History of wave soldering

Wave soldering manufacturer Chengyuan will introduce to you that wave soldering has existed for decades, and as the main method of soldering components, it has played an important role in the growth of PCB utilization.

There is a huge push to make electronics smaller and more functional, and the PCB (the heart of these devices) makes this possible. This trend has also spawned new soldering processes as an alternative to wave soldering.

Before Wave Soldering: PCB Assembly History

Soldering as the process of joining metal parts is thought to have emerged shortly after the discovery of tin, which is still the dominant element in solders today. On the other hand, the first PCB appeared in the 20th century. German inventor Albert Hansen came up with the idea of a multilayer plane; consisting of insulating layers and foil conductors. He also described the use of holes in devices, which is essentially the same method used today for through-hole component mounting.

During World War II, the development of electrical and electronic equipment took off as nations sought to improve communications and accuracy or precision. The inventor of the modern PCB, Paul Eisler, developed a process in 1936 for joining copper foil to a glass insulating substrate. He later demonstrated how to assemble the radio on his device. Although his boards used wiring to connect components, a slow process, mass production of PCBs was not required at the time.

Wave Welding to the Rescue

In 1947, the transistor was invented by William Shockley, John Bardeen, and Walter Brattain at Bell Laboratories in Murray Hill, New Jersey. This led to a reduction in the size of electronic components, and subsequent developments in etching and lamination paved the way for production-grade soldering techniques.
Since the electronic components are still through holes, it’s easiest to supply solder to the entire board at once, rather than soldering them individually with a soldering iron. Thus, wave soldering was born by running the entire board over “waves” of solder.

Today, wave soldering is done by a wave soldering machine. The process includes the following steps:

1. Melting – The solder is heated to about 200°C so it flows easily.

2. Cleaning – Clean the component to make sure there are no obstructions preventing the solder from adhering.

3. Placement – Place the PCB properly to ensure the solder reaches all parts of the board.

4. Application – Solder is applied to the board and allowed to flow to all areas.

The Future of Wave Soldering

Wave soldering was once the most commonly used soldering technique. This is because its speed is better than manual soldering, thus realizing the automation of PCB assembly. The process is particularly good at soldering very fast, well-spaced through-hole components. As the demand for smaller PCBs leads to the use of multilayer boards and surface mount devices (SMDs), more precise soldering techniques need to be developed.

This leads to a selective soldering method where the connections are soldered individually, as in hand soldering. Advances in robotics that are faster and more precise than manual welding have made possible the automation of the method.

Wave soldering remains a well-implemented technique due to its speed and adaptability to newer PCB design requirements which favor the use of SMD. Selective wave soldering has emerged, which uses jetting, which allows the application of solder to be controlled and directed only to selected areas. Through-hole components are still in use, and wave soldering is certainly the fastest technique for quickly soldering large numbers of components, and may be the best method, depending on your design.

Although the application of other soldering methods, such as selective soldering, is steadily increasing, wave soldering still has advantages that make it a viable option for PCB assembly.