PCBA Tech - SMT placement operation content and its difference with SMD

1. Print the second film and repeat to the visual inspection.

2. Before brushing solder paste, adjust the stencil and clean the printing table and stencil with alcohol.

3. After scraping to the boundary of the mesh, quickly lift the printing knife to return the solder paste to the original printing position.

4. Open the lid of the solder paste bottle, take out the inner lid, and place the solder paste side up on a clean tabletop.

5. Lift the stencil and take out the PCB to check whether the printed thickness on the PCB is consistent with the thickness of the template position.

6. Choose the squeegee consistent with the substrate to be brushed, first check whether it is in good condition, and replace it if there is a gap.

7. The printing knife is to the outside of the solder paste, the angle between the printing knife and the stencil is 45-90O, and it is evenly scraped in the direction of printing.

8. After taking the solder paste, wipe off the mixing knife and the solder paste bottle at random, and cover the bottle cap to prevent the solder paste from drying out and producing solder paste particles.

9. Put the PCB board in the direction you are going. The PCB should be flat. Make sure that no foreign matter is placed under the PCB, and then press the stencil onto the PCB.

10. The mixing knife takes the solder paste and puts it into the steel mesh. The amount of solder paste should be just after the printing knife is scraped each time and the amount of solder paste should not be less than 2/3 of the printing knife.

11. Use a solder paste stirring knife and stir evenly. After the solder paste is scraped up with the stirring knife, the solder paste can automatically fall off, and there is no clear observation with the naked eye.

What is the difference between SMT and SMD

SMD is the abbreviation of Surface Mounted Devices, which means: surface mount device, which is one of SMT (Surface Mount Technology) components, including CHIP, SOP, SOJ, PLCC, LCCC, QFP, BGA, CSP, FC, MCM etc.

Surface mount components were introduced about twenty years ago, and this opened a new era. From passive components to active components and integrated circuits, they eventually become surface mount devices (SMD) and can be assembled by pick and place equipment. For a long time, people believed that all pin components could eventually be packaged in SMD.

SMT is the abbreviation of Surface Mount Technology, which means: surface mount technology, which is currently the most popular technology and process in the electronics assembly industry.

SMT is a new generation of electronic assembly technology, which compresses traditional electronic components into a device with a volume of only a few tenths, thus realizing high-density, high-reliability, miniaturization, low-cost, and automatic production of electronic products. . This kind of miniaturized components is called: SMD device (or SMC, chip device). The process method of assembling components on the printed board PCB is called SMT process.

At present, SMT technology is mainly realized through equipment, called SMT equipment, which mainly includes board loading machine, solder paste printing machine, automatic placement machine, reflow oven, and various auxiliary tools and equipment.