Last update:


Site Map Location FAQ



PCB Design



History Menu













History of PCB Design

  Scope: A brief history of where we have been ...

Definition: Printed Circuit Board (PCB) or Printed Wiring Board (PWB)
" Printed circuits were developed during World War II by the National Institute of Standards and Technology for use in the proximity fuze for artillery shells. Subsequently the printed circuit found wide use in communication equipment, such as television and radio receivers, radar, and hearing aids, computers, and in instrumentation for guided missiles and airplanes." - Microsoft® Encarta® Online Encyclopedia 2000 http://encarta.msn.com © 1997-2000 Microsoft Corporation. All rights reserved.

Antique Radio / Phonograph

   " In the early days of radio and up to the end of World War II, radio receivers consisted of resistors, capacitors, inductors (coils), and electronic tubes joined together by wires with coloured insulation. A colour code, whereby a particular colour was assigned to a particular circuit connection, such as black leads for filaments, green for grid, was adopted throughout the world to facilitate manufacture and the tracing of faults. Later, wires cut to the right length were laced together into a harness to speed assembly. Plugs and sockets were employed for connecting one major part with another. Printed circuit wiring, developed during the 1940s, eliminated much of the hand work and produced important manufacturing economies.

Antique Radio

With printed wiring, the layout of the circuit is planned with component size and position in mind, and connections are made by suitably shaped copper strip or foil bonded to an insulating board or substrate. An extension of this technique was the printed component; resistors, capacitors, and low value inductors became a part of the printing process.

The development of the transistor simplified the exploitation of printed circuitry by eliminating one of the bulkiest components, the vacuum tube. Further development led to the manufacture of the integrated circuit in the 1960s. Compact circuits of this type can perform a multiplicity of tasks such as amplification and switching. They are widely used in computers where space is at a premium. Integrated-circuit amplifiers are likely to become more important because of their ability to amplify very high frequencies."- Encyclopedia Britannica

Printed Circuit Board - 
" Electrical device in which the wiring and certain components consist of a thin coat of electrically conductive material applied in a pattern on an insulating substrate by any of several graphic art procedures. After World War II, printed circuits replaced conventional wiring in much electronic equipment, such as radio and television sets, computers and control equipment, and airborne and guided-missile electronic systems. They greatly reduced the size and weight of the equipment while improving reliability and uniformity over the hand-soldered circuits formerly used.

Basic Stamp development 'breadboard'

Of the many techniques of manufacture, most involve photoetching or stencil etching. The insulating board is coated with copper and a protective film is deposited, photographically or by silk-screening, in the pattern desired for the circuit. The unprotected copper is then etched away either in an acid bath (for photographically deposited film) or by stencil-etching methods (for silk-screen film). The remaining conductive copper is left intact in the pattern of the circuit." - Encyclopedia Britannica


  My experience with PCB design goes back to the late 1960's and early 1970's. My father ran a PC Board manufacturing business in Vista, CA called Commercial Electronics Services. We made 'short run' proto boards for Hughes Aircraft Co. (and others) for about 5 years while I was still attending High School and training to become an electronics technician. I took Electronics I and II in High School from a great instructor, Mr. Vito Busalacchi, and made a PCB design by drawing on a copper clad board using a resist pen and etched it with FERRIC CHLORIDE (FeCl3·6H2O) in class. Later, after etch and rinse and resist removal with cleanser, I drilled holes in the board to mount the axial and radial leaded components to the board by soldering the leads to the etched circuit. Later, when I started working at my dad's shop, I was introduced to KPR, Kodak Photo Resist, a light sensitive colorless liquid that was applied to the surface of the copper laminate to 'sensitize' it to the image of the circuit we needed to print on the board. This gave us an accurate reproduction from an orthographic film (2 color, black or opacity and clear or translucent.. no gray color)...(A major  improvement over hand drawing..) and we used triclorethelyne, (a solvent ) as a developer... (now a banned substance due to the cancer risk)... And we etched the boards with AMMONIUM PERSULFATE (NH4)2S2O w/ 10cc of MERCURIC CHLORIDE (HgCl2)  per 10 gallons of etchant. (Note..these chemicals were not as tightly controlled or the hazards as well known as they are today...see safety sheets below in the notes. There are newer safer more environmentally responsible methods of etching PCB's today. ) This gave us a fast etch and a very clean board image in copper. We then drilled the holes in the board with a Precision Drill Press made by Cameron using the pad centers as guides and trimmed the boards to shape with routers and sheet metal shears made by Diacro and shipped them. It was a good experience, one that has served me well through my career as a designer.

Printed Circuits were developed to take the place of the 'BREADBOARD'. (Where exactly that term came from I can't answer...) But... here is a definition I found on the web...

Breadboard - A hand-made system prototype built as a proof of concept. In the early days of electronics (even before transistors were invented), engineers actually mounted circuit components on blocks of wood; hence the term "breadboard."

( I imagine the use of your families' breadboard  (or cutting board) in the kitchen was not uncommon...?  Although, my mother would have killed me if I had used her breadboard to prototype my audio amplifier circuit...)

Suffice it to say that most  electronic circuits were developed by using a perforated board with holes at 100 mil centers or some even distance that you could put 'push terminals' into to mount electronic components to. In my electronics class we built a superheterodyne tube type radio receiver as one of our projects completely without the use of any printed circuits. We wired up the radio using terminal strips and tube sockets. Some guys were real creative and made what we called 'air sculpture' with their circuits. (This was a sort of disorganized tangle of wires that was difficult to even see through, let alone trace.)


We also breadboarded a 400VDC power supply...which is where I found out about stored electrical charges in large capacitors the hard way...(ouch) but that's another shocking story. We were taught to wire the many connections by bundling the wires into harnesses and routing the harnesses in such a way to make test and troubleshooting easier. It was fairly time consuming, but made you realize the benefits of being organized in the building process. Neatness really makes a difference when you have a bad connection and are trying to find it with an ohm meter. 
Now, these kinds of things can be fun to build as a one time project, but if you wanted to make thousands of them, as I'm sure you can see, the labor costs would be greater than what you could sell the device  for... thus making it an impractical product. That's why we make PCB's. Cost, reliability, serviceability, labor savings....the main benefits of using printed circuit boards for electronics.

So, to put it in a nutshell, Printed and Etched Circuit Boards were invented to make a repeatable, mass produced, cost effective, electronic product.  The etched copper on the board takes the place of all those wires that were in the prototype model that was 'breadboarded' by the technician or engineer. Thus reducing the cost to go to market with their electronic gadget...like a cell phone, stereo, tv or computer, etc.

- Bill Brooks

Pentium class multilayer high speed motherboard
A Modern Computer Printed Circuit Board Assembly 


1953 - The company introduced KODAK Photo Resist, designed for making photolithographic printing plates; the business was sold to Union Carbide Corporation in 1987. A new subsidiary, Eastman Chemical Products, Inc., was formed to market products made by Tennessee Eastman and Texas Eastman.

Proximity fuze - Date: 1945 - a fuze for a projectile that uses the principle of radar to detect the presence of a target within the projectile's effective range 
 - Merriam Webster's Collegiate Dictionary

Ferric Chloride Safety Sheet

Ammonuim Persulfate Safety Sheet

Mercuric Chloride Safety SheetPOISON


Superhetrodyne tube type radio receiver

A form of radio reception in which the frequency of an incoming radio signal is mixed with a locally generated signal frequency (L.O. or local oscillator) and converted to an intermediate frequency (I.F.) in order to facilitate amplification of the preferred frequency and the rejection of all other unwanted signals.  Based on an ancient Chinese principle called 'Ning' applied to 2 frequencies (Tu) thus we get Tu-Ning or tuning...   :-) 
(sorry, I couldn't help myself.., the last part is a joke..in case you didn't know) 




Old folks - Respect them!


  A very self-important college freshman attending a recent football game, took it upon himself to explain to a senior citizen sitting next to him why it was impossible for the older generation to understand  his generation. 
 "You grew up in a different world, actually an almost primitive one."  The student said, loud enough for many of those nearby to hear.... "We, the young people of today, grew up with television, jet planes, space travel, men walking on the moon, our spaceships have visited Mars. We have nuclear energy, electric and hydrogen cars, computers with light-speed processing and...," pausing to take another drink of beer. 


The Senior citizen took advantage of the break in the student's litany and said, "You're right, son..."

"We didn't have those things when we were young." he pause... "So we invented them!"

Now, you arrogant little !$%,... What are YOU DOING for the next generation?" 


The applause was resounding... I just love senior citizens.  :-)






Hit Counter

Copyright © 2004 PCB Wizards.COM
 Home Up Next