When Wilhelm Conrad Roentgen, a professor at Würzburg University in Germany, accidentally discovered X-rays In 1895, he had no idea what was to come in the future. From those humble beginnings, a scientific revolution began that is still growing today. Looking back to the early years—when the side effects were unknown—and forward to modern, shielded, solid-state machines, the legacy of X-ray science is one of discovery, medical miracles, and the industrial revolution. The first use of X-rays under clinical conditions was by John Hall-Edwards in Birmingham, England, on January 11, 1896, when he radiographed a needle stuck in the hand of an associate. On February 14, 1896, Hall-Edwards was also the first to use X-rays in a surgical operation. Later, X-rays took on a whole new form.
But the history of X-rays isn’t complete without the mention of Marie Curie. Alongside her husband, Pierre, they studied the science of radioactivity and its possible application to medical fields. Together, they worked on the secrets and science of radiation. Their research was well on its way when he was killed in an accident. In his memory, she carried on their legacy alone.
When Marie Curie’s discoveries outgrew her laboratory, the Austrian government seized the opportunity to recruit Curie and offered to build her a cutting-edge lab. She then negotiated with the Pasteur Institute to construct a radioactivity research laboratory. By July 1914, the “Radium Institute” at the Pasteur Institute was almost complete. But when World War I broke out, Curie suspended her research and organized a fleet of mobile X-ray machines for use by doctors on the front—the very first X-ray van. Marie Curie became the first woman to be awarded the Nobel Prize for her work and dedication, and her legacy continues to this day.
Later, X-rays became a novelty in the United States—familiar fixtures outside of medicine. Who can forget the smallish wooden podiums offering casual foot X-rays? Shoe-fitting fluoroscopes started showing up in shoe stores around the 1920s. At first, the X-ray wielding boxes were seen largely as gimmicks, but eventually, they came to be respected as valuable shoe-fitting tools. But the dangers of this type of unshielded usage soon became apparent, and the technology was eventually handled with the shielded-environment care it deserved.
X-rays were recognized as possible tools in manufacturing as well, but it took roughly a decade before they were used in the industrial fields. The amount of voltage required to produce a strong-enough X-ray was too much for traditional cathode tubes. In 1913, William Coolidge invented a high-vacuum X-ray tube that could withstand higher power voltage. This development allowed X-rays to contribute to the industrial revolution across the globe. Due to the continuing development of better technologies, the refinement and versatility of X-rays have never ceased to expand.
One such expansion was in airline travel. In 1973, airlines began using X-rays to screen passengers as a way to maintain safety and prevent smuggling. Medical technology grew expansively, and today, millions of lives have been saved by the power of X-rays in all its types. In this day and age, X-ray technology is used to discover weaknesses in manufacturing and detect counterfeit components. This technology has revolutionized the industry of small part inventory control and is an invaluable tool in manufacturing and quality control industries.
Printed circuit boards (PCBs) are no exception. In fact, X-ray technology is essential to the quality control and evolution of the industry. The first PCBs can be traced all the back to the early 1900s. In 1925, Charles Ducas first submitted a patent for creating an electrical path directly on an insulated surface—an idea that became popular until after WWII when in 1943, Austrian Dr. Paul Eisler began making the first operational PCBs.
With rapid growth and automation, a failsafe way of maintaining manufacturing integrity and quality became a necessity. Though all precautions were taken to maintain quality control through testing at the manufacturing level, a random test of a production line did not ensure proof of quality. With this need, the importance of X-ray technology in the quality control field grew. Today, by viewing a completed circuit board with X-rays, even microscopic problems can be detected.With today’s technological advancements, miniaturization of electronic products, PCB manufacturing technology continues to move towards smaller and more densely packed boards with increased electronic capabilities. Future advancements may include three-dimensional molded plastic boards and the increased use of integrated circuit chips, package-on-package (PoP), as well as embedded components. Though these and other advancements will keep the design and manufacturing of PCBs a dynamic and constantly evolving industry for many years to come, the easiest and most effective way to maintain quality control is with X-rays.