PCBA Tech - The quality of solder joints for PCBA soldering depends on the reflow soldering equipment

The quality of solder joints for PCBA soldering depends on the reflow soldering equipment
With the rapid growth of new energy automotive electronics, it has driven the growth of demand for automotive electronic equipment including charging piles, and has also promoted the growth of demand for SMT patch processing. Based on the high-precision requirements of automotive electronic equipment, the quality of SMT patches is also In the continuous improvement, every link in the SMT placement process is very important and there can be no mistakes. Today, will take you to learn the introduction and key technology of the reflow soldering machine in the SMT placement process.

Reflow soldering equipment is the key equipment of the SMT assembly process. The quality of solder joints for PCBA soldering depends entirely on the performance of the reflow soldering equipment and the setting of the temperature curve.

Reflow soldering technology has undergone different forms of development processes such as plate radiant heating, quartz infrared tube heating, infrared hot air heating, forced hot air heating, forced hot air heating and nitrogen protection.

The increased requirements for the cooling process of reflow soldering also promote the development of the cooling zone of reflow soldering equipment. The cooling zone is cooled from room temperature and air-cooled to a water-cooled system designed to adapt to lead-free soldering.

Reflow soldering equipment has increased requirements for temperature control accuracy, temperature uniformity, and transmission speed due to the production process. Different welding systems have been developed from the three-temperature zone, such as five-temperature zone, six-temperature zone, seven-temperature zone, eight-temperature zone, and ten-temperature zone.

1. The key parameters of reflow soldering equipment

1. The number, length and width of the temperature zone;

2. The symmetry of the upper and lower heaters;

3. The uniformity of temperature distribution in the temperature zone;

4. Independence of transmission speed control in temperature zone;

5. Protective welding function of inert gas;
6. Gradient control of temperature drop in cooling zone;

7. The maximum temperature of the reflow soldering heater;

8. Temperature control accuracy of reflow soldering heater;

Second, the key process parameters of the reflow soldering process

1. Welding temperature curve: According to the dimensions of the PCB A, the number and thickness of the multilayer board, the volume and density of the welding components, the area and thickness of the copper layer on the PCBA, etc., the actual welding temperature at the test solder joint is set Temperature curve.
2. Control the preheating time, recirculation time, and cooling time: According to the length of the heater, the trajectory of the recirculation curve is controlled by controlling the speed of the conveyor belt. The roll-off gradient of the cooling zone is controlled by the cooling time and the air volume of the cooling zone.

3. The reflow temperature curve should overlap with the reference temperature curve provided by the solder paste supplier as much as possible.

4. When processing two-sided SMT reflow soldering, generally solder one side of a small-quality component first. If there are large-quality components on both sides or the process must first mount a large-quality component surface, when performing the second side reflow soldering, the bottom should be soldered. The soldered large-mass devices are protected to prevent the large-mass devices from falling off due to secondary reflow.
5. When performing through-hole reflow soldering, attention should be paid to component displacement caused by the jitter of the equipment and transmission system. The Internet era has broken the traditional marketing model, and a large number of resources have been gathered together to the greatest extent through the Internet, which has also accelerated the development speed of FPC flexible circuit boards, and then as the development speed accelerates, environmental problems will continue to appear in PCB factories. In front of you. However, with the development of the Internet, environmental protection and environmental informatization have also been developed by leaps and bounds. Environmental information data centers and green electronic procurement are gradually being applied to the actual production and operation fields.