First, check the color and luster. The surface must be smooth, without pores inside. The color should be bright, and the solder joints must be neat and uniform, with a uniform width. 2. Firstly, it is the quality of soldering, which involves soldering with rosin inside. Secondly, the temperature control of the soldering iron is generally 350 degrees Celsius. The most common soldering technique is to weld the soldering iron at a 45 degree angle to the horizontal. When leaving, it should be clean and tidy. Finally, practice is enough. Practice makes perfect. 3. We have been soldering circuit boards these days. But I often experience missing or missing welds, and the solder joints are also relatively large and unattractive. Please ask experienced experts in this field for guidance! It is related to the soldering iron head and operation you are using. The general steps for welding are 1. Preparation 2. Heating 3. Adding solder 4. Removing solder 5. Removing soldering iron. During welding, special attention should be paid to removing the solder first and then removing the electric soldering iron after 2-3 seconds. It is also easier to weld the tip of the soldering iron, but if not possible, a small amount of rosin can be added as soldering flux