Soldering plays a vital role in PCB production. So, what should you pay attention to when welding? Before welding, observe whether each solder joint (copper skin) is clean and oxidized. The order of component soldering is:  resistor, capacitor, diode, transistor, integrated circuit, high power tube. When welding objects, it is necessary to look at the solder joints to avoid short circuits caused by poor soldering of the lines. Both the chip and the base are oriented. When soldering, strictly follow the direction indicated by the notch on the PCB, so that the chip, the base and the PCB are corresponding to the gap. If the pins of the integrated circuit are gold-plated, do not use a knife to scrape it. Use a clean eraser to clean it. For CMOS integrated circuits, if the pins are short-circuited first, do not remove the short-circuit before soldering. Low melting point solder should be used, and the temperature should not be higher than 150 degrees Celsius. The internal heat type 20-35W or temperature-controlled soldering iron and the shape of the soldering iron should be conical according to the size of the printed circuit board pad. When heating, the temperature of the soldering iron tip should be adjusted to not more than 300 degrees Celsius. When heating, try to avoid leaving the tip in a place for a long time to avoid local overheating and damage to copper foil or components. Do not use the tip of the soldering iron to solder the solder pad when soldering, but use surface cleaning and pre-tinning. When soldering the metallization holes, the solder should be wetted and filled over the entire hole, not just soldered to the surface pads. After soldering, use a magnifying glass to check the solder joints to check for the occurrence of solder joints and short circuits. When there is a connection, be careful not to make the connection too deep, so that it is screwed on the rubber skin of the wire, and there is a disconnection. After the circuit is connected, it is best to clean the surface of the circuit with a cleaning agent to prevent the circuit from being short-circuited by iron filings on the surface of the board. To carry out the aging process, many problems can be found; the wires should be tightened, and the screws should be tightened. When repeatedly plugging and unplugging, it is necessary to pay attention to whether the wire connectors are damaged.