Hot air leveling of printed circuit board is the tinning process we often talk about in Sulikou. Its working principle is to remove the residual solder on the surface and hole of the printed circuit board through hot air, and evenly apply the residual solder on the bonding pad, solderless wire and surface sealing ornament. The specific operation process of this process is as follows: placing plates (sticking gold plated plug protective tape), hot air leveling pretreatment, hot air leveling, hot air leveling, cleaning and inspection. Next, we described the common problems and countermeasures in the process of PCB tin plating.

1. The residual liquid drops from the hot air leveling exhaust outlet. This phenomenon is that yellow liquid drops down from the hot air leveling exhaust outlet. This liquid is mainly the flow rate inhaled by the exhaust port. It is piled up in the exhaust pipe for a long time and cannot be discharged. It drops around the exhaust port everywhere, such as hot air duct and fan blade. Sometimes during operation, the protective cover on the wind blade drops on the operator's head, and most of the residual liquid drops on the work clothes, such as hot melting, covering the equipment, which will cause great residual erosion to the equipment over a long period of time. Referring to the structure of the range hood, make a funnel shaped wire mesh at the exhaust port to discharge residual liquid, which can reduce or deal with this situation. You can introduce a drain or put it into the waste liquid tank at the lower end of the funnel screen. When the residual liquid moves down from the exhaust port, most of the residual liquid will flow down the wire. In addition, make some spare parts and replace them if they are corroded.

2、 The gloves worn by the thermal air conditioner are usually canvas gloves, and one pair of gloves is put into the other pair of gloves for operation. After a while, the welding flux will be immersed in the gloves, and the heat insulation ability of the gloves will be greatly reduced. Moreover, opponents immersed in traffic will also be hurt to some extent. Gloves dipped in flux can be reused after washing, but the effect is not good because the canvas is soft. The flux is immersed rapidly and in large quantities. It is recommended to add a thin canvas glove inside the plastic dipped gloves. The key problem is: this rubber gloves should be of proper size, good heat insulation and flexibility.

3. How to mill the reshaped and reworked flexible boards and printed boards with hot air? Due to the softness of the plate, the flexible plate is prone to problems during hot air leveling, which requires special caution. Before hot air leveling, mill out the frame matching the edge of the flexible plate, and then punch several opposite holes on the frame and the edge of the flexible plate. In general, three holes should be made on each side of the frame. The flexible plate with wide side and long side can be perforated more to avoid hot air leveling due to fewer holes. Match the frame holes with the edge holes of the flexible plate one by one, and then tie them with fine copper wires through the holes. After the binding is firm, hot air leveling shall be carried out. During the whole process, attention shall be paid to shortening the immersion welding time and reducing the air knife pressure. When reworking the milled plate, the matching frame shall also be milled, the plate shall be placed in the frame, the leveling belt shall be bonded with the leveling belt, and the belt on the surface of the plate shall be flattened with the pressure roller. After processing, hot air leveling can be carried out. 1. If the distance between the guide rail and the plate is too close or too far, it can be handled by adjusting the guide rail.

2. The hanging hole is not in the center of the edge of the printed board, which can be handled by correcting the position of the hanging hole.

4. When reworking the printed board, the tin hanging on the side is too thick. Insert the PCB into the solder pool by hand and take it out.

5. The tin outlet hole of the guide rail is blocked too much by lead and tin, forming a splint that is melted by hot solder and ejected by hard objects.

6. After hot air leveling, the printed circuit board is nailed and the top of the guide rail is deformed, and the suspension arm shock absorber should be replaced in time.