Meaning: surface assembly technology. Surface assembly technology is a matrix arrangement package without pins or short leads or balls surface assembly components (SMC\/SMD, Chinese called chip components) installed on the surface of the Printed Circuit Board (PCB) or other substrate surface, Circuit assembly by welding by reflow or dip welding. China's SMT industry is still mainly concentrated in the Pearl River Delta region and the Yangtze River Delta region, the two regions of the industrial sales revenue accounted for more than 90% of the overall industrial scale, of which only the Pearl River Delta region accounted for 67.5% of the overall proportion. In addition, the sales of the SMT industry in the Bohai Rim region also reached 310 million yuan, accounting for 7.6% of the overall industry. Surface assembly technology features: 1, high assembly density, small size of electronic products, light weight, the size and weight of the patch component is only about 1\/10 of the traditional plug-in components, generally after the use of SMT, the volume of electronic products reduced by 40% to 60%, the weight reduced by 60% to 80%. 2, high reliability, strong vibration resistance. Low defect rate of solder joint. 3, good high-frequency characteristics. Reduced electromagnetic and radio frequency interference. 4, easy to achieve automation, improve production efficiency. Reduce the cost by 30%~50%. Save materials, energy, equipment, manpower, time, etc.