EFFECT OF ULTRASONIC POWER ON THE HEAVY ALUMINUM WEDGE BONDING STRENGTH

Eleven groups of wire bonding experiments are carried out on an experiment platform （restructured with a U3000 heavy aluminum wedge wire bonder）. Pure silicon aluminum wire （300 μm in diameter, 2.94-3.92 N in average pull force） and nickel coated aluminum substrates are used in the experiments. During the experiment process, only ultrasonic power rate parameter is changed and the other bonding parameters are kept as constant, The bonding force and time are 4.90 N and 100 ms respectively. After the bonding experiments, shear strength tests are carried out on the bonds as the bonding strength criterion. From those experiments and test results, some conclusions are obtained： In the small ultrasonic power rate conditions （about 20%-30%）, with the power increasing, the bonding strength enhances accordingly; However, in the large ultrasonic power rate conditions （about 45%-70%）, the bonding strength decreases accordingly and over bonding happens. Only when the ultrasonic power rate is in a moderate condition （about 35%-40%） can good and stabilized bonding strength be acquired.

Study on Simulation Method of Pipeline Networks' Dynamic Characteristic in Hydraulic Manifold Block

In the design of Hydraulic Manifold Blocks (HMB), dynamic performance of inner pipeline networks usually should be evaluated. To meet the design requirements, dynamic characteristic simulation is often needed. Based on comprehensive study on the existing simulation methods, a new method combined of Power Bond Graph(PBG) and Computational Fluid Dynamic (CFD) is proposed. In this method, flow field of typical channels inside HMB is analyzed with CFD to obtain the local resistance coefficients. Then, with these coefficients, a new sectional lumped-parameter model including kinetic friction factor is developed using PBG. A typical HMB design example is given and the comparison between the simulation and the experimental results demonstrates the feasibility and effectiveness of the proposed method.

Switching mechanism and optimisation research on a pressure-attitude adaptive adjusting coal seam water jet slotter

To investigate the attitude-switching mechanisms of existing jet slotters,which integrate drilling,punching and slotting operations,and to improve its fracture ability,we used the power bond diagram theory to analyse the dynamic flow pressure,and force of slotters.A mathematical model was developed for the dynamic characteristics of slotter systems.Furthermore,to study the effect of the main characteristic parameters on the ability of the nozzle to erode sandstone,multi-orthogonal experiments were carried out.And the optimised slots were applied in later practical operations.The research results show that the inlet fluid passed through the time-varying orifice to generate pressure differential thrust,which overcame the spring force,pushed the valve core to open the side nozzle,and closed the rear cavity channel thereby realising the switch of the slotter attitude.An optimal plan was established to balance the diameter,depth,and volume of punching,and a rock-breaking plan was developed for the slotter.Subsequently,the optimised water jet slotter was practically used in coal seam gas drainage.Compared with conventional dense drilling,water jet slotting technology significantly improves the ability,efficiency,and effect of increasing the permeability of the coal seam.

A Comparative Study of Epi-up and Epi-Down Bonding of High Power 980 nm Single-Mode Semiconductor Lasers

Epi-up and epi-down bonding of high power 980nm lasers have been studied in terms of bonding process, thermal behavior, optical performances, thermal stress effects and long-term laser reliability. We demonstrated that epi-down bonding can offer lower thermal resistance and improved optical performances without significantly degrading the long-term laser reliability.

Modeling and Simulation of Hydraulic Hammer for Sleeve Valve

Hydraulic hammer is commonly used hydraulic equipment in engineering work. The characteristics, high acceleration, high frequency and inertial working pressure, make it greatly different from the working conditions of conventional hydraulic equipment, while hydraulic hammer for sleeve type is also not the same as other hydraulic hammers in structure, efficiency and working performance. Based on the principle of hydraulic hammer for sleeve type, the mathematical model of hydraulic hammer for sleeve type was set with various conditions in the reciprocating movement of piston. In addition, more detailed sketch model can be easily built with the mathematical model in multi-domain system analysis software, AMESim. The simulation system of breaker built based on the principle of power bond graph structures in AMESim system is considered comprehensively to achieve its functions and characteristics, which can quickly realize the calculation of main simulation parameters for impactor. The calculated parameters can be proved to be biased with the test prototype. So these parameters must be optimized by Design Exploration to find the appropriate parameters.

A powerful approach to alkoxy radical-mediated remote C(sp^3)–H bonds functionalization

The activation of inert C（sp^3）–H bonds with control of reactivity and selectivity is one of the central topics in chemical sciences.