Decades ago RCA had a soldering problem. One day nearly half of the assemblies had to be reworked, but nothing seemed amiss at the board shop. What was the cause? Mysteries of Science
Transcript
RCA was a major TV manufacturer several decades ago when the US led the world in radio and TV production. RCA made many of their own components including printed circuit boards.
The RCA factory used rosin flux to remove copper tarnish. This mild organic flux always worked well and is still used today. One fall day soldering yield dropped off. The solder wasn't wetting the copper sufficiently. The next day yield was measurably worse and nearly half of the assemblies had to be reworked.
Nothing seemed amiss. The boards looked fine and passed all tests. Some thought that the boards that soldered poorly looked different. A darker color suggested thicker oxide or maybe contamination.
Engineers were tracking down leads and expounding theories. What could have changed?
Here's the rest of the story.
The RCA plant was close to a Campbell's Soup plant. Since it was fall, tomato soup and other tomato products were being processed. It turned out the poor soldering and tomato products production had begun at about the same time.
The tomato season meant that all of Campbell's tomato products, especially soup, were in full production with the windows wide open. There was enough acidic airborne material leaving Campbell's to cause problems with the RCA circuits. The solution was obvious, but costly. The RCA plant would have to control their environment.
Today, nearly all electronic plants have highly-controlled environments, but this was one of the first. It appeared that the acidic tomato vapors were probably accelerating the copper tarnishing. While the acidic tomato theory was never proven in the scientific sense, it's a reasonable hypothesis.
