Wang Chunqing

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The bonding procedure of copper wire ball bonding on an aluminum-metallized silicon substrate was investigated in this paper. The four crucial parameters: ultrasonic power, impact force, frequency duration and bonding temperature were optimized. It was found that the process window was quite narrow, thus the bonding process was less stable. In conjunction(More)
Shear behavior of Sn-3.0Ag-0.5Cu solder joints on ball grid array substrates was investigated with different solder volumes and shear speeds to study the solder volume effect on shear properties. Both solder volume and shear speed were found to have strong effect on the shear strength. The shear force decreases obviously with the decrease of the solder(More)
Fiber attachment soldering is low cost and high-precision technology in direct-coupling optoelectronic packaging. The three-dimensional shape of solder joint in fiber attachment soldering was predicted by using the public domain software called Surface Evolver. The influences of material and manufacturing parameters on solder joint geometry and the(More)
Solder joint reliability in hard disk drive head assemblies is of great concern due to the increasing demand and popularity of portable electronic products such as mobile hard disk and laptop computers. The mechanical shock resulting from mishandling during transportation or customer usage may seriously affect the solder joint reliability and lead to(More)
The 3D shape of solder joint in fiber attachment soldering was predicted by employing finite element method (FEM). Based on the minimum potential energy theorem and data from shape simulation, the influence of material and manufacturing parameters on the stand-off height (SOH) between optical fiber and substrate was analyzed in detail. The results showed(More)
In this paper, a LED multi-chip module with a heat pipe was designed for automotive headlights, which took advantages of the relative air flow during vehicle travelling for forced convection to keep the junction temperature of LED chips below 60°C. The Structure is compact enough to be suitable for placement in a small space for automotive lighting.(More)
In this paper, the influence of nano-CeO<sub>2</sub> and micro-CeO<sub>2</sub> with different amounts were discussed after they were added into low phosphorus content Ni-P composite coating. The microstructure and crystal structure of the coating were observed by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) respectively. The(More)
Sn-3.5Ag nanosolder in tiny sizes can provide a practical way to solve the high soldering temperature problem of lead-free solder alloy in fine pitch interconnectivity owing to the unique nanosize effect and meantime stand a higher working temperature just as the bulk material after welding. In this paper, a simple approach to synthesis Sn-3.5Ag(More)
Design of Engineering-to-Order (ETO) product is a process describing various constraints with manifold knowledge to meet customer need in mass customization (MC). With the increase of parts' number and design complexity of ETO product, configuration knowledge including those supporting variant design became more and more. Consequently, reasoning and sharing(More)
This article adopts the Primary Energy Ratio(PER) to evaluate the performances of air conditioning heat and cold sources (refrigerator/ electric heat pump, LiBr absorption unit, gas air conditioning unit and boiler) and compares different Heat and Cold Sources in building Air Conditioning. The result shows that air conditioning unit driven by electrical(More)