PCBA Tech - Major introduction of SMT-related basic knowledge

Major introduction of SMT-related basic knowledge

This article introduces the basic knowledge of SMT from 4 aspects, including the introduction, characteristics, composition, and basic process components of SMT.

1. Introduction to SMT

Electronic circuit surface mount technology (Surface Mount Technology, SMT) is called surface mount or surface mount technology. It is a kind of surface assembly components with no leads or short leads (SMC/SMD in Chinese, chip components in Chinese) mounted on the surface of a printed circuit board(Printed Circuit Board, PCB) or on the surface of other substrates. Circuit assembly technology in which reflow soldering or dip soldering is used for soldering and assembly.

Two, SMT features

High assembly density, small size and light weight of electronic products. The volume and weight of SMD components are only about 1/10 of that of traditional plug-in components. After general use, the volume of electronic products is reduced by 40%~60%, and the weight is reduced by 60%~80. %.

High reliability and strong earthquake resistance. The defect rate of solder joints is low.

Good high frequency characteristics. Reduce electromagnetic and radio frequency interference.

It is easy to realize automation and improve production efficiency. Reduce costs by 30%~50%. Save materials, energy, equipment, manpower, time, etc.

Three, SMT composition

In general, SMT includes surface mount technology, surface mount equipment, surface mount components, and SMT management.

Why use SMT

Electronic products are pursuing miniaturization, and the previously used perforated plug-in components can no longer be reduced.

Electronic products have more complete functions, and the integrated circuits (ICs) used have no perforated components, especially large-scale, highly integrated ICs, and surface mount components have to be used.

With mass production of products and automation of production, the factory must produce high-quality products with low cost and high output to meet customer needs and strengthen market competitiveness

The development of electronic components, the development of integrated circuits (IC), and the multiple applications of semiconductor materials.

The revolution of electronic technology is imperative and chasing the international trend.

Four, SMT basic process components

Printing (red glue/solder paste) -> inspection (optional AOI automatic or visual inspection) -> (small devices first and then large devices: divided into high-speed placement and integrated circuit placement) -> inspection (optional AOI optical/visual inspection) -> soldering (using hot air reflow soldering for soldering) ->

Inspection (can be divided into AOI optical inspection appearance and functional test inspection) -> maintenance (use tools: soldering station and hot air desoldering station, etc.) -> board splitting (manual or splitting machine for cutting boards)

The SMT process is simplified as follows: printing --- patch --- welding --- overhaul (testing links can be added to each process to control quality)