Basic knowledge of welding: precautions for each step of manual welding

Date：2022-05-12 15:23:44Views：818

Welding is a non detachable connection method. It is a process in which two or more same or different materials are connected into one through the combination and diffusion between atoms or molecules. Welding can use filler materials or no filler materials, which can be applied to the connection of metal and non-metal. The following is a brief analysis of the precautions for each step of manual welding for your reference.

Pre welding treatment mainly includes two aspects: pad treatment and cleaning the pins of electronic components.

1) Pad treatment: after polishing the copper foil of PCB pad with fine sandpaper, evenly apply a layer of rosin alcohol solution on the surface of copper foil. If the printed circuit board has been welded, each welding hole shall be connected (after melting the solder joint with an electric soldering iron, connect the welding hole with a needle while it is hot).

2) Clean the pins of electronic components: scrape them slightly with a knife or fine sandpaper, and then tin each pin separately.

Precautions for each step of manual welding:

1. Improper use of flux, excessive use of flux will lead to corrosion and electromigration;

2. Too high temperature and too long time will invalidate the flux and increase the thickness of intermetallic compound;

3. Incorrect size, shape and length of soldering iron head will affect heat capacity and contact area;

4. Unnecessary modification and rework will increase intermetallic compounds and affect the strength of solder joints;

5. Excessive pressure is not conducive to heat conduction, but it will only lead to oxidation of soldering iron head, depression and warpage of pad;

6. The tin wire is placed incorrectly and cannot form a thermal bridge. Solder transfer cannot transfer heat effectively;

7. The transfer welding method will volatilize the flux in advance and cannot be used in the welding of through-hole components. The welding SMD can be used.

After welding, the electric soldering iron must be placed on the special rack to prevent burning other articles. When not in use for a long time, it is best to unplug the power plug of the electric soldering iron to prevent the soldering iron head from "aging". When the electric soldering iron is used for a long time, there will be black oxide and residual solder slag on the soldering iron head, which will affect the future welding. The soldering iron head should be continuously cleaned with rosin to keep it in good working condition.

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