source:Other information release time:2023-07-14 Hits: Popular:PCB Assembly company
Back welding is also called re -welding, which is a welding technology developed with the emergence of miniature electronic products. It is mainly used for welding of various surface assembly components. This welding technology is a welded paste. Apply a proper amount and appropriate form of welded paste on the pads of the circuit board, and then put the SMT components to the corresponding position; the weld paste has a certain stickiness to fix the component; then let the circuit of the component device be installed with the component device The board enters the re -welding equipment. The transmission system drives the circuit board through the temperature area set in the device. The weld paste is welded, preheating, melting, wetting, and cooling, and the components are welded to the printed board.
The core link of the return welding is to use the external thermal source to heat, so that the solder is melted and flowing again, and the welding process of the circuit board is completed.
There are many factors that affect the circuit board sticker background welding process, and it is also very complicated. It requires craftsmen to continuously study and discuss in production and discuss from multiple aspects.
1. The establishment of temperature curve
Temperature curve refers to a curve where the temperature on the SMA changes with the time when the SMA is returned. The temperature curve provides an intuitive method to analyze the temperature changes of a certain component during the entire return welding process. This is very useful for obtaining the best weldability, avoiding damage to elements due to over -temperature, and ensuring welding quality. The temperature curve is tested by a furnace temperature tester, such as SMT-C20 furnace temperature tester.
2. Preheat section
The purpose of this area is to heat the PCB of the room temperature as soon as possible to achieve the second specific target, but the heating rate should be controlled within an appropriate range. The discharge of solvents is insufficient, affecting the quality of welding. Due to the fast heating speed, the temperature difference in the SMA in the rear section of the temperature area is large. In order to prevent the damage to the component, the maximum speed is generally 4 ° C/s. However, the increase rate is usually set to 1-3 ° C / s. The typical heating rate is 2 ℃ / s.
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