Everything You Need to Know About Soldering

Soldering plays an important role in a number of different industries, including commercial and residential electrical operations, plumbing, and electronics manufacturing.

Soldering refers to joining metals using a fusion of alloys which have relatively low melting points. In layman’s terms, that means gluing things together using molten metal.

Some people get confused between welding and soldering. Welding involves melting and combining base metals, while soldering involves using an alloy to adhere one surface to another.

Materials Required for Soldering

Soldering Iron or a Soldering Gun: The soldering iron or gun is your heat source and is used to melt solder. Those who work with electronics typically use 15W to 30W guns, which are hot enough to melt solder but not hot enough to damage printed circuit boards and electronics. Heavier applications generally require guns rated 40W and higher. A soldering iron is a small, pencil-shaped device designed for precise work, while a soldering gun is a gun-shaped object that uese a high-wattage tip suited for heavier applications.

Solder: “Solder” is the metal alloy used to join materials together. Solders vary according to their thickness and the specific alloy blend. There are also different types of solders, including rosin core solders and acid core solders. Rosin core solders are generally used for electronics, while acid core solders are used on hardware, stainless steel, and home improvement projects, such as plumbing. Avoid using acid core solders with electronics, as the acid will damage the printed circuit board and create short circuits.

How to Solder

Step 1) Create a safe workspace

Soldering can be messy and dangerous. Before you begin soldering, consider wearing protection on your hands, eyes, and body. You should also clear a space where you can safely work. Solder can drip or splash, so lay down cardboard or another protective material beneath your soldering iron stand. Moisten a small sponge and use it to wipe off any flux residue.

Step 2) Warm up the soldering iron or gun

It’s important to warm up the iron or gun before you begin soldering. On new solders, the manufacturer may have placed an anti-corrosion coating that will only be removed when the solder heats up. Wait until the iron is at the correct temperature before you begin melting solder.

Step 3) Coat the entire tip with solder

This step involves coating every bit of the tip with molten solder in order to optimize heat transfer and avoid flux residue. Run the solder up, down, and around the tip.

Tinning the soldering tip isn’t absolutely necessary, but it’s always a good idea to tin new or dirty soldering tips. Coating the tip with a thin coat of solder gives the solder a solid base from which to flow and also optimizes heat transfer between your soldering iron/gun and the material.

Step 4) Clean flux residue

Remove flux residue from the solder tip immediately after completing step 4. If you wait too long, the flux residue will harden and become difficult to remove.

Step 5) Apply the solder

Soldering is a very straightforward activity. It only gets complicated when working with extremely small electronics and joints. Whether you’re using an iron or a gun, you’ll want to carefully apply the heated solder to a clean surface. When the surface starts to smoke, it’s generally hot enough to melt your solder.

Step 6) Clean the solder

Let the solder cool undisturbed until it solidifies. If using an acid core solder, then you’ll need to remove the flux residue to prevent corrosion. To do that, use a hot water rinse or apply a 2% to 10% solution of neutralizing base.

How to Desolder

Desoldering involves removing solder from a joint in order to disconnect attached components. You will need to desolder if you made a mistake in the steps above or if you want to replace a certain component.

Desoldering attached wires is relatively straightforward: the most effective method is to cut the wires at either end of the solder and then solder the new ends together.

If you’re desoldering a circuit board or other delicate objects, then you’ll want to invest in a desoldering pump which can suck up molten solder and cleanly remove it from the joint or board.

If you’re trying to fix a recently-soldered joint, then you’ll find that soldering is a forgiving process. If you put down too much solder, for example, you can simply reheat the joint to melt the solder, then change the position of the component or material. You can reheat and cool solder multiple times in order to make the joint perfect.

Types of Solder

Solder comes in a few different varieties, including acid core solders, rosin core solders, and water-soluble or low-residue solders:

Acid core solder: Acid core solders use acid-type flux for general purpose soldering applications where a flux cored solder wire is the desired outcome. Acid core solder is particularly popular for use with excessively oxidized metals, although it is absolutely not recommended for electrical or electronic applications due to its corrosive properties and ability to create short circuits when pooled. Typical acid core solder blends include: 40% Tin / 60% Lead; 50% Tin, 50% Lead; and 96% Tin, 4% Silver (for blending with stainless steel).

Rosin core solder: Rosin core solders are designed for electrical and electronic applications where flux residue should not be removable. With rosin core solder, cleaning flux residue on the soldered surface is difficult or even impossible. The rosin flux residue itself is non-corrosive, which reduces the need for post-solder cleaning. While acid core solder is designed for use with steel and other metals, the mild nature of rosin core makes it primarily only useful for copper and brass materials.

You can view Ram Products selection of solder materials here.

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