basics of soldering

8/6/2019 Basics of Soldering

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BASICS OF SOLDERING

What is soldering?

Soldering is merely gluing things together with melted metal. It is the process of

amalgamating metals to provide a good electrical connection. It is not difficult, though it does

take a little practice to get the hang of it. Having the right tool for the job is also very

important.

Tools needed

The basic soldering technique is using a soldering iron and a solder.

The soldering iron is simply a tool that supplies enough heat to melt the solder. Soldering

iron comes either with variable temperature or no temperature control. For various

applications we can choose different watts of soldering irons ranging from 15W to 35W.

Solder is an alloy of two metals, with a relatively low melting point, that will flow onto the

surface of other metals creating a low-resistance electrical connection. It is generally tin and

lead and is usually identified by its tin/lead composition. If you look at a solder roll, you will

usually find numbers like 40/60, 50/50, or 60/40. These are ratios of tin/lead, as percentages.

Solder with a higher tin content melts at a lower temperature.

Preferred Brand:

SOLDRING IRON: SOLDRON 25 WATTS

SOLDERING LEAD: TRIPP

Soldering Technique

Start off by ensuring that all parts you are connecting are clean from dirt and grease. Also

ensure that the mechanical connections are secure before you apply solder, and the parts

should not be able to move in relation to each other. Another important point to note is that

both parts of the joint to be made must be at the same temperature.

It is very important how to position the soldering iron, try to place the soldering tip with thesoldering surface or PCB with an angle of 45º.

To actually solder a joint, first apply heat by applying the top of the soldering iron against the

things you are joining, immediately apply solder to the point where the iron is contacting.

Remember, you should be heating the joints, not the solder!

Feed solder only until there is enough to fill the gap and leave a slight swell. Don't apply too

much solder, as it can flow over into other places and cause a short circuit. Remove the solder

and the iron smoothly. The whole process should only take two or three seconds at most.

Avoid touching the join until it is cooled. A good solder joint will look shiny and smoothwhile a bad solder joint will look dull and crinkly.



Soldering Tips - Preparation

1. The selection of the soldering iron is important. Irons of the 15W to 30W range are good

for most electronics/printed circuit board work. Higher wattage than this might damage either

the component or the board. It is best to select an iron specifically intended for electronics.

Use also the correct tip size.

2. All parts (including the iron tip itself) must be clean and free from dirt and grease. Dirt is

the enemy of a good quality soldered joint.

3. A good mechanical connection is necessary before you solder. Make sure the parts are not

able to move in relation to each other.

Soldering Tips - Soldering

1. When using your soldering iron for the first time, you need to "tin" the tip. This is also trueafter you replace the tip. Just heat up the iron and apply a thin coat of solder to the tip. This

helps to achieve good heat transfer to the item you are soldering.

2. Avoid scratching and scraping the tip. You need to keep the tip clean always. When

soldering, keep a wet sponge beside you and use it to clean the tip periodically while

soldering. When you have finished soldering, put a blob of solder on the tip as it cools, this

seals it, helping to prevent oxidation.

3. Both parts of the joint to be made must be at the same temperature before applying solder.

The solder will flow evenly and make a good electrical and mechanical joint only if both parts of the joint are at an equal high temperature.

4. Apply an appropriate amount of solder. Too much solder is an unnecessary waste and may

cause short circuits with adjacent joints. If it is too little, it may not support the component

properly, or may not fully form a working joint. You will know how much to apply through

practice.

5. Should you need to redo a solder joint, always start from scratch. Remove the solder you

just put on, and clean the surface before you start the process again.

6. If you need to clean solder off a circuit board, use a solder wick. Place the wick on the

joint or track you want to clean up, and apply your soldering iron on top. The solder will melt

and gets drawn into the wick. If there is a lot of solder the wick will fill up, so gently pull the

wick through the joint and your iron, and the solder will flow into it as it passes.

7. Don't move the joints until the solder has cooled.



Soldering Tips - Safety

1. You should always work in a well ventilated area as the fumes from the soldering could be

harmful to your eyes and lungs.

2. Always wear eye protection to protect you from possible solder splashes as well as thesolder fumes.

3. Solder on a fire resistant surface.

4. Never leave your iron plugged in and unattended.

5. Never set your hot iron down on anything other than an iron stand. This is to prevent it

from burning things in your work area.

6. Replace the cord of your iron if it becomes worn or gets burnt.

7. To prevent burning your fingers, use needle nose pliers, tweezers or heat resistant gloves to

hold small pieces.

Soldering Tips - Common mistakes

1. Most beginners tend to use too much solder and heat the joint for too long.

2. The parts being soldered is dirty or greasy, as such the solder won't take (or 'stick') to it.

3. The joints were not mechanically secured and moved during soldering.

Essential soldering tools

Soldering Iron

A device for applying a point source of heat to melt solder for soldering two materials

together. Soldering irons are typically electrically powered. Soldering irons may have

interchangeable tips for different types of work. Pyramid tips with a triangular flat face areuseful for soldering sheet metal. Fine round tips are useful for electronics work. You also

have a choice of either a soldering iron with variable temperature or one with no temperature

control.

Solder

This is an alloy of tin and lead that melts at a fairly low temperature and is used for making

permanent electrical connections between parts and wires. The most commonly used type of

solder is rosin core. The rosin is flux, which cleans as you solder. The other type of solder is

acid core and unless you are experienced at soldering, you should stick to rosin core solder.Acid core solder can be tricky and better avoided for the beginner.



Other useful soldering tips & tools

1. Soldering iron tips - comes in different sizes and shapes (pointed or flat tips)

2. Solder wick , solder sucker or desolder pump for cleaning up solder

3. Small hand tools e.g. clamps for clipping component leads, bending and shaping etc

4. Soldering iron stand - a heat resistant cradle for your iron to sit in, so you don't have

to lie it down on the bench while it is hot. This will prevent it from burning things in

your work area

5. Magnifying glass to inspect the connection

6. A wet sponge to clean soldering iron tips

7. Fume extractors to suck out the poisonous solder fumes and filter it

8. Work safely

9. Practice makes man perfect, so practice hard

Nair Krishna Raveendran (B.E.E.T)

basics of soldering

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