Soldering iron welding method
1. Pre-weld preparation The pre-weld preparation is mainly the pre-treatment of the tip. The rosin and the cleaning block should be prepared in the small box of the soldering iron frame (soaked with water). After the soldering iron is turned on, the temperature of the soldering iron head is about the melting temperature of the rosin (about 150 ° C), and the soldering iron tip is inserted into the rosin. Apply a layer of rosin to the surface. In actual operation, because you do not know when to reach the melting temperature of rosin, you can touch the rosin with a soldering iron tip after turning on the power. Before the rosin melts but does not vaporize, you can get rid of the rosin and tin wire contact, so that the soldering iron head The surface (approximately 3 to 5 mm) is evenly covered with a layer of bright tin, which is the pretreatment of the tip. During the welding process, if the tip of the soldering iron is found to be coked with flux and other black residue, it should be wiped on the cleaning block at any time to make the head residue fall off and the temperature drops, and then insert the rosin into the head. The tin oxide is reduced to maintain a bright coating, which is critical to ensure that the tip is well conducted to conduct heat and clean the solder joints.
2. Welding procedure The operation of soldering iron welding can be decomposed into 4 steps. To obtain good welding quality, it must be carried out strictly according to the steps shown in Figure 1.
Figure 1 soldering iron welding step
Welding according to the above steps is one of the keys to obtaining a good solder joint. In actual production, the most common method of violating 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 first, and the molten solder is dropped on the soldered portion that has not been preheated, so that It is easy to cause false solder joints. More seriously, some operators use a soldering iron tip to bring a little solder to the soldered part. At this time, the flux has been completely volatilized or coked, and the soldering effect is lost. The soldering quality can be imagined. Therefore, in operation, the most important thing is that the soldering iron tip must first be in contact with the soldered part to preheat the soldered portion, which is an effective means to prevent false soldering (the most serious soldering defect).
3. The essentials of welding are the key to obtaining good solder joints. The general soldering methods have the following points:
Figure 2 Schematic diagram of welding operation
(1) The contact method between the soldering iron tip and the soldered part is obtained by the soldering piece by contacting the soldering iron head to obtain the temperature required for soldering, so the following essentials are required for the contact:
1 Contact position: The soldering iron tip should be in contact with two soldered parts (such as leads and pads) that need to be connected to each other at the same time. The soldering iron is generally inclined at 45°, as shown in Figure 2, and should avoid contact with only one of the soldered parts. When the heat capacity of the two welded parts is disparity, the inclination angle of the soldering iron should be properly adjusted, so that the contact area between the welded part with the large heat capacity and the soldering iron head is increased, and the heat conduction is strengthened. The two parts to be welded can be heated to the same temperature in the same time and are considered to be ideal for heating.
2 Contact pressure: When the soldering iron tip is in contact with the material to be welded, the pressure should be slightly applied. The heat conduction intensity is proportional to the applied pressure, but the principle is that no damage is caused to the surface of the welded part.
(2) Method of supplying tin wire The method of supplying tin wire mainly grasps three essentials, namely, supply time, position and quantity.
1 Supply time: In principle, the wire is immediately sent when the temperature of the weldment reaches the melting temperature of the solder.
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