent when they have urethral closure deficiency and/or intractable poor vesical compliance.

Alignment and Performance Considerations for Capacitive, Inductive, and Optical Proximity Communication

We present a comparative analysis of different physical approaches to chip-to-chip proximity communication, PxC, based on capacitive, inductive and optical signalling. Each method is modeled theoretically and the tolerances for packaging are identified. Analytical formulas for performance in terms of the pad size and pad spacing are derived and compared to reported experimental data. The tolerance of each communication method to misalignment is reported. The design space in terms of channel density and chip separation for capacitive and inductive proximity communication is explored for a specified bit-error-rate (BER) or signal-to-noise ratio (SNR) and transmitter power or voltage. The relative merits of each technology are discussed. A general conclusion is that capacitive proximity communication is advantageous for dense communication with small pads at low voltages and when low raw bit-error rates are required; however a hard requirement for vertical separation between chips is identified, independent of the area of the pads, and fixed by the supply voltage and the technology parameters. On the other hand, inductive communication provides a larger working range of chip separations, and is advantageous when larger pad sizes are used; however the minimum voltage is similarly constrained in order to maintain low bit-error rates. Optical proximity communication potentially provides the largest chip separations, but has low tolerance to in-plane misalignment.

Effect of Argon/Hydrogen Plasma Cleaning on Electroless Ni Deposition on Small-Area Al Pads

We investigated effect of Ar/H2 plasma cleaning on electroless Ni under-bump metallurgy (UBM) layer formation on small-area Al pads. When 5 ×5 µm2 pads are cleaned with the plasma, electroless Ni grows successfully on them, whereas no growth occurs on pads cleaned with conventional wet chemicals. In the Ni-UBM layer formation process, Zn is deposited by displacement plating on the Al pads before the electroless Ni plating. Microscopic observations, however, reveal that Zn is not successfully deposited on the wet-cleaned Al-pad surface. X-ray chemical analysis indicates that the plasma cleaning effectively removes C contaminations even for small pad sizes.

A New Anatomic Approach for Robot-Assisted Laparoscopic Prostatectomy: A Feasibility Study for Completely Intrafascial Surgery

Robot-assisted laparoscopic prostatectomy (RALP) has been disseminated widely, changing the knowledge of surgical anatomy of the prostate. The aim of our study is to demonstrate the feasibility of a new, purely intrafascial approach.The Bocciardi approach for RALP passes through the Douglas space, following a completely intrafascial plane without any dissection of the anterior compartment, which contains neurovascular bundles, Aphrodite’s veil, endopelvic fascia, the Santorini plexus, pubourethral ligaments, and all of the structures thought to play a role in maintenance of continence and potency.In this case series, we present our first five patients undergoing the Bocciardi approach for RALP. We report the results of our technique in three patients following two unsuccessful attempts. No perioperative major complication was recorded. Pathologic stage was pT2c in two patients and pT2a in one patient, with no positive surgical margin. The day after removing the catheter, two of the three patients reported use of a single, small safety pad, and one patient was discharged without any pad. One patient reported an erection the day after removing the catheter.The anatomic rationale for better results compared with traditional RALP is strong, but well-designed studies are needed to evaluate the advantages of our technique.

Nondestructive Characterization of Ge Content and Ge Depth Profile Variations in Si1-xGex/Si by Multiwavelength Raman Spectroscopy

A multi-wavelength, micro Raman spectroscopy system was designed and used for non-contact and non-destructive thickness and Ge content characterization of Si1-xGex/Si. The thickness and Ge content estimated by Raman measurements were compared to those values obtained from X-ray diffraction (XRD) and X-ray reflectance (XRR) measurements for cross-reference and showed very good agreement. The multi-wavelength excitation capability of the Raman system allows non-contact and non-destructive probing of Ge concentration as well as Si stress in Si1-xGex/Si along the depth direction. The Ge concentration gradient of small size test pads (as small as 10μm x 10μm) in depth direction were successfully measured using the multi-wavelength Raman system. The multi-wavelength Raman system with high spectral and spatial resolution is found to be very attractive and powerful for characterizing advanced semiconductor materials, such as Si1-xGex/Si and strained Si. It is also very useful for monitoring and controlling process equipment and process conditions.

Beam test of a small MICROMEGAS DHCAL prototype

A sampling hadronic calorimeter with gaps instrumented with thin MICROMEGAS chambers of small pad size and single bit readout is a candidate for an experiment at a future linear collider.Several MICROMEGAS chambers with 1 cm2 anode pads were fabricated using the Bulk technology.Some prototypes equipped with analog readout GASSIPLEX chips were developed for characterisation at the CERN/PS facility.A stack of four chambers and stainless steal absorber plates was used to assess the behaviour of MICROMEGAS in 2 GeV/c electron showers.Longitudinal and transverse shower profile are shown.The Bulk fabrication process was adapted to laminate a mesh on anode PCBs with front-end chips connected on the backside.It is well suited for the construction of a 1 m3 DHCAL MICROMEGAS prototype as large and thin chambers can be made.Such chambers with digital readout chips (HARDROC or DIRAC) were fabricated and tested in a beam.First results are presented.

Effects of Ni addition on the interfacial reactions between Sn–Cu solders and Ni substrate

This research investigates the effects of adding a small amount of Ni to solder. The interfacial reactions between Ni and the Sn–Cu solders at 250 °C are examined. Two sets of Sn–0.7 wt% Cu– xNi solders and Sn–1.0 wt% Cu– xNi solders ( x = 0.02, 0.05 and 0.1 wt%) were prepared. The results reveal that the interfacial reactions are very sensitive to Ni. With increasing Ni addition, the reaction phase grain, Cu 6Sn 5, becomes larger and its morphology changes from a rod-like shape into a faceted structure. The reaction progressions are accelerated in comparison with those without Ni addition. The solder spreading effect on the Cu 6Sn 5 morphology was also investigated. Cu 6Sn 5 exhibits a gradual change in microstructure from the center to the rim for the case when the solder ball spreads over a Ni substrate. However, the solder does not alter the Cu 6sn 5 microstructure while reacting on a small Ni pad without spreading. This suggests that the Cu and Ni contents in the solder near the interface vary during the solder ball spreading process.

Trenched Trailing Pad Air Bearing Surface Structure for Improved Thermal Actuation Efficiency

The thermally actuated flying height control (TFC) technology makes accurate flying height control possible. However, one concern is how to have a proper balance between flying height stability and thermal actuation efficiency, as high air-bearing stiffness at the slider's trailing pad increases the flying height stability but reduces thermal actuation efficiency. A trenched trailing pad ABS structure is explored to solve the abovementioned dilemma. The effects of pad shape, trench depth, and width on the thermal actuation efficiency were investigated. Results indicate that the trenched trailing pad structure significantly improves the actuation efficiency as compared to the conventional ABS. The new structure also improves the ease of fabricating relatively small pad sizes by adopting a multiple etching process which allows the photoresist mask outline to be extended beyond the slider's ABS boundary to provide more footprint and stability to the photoresist pattern.