Preliminary Information About Soldering

About Soldering

Soldering can be defined as merging two metals using an alloy metal with a low melting point. For a good-quality soldering; a good soldering iron and a good flux are required.

solder wire

Soldering is done for two purposes; Electronic device manufacturing and assembly

  • Electronic device repair;
    • Cold soldering removal
    • Changing components for repair purposes

There are two types of solderings by the structure of the alloy.

1-) Leaded solder: Solder, consists of certain mixed amounts of lead and tin. The ideal ratio of lead and tin is; %60 tin, %40 lead. Solders with %63 tin, %37 lead ratios are also used.

2-) Lead-free solder: Lead-free solder wire consists of %95.5 SN (tin), %3.8 Ag (silver), %0.7 Cu (copper).

Lead-free solder melts longer and at higher temperatures than leaded solder. Therefore, more suitable soldering iron tips and solder should be used for lead-free soldering.

Most of the malfunctions of electronic devices are caused by cold soldering. Cold solders are electrically bad connections and cause malfunctions by preventing your circuit from working properly.


In mobile phones and other mobile devices, when the contact of the soldered surfaces (mainboard and elements) in the usage process weakens due to impact, falling, contraction, etc., short-term or permanent malfunctions occur in the devices. By gently hitting the PCB or even bending the board a little, we can understand if there is a cold soldering.

Cold solder can be easily recognized by its granular appearance and non-glossy gray color. To fix a cold solder, the old solder must first be removed. Lead-free solder appears matte, not to be confused with cold solder.

In order to solder well, we must first learn how to solder by getting training from a knowledgeable and experienced person. We should improve our technique by practicing a lot under the supervision of someone who knows how to solder.

Although soldering may seem simple, soldering is a specialist job. Soldering is a must-know skill for any electronics repair technician.

Did you see this article – General Concepts to Know for Mobile Phone Repair

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