SMT basic process elements

Printing (or dispensing) – > mounting — > (curing) – > reflow soldering — > cleaning — > testing — > repair

Printing is to leak solder paste or patch adhesive onto the PCB pad to prepare for the welding of components. The equipment used is a printing press

(solder paste printing machine), located at the front end of SMT production line.SMT basic process elements

Dispensing – most of the circuit boards used now are double-sided patches. In order to prevent the components on the input surface from falling off due to the melting of the solder paste again during the second furnace return, a dispensing machine is installed on the input surface. It drops the glue to the fixed position of the PCB, and its main function is to fix the components to the PCB. The equipment used is a dispensing machine, which is located at the front end of the SMT production line or behind the testing equipment. Sometimes, due to customers’ requirements, the output surface also needs dispensing, but now many small factories do not use dispensing machines. If the input surface components are large, manual dispensing is used.

Mounting – it is to accurately install surface assembled components to the fixed position of PCB. The equipment used is the mounter, which is located behind the printer in the SMT production line.

Curing – melting the patch adhesive to firmly bond the surface assembled components and PCB board. The equipment used is a curing furnace, which is located behind the mounter in the SMT production line.

Reflow soldering – make the surface assembled components firmly bonded to the PCB board. The equipment used is the reflow furnace, which is located behind the mounter in the SMT production line.

Cleaning is to remove the welding residues harmful to human body, such as flux, on the assembled PCB. The equipment used is a cleaning machine, and the position can be fixed, online or offline.

Inspection – it is to inspect the welding quality and assembly quality of the assembled PCB board. The equipment used include magnifying glass, microscope, on-line tester (ICT), flying needle tester, automatic optical inspection (AOI), X-ray inspection system, function tester, etc. The position can be configured in the appropriate place of the production line according to the needs of detection.

Rework refers to reworSMT basic process elementsking the PCB board with fault detected. The tools used are soldering iron, repair workstation, etc. Configure anywhere in the production line.