Dip soldering is a small-scale

soldering Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...

process by which

electronic component An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not ...

s are

soldered Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...

to a

printed circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...

(PCB) to form an electronic assembly. The solder wets to the exposed metallic areas of the board (those not protected with

solder mask Solder mask, solder stop mask or solder resist is a thin lacquer-like layer of polymer that is usually applied to the copper traces of a printed circuit board (PCB) for protection against oxidation and to prevent solder bridges from forming b ...

), creating a reliable mechanical and electrical connection. Dip soldering is used for both

through-hole In electronics, through-hole technology (also spelled "thru-hole") is a manufacturing scheme in which leads on the components are inserted through holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side, either by ...

printed circuit assemblies, and

surface mount Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...

. It is one of the cheapest methods to solder and is extensively used in the small scale industries of developing countries . Dip soldering is the manual equivalent of automated

wave soldering Wave soldering is a bulk soldering process used for the manufacturing of printed circuit boards. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave. As the ci ...

. The apparatus required is just a small tank containing molten solder. A PCB with mounted components is dipped manually into the tank so that the molten solder sticks to the exposed metallic areas of the board.

Dip solder process

Dip soldering is accomplished by submerging parts to be joined into a molten solder bath. Thus, all components surfaces are coated with filler metal.

Solder Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...

s have low surface tension and high wetting capability. There are many types of solders, each used for different applications: * Lead–silver is used for strength at higher-than-room temperature. * Tin–lead is used as a general-purpose solder * Tin–zinc is used for aluminium * Cadmium–silver is used for strength at high temperatures * Zinc–aluminium is used for aluminium and corrosion resistance * Tin–silver and tin–bismuth are used for electronics. Because of the toxicity of lead, lead-free solders are being developed and more widely used. The molten bath can be any suitable filler metal, but the selection is usually confined to the lower melting point elements. The most common dip soldering operations use zinc-aluminum and tin-lead solders. * Solder pot metal: cast iron or steel, electrically heated. * Bath temperature: (for binary tin-lead alloys) or (for lead-free alloys) * Solder composition: 60% , 40% or eutectic alloy.

Process schematic

The workpieces to be joined are treated with cleaning flux. Then the workpiece is mounted in the workholding device and immersed in the molten solder for 2 to 12 seconds. The workpiece is often agitated to aid the flow of the solder. The workpiece holder must allow an inclination of so that the solder may run off to ensure a smooth finish.

Workpiece geometry

This process is generally limited to all-metal work pieces, although other materials, such as circuit boards can also tolerate momentary contact with the hot molten solder without damage.

Setup and equipment

There is not much equipment or setup for this process. All that is needed is the solder pot with its temperature control panel, the bath of molten solder, and the work holding device. Usually the work holding device is custom made for each respective workpiece for either manual or automated dipping.

Solderability

Some materials are easier to solder than others. Copper, silver, and gold are easy to solder. Iron and nickel are a little more difficult. Titanium, magnesium, cast irons, steels, ceramics, and graphites are hard to solder. However, if they are first plated they are more easily soldered. An example of this is

tin-plating Tinning is the process of thinly coating sheets of wrought iron or steel with tin, and the resulting product is known as tinplate. The term is also widely used for the different process of coating a metal with solder before soldering. It is most ...

, in which a steel is sheet coated with tin so that it can be soldered more easily.

Applications

Dip soldering is used extensively in the electronics industry. However, they have a limited service use at elevated temperatures because of the low melting point of the filler metals. Soldered materials do not have much strength and are therefore not used for load-bearing.Soldering of Non-Ferrous Alloys
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References

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