How to solder - Practical Caravan

It may be something many of us have heard of, but few of us appreciate how to solder, what it is and just how much we rely on it.

Most of the electronic gizmos – phones, computers, caravan TVs and the like – that we take for granted these days use solder to interconnect their internal components and hold them in position.

Despite this, there are also few people who have much knowledge of basic soldering techniques and how to solder things together.

That is a pity, because being able to solder offers the ability to repair myriad things, such as connectors, to join wires together and to complete many other DIY tasks.

Here, we outline the rudiments of what solder is and the skills needed for successful soldering – you can also check out our caravan DIY guide for other tasks you can carry out on your ‘van.

What is solder?

Modern solders consist mainly of tin. Previously, high levels of lead were included but, since its toxicity was identified, it has been progressively phased out.

The solder material chosen has to have a low melting point (usually around 180-300°), well below the melting point of the materials being bonded.

Soldering

This is the process of heating the items to be joined to a temperature above the melting point of the solder and then ‘flowing’ the solder between the two items, where it bonds them once cooled. To prevent oxidisation, a flux is usually also introduced to the molten solder. This can be an external application, or solder wire with a flux core can be used.

Solder wire, pot scrubber, flux paste — Peripheral items for soldering. If flux-cored solder is used, flux paste is not required. The pot scrubber is used to rid the iron tip of any scaling before making the joint

Equipment

Most soft soldering (the generic term for soldering that uses tin/lead) is carried out with a soldering iron, which is placed on the items to be joined, raising their temperature to the point where the solder melts and forms the bond.

Soldering irons are usually electric, but can be gas if portability is required.

Thermostatically temperature controlled soldering iron — A thermostatically temperature controlled soldering iron allows the temperature of the iron tip to be adjusted to suit the melting point of the solder and the size of the job being undertaken

The soldering iron MUST be powerful enough to provide sufficient heat to raise the temperature of the WHOLE constituent parts of the job above the melting point of the solder being used.

Gas soldering iron — The main advantages of a gas soldering iron are that it is easily transported to the job and has a significant heat output, which makes it suitable for applications where component parts are large. It is easily refilled from a standard lighter fuel canister

Failure to heed this very important point often leads to dry joints; that is, joints where the solder has not flowed over one or both of the two surfaces to be bonded.

Mains soldering iron — This type of iron uses a step-down transformer to drive a high current heating loop. The iron remains off until the trigger is pressed, then the heater loop reaches the working temperature within seconds. Another advantage is its high-capacity heat output

For many larger jobs, such as central heating plumbing, a naked gas blowtorch flame can be used, although of course, great care should be exercised in this, as the risk of starting fires is ever present.

Key considerations of soldering

Materials to be joined

Not all metals can be soft soldered together. The materials most commonly soldered together are copper, brass and bronze. Steel can be soldered, but not readily. Aluminium is not a metal that solders easily and should be avoided.

Gold and silver can also be soldered, but usually only in the hands of experts, because their melting points are close to those of the solder being used and serious damage can result if care is not taken.

Surface preparation

All parts of the metals to be joined must be clean and free from any contaminants, such as paint and so on.

Setting the solder

Parts being joined must NOT be moved while the solder is setting, as this will result in a poor quality joint.

Acid-based flux

If an acid-based flux is used, residues must be washed away after soldering, or corrosion might occur at a later date.

Wires twisted together — Prepared wires twisted together before soldering

Wire joint after soldering. Note how solder has flowed throughout both pieces of wire

Joint shrouded with heat-shrink sleeving. The joint is low resistance, mechanically strong and watertight – far superior to twisting wires together and wrapping in insulating tape. All thanks to being able to solder!

After some DIY projects to carry out on your ‘van? How about these?

We take a look at how to fit low-cost wheel stands.
We talk you through how to brighten your awning light.
Wondering how to change your water filter? Our guide is here to help!

Future Publishing Limited, the publisher of Practical Caravan, provides the information in this article in good faith and makes no representation as to its completeness or accuracy. Individuals carrying out the instructions do so at their own risk and must exercise their independent judgement in determining the appropriateness of the advice to their circumstances and skill level. Individuals should take appropriate safety precautions and be aware of the risk of electrocution when dealing with electrical products. To the fullest extent permitted by law, neither Future nor its employees or agents shall have any liability in connection with the use of this information. You should check that any van warranty will not be affected before proceeding with DIY projects.

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