How to test the resistance of a soldering iron
The electric soldering iron is an essential tool for electronic production and electrical appliance repair. It is mainly used for welding components and wires. According to the mechanical structure, it can be divided into internal heating type electric soldering iron and external heating type electric soldering iron. According to the function, it can be divided into non-soldering soldering iron and soldering iron. Tin-type soldering irons are divided into high-power soldering irons and low-power soldering irons according to different uses.
The soldering iron test includes three parts: ground resistance test (cold/hot state), leakage voltage test and leakage current test.
1. Ground resistance test of soldering iron in cooling state:
When the power is off, touch one end of the multimeter probe to the ground end of the power plug, and the other end to the tip of the soldering iron to test the data;
2. Ground resistance test of the soldering iron under heating:
Plug in the power, turn on the soldering iron, put one end of the multimeter probe in contact with the ground end of the power strip, and the other end in contact with the test board that the soldering iron is in contact with, and measure the results;
3. The soldering iron leakage voltage test and leakage current test are similar to the resistance test method. It should be noted that the multimeter needs to switch gears or adjust the position of the multimeter lead wire when measuring current.
How to choose a soldering iron?
(1) When soldering integrated circuits, transistors and components that are easily damaged by heat, consider using a 20W internal heating or 25W external heating soldering iron.
(2) When welding thicker wires or coaxial cables, consider using a 50W internal heating or 45-75W external heating soldering iron.
(3) When welding larger components, such as the metal chassis grounding lug, a soldering iron of more than 100W should be used.
(4) The shape of the soldering iron tip must adapt to the surface requirements of the parts to be welded and the product assembly density.
To put it simply, the power and type of the soldering iron should be reasonably selected according to the object to be welded. If the parts to be welded are larger, the power of the soldering iron used should also be larger. If the power is smaller, the welding temperature will be too low and the solder will melt slowly. The flux is not easy to volatilize, and the solder joints are not smooth and firm, which will inevitably lead to substandard appearance quality and welding strength, or even the solder cannot melt and the welding cannot be performed. However, the power of the soldering iron should not be too high. If it is too high, too much heat will be transferred to the workpiece to be welded, causing the component solder joints to overheat, which may cause damage to the components, causing the copper foil of the printed circuit board to fall off, and the solder to be soldered. The flow on the welding surface is too fast and cannot be controlled.
