What’s the SMT?

SMT is a surface assembly technology (surface mount technology), known as surface mount or surface mount technology. It is the most popular technology and process in the electronic assembly industry. It is a non-pin or short lead surface assembly components (referred to as SMC/SMD, Chinese called chip components) installed on the surface of the printed circuit board or other substrate surface, through reflow welding or dip welding and other methods to be welded assembly circuit assembly technology.

Why use SMT?

The pursuit of miniaturization of electronic products, the previously used perforated plug-in components can not be reduced, electronic products have more complete functions, the integrated circuit (IC) used has no perforated components, especially large-scale, highly integrated IC, have to use surface chip components. Product mass, production automation, the factory to low cost and high output, produce quality products to meet customer demand and strengthen market competitiveness. The development of electronic components, the development of integrated circuits (IC), the multiple applications of semiconductor materials. The revolution of electronic science and technology is imperative, chasing the international trend.

What are the features of SMT?

High assembly density, small size and light weight of electronic products. The volume and weight of SMT components are only about 1/10 of that of traditional plug-in components. Generally, after adopting SMT, the volume of electronic products will be reduced by 40%-60%, and the weight will be reduced by 60%-80%.

Basic process elements of SMT

Screen printing (or dispensing) -- -- -- -- > > pasted on the (curing) -- - > reflow soldering -- -- -- -- > > cleaning test > repair

Screen printing: It is used to print solder paste or patch adhesive (mainly epoxy resin) onto the pad of PCB in preparation for the welding of components. The equipment used is screen printing machine (screen printing machine), located at the forefront of the SMT production line.

Dispensing: it is to drop glue to the fixed position of the PCB, its main function is to fix the components to the PCB board. The dispensing machine is located at the front end of the SMT production line or behind the testing equipment.

Mount: its function is to accurately mount surface assembly components to a fixed position on the PCB. The equipment used is the SMT machine, located behind the screen printing machine in the SMT production line.

Curing: its function is to melt the patch adhesive, so that the surface assembly components and PCB board firmly stick together. The equipment used is the curing furnace, located behind the SMT machine in the SMT line.

Reflow welding: its function is to melt the solder paste, so that the surface assembly components and PCB board firmly stick together. The reflow furnace is located behind the SMT machine in the SMT line.

Cleaning: it is used to remove welding residues such as flux which are harmful to human body on assembled PCB board. The equipment used is the cleaning machine, the position can not be fixed, can be online, also can not be online.

Detection: its function is to test the welding quality and assembly quality of assembled PCB board. The equipment used is magnifying glass, microscope, in-line tester (ICT), flying needle tester, automatic optical inspection.

Repair: its function is to detect the failure of the PCB board for rework. The tools used are soldering iron, repair workstation and so on. It can be installed anywhere in the production line.

From the perspective of the industry's own development cycle, although China's SMT industry is still in the early stage of development, it has shown a vigorous vitality. At the same time, SMT industry is an important basic industry, which is of great significance to promote the structural adjustment and industrial upgrading of China's electronic information industry. To promote the rapid and healthy development of SMT industry in China needs the cooperation of upstream and downstream sectors.