Soldering iron selection strategy
1. Power selection of electric soldering iron
The power of the soldering iron used is too high, it is easy to scald the components (generally, when the junction temperature of the diode and triode exceeds 200°C, it will burn out) and the printed wires will fall off the substrate; the power of the soldering iron used is too small, and the solder cannot be fully melted , The flux cannot be volatilized, the solder joints are not smooth and firm, and it is easy to produce false welding. Generally, it is used for welding integrated circuits, printed circuit boards, CMOS circuits, decoration transistors, IC recorders, TV sets, for ordinary circuit experiments, generally 20W is appropriate, and for repairing vacuum tube machines, such as amplifiers and old instruments. , 35W is suitable for external heating, 45W for external heating, 50W for internal heating, 75W for external heating, and some occasions with higher power.
There are various shapes of soldering iron tips. The main point of selection is that it can always maintain a certain amount of solder, can quickly and effectively melt the solder on the joint, does not produce false soldering, tinning, hanging tin, no burrs on the solder joints, and no scalding. boards and components. If the solder joints on the machine are brand new and bright, the soldering iron tip can have a larger tinned cross-section. Use a flat or oval tip for quick heat transfer and easy operation. The oxide layer on the tin surface is thicker, and the tip of the soldering iron is relatively sharp, which is easy to break through.
The density of components is high, so it is necessary to choose correspondingly thin ferroalloy heads to avoid burns and tinning. To assemble and disassemble the IC block, a special-shaped soldering iron tip is often used. Sometimes because the soldering is not possible, and to avoid scalding the plastic parts, a curved soldering iron tip is used. Of course, it also depends on each person's operating habits and hobbies.
2. How to choose a soldering iron
1. According to the choice of electric soldering iron heating form
(1) Selection of internal heating type and external heating type: under the same power condition, the temperature of the internal heating type electric soldering iron is higher than that of the external heating type electric soldering iron.
(2) When low-temperature soldering is required, a voltage regulator is used to control the temperature of the electric soldering iron. The temperature of the electric soldering iron is closely related to the power supply voltage. In actual use, the temperature of the electric soldering iron is often lowered by lowering the power supply voltage.
(3) Control the temperature by adjusting the extension length of the soldering iron tip.
(4) There are mainly the following methods to stabilize the temperature of the electric soldering iron: install a stabilized power supply to prevent changes in the power supply network; maintain a certain volume, length and shape of the soldering iron head; use a constant temperature electric soldering iron; keep the indoor temperature constant; avoid natural wind or electric fan etc.
2. According to the choice of soldering iron power
(1) When welding low-power resistance-capacitance components, transistors, integrated circuits, pads of printed circuit boards or plastic wires, it is advisable to use a 30-45W external heating type or a 20W internal heating type electric soldering iron. It is best to use a 20W internal heating type electric soldering iron in the application.
(2) When welding the soldering points of general structural products, such as wire rings, wire claws, heat sinks, grounding solder pads, etc., it is advisable to use a 75~100W electric soldering iron.
(3) For large solder joints, such as welding metal rack tabs, solder tabs, etc., it is advisable to use a 100~200W electric soldering iron.
