Needle Span Life Analysis And Research For Glue Jetting System

Because of development of encapsulation technology, whole society turns into high informational communication and exchange period. Today is a globalization and systemization developing model for economy. Manufacturers of electronic information are competing drastically. It requires electronic products to be more miniature, compact and exquisite. Microelectronic manufacturing becomes into the mainstream industry in market. Jetting is non-contact dispensing technology. In comparison with traditional dispensing methodology, it has many advantages of dispensing accuracy, high and consistent dispensing quality in jetting. However the needle of jetting valve is apt to be worn and broken during operating. The span life of jetting device is quite low. Therefore the needle span life must be researched in theory in terms of actual application process. It guides to design and manufacture high quality needle, which is qualified to work for required usage life.Based on this point, the jetting device and test platform from author's company were employed for this research. Firstly the fluid dynamic characteristics were imitated and analyzed in terms of powerful CAE simulation engineering tool. According to simulation result, every of factors, which were affecting final jetting result, were broadly studied including of how they contributed to jetting performance. Afterward DOE experiments were designed and applied to verify simulation result. It concluded that both of needle geometry dimensions and needle stroke were most important factors to determine final jetting glue amount and dot size.Secondly, based on CFD simulation result, in order to obtain high jetting performance needle geometrical dimensions and application parameter must be optimized. According to basic material strength analysis principles and fatigue strength calculation formulation, the methodologies of needle strength analysis and fatigue life were established in this paper. In addition, in terms of needle material mechanical property, needle internal impulsive stress and strain results would be derived through running ANSYS mechanical structure analysis software. Considering into needle limiting stress chart, the fatigue strength for needle was verified respectively under different needle tip geometry structure design. The safety factor for needle fatigue strength was checked whether it met with specification too. During this process we kept to optimize needle structure until it reached to request.Finally considering into fluid dynamic characteristics CFD analysis and needle fatigue strength research and calculation result in above, the DOE experiments and needle functionality and fatigue life tests were conducted in terms of existing jetting device and experimental equipment in author's company. DOE test results showed the major factors affecting jetting results were exactly same as CFD simulation result. On the basis of needle mechanical strength theory and fatigue life analysis conclusions, actual jetting performance and actual span life were performed for every of needle geometrical structure dimensions. The function and life test result indicated: needle structure of 0.75 mm was not only jetting 0.3mm glue dot size under spec range, also its life could be easily reaching to 5500 million cycle times, furthermore it continued to work normally. Obviously actual fatigue life was utterly matching with fatigue strength and life calculation chart. Although needle structure of 0.5mm was able to eject small dot size 0.3mm in the beginning, its fatigue strength was not high as expected, the real test life was very low, far beyond of design specification. Also those needles, which were broken in the field site, remained the similar structure design as 0.5mm needle. It proved this kind of design could be worn out and cracked very soon. Taking account of needle machining convenience and economical efficiency, it theoretically explained needle structure design proposals, demonstrated manufacturing process based on actual test conclusions in this thesis. The theoretical support and experimental data reference were presented in this paper to manufacture high performed, reliable and long span life jetting device specifically supporting microelectronic encapsulation business growth.