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The purpose of this paper is to perform experimental tests on fatigue characteristics of chip scale package (CSP) assembly under vibration. Some suggestions for design to prolong fatigue life of CSP assembly are provided.

The CSP assembly which contains different package structure modes and chip positions was manufactured. The fatigue characteristics of CSP assembly under vibration were tested. The fatigue load spectrum of CSP assembly was developed under different excitation. The fatigue life of chips can be estimated by using the high-cycle fatigue life formula based on different stress conditions. The signal–noise curve shows the relationship between fatigue life and key factors. The design strategy for improving the fatigue life of CSP assembly was discussed.

The CSP chip has longer fatigue life than the ball grid array chip under high cyclic strain. The closer to fixed point the CSP chip, the longer fatigue life chips will have. The chip at the edge of the printed circuit board (PCB) has longer fatigue life than the one in the middle of the PCB. The greater the excitation imposed on the assembly, the shorter the fatigue life of chip.

It is very difficult to set up a numerical approach to illustrate the validity of the testing approach because of the complex loading modes and the complex structure of CSP assembly. The research on an accurate mathematical model of the CSP assembly prototype is a future work.

It builds a basis for high reliability design of high-density CSP assembly for engineering application. In addition, vibration fatigue life prediction method of chip-corner solder balls is deduced based on three-band technology and cumulative damage theory under random vibration so as to verify the accuracy of experimental data.

This paper fulfils useful information about the dynamic reliability of CSP assembly with different structural characteristics and material parameters.

Industrial robots are extensively deployed to perform repetitive and simple tasks at high speed to reduce production time and improve productivity. In most cases, a compliant gripper is used for assembly tasks such as peg-in-hole assembly. A compliant mechanism in the gripper introduces flexibility that may cause oscillation in the grasped object. Such a flexible gripper–object system can be considered as an under-actuated object held by the gripper and the oscillations can be attributed to transient disturbance of the robot itself. The commercially available robots do not have a control mechanism to reduce such induced vibration. Thus, this paper aims to propose a contactless vision-based approach for vibration suppression which uses a predictive vibrational amplitude error-based second-stage controller.

The proposed predictive vibrational amplitude error-based second-stage controller is a real-time vibration control strategy that uses predicted error to estimate the second-stage controller output. Based on controller output, input trajectories were estimated for the internal controller of the robot. The control strategy efficiently handles the system delay to execute the control input trajectories when the oscillating object is at an extreme position.

The present controller works along with the internal controller of the robot without any interruption to suppress the residual vibration of the object. To demonstrate the robustness of the proposed controller, experimental implementation on Asea Brown Boveri make industrial robot (IRB) 1410 robot with a low frame rate camera has been carried out. In this experiment, two objects have been considered that have a low (<2.38 Hz) and high (>2.38 Hz) natural frequency. The proposed controller can suppress 95% of vibration amplitude in less than 3 s and reduce the stability time by 90% for a peg-in-hole assembly task.

The present vibration control strategy uses a camera with a low frame rate (25 fps) and the delays are handled intelligently to favour suppression of high-frequency vibration. The mathematical model and the second-stage controller implemented suppress vibration without modifying the robot dynamical model and the internal controller.

This paper aims to consider the experimental and theoretical investigation of the vibratory alignment of the peg-hole, when the peg is fixed in the remote centre compliance (RCC) device, and the vibrations are provided either to the hole or to the peg.

The experimental analysis of the circular and rectangular peg-hole vibratory alignment using the attached to the robot arm RCC device, under vibratory excitation of the hole, has been performed. The parameters of the vibratory excitation and the part-to-part pressing force influence on the alignment process have been analysed. The mathematical approach of the vibratory alignment using the passive compliance device with the vibrations provided to the peg has been proposed, and the simulation has been carried out.

The research has approved the applicability of the RCC device for both of the vibratory alignments of the non-chamfered peg-hole parts either circular or rectangular ones. The compensation of the axial misalignments has been resulted by the directional displacement of the peg supported compliantly. To perform the successful alignment of the parts, it has been necessary to adjust the frequency and the amplitude of the vibrations, the pressing force, the lateral, as well as the angular stiffness of the device.

The experiments on the vibratory alignment of the rectangular peg-hole parts have been carried out considering only the translational misalignment moved into one direction. The non-impact regime of the vibratory alignment has been analysed.

The obtained results can be applied in designing the reliable and efficient devices of the vibratory assembly for the alignment of the non-chamfered peg-hole parts, as well as for chamfered ones, if the axial misalignment exceeds the width of the chamfer. The vibratory technique and passive compliance provide possibility to accomplish the assembly operations using the non-expensive low accuracy robots.

The new method and the mathematical approach of the vibratory assembly using the RCC device can ensure the reliable alignment of the non-chamfered parts, chamfered circular and the rectangular ones, in case the axial misalignment exceeds the assembly clearance, and prevent jamming and wedging.

The paper aims to investigate theoretically and experimentally the process of compliantly supported peg insertion into a bush for high‐speed assembly, when vibrations are provided to the bush in the axial direction, and to analyse the influence of the parameters of the dynamic system and excitation on the assembly process.

The mathematical model of parts vibratory insertion process is formed and the simulation is performed using a numerical computing software environment. The model includes inertia, compliance, dry friction, insertion speed and vibratory excitation. The three‐dimensional simulation of peg‐in‐hole insertion is accomplished using motion analysis software to test the influence of vibratory excitation on assembly failures, such as jamming and wedging. The experimental setup for the robotic vibratory assembly and the investigation methodology were presented. The experimental analysis of the vibratory insertion process of cylindrical parts with clearance is performed when the compliantly supported peg is inserted by the robot into the bush, which is excited in the axial direction.

The vibratory excitation allows preventing the balance between the insertion force and frictional forces and so to avoid jamming and wedging. It is advantageous to select such the frequency of vibrations under which the resonance state of the compliantly supported peg does not occur. The parameters of vibratory excitation and initial assembly state are defined which have the principal influence on the insertion duration and the success of the process. The experimental results show the applicability of the mathematical approach.

The assumption is made that the chamferless rigid peg moves in a plane in respect of the rigid bush with a chamfer. Also, it is considered that there is no impact during the peg and bush contact. The dynamic and static friction coefficient between the parts is equivalent and the insertion speed is constant.

The results can be useful aiming to design the reliable high‐performance vibratory assembly equipment for peg‐hole type parts, which does not require sensors, feedback systems and control algorithms.

The proposed method of applying the vibratory excitation during the peg‐in‐hole insertion process allows to avoid jamming and wedging, and to minimize the duration of the process.

The paper aims to investigate theoretically and experimentally vibrational alignment of parts in an assembly position under kinematical excitement of the movably based part.

Presents developed mathematical model for vibrational alignment when the kinematical excitement of movable part is applied along the insertion axis. Dependencies of alignment duration on stiffness of basing elements and excitation frequency were defined numerically solving the mobile‐based part alignment equations. Alignment experiments of rectangular cross‐section and cylindrical parts under kinematical excitement were carried out.

The mathematical model and the experiments have demonstrated that alignment of the parts being assembled happens due to directed displacement of the movable part resulted by certain parameters of the system and excitement. In the course of the displacement, mating surfaces are aligned and the final mutual orientation of the parts before insertion is realized. Experiments have proved validity of the developed mathematical model. This process reduces allowable axial non‐coincidence and angular misfit of the parts to be assembled.

Impact and non‐impact regimes of the displacement exist depending on the excitement amplitude and initial contact force between the parts. Also, during the vibrational alignment it is possible to control dry friction force between parts by additional high frequency vibrations. Besides, the vibrational excitement can be not only harmonic, but also impulse, bi‐harmonic, etc. Only non‐impact regime of the motion without dry friction force control was investigated and presented in the paper.

The paper investigates the vibrational alignment method based on the directed vibrational displacement of the connecting part, which does not require high preciseness of the interdependent position of the parts in the assembly position.

Vibrational assembly devices of directional action enable compensation of errors of the parts' mutual positioning without use of sensors, feedback systems and control algorithms.

The paper aims to theoretically and experimentally investigate vibratory peg-bush alignment using elastic vibrations of the peg, when the peg is axially excited by a pressed piezoelectric vibrator on the upper end.

Experimental research of part alignment using elastic vibrations was performed and dependencies of alignment duration on excitation signal parameters and initial pressing force were defined for rectangular and circular cross-section parts. Mathematical model of two-mass dynamic systems with elastic contact model representing alignment process was created. Dependencies of system parameters on the alignment duration were obtained by numerically solving systems differential equations.

Theoretical and experimental investigation approved the usage of elastic vibrations for alignment of chamferless circular and rectangular cross-section parts. This novel method of part alignment compensates axial misalignment between mating parts by directional displacement of movably based bush.

Impact and non-impact interaction between bush and peg is possible; however, only non-impact regime was investigated. Static and dynamic coefficients of friction between the parts are equivalent and do not depend on relative velocity of parts.

The results are useful in designing reliable and effective assembly equipment with vibratory assistance alignment for peg-bush operations, which do not require auxiliary sensors and feedback systems. Use of a piezoelectric resonator for peg excitation makes this system easily adaptable to the existing automated assembly equipment.

The proposed method is a new approach to vibratory alignment. The data obtained during investigation expand the insight of the physical processes that drive bush to the axial alignment direction.

The purpose of this paper is to investigate the durability of radio‐frequency identification (RFID) chips assembled on flexible substrates (paper and foil), with materials evaluated with regard to mechanical stresses and dependence on the applied substrate, antenna materials, chip pad printing and chip encapsulation.

RFID chips were assembled to antennas screen printed on flexible substrates. Shear and bending tests were conducted in order to evaluate the mechanical durability of the chip joints depending on the materials used for mounting the RFID chip structures. X‐ray inspection and cross sectioning were performed to verify the quality of the assembly process. The microstructure and the resistance of the materials used for chip pads were investigated with the aim of determining the conductivity mechanism in the printed layers.

Addition of carbon nanotubes to the conductive adhesive (CA) provided a higher shear force for the assembled RFID chips, compared to the unmodified conductive adhesive or a polymer paste with silver flakes. However, this additive resulted in an increase in the material's resistance. It was found that the RFID substrate material had a significant influence on the shear force of mounted chips, contrary to the materials used for printing antennas. The lower shear force for chips assembled on antennas printed on paper rather than on foil was probably connected with its higher absorption of solvent from the pastes. Increasing the curing temperature and time resulted in an additional increase in the shear force for chips assembled to antennas printed on foil. A reverse dependence was observed for chips mounted on the antennas made on paper. An improvement in the durability of the RFID chip structures was achieved by chip encapsulation. Bending tests showed that a low‐melting adhesive was the best candidate for encapsulation, as it provided flexibility of the assembled structure.

Further studies are necessary to investigate the mechanical durability of RFID chips assembled with a conductive adhesive, with different addition levels and types of carbon nanotubes.

The results revealed that the best candidate for providing the highest RFID chip durability related to mechanical stresses was the low‐melting adhesive. It can be recommended for practical use, as it simplified the assembly process and reduced the curing step in the encapsulation of the RFID devices. From the results of shear testing, conductive adhesives with carbon nanotubes can be used in RFID chip assembly because of their ability to increase the shear force of joints created between the antenna and the chip.

In this paper, the influence of the materials used for antenna, chip pads, encapsulation and the curing conditions on the mechanical durability (shear and bending) of RFID chips was analyzed. Commercial and elaborated materials were compared. Some new materials containing a conductive adhesive and carbon nanotubes were proposed and tested in RFID chip assembly to antennas printed on flexible substrates (paper and foil).

The assembly of large component in out-field is an important part for the usage and maintenance of aircrafts, which is mostly manually accomplished at present, as the commonly used large-volume measurement systems are usually inapplicable. This paper aims to propose a novel coaxial alignment method for large aircraft component assembly using distributed monocular vision.

For each of the mating holes on the components, a monocular vision module is applied to measure the poses of holes, which together shape a distributed monocular vision system. A new unconstrained hole pose optimization model is developed considering the complicated wearing on hole edges, and it is solved by a iterative reweighted particle swarm optimization (IR-PSO) method. Based on the obtained poses of holes, a Plücker line coordinates-based method is proposed for the relative posture evaluation between the components, and the analytical solution of posture parameters is derived. The required movements for coaxial alignment are finally calculated using the kinematics model of parallel mechanism.

The IR-PSO method derived more accurate hole pose arguments than the state-of-the-art method under complicated wearing situation of holes, and is much more efficient due to the elimination of constraints. The accuracy of the Plücker line coordinates-based relative posture evaluation (PRPE) method is competitive with the singular value decomposition (SVD) method, but it does not rely on the corresponding of point set; thus, it is more appropriate for coaxial alignment.

An automatic coaxial alignment system (ACAS) has been developed for the assembly of a large pilotless aircraft, and a coaxial error of 0.04 mm is realized.

The IR-PSO method can be applied for pose optimization of other cylindrical object, and the analytical solution of Plücker line coordinates-based axes registration is derived for the first time.

The purpose is to predict the distribution of the residual pretightening force of the bolt group under the action of any initial pretightening force, and to achieve the final residual pretightening force as the target to solve the initial pretightening force value to be applied.

Based on the finite element method and the elastic interaction theory between bolt group, this paper establishes a prediction model for the residual pretightening force distribution of bolt group for one-step pretightening and multi-step pretightening of gasketless flange connection systems. In addition, using the general modeling method given in this paper, the prediction model of residual pretightening force of long plate bolt connection system is established, and compared with reference, which fully proves the effectiveness and universality of the general prediction model of residual pretightening force of bolt group.

The appropriate pretightening sequence, increasing the number of pretightening steps and variable amplitude loading can effectively reduce the influence of elastic interaction and improve the uniformity of residual pretightening force of the bolt group. And the selection of material, number of bolts and connected thickness of bolt connection system also has a great influence on the distribution of residual pretightening force of bolt groups.

The general prediction model for the residual pretightening force of bolt group of connecting structural components considering elastic interaction given in this paper can provide a reference for the design and optimization of the bolt assembly process of the rotor system and the casing system in aero-engine and the prediction of the performance of the connecting system.

Industrial robots are extensively used in the robotic assembly of rigid objects, whereas the assembly of flexible objects using the same robot becomes cumbersome and challenging due to transient disturbance. The transient disturbance causes vibration in the flexible object during robotic manipulation and assembly. This is an important problem as the quick suppression of undesired vibrations reduces the cycle time and increases the efficiency of the assembly process. Thus, this study aims to propose a contactless robot vision-based real-time active vibration suppression approach to handle such a scenario.

A robot-assisted camera calibration method is developed to determine the extrinsic camera parameters with respect to the robot position. Thereafter, an innovative robot vision method is proposed to identify a flexible beam grasped by the robot gripper using a virtual marker and obtain the dimension, tip deflection as well as velocity of the same. To model the dynamic behaviour of the flexible beam, finite element method (FEM) is used. The measured dimensions, tip deflection and velocity of a flexible beam are fed to the FEM model to predict the maximum deflection. The difference between the maximum deflection and static deflection of the beam is used to compute the maximum error. Subsequently, the maximum error is used in the proposed predictive maximum error-based second-stage controller to send the control signal for vibration suppression. The control signal in form of trajectory is communicated to the industrial robot controller that accommodates various types of delays present in the system.

The effectiveness and robustness of the proposed controller have been validated using simulation and experimental implementation on an Asea Brown Boveri make IRB 1410 industrial robot with a standard low frame rate camera sensor. In this experiment, two metallic flexible beams of different dimensions with the same material properties have been considered. The robot vision method measures the dimension within an acceptable error limit i.e. ±3%. The controller can suppress vibration amplitude up to approximately 97% in an average time of 4.2 s and reduces the stability time up to approximately 93% while comparing with control and without control suppression time. The vibration suppression performance is also compared with the results of classical control method and some recent results available in literature.

The important contributions of the current work are the following: an innovative robot-assisted camera calibration method is proposed to determine the extrinsic camera parameters that eliminate the need for any reference such as a checkerboard, robotic assembly, vibration suppression, second-stage controller, camera calibration, flexible beam and robot vision; an approach for robot vision method is developed to identify the object using a virtual marker and measure its dimension grasped by the robot gripper accommodating perspective view; the developed robot vision-based controller works along with FEM model of the flexible beam to predict the tip position and helps in handling different dimensions and material types; an approach has been proposed to handle different types of delays that are part of implementation for effective suppression of vibration; proposed method uses a low frame rate and low-cost camera for the second-stage controller and the controller does not interfere with the internal controller of the industrial robot.