Tips and welding essentials for welding iron wires with electric soldering iron
Manual welding process:
1. Pre operation inspection
(1) 3-5 minutes before welding, insert the electric soldering iron plug into the designated socket and check if the soldering iron is heating. If it is not hot, first check if the socket is plugged in properly. If it is plugged in properly, and if it still does not heat, report to the administrator immediately. Do not disassemble the soldering iron at will, and do not directly touch the soldering iron head with your hands
(2) The oxidized, uneven or hooked soldering iron tip should be updated: 1. It can ensure good heat conduction effect; 2. Ensure the quality of the welded object. If a new soldering iron tip is installed, the maintenance paint should be wiped off and tin should be added immediately for maintenance after being heated. The cleaning of soldering iron should be carried out before soldering operation. If the soldering iron is not used for more than 5 minutes, the power should be turned off. Sponges should be cleaned thoroughly. Sponges containing metal particles or sulfur-containing substances can damage the soldering iron tip.
(3) Check if the tin sponge has water and is clean. If there is no water, add an appropriate amount of water (an appropriate amount refers to the amount of water seeping out when the sponge is pressed to half the normal thickness. The specific operation is: after the sponge is completely wet, hold it in the palm of your hand, and the five fingers should naturally close). The sponge should be cleaned thoroughly. Unclean sponges containing metal particles or sulfur-containing sponges can damage the soldering iron head.
(4) Is the human body reliably grounded to the soldering iron, and is the human body wearing an electrostatic ring.
2. Welding steps
The specific operation steps of soldering iron can be divided into five steps, known as the five step engineering method. To achieve good welding quality, it is necessary to strictly follow the five operations shown in the following figure.
Following the above steps for welding is one of the keys to obtaining good solder joints. In actual production, the most common violation of operating procedures is that the soldering iron head does not first come into contact with the workpiece to be welded, but first comes into contact with the solder wire. The melted solder drops fall on the pre heated part to be welded, which easily leads to solder joint failure. Therefore, the soldering iron head must come into contact with the workpiece to be welded, and preheating the workpiece is an important means to prevent failure.
3. Welding essentials
1) The contact method between the soldering iron head and the two soldered parts (as shown in Figure 6)
Contact position: The soldering iron head should simultaneously contact the two soldered parts that need to be connected to each other (such as solder feet and pads). The soldering iron is generally inclined at a 45 degree angle, and it should be avoided to only contact one of the soldered parts. When there is a significant difference in heat capacity between two welded parts, the tilt angle of the soldering iron should be adjusted appropriately. The smaller the tilt angle between the soldering iron and the welding surface, the larger the contact area between the welded part with larger heat capacity and the soldering iron, and the stronger the heat conductivity. When LCD is soldered, the tilt angle is around 30 degrees, and when soldering microphones, motors, speakers, etc., the tilt angle can be around 40 degrees. Two welded parts that can reach the same temperature in the same time are considered to be in an ideal heating state.
Contact pressure: When the soldering iron head comes into contact with the workpiece, a slight pressure should be applied. The strength of heat conduction is proportional to the magnitude of the applied pressure, but the principle is to not cause damage to the surface of the workpiece.
(2) Supply method of welding wire
The supply of welding wire should grasp three key points, namely supply time, position, and quantity.
Supply time: In principle, the solder wire is immediately sent when the temperature of the soldered part reaches the melting temperature of the solder.
Supply position: should be between the soldering iron and the workpiece being welded, and as close as possible to the solder pad.
Supply quantity: It should be determined by the size of the soldered parts and pads. After covering the pads with solder, the solder should be higher than 1/3 of the pad diameter.
(3) Welding time and temperature settings
A. The temperature is determined by actual use, and it is most suitable to weld a tin point for 4 seconds, with a maximum of 8 seconds. Normally, observe the soldering iron head, and when it turns purple, the temperature is set too high.
B. Generally, when inserting electronic materials directly, set the actual temperature of the soldering iron head to (350-370 degrees); Set the actual temperature of the soldering iron head to (330-350 degrees) for surface mount material (SMC) materials
C. Special materials require special setting of soldering iron temperature. FPC, LCD connectors, etc. need to use silver tin wire, and the temperature is generally between 290 ° C and 310 ° C.
D. Welding large component feet should not exceed 380 degrees Celsius, but the soldering iron power can be increased.
(4) Welding precautions
A. Before welding, each welding point (copper sheet) should be observed for smoothness, oxidation, etc.
B. When welding items, it is important to identify the welding points accurately to avoid short circuits caused by poor wiring
4. Post operation inspection:
(1) After using the soldering iron, the remaining tin from the soldering iron tip should be wiped clean on a sponge.
(2) After work every day, it is necessary to clean the solder beads, slag, dust and other objects on the soldering iron holder, and then place the soldering iron on the soldering iron rack.
(3) Place the cleaned soldering iron in the upper right corner of the workbench.
