SMT patch

1. SMT processing surface mount assembly (SMA): A printed board assembly that is assembled using surface mount technology.

2. Reflow soldering: By melting the solder paste pre-distributed on the PCB pad, the connection between the surface mount component and the PCB pad is realized.

3. Wave soldering: The melted solder is sprayed by special equipment to form the solder wave peak required by the design, so that the PCB pre-installed with electronic components passes through the solder wave peak to realize the connection between the component and the PCB pad.

4. Fine pitch: less than 0.5mm pin pitch.

5. Pin coplanarity: refers to the vertical height deviation of surface mount component pins, that is, the vertical distance between the plane formed by the highest pin bottom and the lowest pin bottom. Its value is generally not greater than 0.1mm.

6. Solder paste: A solder paste with a certain viscosity and good thixotropy is mixed by powdered solder alloy, flux and some additives that play a role in viscosity and other functions.

7. Curing: Under certain temperature and time conditions, the process of heating the patch glue with the components mounted on it, so that the components and the PCB board are temporarily fixed together.

8. Patch glue or red glue: It has a certain initial viscosity and shape before curing, and has sufficient bonding strength after curing.

9. Glue dispensing: the process of applying patch glue to the PCB during surface mount.

10. Glue dispensing machine: the equipment that can complete the glue dispensing operation.

11. Mounting: The operation of picking up surface mount components from the feeder and placing them on the specified position on the PCB.

12. SMT splicing belt: It is used to connect the feeder tray to the tray during the chip processing process. It can be operated and connected without stopping the machine, saving a lot of time and raw material costs.

13. Mounter: Special process equipment for completing the function of surface mount components.

14. Hot air reflow soldering: reflow soldering heated by forced circulating hot air flow.

15. SMT inspection: During or after the SMT is completed, the quality inspection is carried out to check whether there are missing stickers, dislocations, wrong stickers, damaged components, etc.

16. Stencil printing: A printing process in which solder paste is printed onto PCB pads using a stainless steel stencil.

17. Automatic stencil cleaning wipe paper: installed on the printing machine to automatically clean excess solder paste during stencil printing.

18. Printing machine: In SMT, special equipment for steel screen printing.

19. Post-furnace inspection: the quality inspection of the PCBA soldered or cured in a reflow oven after the patch is completed. a

20. Pre-furnace inspection: After the patch is completed, the quality inspection of the patch is carried out before soldering or curing in the reflow furnace.

21. Rework: The repair process for removing local defects of PCBA.

22. Rework workbench: special equipment for repairing PCBA with quality defects.