SMT assembly refers to the abbreviation of a series of technological processes that are processed on the basis of PCB(Printed Circuit Board).
SMT is Surface Mount Technology,which is the most popular technology and process in the electronic assembly industry. Electronic circuit surface mount technology (Surface Mount Technology, SMT), known as surface mount or surface mount technology.
It is a circuit assembly technology.Mount the leadless or short lead surface mount components (SMC/SMD for short) on the surface of the printed circuit board (PCB) or the surface of other substrates,solder and assemble them by reflow soldering or dip soldering.
Under normal circumstances, the electronic products we use are designed by pcb plus various capacitors, resistors and other electronic components according to the designed circuit diagram, so all kinds of electrical appliances need various PCB smt assembly processing technology to process.
The basic process of SMT includes: screen printing (or dispensing), Mounting (curing), reflow soldering, cleaning, testing, rework.
- Screen printing: Its function is to leak solder paste or SMT Adhesives to the pads of the PCB to prepare for the soldering of components. The equipment used is a screen printing machine, which is located at the forefront of the SMT production line.
- Dispensing: it drips glue onto the fixed position of the PCB board, and its main function is to fix the components to the PCB board. The equipment used is a glue dispenser, which is located at the front end of the SMT production line.
- Mounting: Its function is to accurately install the surface-mounted components on the fixed position of the PCB. The equipment used is a placement machine, which is located behind the screen printing machine in the SMT production line.
- Curing: Its function is to melt theSMT Adhesives, so that the surface mount components and the PCB board are firmly bonded together. The equipment used is a curing oven, which is located behind the placement machine in the SMT production line.
- Reflow soldering: its function is to melt the solder paste, so that the surface mount components and the PCB board are firmly bonded together. The equipment used is a reflow oven, located behind the placement machine in the SMT production line.
- Cleaning: Its function is to remove the soldering residues such as flux that are harmful to the human body on the assembled PCB board. The equipment used is a washing machine, the location may not be fixed.
- Inspection: Its function is to inspect the soldering quality and assembly quality of the assembled PCB board. The equipment used includes magnifying glass, microscope, in-line tester (ICT), flying probe tester, automatic optical inspection (AOI), X-RAY inspection system, functional tester, etc. The location can be configured in a suitable place on the production line according to the needs of the inspection.
- Rework: Its function is to rework the PCB board that has detected the failure.The tools used are soldering iron, rework station, etc. Configured anywhere in the production line.