The development of modern printed circuit boards began in the start of the 20th century. Albert Hanson described multiple layers of flat foil conductors which were laminated on a board in 1903. In 1904, Thomas Edison worked on chemical ways of plating conductors using linen paper. In 1913, Arthur Berry patented a method on print-and-etch in Britain, while Max Schoop did the same in the United States, using flame to spray metal onto a board with the help of a patterned mask. In 1927, Charles Durcase patented an electroplating method for circuit patterns.
In 1936, Paul Eisler invented the printed circuit. The U.S. used this technology on a larger case during World War II in 1943. It was later released commercially after the war, but it wasn’t until the mid-50s when they became common in the consumer market. This was due to the U.S. Army’s auto-sembly process. Geoffrey Dummer did similar work in Britain at about the same time.
Before PCBs came to be, point-to-point construction was prevalent. John Sargrove’s “Electronic Circuit Making Equipment” (ECME) predated printed circuit boards, but performed similar tasks. In 1936 to 1947, the ECME sprayed metal onto plastic boards, and was able to create three radios per minute.
During World War II, developing anti-aircraft proximity fuse needed circuits that can withstand gunfire – and that can be mass produced. The Globe Union’s Centralab Divisionproposed a prototype which met these requirements. For conductors, they would screen-print a ceramic plate with metallic paint, and use carbon material for resistors. Subminiature vacuum tubes and ceramic disc capacitors will be soldered – a technique that ended up with a patent and was classified by the U.S. Army.
It wasn’t until 1984 that the head of this project, Harry W. Rubinstein was awarded by the Institute of Electrical and Electronics Engineers (IEEE) the Cledo Brunetti Award for his contributions.
The original PCBs had drilled holes for every wire of each component. The components had wire leads, which were passed through holes and then soldered to the trace. This is called the “through-hole” method, which is still used by some today. The Auto-Sembly process was developed in 1949 by Stanislaus Danko and Moe Abramson of the U.S. Army Signal Corps. The method involved inserting component leads into a copper foil with an interconnected pattern, and then were dip soldered. They obtained a patent which was assigned to the army. As the techniques on lamination and etching were developed, the process has developed more and more like the standard printed wiring boards fabrication known today. Now, of course, soldering can be automated by passing the printed circuit boards over a wave or ripple of molten solder using machines. The holes and wires are wasteful, though, because drilling holes is very costly and the excess wires are just cut off.
As the 1980s came in, surface-mount components were used significantly, and through-hole components less frequently. As a result, smaller boards came to be, ending in lower costs for production and better functionality. However, there has been a lot of difficulty experienced in servicing boards that are faulty.
A lot of the measurements used in the design of printed circuit boards have been expressed in units called “mils” (multiples of a thousandth of an inch). For instance, to be considered breadboard-friendly, through-hole components have pins found on a grid spacing of 100 mils. On the other hand, surface-mount components use a 50-mil pin pitch.
All in all, PCBs have gone through lots of changes – most of them for the better. Now, the manufacturing is less labor-intensive, more cost-effective, and efficient for both manufacturers and consumers. This is great news since PCBs are used in almost every electronic appliance and machine today.