Printed circuit board soldering process
1. Preparation before welding
First of all, you must be familiar with the assembly drawing of the printed circuit board to be welded, and mix the ingredients according to the drawing, check whether the model, specification and quantity of the components meet the requirements of the drawing, and make preparations for the lead forming of the components before assembly.
2. Welding sequence
The order of component assembly and welding is as follows: resistors, capacitors, diodes, triodes, integrated circuits, high-power tubes, and other components are first small and then large.
3. Requirements for component welding
1) Resistor soldering
Accurately install the resistor in the specified position according to the figure. It is required that the mark is upward and the word direction is consistent. After installing the same specification, install another specification, and try to make the height of the resistors consistent. After soldering, cut off the excess pins exposed on the surface of the printed circuit board.
2) Capacitor soldering
Install the capacitor in the specified position according to the figure, and pay attention to the "+" and "-" poles of polarized capacitors that cannot be connected incorrectly, and the direction of the mark on the capacitor should be easy to see. First install glass glaze capacitors, organic dielectric capacitors, ceramic capacitors, and finally electrolytic capacitors.
3) Diode welding
The following points should be paid attention to when welding diodes: first, pay attention to the polarity of the anode and cathode, and do not install them incorrectly; second, the model mark should be easy to see; third, when welding vertical diodes, the welding time for the shortest lead wire should not exceed 2S.
4) Triode welding
Pay attention to the correct insertion and insertion of the three leads e, b, and c; the welding time should be as short as possible, and the lead pins should be clamped with tweezers during welding to facilitate heat dissipation. When welding a high-power triode, if it is necessary to install a heat sink, the contact surface should be flattened, polished and smooth, and then tightened. If it is required to add an insulating film, do not forget to add a film. When the pins need to be connected to the circuit board, plastic wires should be used.
5) IC welding
First, according to the requirements of the drawing, check whether the model and pin position meet the requirements. When soldering, first solder the two pins on the edge to position them, and then solder one by one from left to right from top to bottom.
For capacitors, diodes, and triodes exposed on the printed circuit board, the redundant pins must be cut off at the root.
