I am an apprentice of SMT patch. Can you tell me the workflow of SMT patch?

The process of SMT is printing->; Inspection (AOI automatic or visual inspection is optional)->; Mounting (attaching small devices first, then attaching large devices: high-speed mounting and integrated circuit mounting)-> Inspection (optional AOI optical/visual inspection)->; Welding->; Testing (AOI optical testing, appearance and function testing)->; Maintenance->; Dismantle the board.

The process flow is simplified as: printing-pasting-welding-maintenance (each process can increase the control quality of inspection links).

1, solder paste printing

Its function is to print solder paste on the bonding pad of PCB at a 45-degree angle with a scraper to prepare for the welding of components. The equipment used is a printing machine (solder paste printing machine), which is located at the forefront of SMT production line.

2. Parts installation

Its function is to accurately install surface mount components on the fixed position of PCB. The equipment used is mounter, which is located behind the printing machine of SMT production line. Generally, high-speed machines and universal machines are used together according to production needs.

3. Reflow welding

Its function is to melt the solder paste and make the surface assembly components and PCB firmly welded together. The equipment used is a reflow oven, which is located behind the mounter in the SMT production line. The requirements for temperature are quite strict, and it is necessary to measure the temperature in real time. The measured temperature is reflected in the form of curve.

4.AOI optical detection

Its function is to test the welding quality of PCB after welding. The equipment used is automatic optical inspection machine (AOI), which can arrange the position in the appropriate place on the production line according to the inspection needs. Some are before reflow soldering and some are after reflow soldering.

5. Maintenance

Its function is to repair the faulty PCB. Tools used include soldering iron, maintenance workstation, etc. AOI optical inspection post-configuration.

Step 6 split the board

Its function is to cut multi-connected PCBA into individual blocks, usually by V-cutting and machine cutting.