Printed circuit board

What is soldering

Soldering is the process of joining metal parts using various fusible alloys (solder). The melting point of solder is lower than that of the material to be soldered, so that the parts will be soldered without being melted, creating an intermolecular bond through their surfaces.

Soldering can be divided into soft soldering and hard soldering, with soft soldering temperatures below 450°C and hard soldering above 450°C. Hard soldering is usually used for metals such as silver, gold, steel, copper, etc. The joints are much stronger than soft soldering and the shear strength is 20 – 30 times higher than soft soldering. The term solder is usually used for both types of thermal connections because in both cases molten solder is injected into a thin gap between two clean and close together solid metal surfaces to be assembled.

Soldering ensures the continuity of the metal. On the one hand, two metals are bonded to each other by bolting or physical attachment and behave as a solid metallic whole, but this connection is discontinuous and sometimes the metals are even in non-physical contact if they have an oxide insulating film on their surfaces. Another disadvantage of mechanical connections compared to welding is the increase in resistance due to the continued oxidation of the contact surfaces. In addition, vibration and other mechanical shocks can loosen the joint. Welding eliminates these problems; no relative movement of the weld area occurs, the contact surfaces do not oxidize, and a continuous conductive path is maintained. Soldering is a fusion process between two metals, solder in a molten state, will dissolve part of the metal in contact with it, while the surface of the metal being soldered is often a thin layer of solder can not dissolve the oxide film, flux is used to remove this oxide film. The soldering process usually includes:

1 ) Melting of the flux, which removes the oxide film from the surface of the metal to be soldered;

2) Melting the solder so that impurities and lighter fluxes suspended in it float to the surface;

3) Partially dissolve some of the metal connected to the solder;

4) cooling and completing the melting of the metal to the solder.

Often, in order to locate problems with the circuit function, it is necessary to remove the components from the printed circuit board to perform the necessary measurements:

1 ) Removal of special components;

2) Testing of components;

3) Replacement of defective components;

4) Testing to check circuit performance.

The operation of removing and replacing electronic components requires the implementation of the soldering process.

The reliable and successful operation of space, defense, medical electronics, traffic control systems, communication systems, and surveillance and control system equipment all depend on good soldering. Under brutal and hostile environmental conditions

such as changes in temperature, humidity, vibration, etc., even a single bad solder joint can cause a system to go partially or completely out of control. There are thousands of welded joints in the equipment, and these joints should be even more reliable than the equipment itself. Research in this area has led to a growth in knowledge of materials and their properties, and many advances in possible welding processes have been made. Soldering technology is a concomitant technology, and as the electronics industry evolves, it will inevitably continue to produce more effective packaging technologies and smaller components, and soldering technology will continue to evolve to meet the changing needs of the electronics industry and environmental issues. This is why soldering is now becoming more and more specialized for technology professionals working in the electronics industry.


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