Welding essentials of Weile welding head

(1) Touch mode and touch position of Willard welding head and two weldments: Willard welding head should touch two weldments (such as solder legs and pads) to be connected with each other at the same time, and the soldering iron is generally skewed by 45 degrees, so it should be avoided to touch only one of the weldments. When the heat capacity of two weldments is very different, the skew angle of soldering iron should be properly adjusted. The smaller the skew angle between soldering iron and soldering surface, the larger the touch area between the weldment and soldering iron with larger heat capacity, and the stronger the heat conduction ability. For example, when lcd is pulled and welded, the skew angle is about 30 degrees, and the skew angle of welding microphone, motor and horn can be about 40 degrees. If two weldments can reach the same temperature at the same time, it is regarded as an ideal heating condition. Touch pressure: when the Willard welding head touches the weldment, a little pressure should be applied. The strength of heat conduction is directly proportional to the applied pressure, but the principle is that it will not damage the appearance of the weldment.

(2) Supply Method of Welding Wire At least three methods should be mastered in the supply of welding wire, namely, supply time, position and quantity. Supply time: in principle, the welded parts shall be sent to solder wire immediately when they reach the melting temperature of solder. Supply position: it should be between the soldering iron and the weldment and should be as close as possible to the bonding pad. Supply quantity: it should be decided according to the size of the welded part and the pad, and the solder is higher than one third of the pad diameter after the solder covers the pad. (3) Setting of welding time and temperature. A) The temperature is determined by practical use. It is most appropriate to weld a tin spot for 4 seconds, and the longest time is no more than 8 seconds. Observe the welding head at ordinary times. When it turns purple, it is that the temperature is too high. B. Under normal circumstances, insert electronic materials directly, and set the practical temperature of welding head to (350-370); For surface mounted materials (smc), the practical temperature of welding head is set to (330-350℃). For special materials, the soldering iron temperature needs to be specially set. Fpc, lcd connectors, etc. should use silver-tin wires, and the temperature is generally between 290 and 310 degrees. D, welding large component feet, the temperature should not exceed 380 degrees, but can increase the soldering iron power.