It is the most popular production process in SMT electronic assembly industry, which meets the requirements of thin and mass production of mobile phones and computers. PCBA assembled by SMT patches has high relative density and light weight, and has completed mass production of automation technology. Characteristic spot welding is on the same plane as the components on the upper panel, and the welding process is reflow soldering.
The application of THT in the automotive electronics industry still can’t be replaced in a short time, but it has been gradually replaced in the consumer electronics industry. The electronic components on PCBA made of THT processing technology are far apart, and the total board area is also very large. The characteristic components and spot welding are respectively located on both sides of the board.
Solder paste packaging and printing: the scraper scrapes the solder paste into it, hollows out and carves it into the screen plate required for welding, and the solder paste moves down to be accurately applied to the parts that must be welded. The cost of the net varies from several thousand pieces, but the usual maintenance cost of tin slag and scratches on the net can’t be ignored.
Note: the solder paste should be heated naturally before application, and it is unnecessary to heat the solder paste with equipment. The reason is that the solder paste will crack if the temperature is too fast.
Reflow soldering is a special process flow in SMT process. In reflow oven, the plastic circulation system vapor is injected to ensure a high-temperature vapor atmosphere, and the solder paste distributed on the solder layer is melted again, and finally condensed by cooling air.
There is only one single and double-sided reflow soldering. If it is SMT on both sides, it must be reflowed for the second time. Because the reflow temperature of the solder paste after drying and curing exceeds the reflow temperature, the SMT original on the back is not easy to fall off.
Wave soldering is to make the welding surface of the software board immediately touch the high-temperature liquid tin to achieve the purpose of welding. The high-temperature liquid tin maintains a slope, and the unique equipment makes the liquid tin produce similar wavy lines, so it is called “wave soldering”.
According to the requirements of both SMT and THT, it is difficult to avoid the mixed application of reflow soldering and wave soldering. It should be noted that wave soldering must be carried out after reflow soldering. First, because the reflow oven is covered with hot air, the solder paste will be melted again after going through wave soldering and then entering reflow oven. Second, because most of the electronic components assembled in THT process contain feet, it will cause uneven placement if they are put into the conveyor belt of reflow soldering again.
According to the requirements of both SMT and THT, it is difficult to avoid the mixed application of reflow soldering and wave soldering. It should be noted that wave soldering must be carried out after reflow soldering. First, because the reflow oven is covered with hot air, the solder paste will be melted again after going through wave soldering and then entering reflow oven. Second, because most of the electronic components assembled in THT process contain feet, it will cause uneven placement if they are put into the conveyor belt of reflow soldering again.
