A brief introduction to the characteristics of external heating soldering irons
1. External heating soldering iron
It consists of a soldering iron head, a soldering iron core, a shell, a wooden handle, a power lead, a plug and other parts. The soldering iron head is installed inside the soldering iron core, which is called an externally heated electric soldering iron.
2. Components
The soldering iron core is a key component of the electric soldering iron. The heating wire is wound in parallel on a hollow porcelain tube. The mica sheet in the middle is insulated, and two wires are drawn out to connect to the 220V AC power supply.
3. Product specifications
There are many specifications for externally heated soldering irons. Commonly used specifications include 25W, 45W, 75W, 100W, etc. The higher the power, the higher the temperature of the soldering iron tip.
The power specifications of soldering iron cores are different, and their internal resistances are different. The resistance of a 25W soldering iron is about 2k Ω, the resistance of a 45W soldering iron is about 1 k Ω, the resistance of a 75W soldering iron is about 0.6 k Ω, and the resistance of a 100W soldering iron is about 0.5 k Ω.
4. Use materials
The soldering iron tip is made of copper material. Its function is to store and conduct heat. The temperature must be much higher than the temperature being soldered.
The temperature of the soldering iron is related to the volume, shape, length, etc. of the soldering iron tip. When the volume of the soldering iron tip is relatively large, the holding time will be longer.
In order to adapt to the requirements of different welding objects, the shape of the soldering iron tip is different, generally tapered, chisel-shaped, rounded bevel and other shapes.
The correct way to use a soldering iron
1. Choose appropriate solder, low melting point solder wire for welding electronic components.
2. Flux, use 25% rosin dissolved in 75% alcohol (weight ratio) as the flux.
3. The electric soldering iron must be tinned before use. The specific method is: heat the electric soldering iron. When the solder has just melted, apply flux, and then apply the solder evenly on the soldering iron tip so that the soldering iron tip can be evenly coated. A layer of tin.
4. For welding method, polish the pads and component pins cleanly with fine sandpaper and apply flux. Dip an appropriate amount of solder with the tip of the soldering iron and touch it to the solder joint. After all the solder on the solder joint melts and immerses the lead of the component, gently lift the tip of the soldering iron up along the lead of the component and away from the solder joint.
5. The welding time should not be too long, otherwise it is easy to burn the components. If necessary, use tweezers to clamp the pins to help dissipate heat.
6. The solder joint should be in the shape of a sinusoidal wave peak, the surface should be bright and smooth, without tin thorns, and the amount of tin should be moderate.
7. After the soldering is completed, use alcohol to clean the remaining flux on the circuit board to prevent the carbonized flux from affecting the normal operation of the circuit.
8. The integrated circuit should be soldered last, and the soldering iron should be reliably grounded, or the residual heat should be used for soldering after power failure. Or use a special socket for integrated circuits, and then plug in the integrated circuit after soldering the socket.
9. The soldering iron should be placed on the soldering iron stand.
