Printed circuit boards are a fundamental part of both of commercial electronic equipment and of the projects we feature here on Hackaday. Many of us have made our own, whether done so from first principles with a tank of etchant, or sent off as a set of Gerbers to a PCB fab house.
To say that the subject of today’s Retrotechtacular is the manufacture of printed circuit boards might seem odd, because there is nothing archaic about a PCB, they’re very much still with us. But the film below the break is a fascinating look at the process from two angles, both for what it tells us about how they are still manufactured, and how they were manufactured in 1969 when it was made.
Tektronix were as famous for the manufacturer of particularly high quality oscilloscopes back then as they are now. The Tektronix ‘scopes of the late 1960s featured several printed circuit boards carrying solid-state electronics, and were manufactured to an extremely high standard. The film follows the manufacturing process from initial PCB layout to assembled board, with plenty of detail of all production processes.
In 2017 you would start a PCB design in a CAD package, but in 1969 the was incredibly manual. Everything was transcribed by hand from a paper schematic to transparent film. Paper mock-ups of component footprints four times larger than actual size are placed on a grid, and conductors drawn in pencil on an overlaid piece of tracing paper. Then the pads and pattern of tracks are laid out using black transfers and tape on sheets of film over the tracing paper, one each for top and bottom of the board. A photographic process reduces them to production size onto film, from which they can be exposed and etched in the same way that you would in 2017.
Most of the physical process of creating a PCB has not changed significantly since 1969. We are shown the through-plating and gold plating processes in detail, then the etching and silkscreening processes, before seeing component installation and finally wave soldering.
What are anachronistic though are some of the machines, and the parts now robotised that were done in 1969 by hand. The PCB drilling is done by hand with a pantograph drill for small runs, but for large ones a fascinating numerically-controlled drilling rig is used, controlled by punched tape without a computer in sight. Component placement is all by hand, and the commentator remarks that it may one day be done by machine.
The film remains simultaneously an interesting look at PCB production and a fascinating snapshot of 1960s manufacturing. It’s probable that many of the Tek ‘scopes made on that line are still with us, they’re certainly familiar to look at from our experience at radio rallies.
Continue reading “Retrotechtacular: Circuit Boards The Tektronix Way”
