The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Heather Bradley - One of the best experts on this subject based on the ideXlab platform.
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Lord SolderBrace™ Wafer Applied Coating for Improved Reliability and Throughput in WLCSP
2013Co-Authors: George Sears, Guoyun Tian, Duy Le, Heather BradleyAbstract:As more manufacturers look to increase the size of Wafer Level Chip Scale Package (WLCSP) dies and also look to decrease the ball pitch, the susceptibility of the die to fail during thermal cycling and drop shock testing increases. The stress conditions introduced during thermal cycling from the mismatches in Coefficients of Thermal Expansion (CTE) lead to solder fatigue. The failure of WLCSPs during drop shock is found at the solder/pad interface. The general solution to address solder fatigue during thermal cycling and solder joint stress at the copper pad interface has been capillary underfilling the chips after chip attachment. To address these issues, a new material from Lord Corporation – SolderBrace™ wafer applied coating, can be used to partially underfill the WLCSP die at the wafer level. This type of technology can be applied using existing equipment and processing techniques making these materials a more cost effective solution. This new material technology has enabled thermal cycling reliabili...
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Lord SolderBrace™ Wafer Applied Coating for Improved Reliability and Throughput in WLCSP
International Symposium on Microelectronics, 2013Co-Authors: George Sears, Guoyun Tian, Heather BradleyAbstract:As more manufacturers look to increase the size of Wafer Level Chip Scale Package (WLCSP) dies and also look to decrease the ball pitch, the susceptibility of the die to fail during thermal cycling and drop shock testing increases. The stress conditions introduced during thermal cycling from the mismatches in Coefficients of Thermal Expansion (CTE) lead to solder fatigue. The failure of WLCSPs during drop shock is found at the solder/pad interface. The general solution to address solder fatigue during thermal cycling and solder joint stress at the copper pad interface has been capillary underfilling the chips after chip attachment. To address these issues, a new material from Lord Corporation – SolderBrace™ wafer applied coating, can be used to partially underfill the WLCSP die at the wafer level. This type of technology can be applied using existing equipment and processing techniques making these materials a more cost effective solution. This new material technology has enabled thermal cycling reliability improvements by replacing the final passivation layer with a new low CTE material as the partial underfill. This wafer applied partial underfill material technology has been successfully used to provide increased thermal cycling and drop shock reliability in WLCSPs using a number of different methods that have been previously described. The method to be discussed in this paper is a production process using a screen printed, photo defined polymer system that does not require any in-process post cure.
Bogdan Sapinski - One of the best experts on this subject based on the ideXlab platform.
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INVESTIGATION OF MR FLUIDS IN THE OSCILLATORY SQUEEZE MODE
Acta Mechanica et Automatica, 2013Co-Authors: Bogdan Sapinski, Wojciech Horak, Marcin SzczęchAbstract:The paper summarises the results of laboratory testing of three commercially available magnetorheological (MR) fluids operated in the oscillatory squeeze mode. Tested fluids include the Basonetic 204 and Basonetic 4035 (BASF) and MRF-122EG (Lord Corporation). The oscillatory squeeze mode produces large forces at small displacements. This feature may be well utilised in fabrication of new MR de- vices. The purpose of the experiments was to evaluate the suitability of MR fluids for applications in MR vibration dampers being devel- oped under the current research project. The results enable a comparative analysis of investigated fluids and verification of phenomena encountered in the oscillatory squeeze mode and reported in the literature.
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experimental study of a self powered and sensing mr damper based vibration control system
Smart Materials and Structures, 2011Co-Authors: Bogdan SapinskiAbstract:The paper deals with a semi-active vibration control system based on a magnetorheological (MR) damper. The study outlines the model and the structure of the system, and describes its experimental investigation. The conceptual design of this system involves harvesting energy from structural vibrations using an energy extractor based on an electromagnetic transduction mechanism (Faraday's law). The system consists of an electromagnetic induction device (EMI) prototype and an MR damper of RD-1005 series manufactured by Lord Corporation. The energy extracted is applied to control the damping characteristics of the MR damper. The model of the system was used to prove that the proposed vibration control system is feasible. The system was realized in the semi-active control strategy with energy recovery and examined through experiments in the cases where the control coil of the MR damper was voltage-supplied directly from the EMI or voltage-supplied via the rectifier, or supplied with a current control system with two feedback loops. The external loop used the sky-hook algorithm whilst the internal loop used the algorithm switching the photorelay, at the output from the rectifier. Experimental results of the proposed vibration control system were compared with those obtained for the passive system (MR damper is off-state) and for the system with an external power source (conventional system) when the control coil of the MR damper was supplied by a DC power supply and analogue voltage amplifier or a DC power supply and a photorelay. It was demonstrated that the system is able to power-supply the MR damper and can adjust itself to structural vibrations. It was also found that, since the signal of induced voltage from the EMI agrees well with that of the relative velocity signal across the damper, the device can act as a 'velocity-sign' sensor.
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MR damper performance for shock isolation
Journal of Theoretical and Applied Mechanics, 2007Co-Authors: Bogdan Sapinski, Maciej RosółAbstract:The paper is focused on the shock isolation performance of a drivers seat whose suspension is completed with a linear magnetorheological fluid damper (MR damper). The aim of experimental investigations was to recognize the MR damper performance against shock effects. The experiments were performed on a linear damper of RD-1005-3 series manufactured by Lord Corporation operating in open loop and closed-loop system configurations under shock displacement-inputs (rounded pulses and square waves). In the first case, the MR damper was operating as a passive damper and in the second case, as a controllable damper for which real-time controllers were developed in the MATLAB/Simulink environment. The system performance for shock isolation was evaluated basing on measured system responses.
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Parametric identification of MR linear automotive size damper
Journal of Theoretical and Applied Mechanics, 2002Co-Authors: Bogdan SapinskiAbstract:The paper deals with the problem of parametric identification of phenomenological models of a MR damper. The rheological structures of the MR damper described by two fundamentals parametric models that are due to Bingham and Spencer are reviewed. The problem of identification is considered, exemplary results of MR damper experimental tests and an adjustment procedure of the estimated parameters with respect to experimerital data are discussed. A linear MR damper of RD-1005 series developed by Lord Corporation has been tested and modelled.
Rama B. Bhat - One of the best experts on this subject based on the ideXlab platform.
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Design optimization and experimental characterization of a rotary magneto-rheological fluid damper to control torsional vibration
Smart Materials and Structures, 2020Co-Authors: Ehab Abouobaia, Ramin Sedaghati, Rama B. BhatAbstract:This paper aims at optimum design formulation of a rotary disk-type magneto-rheological (MR) fluid damper to increase its torsional vibration control performance. The objective is to maximize the torsional damping torque for a given volume, geometric and inertia constraints. The damping torque has been derived based on Bingham plastic model for a commercial MR fluid provided by Lord Corporation. As MR fluid's yield strength directly depends on the applied magnetic field intensity, an analytical magnetic circuit analysis has been conducted to approximately evaluate the magnetic field intensity in the MR fluid gap. A finite element model of the rotary MR damper has also been developed to evaluate the magnetic field distribution. A formal design optimization problem has then been formulated to maximize the dynamic range for a given volume under geometric, inertia and torque ratio constraints. Genetic Algorithm (GA) combined with Sequential Quadratic Programming (SQP) method has been utilized to accurately capture the global optimum solution. Finally, a proof-of-concept of the optimal design has been manufactured and then tested experimentally to investigate the generated damping torque under different current excitation and also to validate the model and optimization strategy.
Nagi G Naganathan - One of the best experts on this subject based on the ideXlab platform.
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study of the behavior of mr fluids in squeeze torsional and valve modes
Journal of Intelligent Material Systems and Structures, 2003Co-Authors: Prashant Kulkarni, Constantin Ciocanel, Sheila L Vieira, Nagi G NaganathanAbstract:In order to understand the effectiveness of MR fluids in some applications, such as bearings, this work focuses on the properties of MR fluids under squeeze mode, torsional mode and squeeze combined with torsional mode. A special device was designed and fabricated to perform these experiments, which were carried out on an Instron Multiaxial Testing Machine. The hysteresis loops of the MR fluids were studied for different intensities of electric current, frequency, strain amplitude and angle amplitude. The results showed that the damping force and the area of the hysteresis loop of MR fluids increase with the current and strain amplitude. Changes on the frequency did not influence the stress values significantly, within the range of frequencies used in these experiments. In order to evaluate the performance of a squeeze film damper (SFD), measurements were made using a MR damper manufactured by Lord Corporation (RD1005), which operates in valve mode. The results of the SFD were compared to the ones obtained with the RD1005 damper. The shape of the hysteresis loop curves and the MR effect were found to be different for the squeeze film damper and the RD1005 damper.
George Sears - One of the best experts on this subject based on the ideXlab platform.
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Lord SolderBrace™ Wafer Applied Coating for Improved Reliability and Throughput in WLCSP
2013Co-Authors: George Sears, Guoyun Tian, Duy Le, Heather BradleyAbstract:As more manufacturers look to increase the size of Wafer Level Chip Scale Package (WLCSP) dies and also look to decrease the ball pitch, the susceptibility of the die to fail during thermal cycling and drop shock testing increases. The stress conditions introduced during thermal cycling from the mismatches in Coefficients of Thermal Expansion (CTE) lead to solder fatigue. The failure of WLCSPs during drop shock is found at the solder/pad interface. The general solution to address solder fatigue during thermal cycling and solder joint stress at the copper pad interface has been capillary underfilling the chips after chip attachment. To address these issues, a new material from Lord Corporation – SolderBrace™ wafer applied coating, can be used to partially underfill the WLCSP die at the wafer level. This type of technology can be applied using existing equipment and processing techniques making these materials a more cost effective solution. This new material technology has enabled thermal cycling reliabili...
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Lord SolderBrace™ Wafer Applied Coating for Improved Reliability and Throughput in WLCSP
International Symposium on Microelectronics, 2013Co-Authors: George Sears, Guoyun Tian, Heather BradleyAbstract:As more manufacturers look to increase the size of Wafer Level Chip Scale Package (WLCSP) dies and also look to decrease the ball pitch, the susceptibility of the die to fail during thermal cycling and drop shock testing increases. The stress conditions introduced during thermal cycling from the mismatches in Coefficients of Thermal Expansion (CTE) lead to solder fatigue. The failure of WLCSPs during drop shock is found at the solder/pad interface. The general solution to address solder fatigue during thermal cycling and solder joint stress at the copper pad interface has been capillary underfilling the chips after chip attachment. To address these issues, a new material from Lord Corporation – SolderBrace™ wafer applied coating, can be used to partially underfill the WLCSP die at the wafer level. This type of technology can be applied using existing equipment and processing techniques making these materials a more cost effective solution. This new material technology has enabled thermal cycling reliability improvements by replacing the final passivation layer with a new low CTE material as the partial underfill. This wafer applied partial underfill material technology has been successfully used to provide increased thermal cycling and drop shock reliability in WLCSPs using a number of different methods that have been previously described. The method to be discussed in this paper is a production process using a screen printed, photo defined polymer system that does not require any in-process post cure.
