The process of hot air leveling in circuit board factories is relatively simple, mainly including board placement (pasting gold-plated plugs and maintenance tape), hot air leveling pre-treatment → hot air leveling → cleaning after hot air leveling → inspection. Although the process of hot air leveling is simple, there are still many process conditions that need to be mastered in order to achieve excellent and qualified printed boards through hot air leveling, such as solder temperature, air knife airflow temperature, air knife pressure, immersion welding time, lifting speed, and so on. These conditions have set values, but they also need to be adjusted according to the external conditions of the printed circuit board and the requirements of the processing order during operation, such as single-sided, double-sided, and multi-layer boards with different board thicknesses and lengths. The conditions used vary. Only by familiarizing oneself with various process parameters, adjusting the machine patiently, meticulously, and reasonably according to different types and requirements of printed boards, can qualified printed boards be produced by hot air leveling. The following common problems often occur in hot air leveling. Based on work experience, some solutions are proposed for reference only.

1、 Residual liquid drips from the hot air leveling exhaust port, which is a phenomenon where yellow liquid drips down from the exhaust port of the hot air leveling. This liquid is mainly the flux that is usually sucked in by the exhaust port. Over time, it accumulates in the exhaust duct and cannot be discharged, so it drips around the exhaust outlet. Droplets can be found everywhere, such as in the hot air duct, at the blade edge, and on the maintenance cover of the blade edge. Sometimes, it also drips on the operator's head, work clothes, and after closing the exhaust after work. The most residual liquid drips, such as hot melt, which covers the equipment over time and causes significant corrosion to the equipment. You can refer to the structure of the range hood. A funnel-shaped wire mesh is made on the exhaust port to drain the residual liquid, which can reduce or deal with this situation. It can be introduced into a trench or placed in a waste liquid tank at the lower end of the funnel mesh. After this is done, when the residual liquid flows down from the exhaust port through the wire, a large part of the residual liquid will flow down along the wire in the circuit board factory. And make a few extra backups that can be replaced if they are corroded or damaged.

2、 Gloves commonly used for hot air leveling are canvas gloves. When working with hot air leveling, one pair of gloves is put on top of another pair of gloves and worn on the hand. Over time, the soldering flux will penetrate into the gloves, greatly reducing the insulation ability of the gloves. Moreover, if the soldering flux is immersed in the hands, it can also cause some harm to the opponent. These gloves soaked in soldering flux can be reused after washing, but the effect is not good because the canvas becomes soft and the soldering flux penetrates very quickly and in large quantities. It is recommended to use a thin canvas glove inside the impregnated gloves. The key issue is that the size of these rubber gloves should be suitable, with good insulation and softness.

3、 How to perform hot air leveling on flexible boards and printed boards that have been reworked after milling the shape? Flexible boards are prone to problems during hot air leveling due to their softness, so extra caution is required. Before hot air leveling, the frame should be milled to match the edge of the flexible board, and then several opposite holes should be drilled on each side of the frame. Generally, three holes can be drilled on each side of the frame. Flexible boards with wide and long edges can have several more holes drilled to avoid hot air leveling. Due to the lack of holes, the circuit board factory cannot fix them firmly, which may cause wrinkles on the flexible board surface. Align the border holes with the edge holes of the flexible board one by one, and then tie them with a thin copper wire through the holes. After tying them firmly, perform hot air leveling. When leveling, attention should be paid to shortening the time of solder immersion and reducing the pressure of the air knife. When reworking the board with a milled shape, the matching border should also be milled, and the board should be placed inside the border. Then use leveling tape to bond it, and flatten the tape on the board surface with a pressure roller. After this treatment, hot air leveling can be carried out.

4、 The reason for the circuit board factory getting stuck between the guide rails is:

Adjust the guide rail to handle it. The distance between the guide rail and the board is too close or too far.

Correcting the position of the hanging plate hole can be handled. The hanging board hole is not located at the center of the printed board edge.

Adding borders can handle it. The edges and corners of the printed board are irregular.

Insert the printed circuit board into the solder slot by hand and then remove it. When the circuit board factory reworks, the edge solder is too thick.

Hot solder can be used to melt it away, and the tin holes on the guide rail are blocked too much by lead tin, forming a card board. Can be pushed out with a hard object.

Article sourced from Jiangmen single and double-sided circuit boardhttp://www.yonghongpcb.com