PCB Tech - Analysis of related skills in SMT processing

Analysis of related skills in SMT processing
In the process of SMT processing, there will be various problems. The most common ones are abnormal materials, poor soldering, solder paste failures and so on. Some friends may think that when a problem occurs during the SMT processing of the SMT, as long as it is removed and soldered, most of the problems can be easily solved, but they do not know that there is more knowledge in this. Let the engineers of Electronics Co., Ltd. analyze it below:

PCB SMT factory

First of all, let’s talk about the situation that there are many component pins in the process of SMT processing. Their spacing is often too wide. The best method is to first tin plating on a certain pad, and then use the tweezers in the left hand to remove One leg of the component is soldered well, and the remaining legs are soldered with tin wire. A hot air gun can not be used during the operation. Some friends may ask how to operate? It's very simple. Just hold the hot air gun in one hand to blow the solder, and use tweezers and other fixtures to remove the components while the solder is melted in the other hand.

Furthermore, it is necessary for us to introduce the small number of device pins during SMT processing. The most direct devices are probably resistors, capacitors, diodes and so on. During operation, it is best to tin-plate the pads on PCB board, and then use tweezers to clamp the components and place them on the mounting position. At this time, you need to specifically close the pins and loosen the left hand properly. Tweezers, solder the rest of the legs with tin wire; of course, it is also very easy to remove, you only need to use a soldering iron to heat the two ends of the component, and then gently lift it to achieve the purpose of easy removal.

Finally, the Electronics Co., Ltd. also had to mention the components with high pin density, which are similar to each other when soldered, which is basically the same as the above description. When operating, solder one foot first, and then use tin wire to solder the rest. After all, the number of feet is relatively large, so it is very important to align the feet with the pads during the operation. When performing this step, it is best to control the strength to avoid damaging the pins.

SMT processing plant

Now that we talked about welding and dismantling, we have to extend a common topic in the middle of the operation. Why is there insufficient tin on the solder joints in SMT processing? Soldering tin has always been a very important step, it will even affect the performance and appearance of the circuit board, but in the actual operation, there will always be the problem of insufficient tin, which leads to the quality of SMT processing. Greatly discounted.

SMT manufacturers

The engineers of PCB Electronics Co., Ltd. gave a rough list. The problem involved is that the wettability of the flux in the solder paste is not strong, and the performance is not good, which causes the soldering to fail to achieve the desired effect; for the purchased solder When the activity of the flux in the paste is not up to the standard, it must be impossible to remove the oxide material at the pad or soldering position of the circuit board; but once the expansion rate of the flux is too high, the phenomenon of voids will appear; and regularly Workers are required to check to avoid insufficient solder paste, resulting in insufficient soldering and vacancies, or the solder paste is not sufficiently stirred before use, which will easily cause the flux and tin powder to fail to fuse Finally, once the preheating time is too long during reflow soldering, and the temperature is too high, then the flux activity in the solder paste will be invalid, and everyone should pay attention to this point.