PCB Technical - How to solder the circuit board correctly

Circuit board soldering is an important part of electronic technology. Proper solder joint design and good processing technology are the key factors for reliable welding. The so-called "reliable" means that the solder joints not only have all the required properties when the product is first produced, but also ensure that the work is correct during the entire service life of the electronic product.

Circuit board

1. The weldment is weldable

The quality of soldering mainly depends on the ability of the solder to wet the surface of the weldment, that is, the wettability of the two metal materials is the solderability. If the weldability of the weldment is poor, it is impossible to weld qualified solder joints. Solderability refers to the performance of weldment and solder to form a good bond under the action of appropriate temperature and flux. Not all materials can be connected by soldering. Only some metals have good solderability. Generally, copper and its alloys, gold, silver, zinc, nickel, etc. have good solderability, while aluminum, stainless steel, and cast iron The solderability is very poor. Generally, special flux and methods are required to solder.

2. The surface of the weldment should be clean

In order to achieve a good combination of solder and weldment, the surface of the weldment must be kept clean. Even for weldments with good weldability, if there is an oxide layer, dust and oil on the surface of the weldment. Be sure to clean it up before welding, otherwise it will affect the formation of the alloy layer around the weldment, and the welding quality cannot be guaranteed.

Three, suitable flux

There are many types of fluxes, and their effects are different. Different fluxes should be selected according to different welding processes and materials of weldments. If the amount of flux is too much, the side effects of flux residue will increase. If the amount of flux is too small, the effect of flux will be poor. The flux used for soldering electronic products usually adopts rosin flux. The rosin flux is non-corrosive, removes oxidation, enhances the fluidity of the solder, helps to wet the soldering surface, and makes the solder joints bright and beautiful.

Four, suitable welding temperature

Thermal energy is an indispensable condition for welding. During soldering, the function of heat energy is to diffuse the solder to the component and raise the temperature of the weldment to an appropriate soldering temperature in order to form a metal alloy with the solder.

Five, suitable welding time

Welding time refers to the time required for physical and chemical changes during the welding process. It includes the time for the weldment to reach the welding temperature, the melting time of the solder, the time for the flux to function and the formation of metal alloys. The soldering time of the PCB circuit board should be appropriate. If it is too long, it will damage the soldering parts and components. If it is too short, it will not meet the requirements.

Circuit board welding method

Regarding the soldering method of the circuit board, the small batch soldering method is mostly manual soldering, and for the mass production of electronic products, dip soldering and wave soldering are used.

Circuit board welding equipment

In the entire welding process, manual welding is used, and the tools used are mostly electric soldering irons. Electric soldering irons are divided into externally heated electric soldering irons and internally heated soldering irons. In the batch circuit board soldering process, the equipment used is: wave soldering machine.