Finite element models of heat spreader enhanced plastic ball grid array (EPBGA) packages with different structures, materials and process treatments had been developed in this study. Predicted result indicated that the difference of stress were not significant generated in the structures with single layer and double-layer spreader respectively. The stress became smaller gradually with the increasing of glue thickness. Moreover, the encapsulation material of CV5420 brought less stress for package than FP4654. The result of reliability test revealed that product using the spreader dealt with ENEPIG all failed after reflowed three times, which had the worst reliability. Plasma proved beneficial to the reliability of package. The performance of 2200 was better than that of 2100A and 2300. Finally, the optimal structure design and material collocation were achieved for the EPBGA package.
ZrO2 nano-particles were successfully prepared by supercritical hydrolysis in two steps (hydrolysis and dehydration) and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle-size analyzer. The influences of operation parameters, including operation pressure and temperature, CO2 total flow and ratio of CO2 branch flow, on the particles were investigated experimentally. The results show that average particle size increases with the increase of the operation temperature, while it decreases with the increase of the operation pressure and the CO2 total flow. The smallest particles with average diameter of 793nm can be prepared under the condition: operation temperature and pressure of 50°C and 8MPa, CO2 total flow of 30 standard cubic centimeter per Minute and ratio of CO2 branch flow of 3.
Models with main-branch channel, crossing channel and net type channel are established and nutrient liquid with a velocity of 0.01m/s is adopted in the study to investigate the fluid field in the channel by using FEA software FLUENT. The velocity and pressure distribution have been obtained in the investigation. By comparing the results in the three models, pressure and velocity distribution in the second and the third models are relatively uniform and are appropriate for the bionics principles. Studies in this paper will be of benefits for the development of tissue engineering.
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