| With the vigorous development of the microelectronics packaging technology, the traditional distribution of solder paste process cannot meet the increasing technical requirements. Solder paste distribution is the first process of SMT technology, but also it is the most critical and important process. The accurate distribution of solder paste padded on the circuit board, determines the performance of electronic components fixed mechanical and electrical connection. Piezoelectric drive valve as a new type of solder paste drip of solder paste distribution technology, has been widely attention due to its advantages of high accuracy and good consistency; Because of foreign technology monopoly, piezoelectric drive valve type solder paste drip technology has not been popularized in domestic. Therefore, studying the driving mechanism of the slide valve type solder paste drip, which is driven by piezoelectric, is particularly important. This paper researches the mechanism of piezoelectric drive spool solder paste drip, and according to the theoretical analysis to make the prototype and analyze the test. The main content of this paper is as follows:First of all, in this paper, the distribution of common solder paste technology of domestic and foreign as well as the corresponding products are introduced. And the advantages and disadvantages are analyzed. This paper describes the piezoelectric drive spool type solder paste injection technology research status and research significance. And analyzes the further study on the structure and material properties of the piezoelectric pile and the driving ability of the piezoelectric pile and driving characteristics, providing theoretical basis for lever displacement amplifier system.Second, use the fluid dynamics to analyze the piezoelectric drive valve type solder paste drip. Solder paste, as a kind of solid liquid two phase fluid, in small channel is laminar flow. And the solder paste droplet forming principle is introduced, the influence of piezoelectric drive valve type of solder paste drip factors is analyzed; The fluid dynamics of piezoelectric drive valve type solder paste drip is analyzed in theory. Use Fluent software to analyze the influencing factors of solder paste drip finite element, and get the influence of characteristics of the position of the slider, solder paste supply pressure and needlepoint aperture of slide valve drip.Moreover, design the structure of the piezoelectric drive valve type solder paste drip device and analyze its dynamic. According to the previous theoretical analysis, the structure of piezoelectric drive spool solder paste infusion device is designed and the principle is introduced. Then structural analysis the lever amplification system on the displacement and establish the piezoelectric driving dynamics model of valve solder paste infusion device. The response time of the device is obtained by numerical analysis, and the finite element analysis software is used to analyze the inherent frequency of the device, which proves the feasibility of the system.Finally, make the prototype and set up the experiment platform according to the experiment requirement. Then test the lever displacement amplifier system, and analysis the output characteristic of the drive system of the piezoelectric pile displacement; Respectively from the valve open time, solder paste supply air pressure and pore diameter and other aspects of the trial prototype experiments to analyze their influence law of solder paste drip performance analysis; Finally through the test can obtain drip solder paste properties under the experimental conditions: in the piezoelectric stack driving voltage 100 v, needle aperture size 0.2 mm, valve opening time 400 ms, driven pressure 0.4 MPa, the average quality of solder paste droplets 2.81 mg, quality precision of error of plus or minus 1.1%. |
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