The accepted definition of soldering is:-

• The joining of metals using a filler material of a lower melting point than that of the parent metals to be joined.

Note that some metals are easier to solder than others:-

• Tin, Copper and Brass are far easier to solder than Steel or Aluminium

• The secret of a good solder joint is clean, clean and clean again.

• A solder joint is produced by:-

1) First thoroughly cleaning both surfaces to be joined.

2) Tin both surfaces.

3) Mechanical fix the components together.

4) Then apply heat to the joint and bring the solder to the joint.

Method Of Soldering:- Two pieces of metal to be soldered together must be filed or scraped

to a clean metallic surface if not already bright. They are brought into the position in which they are to be soldered

and firmly held together. The joint is sprinkled or swabbed with flux to remove grease and

prevent the formation of oxide. Holding a bar of solder in one hand and a heated soldering copper in

the other, the operator brings the copper against the bar, melting a slight amount of solder which either drips on the joint or sticks to the point of the copper by which it is wiped and spread over the joint.

The two parts to be joined must be heated by the copper to the fusion point of the solder in order to make the molten solder stick to them.

A stronger joint may be made by first carefully tinning the surfaces joined in soldering.

Traditional Solder is an amalgam of Tin and Lead. The percentage of each of these materials defines the use for the solder

%Tin %Lead Use

60 40 Good for all electrical and mechanical work

45 55 Very liquid used in plumbing

50 32 Low melt solder for white-metal casings

Plumbers solder is not suitable for electrical work

Modern Lead Free solders need higher temperaturesand greater care is needed

Solder comes in many forms:-

• A solder stick with separate flux

• Solder Pastes good for joints outside, easy to use

• Multi-core solder is the usual form for electrical work

• Flux is present in many solders to remove surface Oxide layers and assist solder flow

Flux is a chemical compound that is applied and shields the joint surface from air and prevents oxide formation. Although flux will dissolve and absorb oxides, the metals that are being joined should be properly cleaned prior to brazing.

Soldering is use in plumbing in electronics and in jewelry metalwork. Jewelry components, machine tools and some refrigeration and plumbing components are often assembled and repaired by the higher temperature silver soldering process

It can also be used as a semi-permanent patch for a leak in a container or cooking vessel.

Electronic soldering connects electrical wiring and electronic components to printed circuit boards (PCBs)

Remember:-

Use soldering-iron stands to prevent accidental contact with the hot bit of the iron when not in use.

Soldering work benches must be well ventilated to avoid inhalation of solder fumes.

Always use eye protection when soldering to prevent solder or boiling flux from splashing into the eyes.

Low power is required; Low process temperature; No thermal distortions and residual stresses in the joint

parts; Microstructure is not affected by heat; Easily automated process; Dissimilar materials may be joined; High variety of materials may be joined; Thin wall parts may be joined; Moderate skill of the operator is required.

Careful removal of the flux residuals is required in order to prevent corrosion;

Large sections cannot be joined; Fluxes may contain toxic components; Soldering joints can not be used in high temperature

applications; Low strength of joints.

The basic difference between soldering and brazing is the temperature necessary to melt the filler metal. That temperature is defined to be 842ºF/450ºC by the American Welding Society (AWS) but is often rounded to 840ºF. If the filler metal melts below 840ºF the process being performed is soldering. Above that temperature, the process is brazing.

Welding uses steel rod, which is melted into the joints or voids. Strongest of the three.

Soldering is similar, except a low temperature melting point lead//tin alloy is used. Weakest of the three. Also there is silver solder, somewhat stronger.

Brazing is similar to soldering, except higher melting point material is used, and it's stronger than soldering, but not as strong as welding.

Unlike welding, brazing only has minimal impact on material properties. Braze alloys can also be expensive. Copper alloys are commonly brazed, particularly since copper's properties make it very difficult to weld.

Soldering uses an alloy that is liquid at relatively low temperatures to join two other metals. It has the least impact on the base materials, and also provides the weakest joint. It is particularly useful when heat can damage or distort the materials being joined. Electrical components are commonly soldered to avoid heat damage. Various metals can be soldered together, such as gold and sterling silver in jewelry, brass in watches and clocks, copper in water pipes, or iron in leaded glass stained window.