Folks,
The following post is some of what I presented at SMTA PanPac February 2-6, 2026, with a little of the history of soldering added.
My interest in the history of electronics was piqued when I attended a mid-1990s lecture by Noble Laureate Arno Penzias on the same topic. Penzias was a co-discover of the Cosmic Microwave Background, which strongly supports the Big Bang creation theory of the universe.
A striking feature of Penzias’s talk was when he said, “In 1972, one megabyte of computer memory costs $1 million. That is about what a small apartment building in New Jersey costs then. Today (1994) a megabyte of memory could not buy a hinge on a door in the apartment building.”
I go back to this thought frequently when thinking about the rapid advances in electronics. These advances have led to today’s $1,000 smartphone having several times the computing power of the fastest supercomputer of 1995, and more than the computing power of all super computers of 1990.
Let’s start with a simple question: what defines modernity? The smartphone? A TV? The internet? The electric light? I think it is a simpler answer: electricity. Electricity is the enabler of it all. And without the electron, electricity wouldn’t exist.
The History of the Electron
The most useful thing in physics, the electron, was born about 13.8 billion years ago in the Big Bang. The electron was born with about 1080 siblings. Its birth was also shared with all the other matter that would become the trillions and trillions of stars in the observable universe. These stars are so numerous, that if each were a grain of sand, they would cover the earth more than a meter deep.
Figure 1 shows a deep space image from James Webb telescope. The small, red galaxies were formed less than a few hundred million years after the Big Bang. Therefore, we are seeing the galaxies a short time after they formed. They contain the youngest electrons ever seen. The galaxies are red because they are red shifted as they speed away from us.
Figure 1. The Webb telescope deep space image. The red galaxies are only a few hundred million years old in this image. Image source: NASA, CSA, and STScI; Processing by E. Siegel.
The electron had to wait until 1820 C.E. to be exploited by humans. However, it would be a mistake to minimize the role of this diminutive particle up until then. All of the material in nature is bound by its electrical force, from the tiny virus to a massive star. Without the properties of the electron, nothing material would exist.
Why is 1820 C.E. important? It was this year that Hans Christian Ørsted made an accidental discovery that led to useful applications of electricity. He was giving a public science lecture at the University of Copenhagen on the heating effects of electricity. He was using a battery, invented in 1800 by Volta. During the lecture, Ørsted was surprised that when a compass was held near a wire, in which current was flowing, the compass needle was defected. This discovery showed that electricity and magnetism were related. Subsequent work by André-Marie Ampère, Michael Faraday, and eventually James Clerk Maxwell led to the codifying of electromagnetic (EM) theory into Maxwell’s Equations by 1865. These equations are the foundation for the design of essentially all electrical devices.
Soldering was older to Julius Caesar (100 – 44 B.C.E.) than he is us. Early soldering was performed around 3500 B.C.E. However, early researchers such as Hans Christian Ørsted and Michael Faraday did not use soldering. Most of their electrical connections, for their experiments, were temporary, so they used mechanical means or even put the wires they wanted to connect into a container of mercury.
The Telegraph, Telephone and Electric Light
However, well before 1865, inventors were putting electromagnetism to work. One of the first inventions to use electromagnetism was the telegraph. Samuel F. B. Morse perfected it and chose as a partner to implement it, the founder of my alma mater, Ezra Cornell. It would be difficult to overstate the importance of the telegraph. With the railroad and photography, it made the American Civil War the first modern war. President Lincoln was a regular at the Washington D.C. telegraph office, using telegraphy to direct the war, far from the battlefields. The Union’s use of trains was unprecedented to transport troops and supplies vastly outstripping the capabilities of the South. The North’s use of these two modern tools was significant in its victory. All the while, photographers like Mathew Brady brought the horrors of war home to the people.
The invention of the telegraph did give birth to electric soldering, as now a permanent bond was needed for the wires and components. The soldering would be performed with techniques developed by the tinsmiths of the day. Tin-lead solder of 60-40 composition was used, which is close to the 63-37 formulation most recently phased out of the commercial world. Soldering irons were made of a copper block shaped to a point that was heated in burning coals, similar to how a blacksmith would heat metal. Electric soldering irons did not arrive until the 1890s. Solder in bar or wire form was used, as shown in Figure 2.
Figure 2. Bar solder and solder wire were used in soldering for the telegraph industry starting in the mid 1800s. Although Indium Corporation didn’t exist yet, the solder used in this period was quite similar to the bar and wire solder of today.
The true impact of the telegraph was shown by its marriage with the train in the transcontinental railroad. The railroad men pleaded with congress for money to build the line from sea to shining sea, as they claimed they could not do such a massive undertaking without financial government help. A pliant Congress agreed, only if the railroad would put telegraph lines accompanying all rail tracks. The transcontinental railroad was finished in 1869 to much fanfare and had a stunning effect on the development of the American West.
The “49ers” traveling from New England needed up to 8 months to get to the California gold fields. By 1870, the trip could be made in 4 days, and a message could be sent by telegraph to friends and family instantly that you were coming. Never in history has there been such a change. In 1850, it could take months to get a message from NYC to San Francisco. In 1870, mere minutes.
By 1877, the theory of electromagnetism saw its first practical application of a telephone line from Boston to Somerville, MA, a distance of 3 miles. By 1900, there were close to 1.5 million phones in the United States. Telephones increased the demand for soldering. By this time, using an electric soldering iron for solder wire was becoming more common.
We could overstate the importance of telegraphy and telephony compared to electric lighting. In the mid-1800s, whale oil was often the best choice for home lighting. It burned clean and bright, but stank and cost $100s of today’s dollars per month. Kerosene was a welcome replacement, especially with John D. Rockefeller’s “Standard Oil.” But, inexpensive electric lighting replaced all these stinky and dangerous lighting technologies. The implementation of electric lighting set off the battle of the war of the currents between Edison versus Tesla and Westinghouse. Spoiler alert, Tesla’s AC current won. All of these advances created the need for more and more soldering with solder wire and soldering irons.
As electric lights became more common, radio was emerging. Initially, hobbyists used crystals of lead sulfide (galena) to catch the EM waves. The crystals required no amplification, but the signal was very weak, so headphones were needed to hear the sound. Lee DeForest’s invention of the triode vacuum tube revolutionized radio, as the weak signals could be amplified to drive speakers. Now the entire family could listen to a radio broadcast. Surprisingly, the radio industry did not boom overnight. The development of today’s business model (the funding of radio by advertising) did not immediately emerge; it took almost a decade.
The Radio
By the 1930s, the radio became an indispensable part of American life. During the Great Depression, radios served as a primary source of news, entertainment, and a sense of connection for many families. Despite financial struggles, the affordability and value of radio made it a staple in American households. By 1930, over 40% of American households owned a radio, and by the end of the decade, that number had more than doubled to 83%.
The radio’s role extended beyond mere entertainment; it was a tool for unity and reassurance. President Franklin D. Roosevelt’s “Fireside Chats,” for instance, provided comfort and direct communication to citizens during uncertain times.
Manufacturing radios created the electronic assembly industry. Radio assembly began in the late 1920s and had established a methodical process by the unprecedented demands of World War II. The establishment of military specifications also created a sense of discipline in the assembly processes. A radio like this would have been assembled by hand with solder and fluxes like Indium Corporation’s solder wire.
A radio like this would have been assembled by hand with solder and fluxes like Indium Corporation’s solder wire.
Through the 1950s, electronics grew as radio became supplanted by TVs. The significant adoption of the printed wiring board in the 1940s to 1950s reduced the hassle of point-to-point wires in the radio or TV. At first, hand soldering was still performed, but by the 1950s, wave soldering had emerged using solder like Indium Corporation’s bar solder and fluxes. Wave soldering led the way for electronics assembly for computers.
Stay tuned to see how television manufacturing led to modern electronic assembly and personal camera manufacturing gave us the technologies to enable the smartphone.
Cheers,
Dr. Ron
