The mechanical principle of a SOLDERING IRON
2018-12-06
Cold solder joints occur when only a small amount of solder is used, resulting in poor contact and intermittent connection. A false solder joint appears soldered on the surface, but is not actually soldered; sometimes the lead can be pulled out of the joint by hand.
These two situations will cause great difficulties in debugging and repairing electronic devices. Only through extensive and careful soldering practice can these situations be avoided.
When soldering circuit boards, be sure to control the time. Too long, and the circuit board will be burned or the copper foil will peel off. When removing components from the circuit board, place the soldering iron tip on the solder joint.
After the solder on the solder joint melts, remove the component. The temperature of the soldering iron is related to the size, shape, and length of the soldering iron tip.
When the soldering iron tip is larger, the holding time is longer. In addition, to meet the requirements of different welding materials, the shape of the soldering iron tip is different. Common shapes include conical, chisel, and round bevel.
Use the ohmmeter of a multimeter to measure whether there is an open or short circuit between the two ends of the plug, and then use the Rx1000 or Rx10000 range to measure the resistance between the plug and the shell. If the pointer does not move or the resistance is greater than 2-3MΩ, it can be used safely without leakage.
The soldering iron core of an internal heating soldering iron is made of relatively thin nichrome resistance wire wound on a porcelain tube, with a resistance of about 2.5kΩ (20W). The temperature of the soldering iron generally reaches about 350℃.
Because internal heating soldering irons have the advantages of fast heating, light weight, low power consumption, small size, and high thermal efficiency, they have been widely used.
If the soldering iron does not heat up or does not heat up sufficiently after the power is turned on, check whether the supply voltage is lower than AC210V (the normal voltage should be AC220V). Low voltage may cause insufficient heat and difficulty in soldering.
Oxidation of the soldering iron tip or oxidation at the fastening point between the soldering iron tip root and the outer tube wall. Neutral wire energized: In a three-phase four-wire power supply system, the neutral wire is grounded, and is at the same potential as the ground.
If the neon bulb lights up when tested with a test pen, it indicates that the neutral wire is energized (there is a potential difference between the neutral wire and the ground). An open neutral wire, increased neutral wire grounding resistance, or an open neutral wire grounding lead will all cause the neutral wire to be energized.
Regarding soldering iron usage, the soldering iron should be grounded. It is best to use a pointed soldering iron tip with a temperature of 260℃-300℃. Appropriate amounts of soldering aids (rosin, flux) can be added.
For surface-mount chips, appropriate solder wire (0.6-0.8) should be selected. If possible, use a constant temperature soldering iron. Wear an anti-static wrist strap during soldering, and pay attention to the direction of the chip, which should be consistent with the silkscreen.
Soldering iron cores with different power specifications have different internal resistances. The resistance of a 25W soldering iron is about 2kΩ, a 45W soldering iron is about 1kΩ, a 75W soldering iron is about 0.6kΩ, and a 100W soldering iron is about 0.5kΩ.
The soldering iron tip is made of copper material. Its function is to store and conduct heat. Its temperature must be much higher than the temperature of the object being soldered.
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