Wave flow soldering is a method of soldering all the connections on a printed circuit board in a single step on a machine (instead of one at a time by hand).

A wave flow soldering machine has the following parts:

• a heated tank containing molten solder covered with a thin layer of flux
• one or more printed circuit board fixtures
• a mechanical wave generator

Printed circuit boards are populated with components (on automatic part placement machines and/or manually by human assemblers). The populated printed circuit boards are placed in the fixtures. As each fixture goes into the wave flow soldering machine the wave generator sends a wave of solder down the length of the heated tank. The top of this wave just touches the bottom of the printed circuit board, soldering all the connections. After the fixtures leave the wave flow soldering machine they are allowed to cool a while and the printed circuit boards are removed.

The soldered printed circuit boards are then washed to remove any flux residue left by the wave soldering machine, then sent to be tested to make sure they function as intended.

Wave flow soldering works best for "through hole mounted" components.

It is the oldest method of soldering, it is still popular method in certain kinds kinds of applications:

• Development of prototype boards
• Low volume production
• Soldering of extremely temperature sensitive components
• Solder reflow of fine pitch components using hot bar
• Rework or repair of machine soldered boards

The main disadvantages are operator training, speed, and consistent quality.

1.4.2 Machine Soldering:

Two prominently used machine soldering types are:

A. Wave Soldering - Primarily used for soldering through-hole components on to PCBs.

B. Reflow Soldering. - Used for soldering SMD components on to PCBs. Reflow soldering of SM components have the following advantages over manual soldering:

• Mass soldering
• Consistency in manufacture through precise control of process parameters.
• flexible for small production runs as well.

Soldering irons come in a variety of sizes and shapes. There is a wide selection of soldering irons, soldering pencils, soldering stations and soldering guns available on market in the USA.

Which soldering iron is the best soldering iron for you depends on the soldering work you are planning to do and how often you are planning on using your soldering iron. The following four factors should be taken into consideration when picking a soldering iron that will be used for soldering projects on circuit boards:

1) ) type of the soldering tools

2 wattage of the soldering iron

3)temperature control

4) tip size and shape

Types of soldering tools

All soldering tools can be divided in four different groups

-Soldering pencils

-Soldering station

-Soldering rework /repair stations systems

-Soldering guns

Soldering pencils

Soldering pencils are the simplest (and the cheapest) soldering tool. Soldering pencils are good only for simple do-it-yourself projects. The price range of the soldering pencils is $10-$30

Soldering stations

Soldering station consists of two parts: soldering pencil and a power station. Soldering pencil is attached to a power station. Power station controls temperature of the iron tip in the wide range. It automatically keeps the iron tip at an appropriate temperature. Desired temperature of soldering iron is set with knob on the face plate of power station. Soldering station can be used for most of soldering projects. It can be used for soldering of through-hole components on circuit board as well as for soldering of very fine surface-mount components as small as 0603 and 0805. The price range of the soldering stations is $40-$150.

Soldering rework /repair stations systems

Soldering rework/repair systems are complex soldering tools which are mostly used in industry or in the high-volume manufacturing facilities. This soldering systems are the most expensive soldering tools since they usually consist of power station and 4 or 5 hand pieces including soldering iron, hot-air gun, tweezers , vacuum pump which is used for the de-soldering work. The price range of the soldering systems is $250-$2500.

Soldering guns

I do not recommend using soldering guns for fine soldering projects on circuit boards.

The most popular brand names for soldering irons in the USA are Weller, Pace and Hakko. Aoyue soldering irons are less popular brand name in the United States then Weller or Pace. However, Aoyue soldering irons are much cheaper and they are good combination of quality and price.

There is a wide selection of iron tips. Iron tips come in different shapes and sizes. For most soldering projects you can use screwdriver tip 0.062" or 0.032". For fine soldering projects and for soldering of small surface-mount components you can use conical tip 1/16".

Conclusion

I recommend a temperature controlled 50W soldering station. This soldering station will be excellent tool for most of soldering projects. My top recommendations are:

-Weller WESD51 soldering station (digital)

- Weller WES51 soldering station (analog)

- Hakko FX-888 soldering station

- Aoyue 2702A soldering station

- Pace ST-25 soldering station