威廉希尔官方下载Apr 01, 2020
Perfect spot welding paste system, it can use a variety of technical methods to complete the welding according to the heating requirements of different products. Similar to other heating methods, it is easy to burn parts by misuse of laser energy. The laser heater makes full use of the characteristics of laser energy transmission and absorption and creates a reflow environment according to the reflow characteristics of the solder paste, which can make very difficult welding tasks that can be completed with a high pass-through rate.
It is a mature method to determine whether the laser reflow is suitable for the product and the process parameters that must be controlled in order to achieve the expected solder joint quality. It is one thing to analyze and study how the laser works, but it is another thing to apply it in practice. If it is a feasible method to complete the reflow of solder paste with laser on a product, then we can cooperate with the suppliers of solder paste and laser equipment system to optimize the combination of product materials and equipment.
The CO2 laser is the most powerful CW laser available at present. The CO2 laser can produce infrared light with a wavelength of 10600nm and 20% power. The CO2 laser is mostly used for metal cutting and welding. Carbon dioxide laser is made of yttrium aluminum garnet doped neodymium metal. It is usually called Nd: YAG laser. Nd: YAG laser can produce high energy, and the wavelength is 1064nm in the infrared spectrum. Similar to CO2 lasers, they are mainly used for cutting and welding metals, as well as marking metals and other materials. High power diode laser (HDL) mainly relies on GaAs semiconductor bars. It can provide a wavelength of 790-980nm and an output power of 50W each. In the past few years, the improvement of diode cooling technology aiming at maintaining diode temperature has significantly increased the power, life, and efficiency of the diode.
Some users choose to use laser heating because it is the best choice among many means, while others find that laser will be the solution to the heating problem they are facing due to the limited feasible heating means. The most direct reason for using laser heating is the desire for non-contact local heating. Although the motives are different, the purpose is the same: the reflux is limited to one location without affecting other areas, and it should be completed in a very short time, so as to effectively avoid other parts of the product being conducted more heat.
The solder paste is on all pads before the cable is placed. Laser heating is done in one line immediately after the spot solder paste process, and the added heat just forms the solder joint. The time when the solder is in the molten state shall not exceed 3 seconds. When heated, the heat transferred to the surface of the glass substrate is very small, which can prevent thermal expansion and burst. The appearance of solder joints meets the requirements of consistency. As in the previous process, spot weld pastes at each pin and heat each pin separately with the laser. Due to heat conduction, the heating time of the first pin is longer than that of the fourth pin. The local heating temperature is enough, and the total heat is safe for plastic parts.