SMT is a surface mount technology, which is called surface mount or surface mount technology. It is the most popular technology and process in the electronic assembly industry at present.
it is a kind of circuit assembly technology, in which surface assembly components without leads or short leads (SMC/SMD for short) are mounted on the surface of printed circuit boards or other substrates, and then soldered and assembled by methods such as reflow soldering or dip soldering.
SMT/MES industry is three pillars. The SMT/MES industry in China is mainly concentrated in the eastern coastal areas, in which Guangdong, Fujian, Zhejiang, Shanghai, Jiangsu, Shandong, Tianjin, Beijing and Liaoning provinces and cities account for more than 8% of the total SMT/MES in China.
by region, the pearl river delta and its surrounding areas are the strongest, followed by the Yangtze river delta and the Bohai rim.
Although there is a big gap between the total SMT/MES in Bohai Rim and the Pearl River Delta and the Yangtze River Delta, it has great growth potential and stronger development momentum. The relevant state departments have announced that Binhai New Area in Tianjin will become the roof of the world of China's economic growth after Shenzhen and Pudong.
Extended information:
Assembly process:
SMT assembly process is closely related to every process step before soldering, including capital investment, PCB design, solderability of components, assembly operation, flux selection, temperature/time control, solder and crystal structure, etc.
1. Solder
The most commonly used solder for wave soldering is * * * crystalline tin-lead alloy: 63% tin; Lead is 37%, and the solder temperature in the solder pot should always be controlled, which should be higher than the alloy liquid temperature of 183℃ and make the temperature uniform. In the past, the solder pot temperature of 25℃ was regarded as "standard".
2. Wave crest
In the wave soldering process, the wave crest is the core. Preheated metal coated with flux and free from dirt can be sent to the welding workstation through the conveyor belt, contacted with solder with a certain temperature, and then heated, so that the flux will have a chemical reaction, and the solder alloy will form interconnection through wave crest power, which is the most critical step.
3. Cooling after welding
Usually, a cooling workstation is added at the tail of the wave soldering machine. In order to limit the tendency of copper-tin intermetallic compound to form solder joints, another reason is to accelerate the cooling of the assembly and avoid the displacement of the board when the solder is not completely solidified.
Reference: Baidu Encyclopedia -SMT