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To obtain better fatigue resistance for marine engineering equipment welded joints in the design stage, the design method of the marine engineering equipment welded joint design stage needs to be studied.

Based on the structural stress theory, a design method of the marine engineering equipment welded joints with better fatigue performance is proposed. The effectiveness of the method is demonstrated through the simulation analysis and fatigue test of typical marine engineering equipment welded joints.

Methods based on the theoretical advantages of structural stress and the principle of ensuring that the welded joint has a low degree of stress concentration.

The design method of marine engineering equipment welded joints proposed in this study provides a set of operable design routes for technicians, which can better meet the needs of engineering applications.

The purpose of this paper is to study the reliability of sintered nano-silver joints on bare copper substrates during high-temperature storage (HTS).

In this study, HTS at 250 °C was carried out to investigate the reliability of nano-silver sintered joints. Combining the evolution of the microstructure and shear strength of the joints, the degradation mechanisms of joints performance were characterized.

The results indicated that the degradation of the shear properties of sintered nano-silver joints on copper substrates was attributed to copper oxidation at the silver/copper interface and interdiffusion of interfacial elements. The joints decreased by approximately 57.4% compared to the original joints after aging for 500 h. In addition, severe coarsening of the silver structure was also an important cause for joints failure during HTS.

This paper provides a comparison of quantitative and mechanistic evaluation of sintered silver joints on bare copper substrates during HTS, which is of great importance in promoting the development of sintered silver technology.

This study proposes a predictive neural network model reference decoupling control method for the coupling problem between the leg joints of hydraulic quadruped robots, and verifies its decoupling effect..

The machine–hydraulic cross-linking coupling is studied as the coupling behavior of the hydraulically driven quadruped robot, and the mechanical dynamics coupling force of the robot system is controlled as the disturbance force of the hydraulic system through the Jacobian matrix transformation. According to the principle of multivariable decoupling, a prediction-based neural network model reference decoupling control method is proposed; each module of the control algorithm is designed one by one, and the stability of the system is analyzed by the Lyapunov stability theorem.

The simulation and experimental research on the robot joint decoupling control method is carried out, and the prediction-based neural network model reference decoupling control method is compared with the decoupling control method without any decoupling control method. The results show that taking the coupling effect experiment between the hip joint and knee joint as an example, after using the predictive neural network model reference decoupling control method, the phase lag of the hip joint response line was reduced from 20.3° to 14.8°, the amplitude attenuation was reduced from 1.82% to 0.21%, the maximum error of the knee joint coupling line was reduced from 0.67 mm to 0.16 mm and the coupling effect between the hip joint and knee joint was reduced from 1.9% to 0.48%, achieving good decoupling.

The prediction-based neural network model reference decoupling control method proposed in this paper can use the neural network model to predict the next output of the system according to the input and output. Finally, the weights of the neural network are corrected online according to the predicted output and the given reference output, so that the optimization index of the neural network decoupling controller is extremely small, and the purpose of decoupling control is achieved.

Tensile pull strength tests were used to study the strength of solder joints of 25 mil gull wing leads on 132 pin quad flat pack components. The authors generated quadratic and linear models which can be used to predict the pull strength of a solder joint given its geometry. The shape parameters studied were stand‐off height between the lead and substrate, height of heel fillet, radius of curvature of heel fillet, length of heel fillet, height of solder at toe region, and thickness of solder on the lead. The most significant parameters in determining the tensile pull strength of the solder joint are the height and length of the heel fillet. A study was performed to quantify the effect of lead finish on the accuracy of these models. The lead finish was found to have a significant effect on the solder joint strength. The effect of lateral misregistration on the tensile pull strength of solder joints was also investigated. No correlation between the extent of lateral misregistration and joint pull strength has been found.

This paper aims to find a new method that could be applied to the high and mid-grade prosthesis knee joint.

Based on analysis, calculation, modeling, simulation and experimental study of the motion law of knee joint, this paper not only determines the structure and parameters of the knee joint and calculates the instantaneous center but also analyzes the stance stability and completes the optimization. With the help of experimental tests (fatigue test and gait curve test), the quality and performance of the designed knee joint is verified.

The experimental results show that the gait curve of the designed knee joint is much closer to health people. The designed prosthesis knee joint, with adjustable swing speed and gait curve which are close to health limb, has a better performance when compared to the ordinary knee joint with four-bar linkage structure.

This paper developed a prosthesis knee joint based on a novel design method that could be applied to the “high and mid” grade prosthesis knee joint and verified its function on an amputee performed the lower amputation, which could provide theoretical support for researches and designs related to prosthesis knee joint in future.

This paper aims to present the design and a prototype experiment of a robotic joint module for tokamak in-vessel manipulator-related research; the results will promote the adaptation of current in-vessel inspection manipulator to achieve full tokamak in-vessel environment compatibility.

A flexible metallic bellow-enclosed working chamber is used to protect the main servo drive components, the active cooling method for high temperature protection and the servo control structure simplification for high radiation endurance. A joint module prototype is manufactured and tested under a similar in-vessel environmental condition for extreme condition protection validation and basic servo control ability evaluation.

The joint module prototype successfully survived the similar in-vessel environment tests and proved good mobility via closed-loop servo control. A conceptual design of a serial linkage manipulator with joint module structure is proposed for future in-vessel inspection manipulator development.

The proposed joint module uses common industrial servo components to achieve its full extreme in-vessel environment compatibility. Different from traditional metallic bellow application in a vacuum environment to produce a linear movement result, the proposed joint module aims to achieve rotating movement directly from the metallic bellow structure, thereby reducing the joint structure space requirement, simplifying the vacuum environment movement transmission structure and increasing the vacuum environment compatibility degree.

This study aims to study the mechanical, photoelectric, and thermal reliability of SAC307 solder joints with Ni-decorated MWCNTs for flip-chip light-emitting diode (LED) package component during aging. By adding nanoparticles (Ni-multi-walled carbon nanotubes [MWCNTs]) to the solder paste, the shear strength and fatigue resistance of the brazed joint can be improved. However, the aging properties of Ni-modified MWCNTs composite solder joints have not been deeply studied. In this research, the mechanical, photoelectric and thermal reliability of SAC307 packaged flip-chip LEDs with Ni-MWCNTs added during aging were studied.

Compared with SAC solder alloys, the effects of different contents (0, 0.05, 0.1 and 0.2 Wt.%) of Ni-MWCNTs on the photoelectric and thermal properties of composite solder joints were examined. To study the aging characteristics of composite solder joints, the solder joints were aged at 85°C/85% relative humidity.

The addition of an appropriate amount of reinforcing agent Ni-MWCNTs reduces the density of the composite solder to 96% of the theoretical value of the SAC solder alloy. In addition, the microhardness increases and the wetting angle decreases. Two different phase compositions were observed in the solder joints with Ni-MWCNTs reinforcement: Cu₃Sn and (Cu, Ni)₆Sn₅. The solder joints of SAC307-0.1Ni-MWCNTs exhibit the highest luminous flux and luminous efficiency of flip-chip LED filaments, the lowest steady-state voltage and junction temperature. And with the extension of the aging time, its aging stability is the best. In short, when the addition amount of Ni-MWCNTs is 0.1 Wt.%, the solder joints exhibit the best wettability and the thinnest intermetallic compound layer. And the shear strength of the tested solder joints is the best, and the void ratio is the lowest. At this time, the enhancement effect of Ni-MWCNTs on the composite solder has been best demonstrated.

The content range of enhancer Ni-MWCNTs needs to be further reduced.

The authors have improved the performance of Ni-modified MWCNTs composite solder joints.

Composite solder with high performance has great practical application significance for improving the reliability and life of the whole device.

Long‐term fatigue life estimation for solder joints of surface mount IC packages is studied through elasto‐plastic stress analysis and temperature cycling tests. Strain on the solder joint induced by thermal expansion mismatch between package and substrate has been analysed by considering elasto‐plastic behaviour of the solder and by treating leads as rigid frames. Validity of the analysis has been confirmed by stiffness measurement of the soldered leads. Dynamic shear stress‐strain relationships of type 60Sn/40Pb solder are obtained as a function of temperature and frequency using hollow solder specimens of 15 mm in diameter and hollow solder joint specimens with the same diameter in the temperature range of −60°C to 150°C with frequencies of 0.01 Hz and 0.3 Hz. Fatigue tests are carried out for the solder specimens and the solder joint specimens under shear strain control and for the solder joints of the real IC packages under displacement control. All fatigue tests are conducted at room temperature with a frequency of 1 Hz. Fatigue test data of solder, solder joint and the solder joints of real IC packages fall in the same scatter band in the stra'un‐cycles to failure diagram. A fatigue life estimation model for solder joints of surface mount IC packages is proposed, which is derived by combining the strain calculated by the elasto‐plastic analysis and the fatigue data. To apply the proposed model to IC packages, the temperature cycling test between −55°C and +150°C is performed for two IC packages with different lead designs mounted on two different substrates (ceramics and glass‐epoxy). It is found that the fatigue life of solder joints by the temperature cycling test can be estimated by the proposed fatigue life estimation model. The proposed method is viable because it has sufficient accuracy with a cost of less than 1/100 when compared with the finite element method.

The wearout characteristics were investigated for soldered interconnections of surface mount technology (SMT) chip resistors, chip capacitors and a 44 I/O ceramic leaded chip carrier (CLCC) package. Four double‐sided test vehicles were subjected to accelerated thermal cycling in the — 10°C to + 110°C range; 30°C/min ramp rate; and 1 minute dwell time at each temperature extreme. The test was interrupted at initially 500 cycle and later at 1000 cycle intervals to perform visual inspection of all soldered interconnections, functional performance verification for the test vehicles, and resistance measurement on leaded SMT joints. Metallographic examinations and fractographic studies were also performed after 0, 4500 and 13000 cycles to characterise the micromechanisms of soldered joint strength degradation and failure. The wearout thresholds for soldered joints of chip resistors and capacitors on side 1 were respectively 2500 and 4500 cycles. The greater thermal fatigue resistance of the latter joints was attributed to a lower device‐substrate coefficient of thermal expansion (CTE) mismatch and a more favourable device geometry compared with chip resistors. These passive components on side 2, however, showed a virtually identical soldered joint wearout threshold of 6500 cycles. The constraints imposed by the applied mounting adhesive were primarily responsible for this behaviour. No correlation appeared to exist among various failure criteria used to determine the onset of failure for leaded SMT soldered connections. The concurrent monitoring of electrical resistance and the applied tensile load showed a modest relationship between the load drop and resistance increase, however. The test vehicles continued to pass the functional performance verification, even after 13000 thermal cycles. Nonetheless, the joint wearout thresholds were considered to be 2500, 4500 and 4500 cycles for chip resistor, chip capacitor and CLCC components, respectively. A 50% soldered joint strength drop was considered as the wearout threshold for the CLCC device. Metallographic examination showed limited barrel wall cracking of the vias and no evidence of cracks with the through‐hole soldered joints, even after 13000 thermal cycles.

The purpose of this paper is to present a novel Sn7In4.1Ag0.5Cu/Plastic Core Solder Ball/Sn4Ag0.5Cu composite solder joint configuration for second‐level ball grid array (BGA) interconnections of low temperature co‐fired ceramic (LTCC) modules and the thermal fatigue durability of the configuration. The purpose of using the Sn7In4.1Ag0.5Cu solder was to increase the creep/fatigue resistance of critical regions on the LTCC side of the joint.

Test LTCC module/printed wiring board (PWB) assemblies were fabricated and exposed into temperature cycling tests over the 0 to 100°C and −40 to 125°C temperature ranges. The characteristic lifetimes of these assemblies were determined using DC resistance measurements. The failure mechanisms of the test assemblies were verified using scanning acoustic microscopy, FE‐SEM, and SEM investigation.

The test assemblies were exposed to thermal cycling tests (TCT) over test ranges of 0 to 100°C and −40 to 125°C, and characteristic lifetimes of over 5,500 and 1,400 cycles, respectively, were achieved. Compared with Sn4Ag0.5Cu/plastic‐core solder balls (PCSB)/Sn4Ag0.5Cu joints, the characteristic lifetime of the SAC‐In/PCSB/SAC joints increased over 55 per cent in the harsh (−40 to 125°C) TCT conditions. In the milder test conditions (0 to 100°C), the characteristic lifetime of the SAC‐In/PCSB/SAC joints increased 30 per cent compared with the SAC/PCSB/SAC joints.

The results proved that the enhanced creep/fatigue properties of the solder matrix resulted in satisfactory lifetime durations in the present lead‐free composite solder joints and, consequently, different primary failure mechanisms on the LTCC side due to the use of indium alloyed solder. Thus, the present joint configuration is assumed to be a promising solution for the further design of a reliable second‐level solder interconnection in LTCC/PWB assemblies with a high‐global thermal mismatch.