SMT refers to a series of processes based on PCB.
SMT is the abbreviation of Surface Mounted Technology, which is the most popular technology and process in the electronic assembly industry. It is a circuit assembly technology in which a pin less or short lead surface assembly component (SMC/SMD) is installed on the Printed Circuit Board (PCB) surface or other substrate surface and is welded and assembled by reflow oven welding or immersion welding.
Under normal circumstances, the electronic products we use are made of PCB plus a variety of capacitors, resistors and other electronic components designed according to the circuit diagram, so all kinds of electrical appliances need a variety of different SMT processing technology to process.
Basic process elements of SMT: solder paste printing > parts mounting > reflow welding > AOI optical inspection > maintenance > board splitting.
Due to the complexity of SMT processing, so there are a lot of SMT processing factories, the quality of SMT is also improving, and SMT process, every link is crucial, can not have any mistakes.
Reflow welding equipment is the key equipment in SMT assembly process, and the solder joint quality of PCBA welding completely depends on the performance of reflow welding equipment and the setting of temperature curve.
Reflow welding technology has experienced different forms of development, such as plate radiation 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 welding also contribute to the development of the cooling area of reflow welding equipment, which ranges from room temperature natural cooling and air cooling to water cooling system designed for lead-free welding.
Reflow welding equipment due to the production process of temperature control accuracy, temperature uniformity, transmission speed and other requirements. From the three temperature zone developed five temperature zone, six temperature zone, seven temperature zone, eight temperature zone, ten temperature zone and other different welding system.
Key parameters of reflow welding equipment:
1. Quantity, length and width of temperature zone;
2. Symmetry of upper and lower heaters;
3. Uniformity of temperature distribution in the temperature zone;
4. Independence of transmission speed control in temperature range;
5, inert gas protection welding function;
6. Gradient control of temperature drop in cooling area;
7. Maximum temperature of reflow welding heater;
8. Temperature control accuracy of reflow welding heater;
