SMT is an electronic mounting technology, this technology is to install electronic components, such as resistors, capacitors, transistors, integrated circuits, etc., on the printed circuit board, and form an electrical connection through brazing. The components used are also referred to as surface mounted components. The biggest difference between the surface mount technology and the through hole insert technology is that the surface mount technology does not need to reserve the corresponding through hole for the pin of the component, and the component size of the surface mount technology is much smaller than the through hole insert technology. The application of surface mount technology can increase the overall processing speed, but due to the miniaturization of parts and the increase in the density of the board defect risk, so in any surface mount technology board manufacturing process, error detection has become a necessary part.
What are the advantages of SMT chip processing technology:
First, high reliability, strong vibration resistance
SMT patch processing adopts flake components, with high reliability, small and light devices, so strong vibration resistance, automated production, high mounting reliability, generally bad solder joint rate is less than 10 per million, an order of magnitude lower than through hole insertion components wave welding technology, to ensure that electronic products or components solder joint defect rate is low, At present, almost 90% of electronic products use the SMT process.
Second, small size of electronic products, high assembly density
The volume of SMT chip components is only about 1/10 of the traditional plug-in components, and the weight is only 10% of the traditional plug-in components, usually the use of SMT technology can reduce the size of electronic products by 40% to 60%, the quality is reduced by 60% to 80%, and the area and weight are greatly reduced. The SMT patch processing assembly component grid has developed from 1.27MM to the current 0.63MM grid, and individual is up to 0.5MM grid, using through hole installation technology to install components, which can make the assembly density higher.
Third, high frequency characteristics, reliable performance
Because the chip components are firmly mounted, the devices are usually leadless or short leads, which reduces the influence of parasitic inductance and parasitic capacitance, improves the high-frequency characteristics of the circuit, and reduces electromagnetic and RF interference. The maximum frequency of circuits designed with SMC and SMD is 3GHz, while the chip components are only 500MHz, which can reduce the transmission delay time. It can be used for circuits with a clock frequency of more than 16MHz. If MCM technology is used, the high-end clock frequency of the computer workstation can reach 100MHz, and the additional power consumption caused by parasitic reactance can be reduced by 2-3 times.
4. Improve productivity and achieve automated production
At present, to achieve full automation of perforated printed boards, it is necessary to expand the area of the original printed board by 40%, so that the cartridge head of the automatic plug-in can insert the components, otherwise there is not enough space gap, and the parts will be damaged. The automatic placement machine (SM421/SM411) uses a vacuum nozzle suction and discharge element, and the vacuum nozzle is smaller than the element shape, but the installation density is increased. In fact, small components and fine-pitch QFP devices are produced by automatic placement machines to achieve full line automation.