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Milestones: Paul Eisler's PCB Patent Turns 60

It was 60 years ago, on June 21, 1950, that Paul Eisler's PCB patent was published (Hat tip to Colin Warwick at Agilent--how many of you have that date marked on your calendar?).

Eisler's life story (described in his autobiography, My Life with the Printed Circuit) comes across like a mystery novel, rife with persecution (Jewish engineer fleeing 1930s Austria), inefficient government agencies (all of them), and the ever-popular "illegal immigrant just wants an honest job" meme.

Born in 1907, Eisler graduated from Vienna University in 1930 with an engineering degree. He was already a budding inventor. But his primary objective was to land a job in a country that wasn't run by the Nazis. All the good engineering jobs were going to party members in 1930s Austria anyway.

So in 1934 he got a job in Belgrade designing the electronic system for a train--it would have allowed passengers to play individual records through headphones, like an iPod. But that job ended when the customer offered payment in grain instead of currency.

I guess the whole "payment in grain" angle never surfaced during negotiations.

Back in Austria, Eisler wrote for newspapers and founded a radio journal, and began to learn about printing technology. Printing was a fairly robust technology by the 1930s, and he started to imagine how the printing process could be used to lay down circuits on an insulating base, and do so in volume.

In 1936 he decided to leave Austria. He secured an invitation to work in Britain based on two patent applications he had already filed: One for a graphical sound recording and one for a stereoscopic television with vertical resolution lines.

He sold the TV patent for ₤250, enough money to live for a while in a Hampstead boarding house, which was a good thing, because he couldn't find a job. One telephone company really liked his printed circuits idea--it would have eliminated those bundles of wiring used for phone systems back then.  But the manager told him that the manual wiring work was being done by "girls" and "girls are cheaper and more flexible." Well.

At least we're past the point of using cheap labor to do what a decent tool can do in half the time.

As WWII loomed, Eisler worked at getting his family out of Austria. His sister committed suicide and when the war began, the British interned him as an illegal alien. Even locked up, Eisler kept thinking of new ways to help the war effort.

Once released, Eisler went to work for the music printing company Henderson & Spalding. Originally, his objective was to perfect the company's unworkable Technograph music typewriter, operating out of a laboratory in a bombed-out building. Company owner H.V. Strong made Eisler sign over to him the title to any patents emerging from that research. It wasn't the first or last time Eisler would be taken advantage of.

Part of the trouble with doing military work was his status: He had just been released from internment. You can imagine Eisler approaching military contractors to discuss how his printed circuit idea might be of some use to the war effort.

Through his work at Henderson & Spalding, Eisler developed the concept of using etched foil to lay down traces on a substrate. His first boards look much like plates of spaghetti, with almost no straight traces. He filed a patent application in 1943.

No one really paid attention to this invention until it found its way into proximity fuses of shells used to shoot down V-1 buzz bombs. After that, Eisler had a job and some small amount of fame. After the war, the technology spread. The U.S. mandated in 1948 that all airborne instrument circuitry was to be printed.

Eisler's 1943 patent application was eventually split into three separate patents: 639111 (Three-Dimensional Printed Circuits), 639178 (Foil Technique of Printed Circuits), and 639179 (Powder Printing). These three were published on June 21, 1950, but very few companies actually licensed the patents.   

In the 1950s, Eisler was exploited again, this time while working with Britain's National Research and Development Corporation. The organization basically gave away Eisler's US patents. But he kept on experimenting and inventing. He came up with the idea for the foil battery, heated wallpaper, pizza ovens, concrete molds, rear-window defrosters, and more. He found success in the medical field, and died in 1992 with dozens of patents to his name. He had just received the Institution of Electrical Engineers' Nuffield Silver Medal.

Who are going to be the next Eislers, or the next Shockleys or Kilbys? They're out there..maybe in the office down the hall.