As electronic devices continue to move towards miniaturization, the processing speed of processing chips is increasing. Whether it's laptops, smartphones, medical machinery, small car electronic devices, military and aerospace products, the application of BGA, CSP and other devices in array packaging in products is increasing, and the quality requirements for products are also increasing. All of these require us to continuously advance the SMT processing technology, coupled with high-quality machinery and equipment, to ensure high reliability of products based on high-quality welding.

Generally, after SMT patch welding, there will be a residual part of the welding in the equipment that is one-sided, which poses a potential risk to the stability of product quality. Although there are many factors that contribute to this one-sidedness, such as solder paste, surface treatment methods for PCB solder layers, setting of countercurrent curves, natural environment of countercurrent, overall planning of solder layers, microporous plates, and voids in the plate, the most important reason is often composed of residual vapors from the melted solder material during electric welding. When the melted welding material condenses, this type of bubble is frozen out to form a one-sided state. Unilateralization is a common condition in electric welding, and it is impossible to have all welds in electronic product assembly products without unilateralization. Due to the harm caused by one-sided factors, the reliability of most welded products is uncertain, resulting in a decrease in welding impact toughness and affecting the heat transfer and conductivity functions of the welding process. Subsequently, it seriously endangers the electrical equipment functions of the equipment. N2 reflow soldering furnace

Based on this, regarding the welding of power electronics professional skills in PCB, the one-sided composition seen in the X-ray pattern cannot exceed 5% of the overall welding area. The minimum area of this type of scale cannot be achieved by adjusting the current processing technology, which means that new welding methods, such as vacuum pump reflux furnace welding professional skills, are required. The vacuum pump reflow welding process is a professional skill for welding in a vacuum environment. This can solve the problem of air oxidation of welding materials under general vacuum pump conditions at the source during SMT chip sampling or production and processing. Moreover, due to the pressure difference in the welding table, the bubbles in the welding can easily overflow from the welding process, and the probability of bubbles reaching the welding process is very low or even non-existent, achieving the estimated purpose.

The professional skills of vacuum pump reflow welding provide the probability of avoiding the formation of one-sided welding after deep sinking of the vapor, which is crucial in large-scale welding processes. Therefore, these large-scale welding processes need to transmit high-power power and heat, so reducing one-sided welding can adjust the heat transfer conductivity of the equipment from the source. Vacuum pump welding is sometimes applied in conjunction with repair gas and H2 mixture, which can reduce air oxidation and remove metal oxides.

The principle of reducing one-sided welding process in vacuum pump reflux furnace can be analyzed from four aspects. Below is a brief introduction and analysis.

1. The vacuum pump reflux furnace can provide extremely low oxygen content and appropriate recovery atmosphere, which greatly reduces the oxidation level of welding materials;

2. Due to the decrease in air oxidation level of welding materials, the metal oxide and flux reflect a significant reduction in gas, which reduces the probability of one-sidedness;

3. A vacuum pump can enhance the activity of molten welding materials, and the friction resistance of the theme activity is relatively small. In this way, the buoyancy of the water in the bubbles detected by molten welding is much greater than the friction resistance of the welding material activity, and the bubbles can be easily guessed and discharged from the molten welding; Lead-free reflow soldering

4. Due to the pressure difference between the bubble and the external vacuum, the buoyancy of the water in the bubble will be significant, causing the bubble to easily derail and melt the welding material. After vacuum pump reflow welding, the reduction rate of bubbles can reach 99%, the one-sided rate of individual welding can be less than 1%, and the one-sided rate of the entire plate can be less than 5%. On the one hand, it can promote the improvement of welding stability and bonding strength, enhance the moisture function of the solder wire, and on the other hand, reduce the application of solder paste during the application process. Moreover, it can also adapt to different environmental conditions, especially high humidity, ultra-low temperature, and high temperature natural environments.