| With the rapid development of electronic products in intelligence,diversification,flexibility and miniaturization,the chip area in integrated circuits is small,the number of solder joints is huge,the circuit density is high,the chip characteristic size is small,and the integration scale is gradually expanding.At the same time,the welding shape is varied,the I/O spacing will continue to decrease,and the welding difficulty will increase.The current welding technology and welding equipment are difficult to meet the needs of production,so it is necessary to find a new technical way to study the micro-tin welding equipment and key technologies.Adopt pneumatic injection valve,laser,mobile platform,set up based on the laser welding of the solder paste droplet spray experiment platform,affects the quality of solder paste injection,the mechanical behavior of laser welding quality,welding points related factors,respectively through single factor experiment and orthogonal experiment,explore based on laser micro welding process of the solder paste droplet spray.The main conclusions are as follows:1.Based on the laser welding experimental platform,single factor experiments were conducted on the main factors affecting the quality of solder paste injection point,such as injection time,feeding pressure,nozzle diameter and firing needle stroke.The experimental results show that: The solder paste point diameter increases with the increase of injection time,feeding pressure and nozzle diameter,while the injection time,feeding pressure and nozzle diameter have little effect on the solder paste point height,and when the firing needle stroke is more than 6mm,the solder paste point diameter has little effect.The orthogonal experiment was carried out with feeding pressure,injection time and nozzle diameter as orthogonal factors.The experimental results show that when feeding pressure is 0.35 MPa,injection time is 170 ms and nozzle diameter is 0.3mm,the solder paste diameter stability is the best.2.Based on laser welding experiment platform,the main factors affecting the quality of laser welding peak current,welding time,welding frequency,duty cycle,from the single factor experiment of coke,the experimental results show that the spot size with the peak current,welding time,the duty ratio increases,along with the augment of from coke increases after the first decreases,and with the increase of welding frequency decreases slowly;Orthogonal experiments were conducted with peak current,welding time,welding frequency,duty cycle and defocus as orthogonal factors,and the experimental results showed that: When the peak current is 4.0A,the welding time is800 ms,the welding frequency is 10 Hz,the duty cycle is 70%,and the defocusing quantity is-2mm,the average diameter of the solder joint is 0.915 mm,and the standard deviation of the diameter is 0.056 mm.The welding joint forming effect is the best,and the laser welding process based on pure copper plate is formed.3.Based on the laser welding experimental platform and tensile strength tester,single factor experiments were conducted on the main factors affecting the mechanical properties of welding joints,including peak current,welding time,welding frequency,duty cycle and defocus.The experimental results show that: The tensile stress increases with the increase of welding time and duty ratio,decreases with the increase of welding frequency,and increases first and then decreases with the increase of peak current and defocus amount.The experimental results also show that when defocus amount is 0mm,the tensile stress of pads is the largest.Orthogonal experiments were carried out with peak current,welding time and defocus as orthogonal factors,and the experimental results showed that: When the peak current is 3.5A,the welding time is 900 ms,and the defocusing amount is 0mm,the tensile stress of the welding point is 17 MPa,the standard deviation of tensile stress is 1.93 MPa,and the tensile stress of the welding point is relatively stable,forming the laser welding process based on PCB as welding substrate. |
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