Vintage PCB Artwork From the 1970s
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- Опубликовано: 3 июл 2024
- #pcb #vintagecomputer #retro I was recently given some original artwork for circuit boards created in the late 70s and early 80s by a member of the Association of Computer Experimenters. Having created PCBs for my TV Typewriter project with the benefit of modern tools, I was intrigued in the processes used many years ago. Not a lot of these original works survive, so I was really grateful yo be given these!
00:00 Wavy hands pre-ramble
07:43 Actually showing the stuff you came to see 
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Sorry in advance for the seven minute 'pre-ramble', but I felt I needed to explain the drawings' provenance, their historical importance and some of the challenges people faced creating these things in an era before computers were widely available to help us, and only had so much I could show while talking about that. I am still working on my 'off the cuff', handsy speaking style. But at least as far as I can tell the audio didn't suck. So some progress. :)
The explanation of the historical importance is why I'm here. Love this content!
Hi
There was the rub on decals. And then there were the tape and pads I would use made by companies like Bishops Graphics.
All the pads, were all to scale. 1x 2x and 4x for pads. Track tape was available in a bunch of different widths from super skinny to quite thick, though I used electrical tape for big high current pads
You would make a positive and use that to create negatives for the Riston coated PCBs.
The coating would fix to the board under UV light so once you exposed the board, you’d wash off the non exposed coating off before etching it
Once the board was etched, you would scrub off the coating on the tracks with some steel wool.
I rarely did double sided boards as there was no easy way to get through hole joins between the top and bottom of the board.
I used that technique to make custom boards up until the mid 90s
I threw my stuff out sometime in the early 2000s
They are important documents. My suggestion is to scan them, identify those which you can, and post the clean images to the Internet Archive. They're not exactly Gerber files, but if someone wanted to build a TV Typewriter II these seem like a good start.
I started my career as a "layout engineer" using this method with two times oversized sheets of semi transparent paper (fake vellum, so no real calf skin was used) using crepe tape and dots you could pick up from a cardboard carrier with tweezers. and having a 1/10 inch raster sheet below the "vellum". You started with drawing a schematic diagram, then assembled a list of connections to use while creating the traces. One very important step was placing the components on the sheet, as a wrong placement could make connecting up IC's impossible. You used the list of connections, ticking off every finished one. Luckily I am a "picture thinker" so I could imagine in my head what the best placement would be.
After you had finished the layout the sheet was photolithographically reduced to half sized, and the result would be used to flash on the photosensitive layer (the photosensitive layer was either sprayed on, or you used boards that where already photo sensitive, and had a dark plastic sheet over them that you had to remove first).
The first "CAD" system to help laying out boards, was a simple grid based affair written in turbo pascal, you could place on one of a number of shapes the program offered for example a circle (dot), of a horizontal or vertical trace segment etc, you still had to use a spreadsheet (paper printout) to keep track of connections, as the program was only for layout, it was not integrated with a schematic drawing program, that came much later. The great advantage of using CAD was that you could easily made corrections. Later I used programs like orcad and many others I ended up using Altium 10, and at home (for hobby) I used KiCad. you can see my projects on the website of my maker space Revspace (www.revspace.nl) user Mahjongg, I also publish designs on GitHub.
I think for me the intimidating part is knowing how to lay things out so you can make those connections. Apparently that was one of the things that bedeviled the Sol project- Lee Felsenstein and another guy worked overtime to make the magazine deadline and had so many mistakes on the first board revision that they needed 100 jumper wires just to get the thing going. I find that incredibly intimidating and not having a computer to simply wipe away bad choices or reorient things.. yikes.
@@TechTimeTraveller As a "picture thinker" its easy for me to imagine the best placement that needs the least amount of difficult routing.
In the 70's we used tape and ic pad layouts and worked original artwork in 2x. we used thick velum and punched registration holes to align the layers (a metal strip with pins placed along the top or the art) we did a 4 layer thru hole circuit for the a DEC pdp11 add on. you put a 2x refrence for the photo shop to shoot down and do the color seperations. The photo shop said we were too pick when we told them we needed exactly 50% reduction.
The negative sheets would look great in light boxes on the walls around the house. They are works of art. Thank you for sharing these.
I just discovered your channel. It's fantastic. I was born long after the micro processor became prevalent and I thought I'd seen everything worth seeing about vintage machines... boy was I ever wrong!
It might be niche content but 10/10 for documenting your knowledge for the younger guys to see.
It still amazes me to this day how they kept track of everything, and not only that, but laying each circuit path - how many times do you think it crossed several others and they couldn't use the other side, because a path was already there? Draw, erase, redraw. It must have taken ALOT of time and effort to make these - I truly appreciate these men, they were true designers.
Double-sided PCB etching achievement unlocked. Welcome to drill hell.
I laid out and taped up a number of PCBs in the 70s and early 80s. You've described the process well overall. After exposing the PCB to the UV light I had to use a developer to 'develop' the resist then a warm water rinse to remove the undeveloped resist. I had access to a photo lab with an enlarger/reducer which made reducing 4x or 2x artwork down to the proper size pretty easy. For double sided PCBs I tape the masks together on 3 sides then slid the PCB inside to be UV exposed. The exposer drew a vacuum to draw the mask tightly against the PCB before the UV exposure. Before I taped up a PCB I would lay it out on grid paper using a pencil then once I had a design I taped it up. I loved this kind of work, never saw it as a chore. Today I use KiCAD and a Chinese PCB manufacturer. Once I submit the design to the manufacturer I have PCBs in my hands in under a week. Usually in 4-5 days. We live in amazing times. The process has become so simple and cheap I often skip the prototype stage, design in KiCAD, layout PCB, order PCB, debug any issues, update the design and submit my final design to be manufactured.
Nice! Was it true there was fairly high wastage with double sided boards?
I am so glad you shared these. Thank you for taking the time.
Here I am stressing out about KICAD when I could be stressed out about not noticing that a taped-on trace fell off right before processing onto copper clad.
Arrgghh! Flashbacks 🤣🤣 always enjoy your videos on 70s and early 80s tech.
Respect to those that built anything larger than a small circuit. Having to route everything manually etc... Good skills to have but glad we don't rely on this too often now 😀
Those ARE beautiful, just graphically, on their own.
Very cool! Love the explanation of 70s circuit design.
Worked with the layout guys at my first job in the mid '80s. They would have a layer of grid vellum under the artwork as they layed it out. I remember they used a 25mil grid (12 mil traces and 13 mil spaces.) (mil=0.001") So, 0.050" grid at 4x.
If you made a change when they were near done, you'd get an earful as they had to rip up a lot of tape. These were very dense boards, probably four times the density of chips and large boards.
The guys were amazing, they would stare at the schematic and place the parts. Then just start laying tape. They would feed a data bus out of an area and leave them hanging in the middle of the board. then when they got to the other end of the board, feed them to the chips there. The good ones had a picture of all the traces in their head and could do a whole 8x8" board with near 100 chips with few changes. The tape was exactly like pinstriping tape for auto finishes. Black vinyl IIRC. They did use red and blue for top and bottom boards as it was easy to see on a light table.
What a tedious process the check the layout against a schematic. When I started, we just began using CAD. Still had considerable manual checking. Power and ground planes you had to manually change the pin types to make a connection and the CAD had no knoledge of it.
One of my buddies took a 4-layer artwork and framed them in layers of glass. It created moire' patterns as you looked at it at an angle.
When we got to autorouters, a crowd would just watch amazed at it running.
I'd love to hear what Dave from EEVBlog thought of these. I'm sure he would have plenty of stories.
I will no longer fuss about having to lay out a small PCB using KiCad and having five copies manufactured and shipped for 5-10 bucks. I'm amazed at the effort early hobbyists put into it. Thanks for the video.
I think redoing these in KiCad would be a great way to learn the software, and then make it really easy to send them to a board house to make the boards.
It is literally art to me too. Love your channel
I can't get enough of this retro tech stuff! Keep up the good work!
I love this, thanks so much for sharing :)
I'm a computer engineer (not practicing unfortunately) and remember when we did a project in the "PCB Lab" in mid 1990s using transparent sheets, exposure projectors and chemical etching. I designed and made a PCB for a "smart card", which facilitated purchase for students within the campus. Those were the beautiful old days. I've started working in real-estate almost since graduation and am not quite happy :\
I love this stuff !!!!!!!
Having made PCBs at home it is the thought of drilling all those holes, and how many bits they may have broken that makes me shudder
I have done this very thing with my Mark 8 and TVT project. The Mark 8 has been even worse because it's double sided and in addition to breaking drill bits I'm also sometimes popping the copper off of the other side.
@@TechTimeTraveller are you using a backing board? A flat piece of MDF/whatever under the PCB and a slow speed on the drill press should help keep tearout from happening.
Gosh I enjoyed this video. I'd love to see you making some PCB using these methods. I made some up for the TV Tennis Project last year, and accidentally got all six boards flipped the wrong way. Haha..
It took me too long to realize when you said "deck-al" it was what I've always heard said "dee-kal"
Yeah a lot of Canadians pronounce it 'deck-al', and I think most Americans and British use 'dee-cal'.
@@TechTimeTraveller It seems to be an Australian thing as well.
haha, I didn't get it until I read this. I thought it must be a brand name
Interesting video. I remember seeing PCB making kits at Radio Shack during that era, and thinking that it looked way too hard.
I purchased some of those same kits. Long way back now, but I do remember many failures ... fun times =D
I made a number of boards using stuff from Radio Shack. At one time I think they even had some rub on stuff that acted like a resist. One of my techniques was to lay out the IC's and components on the copper clad, drill the holes and deburr, then draw the traces using Sharpie markers. I made more than a couple of boards that way and although the traces weren't always pretty, they turned out OK enough to work. Most of my more complex digital stuff was made using wire wrap.
Tech Time Traveller Drinking Game: Take a shot every time he says "again, ..."
We did this process in high school (early 80s) in Electronics Shop class. Was fun but cured me from any urge to be a drafting person doing these designs.
Hah! I still have my project box with echant tray, decals etc. Your video tells me I should likely accept I'm not using that process any more and should pitch it. :)
Between the exposure and the etching, you would actually have to clean off the uncured mask. Anyway, good video!
I had a special pen with very think sticky ink. On the copper plated board one could draw the lines, everything in real size, after the ink dried the unwanted copper could be eaten away with chemicals. The chemicals also like to eat through curtains and clothings. I blamed the moths, I knew better.
I still have some of mine from the 80's, nothing so grand as these. (Teenaged me won't let me part with them. 🙂)
I've heard of people using "silicon impregnated" paper to print on and transfer to copper. Silicon impregnated paper is that slimy paper that is used to back stickers.
Photo-resist is the word you are looking for. You washed off the photo-resist that was not cured with UV (light).
Supposed to be a plug-in for KiCad that gives you the "70's traces" on PCBs. I was not able to get it to work.
At least something new relevant to my search regarding printed (drawn?) circuit boards over history. So far the only other one interesting I've seen is the video titled "Tektronix Printed Circuit Boards 1969". I'm unhappy that I can find films on recent professional production of PCBs or lots about current home etching techniques, but it's hard to find anything on how those were made from the beginnings of the technology.
Your best bet is going to be to look for material related to the Apollo program.
Really cool 😎
I had no idea they had decals for that, but it makes total sense. Surprised to hear it was sold at RadioShack.
70s and 80s Radio Shack had some great DIY electronics supplies. It was amazing what you could buy there.
I still have some in unopened packaging. Bought them in the late nineties. Recall seeing whole boards in rubon transfer for a project. It was direct enchant resist.
I pronounce it as key cad, but what do I know I only speak USA ... even in the early 90's I had to bum a ride to make copies at the closest print shop and sit there fixing things with a sharpie ... then still had to jumper a bunch of stuff
the positive process uses NaOH to remove the non-useful resist. I suppose the negative process to be similar, but I couldn't find the information. the Negative process seems to have disappeared
the tapes came in all matter of widths, you only had to cut it to length
There used to be a company called "Bishop" graphics in the USA that used to make the decal IC patterns and the like for PCB layout. The traces were basically a "Roll" of tape in the proper width so that you can run the connections. Manual CAD was used. Do you have the original artwork for the Netronics elf board ?
No that artwork would be with Netronics still if anywhere and I think they just recently closed down.
Niche fiche ? Sorry….:) super interesting thanks
Would you be interested in seeing ones made at Disneyland during the early 80's? My dad is the kind of guy to keep such things.
For sure!