The needle-type droplet jetting dispenser has wide applications in the field of microelectronic packaging, and for which the good quality of droplet formation and separation is the key to successful dispensing. This paper simulates the droplet jetting process which has been divided into 5 stages named backflow, growth, droplet extension, breakage, and separation, and analyses the combined effects of system parameters, such as pressure, viscosity, needle stroke, and nozzle diameter, on the changes of morphologies of ejected droplets, which is verified by experiments. The simulation and experiment results show that a higher driving pressure is quite suitable for the high-viscosity liquid to form normal droplets by avoiding adhesion. When increasing the needle stroke, the pressure should also be lowered properly to prevent the flow-stream. Besides, the nozzle with a large diameter is much more likely to cause sputtering or satellite-droplet problems. The results have a great significance for guiding the parameter settings of the needle-type dispensing approach.

This study presents a life cycle assessment (LCA) study for a buoy-rope-drum (BRD) wave energy converter (WEC), so as to understand the environmental performance of the BRD WEC by eco-labeling its life cycle stages and processes. The BRD WEC was developed by a research group at Shandong University (Weihai). The WEC consists of three main functional modules including buoy, generator and mooring modules. The designed rated power capacity is 10 kW. The LCA modeling is based on data collected from actual design, prototype manufacturing, installation and onsite sea test. Life cycle inventory (LCI) analysis and life cycle impact analysis (LCIA) were conducted. The analyses show that the most significant environmental impact contributor is identified to be the manufacturing stage of the BRD WEC due to consumption of energy and materials. Potential improvement approaches are proposed in the discussion. The LCI and LCIA assessment results are then benchmarked with results from reported LCA studies of other WECs, tidal energy converters, as well as offshore wind and solar PV systems. This study presents the energy and carbon intensities and paybacks with 387 kJ/kWh, 89 gCO₂/kWh, 26 months and 23 months respectively. The results show that the energy and carbon intensities of the BRD WEC are slightly larger than, however comparable, in comparison with the referenced WECs, tidal, offshore wind and solar PV systems. A sensitivity analysis was carried out by varying the capacity factor from 20–50%. The energy and carbon intensities could reach as much as 968 kJ/kWh and 222 gCO₂/kWh respectively while the capacity factor decreasing to 20%. Limitations for this study and scope of future work are discussed in the conclusion.

Fabrication of the injection nozzle micro-hole on the aero engine is a difficult problem in today’s manufacturing industry. In addition to the size requirements, the nozzle micro-hole also requires no burr, no taper and no heat-affected zone. To solve the above problem, an ultra-short voltage pulse and a high-speed rotating helical electrode were used in electrochemical drilling (ECD) process. Firstly, a theoretical model of ECD with ultra-short voltage pulse was established to investigate the effects of many predominant parameters on machining accuracy, and the effect of rotating helical electrode on the gap flow field was analyzed. Secondly, sets of experiments were carried out to investigate the effects of many key parameters on machining accuracy and efficiency. Finally, the optimized parameters were applied to machine micro holes on 500 μm thickness of GH4169 plate, and micro-holes with the diameter of 186 μm with no taper were machined at the feed rate of 1.2 μm/s. It is proved that the proposed ECD process for fabricating micro-holes with no taper has a huge potential and broad application prospects.

The needle-type piezoelectric jetting dispenser is widely applied in the microelectronics packaging field, and it is important to control the droplet size to ensure that the droplet jetting process is successful. In this study, we analyzed the influences of system parameters, such as air pressure, nozzle size, needle strokes, and liquid properties, on droplet size and morphology by considering the droplet formation and separation process through a numerical simulation. An experimental platform was also designed to verify the reliability of the simulations and further analyze strategies for controlling the droplet size. We found that the droplet volume can be increased with an increase in air pressure, needle strokes, and nozzle size until the flow-stream or satellite droplets appear. On the other hand, very small values of these parameters will lead to adhesion or micro-dots. A large nozzle and needle displacement should be chosen for the high-viscosity liquid in order to produce normal droplets. The results also show the recommended ranges of parameter values and suitable droplet volumes for liquids with different viscosities, and these findings can be used to guide the droplet volume control process for needle-type jetting dispensers.

The piezoelectric-driven noncontact jetting dispenser with the characteristics of high accuracy, efficiency and applicability has been widely applied in the microelectronics packaging field to produce small droplets. The process of droplet formation and separation is the key to successful jetting. In order to study the process and show the roles of system parameters in droplet formation, the paper runs some numerical simulations and analyzes the comprehensive effects of the system parameters on the morphological change of droplets by using two dimensionless parameters Weber and Reynolds. The simulation and experiment results show that the scale of system parameters is confirmed by the lower and upper limits of Weber according to different Reynolds. If Weber is bigger than the upper limit value or smaller than the lower limit value, the jetting failure like sputtering, satellite dots jetting or adhesion will occur. During the experiments, the system parameters should be adjusted to keep the values of Weber and Reynolds in the proposed scale. The findings in this paper can be used to guide the design and control of these piezoelectric driven dispensers.

The micro‐displacement amplifier has been widely used to magnify the outputs of piezoelectric actuators for some large displacement required applications, and the amplification and frequency are the most important elements for designing the amplifying mechanisms. This study presents the design of a diamond‐type micro‐displacement amplifier (DMDA) and simulates its working performances by using the finite element method. After the theoretical values of amplification and natural frequency are calculated, the effects of system parameters such as angle, arm and body thicknesses, corner radius, side and edge widths, on the changes of amplification and stability are studied. Then experiments are carried out to verify the theoretical simulations and further study the amplification mechanism. Finally, a micro‐droplet jetting dispenser featuring the DMDA is constructed. The perfect jetting performance shows the good application of DMDA in microelectronics packaging field. This study finds that with the increase of the angle and the arm thickness, the amplification decreases and the natural frequency increases obviously. A larger value of corner radius or side width produces a smaller natural frequency. Besides, the increase of edge width enlarges the amplification and reduces the natural frequency. This study can be used to guide the design of this kind of micro‐displacement amplifier.