First, check before operation (1) 3-5 minutes before going to work every day, put the soldering iron plug into the specified socket, check if the soldering iron is hot, if it is not hot, first check if the socket is plugged in, if plugged in, if it is not hot Should immediately report to the administrator, can not freely open the soldering iron, but also can not directly touch the tip of the iron (2) has been oxidized uneven or hooked iron tip should be updated: 1, can ensure good heat conduction; 2, to ensure the quality of the welded object. If you replace it with a new soldering iron tip, wipe the maintenance paint off after heating and immediately add tin care. The soldering iron should be cleaned before soldering. If the soldering iron is not used for more than 5 minutes, turn off the power. Sponges should be cleaned. Unclean sponges containing metal particles or sulfur-containing sponges can damage the tip.
(3) Check if the suction sponge has water and clean. If there is no water, please add proper amount of water. (Appropriate amount refers to the water seeping when the sponge is pressed to the normal half thickness. The specific operation is: humidity requires the sponge to be completely wetted Hold in the palm of your hand, the five fingers can be closed naturally. The sponge should be cleaned. The dirty sponge contains metal particles, or the sulfur-containing sponge will damage the tip.
(4) Whether the human body and the soldering iron are reliably grounded, and whether the human body wears an electrostatic ring.
Second, the welding step The specific operation steps of the soldering iron can be divided into five steps, called the five-step engineering method, to obtain good welding quality must be strictly operated.
Welding according to the above steps is one of the keys to obtaining a good solder joint. In actual production, the most common way to violate the operation steps is that the soldering iron tip is not in contact with the soldered part first, but is in contact with the solder wire, and the molten solder is dropped on the soldered portion that is preheated. This is easy to produce solder joints, so the soldering iron tip must be in contact with the soldered part, and preheating the soldered part is an important means to prevent the formation of solder joints.
Third, the welding essentials (1) contact angle between the soldering iron head and the two welded parts: the soldering iron tip should simultaneously contact two soldered parts (such as soldering feet and pads) to be connected to each other, the soldering iron is generally inclined 45 degrees, should Avoid contact with only one of the weldments. When the heat capacity of the two welded parts is disparity, the inclination angle of the soldering iron should be properly adjusted. The smaller the inclination angle of the soldering iron and the welding surface, the larger the contact area of ​​the welded part with the heat capacity and the soldering iron, and the heat conduction capacity is enhanced. For example, when the LCD is soldered, the tilt angle is about 30 degrees, and the tilt angle of the welding microphone, motor, and speaker can be about 40 degrees. The two parts to be welded can reach the same temperature at the same time and are considered to be ideal for heating.
Contact pressure: When the soldering iron tip is in contact with the soldered part, the pressure should be slightly applied. The heat conduction intensity is proportional to the applied pressure, but it does not cause damage to the surface of the soldered part.
(2) Method of supplying the welding wire The supply of the welding wire should have three essentials, which are time, position and quantity.
Supply time: In principle, the temperature of the soldered part reaches the melting temperature of the solder and the solder wire is immediately supplied.
Supply position: It should be between the soldering iron and the soldered part and as close as possible to the pad.
Supply quantity: The size of the soldered part and the pad should be considered. After the solder covers the pad, the solder is higher than 1/3 of the pad diameter.
(3) Welding time and temperature setting
A, the temperature is determined by the actual use, to solder a tin point for 4 seconds is most suitable, the maximum is no more than 8 seconds, usually observe the tip, when it is purple, the temperature is set too high.
B. Generally insert the electronic material, set the actual temperature of the soldering iron head to (350~370 degrees); the surface mount material (SMC) material, set the actual temperature of the soldering iron head to (330~350 degrees)
C, special materials, need to set the temperature of the soldering iron. FPC, LCD connectors, etc. use silver-containing tin wire, the temperature is generally between 290 degrees and 310 degrees.
D. Weld the large component feet, the temperature should not exceed 380 degrees, but the soldering iron power can be increased.
(4) Welding precautions
A. Before soldering, observe whether each solder joint (copper skin) is clean and oxidized.
B. When welding objects, it is necessary to look at the solder joints to avoid short circuits caused by poor soldering of the lines.
Fourth, check after operation:
(1) After using the soldering iron, the tin of the soldering iron should be wiped clean on the sponge.
(2) After work, you must remove the tin beads, tin slag, dust, etc. from the soldering iron seat, and then place the soldering iron on the soldering iron frame.
(3) Place the cleaned soldering iron in the upper right corner of the workbench.
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