The Methods of PCB Soldering


Soldering is the name given to the process in which two or more components are fixed by melting and running a filler metal into the joint between them. The filler usually has a relatively lower melting point. Soldering has many applications in electronic projects, particularly in the construction of PCBs. A proper soldering technique helps to give you an excellent operating circuit. Here we have discussed some of the basic methods of soldering in PCB.

Methods of Soldering:

There are two basic methods of soldering: soft soldering and hard soldering.

1: Soft Soldering:

This process involves fitting minute compound parts having low liquefying temperatures which are broken down at high temperature. Typically a tin-lead alloy is used as a space filler method. The liquefying temperature should not be less than 400°C/752°F. Some soldering metals include tin-zinc, tin-lead, zinc-aluminum, cadmium-silver, tin-silver etc.

2: Hard Soldering:

In this type, two elements of metals are united by a solid solder by spreading out into the holes of the component that are unlocked at high temperature. This type of soldering helps give a stronger joint than soft soldering. The temperature is usually more than 450°C/840°F. This type of soldering is made up of two parts:

  • Silver Soldering: This method is supportive to fabricate small components. It uses a silver alloy as a space filler metal. Silver soldering is not recommended for space filling, instead, a different flux is recommended.

  • Braze Soldering: This soldering process is used to connect two terminals of the base metals through liquid metallic space filler. It cools down and forms a solid joint. This process used brass metal as a space filler.

Required Tools for Soldering:

Following are some of the basic tools required for soldering:

1: Soldering Iron:

Soldering iron is the primary tool. It is used as a heat source for liquefying solder. The soldering guns used are usually as 15-30W. For heavier components, this may be as high as 40W. There is one major difference between a gun and an iron, the iron seems like a pencil and is comprised of a pin-point heat supply, and on the other hand, a gun is shaped like a gun with a high wattage point excited through electrical current. A soldering iron is suitable for manual soldering. The heat is used to soften the solder which is then sprinted into the breaks between two terminals.

2: Solder Flux:

Flux acts as a chemical purifying agent; it helps to reduce oxides which tend to form from the contact of hot metals in air. It serves three main functions in soldering metals i.e. it eliminates rust from the components being soldered, it closes out air and hence does not allow rust to form, it makes an easy mix which improves the dripping individuality of the fluid solder.

3: Soldering Paste:

Solder paste is used to connect the SM (surface-mount) components to pads on the board.

The Soldering Process:

The soldering process is made up of the following steps. First, start with the small components, then taller components, and connecting wires. Place the corresponding elements into their positions in the PCB. You may have to twist the leads a little to make sure the component is secure. Then warm up the soldering iron. Next, place the iron on the component of the pad and feed the soldiers’ end onto the board. Now remove the soldering iron and solder from the board. Let the terminals cool for a few seconds. Now use a couple of cutters to neat the excess component terminal.  

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