Hydrogen plasma surface treatment process plasma cleaning BAG to improve the solderability of BGA

• Categories:Technical Support
• Author:plasma cleaning machine-surface treatment equipment-CRF plasma machine-Sing Fung Intelligent Manufacturing
• Origin:
• Time of issue:2021-05-15
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(Summary description)        The solder balls of BGA devices are often very easy to oxidize, and the soldered BGA solder joints are not only inferior in appearance, but their electrical and thermal properties are also greatly reduced. The plasma surface treatment process can effectively remove the oxide on the surface of the BGA solder ball. The method has simple process, significant effect and high efficiency, and is an effective method for removing oxides of BGA components and other surface-mounted components. Plasma surface treatment process         To achieve good reliability in the soldering of BGA devices, the solderability of the BGA solder balls is very important. However, due to various reasons, such as long storage period, exposure to the atmosphere, high baking temperature, and some corrosive industrial waste gas in the atmosphere, it is easy to cause oxidation and corrosion of BGA solder balls.         The oxidative corrosion of the solder ball makes the solder ball look dull, gray, dark and black, making it impossible for the vision system of the automated placement machine to recognize it, making it impossible to carry out large-scale automated production. More importantly, the poor solderability of the solder balls will bring about a series of problems, such as welding voids, false soldering, and desoldering. These soldering defects will cause the reliability and long-term working life of the BGA. Serious impact.         Methods to improve the solderability of BGA solder balls Once the BGA solder balls are oxidized and corroded, appropriate treatment measures must be taken to restore their solderability. Common methods are:         (1) Coat active flux on the solder balls, and then re-melt them. In this way, the BGA has to undergo a high temperature melting, which may cause thermal damage to the BGA. In addition, an additional cleaning process must be added, because active flux is used, and all flux residues must be completely removed, which increases the complexity of the process.         (2) Remove the solder balls of the BGA and replant the balls. The ball planting process is complicated, difficult, time-consuming, and needs to heat the BGA twice. Two times of heating may cause adverse effects on the internal circuit of the BGA. And the work efficiency is low, not suitable for mass production. In addition, the success rate of planting the ball is not very high.         (3) Use high-temperature hydrogen for reduction. Hydrogen has a strong reducing ability and can effectively remove the oxide corrosion layer on the surface of the solder ball. But high temperature is likely to damage BGA devices.         (4) Use reducing acid gas for reduction, but it also requires a high temperature of about 220 degrees Celsius, and formic acid is corrosive to a certain extent.         (5) The method of pickling is adopted. Using a relatively dilute acid, such as dilute hydrochloric acid and citric acid with a volume fraction of about 10%, can remove the oxide on the BGA solder ball, but the acid solution is likely to corrode the BGA device.         (6) Of course, it can be discarded. But many BGA devices are very expensive, and discarding them will cause huge losses.         None of the above methods are very good. Now we introduce a novel method to treat BGA devices with hydrogen plasma in the plasma surface treatment process, which can greatly improve the reliability of BGA devices, and the process is simple, effective and efficient. high.         Advantages of using hydrogen plasma to remove BGA oxide:         The hydrogen plasma is used to reduce the oxide on the BGA solder ball, the process is simple, no high temperature is required, the device is less damaged, no cleaning and drying are required, and the removal effect is good, and the production efficiency is also high.         The application of BGA solder ball oxide layer can draw the following conclusions:         (1) The activity of hydrogen plasma is much stronger than that of molecular hydrogen, and it has good reducing activity at low temperatures;         (2) Proper heating of the hydrogen plasma can greatly improve the reducing activity of the hydrogen plasma;         (3) Hydrogen plasma treatment can improve the appearance of BGA solder joints, making the solder joints appear full, round and bright;         (4) Hydrogen plasma treatment of oxides on BGA solder balls has simple process, good effect and high efficiency;         (5) The method of hydrogen plasma to remove the oxide layer can be extended to the removal of oxides of all surface mount components.