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It's possible that the inkjet printed transistor is both replicable and impractical for building a full microprocessor. The inkjet transistor article says "A t

It's possible that the inkjet printed transistor is both replicable and impractical for building a full microprocessor. The inkjet transistor article says "A total of 216 devices were tested with a yield of greater than 95%, thus demonstrating the true scalability of the process for achieving integrated systems." But 95% yield on the transistor level implies vanishingly low yield at the device level when you need thousands of transistors to build a full microprocessor. Even the new MoS2 microprocessor discussed in the Ars article wasn't fabricated all at once. It was built up from sub-components like shift registers containing fewer transistors, then those components were combined to make a full microprocessor. See for example "Supplementary Fig. 7 | Yield analysis of wafer-level 8-bit registers." in the supplementary information: https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-025-08759-9/MediaObjects/41586_2025_8759_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1038%2Fs415... The yield of 8-bit registers, each consisting of 144 transistors, can reach 71% on the wafer.

godelski 2y ago
My knowledge of transistors is pretty limited[0]. Does the yield percentage refer to number of successful chips on a substrate or look more at the total number of successful transistors? (Or confusing hybrid-term like rain forecasts) I believe your comment implies the latter? So the number of successful processors is quite low? How many failed transistors can you have in a working microprocessor? (Probably not an easy to answer question?) [0] Am I remembering correctly that this is your area?
- Out_of_Characte 2y ago
  Yield would be the amount of functioning chips. This may be chips, entire packages or even a complexer answere where good chips also need to be below certain leakage. Cores and caches could be disabled and the list of potential yield increasing tooling is always increasing when wafers nowadays costs thousands of dollars.
- notjoemama 2y ago
  I’ll add chip designers add redundancy. When errors are detected in testing, they can disable sections of the chip by lasering fuses. That allows routing the circuit through a higher quality area. Quality is measured by not only that the circuit produces correct data but also within tolerances of timing and voltage. IIRC RAM is approximately 10% redundant. A good quality chip will use what meets the spec and leave good transistors unused. A poor quality chip will disable bad ones and only use the ones that meet spec.
exe34 2y ago
if you could print transistors, you could make computers the way Wozniak made them - a bunch of chips with a ton of wiring.
- chongli 2y ago
  You can do that easily and cheaply today without a fancy transistor printer. You can find Apple II schematics easily enough online. All the chips are common, off-the-shelf parts still available today. You can send the KiCAD drawings (also available) to a company like PCBWay and have PCBs made very cheaply and in small quantity. Then all you have to do is solder in the chips and other components and connect the board to a power supply.
  - exe34 2y ago
    I think the appeal is the you can print out a couple of pages of chips and wire them up, not send out for chips and PCBs.
    - chongli 2y ago
      You can order a whole batch of chips and wire them up on breadboards without sending away to have a PCB made. The PCB step is the last one when you want to finalize your computer and package it up. Ben Eater actually has a free course on YouTube [1] all about building a breadboard computer! [1] https://youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565dvjafglHU https://youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565d...
      - fc417fc802 2y ago
        There's just a different emotional sense between manufacturing the lego bricks yourself versus mail ordering the magic blocks that you can assemble into a finished product.
        chongli 2y ago
        Lego bricks is an apt analogy. I don't know how many people would actually care to manufacture their own Lego bricks but millions of people enjoy putting Lego together. Sam Zeloof [1] actually went through the exercise of making his own semiconductors from scratch. It's a lot of chemistry and experimentation and quite interesting as an exercise, but not at all practical for building your own computer. Printable transistors would take away the nasty chemistry bits that Sam had to deal with but otherwise wouldn't help much with making practical devices. Computers have a lot of very standard, "Lego brick" or jellybean components. Stuff like muxes/demuxes, shift registers, adders, and the like. These are the components you can buy off the shelf to build your own computer. Building these yourself on giant sheets of paper with a printer might be interesting but you'd get a far less practical, usable computer out of the deal. [1] https://www.youtube.com/@SamZeloof/videos https://www.youtube.com/@SamZeloof/videos

godelski 2y ago

My knowledge of transistors is pretty limited[0]. Does the yield percentage refer to number of successful chips on a substrate or look more at the total number of successful transistors? (Or confusing hybrid-term like rain forecasts) I believe your comment implies the latter? So the number of successful processors is quite low? How many failed transistors can you have in a working microprocessor? (Probably not an easy to answer question?) [0] Am I remembering correctly that this is your area?

Out_of_Characte 2y ago
Yield would be the amount of functioning chips. This may be chips, entire packages or even a complexer answere where good chips also need to be below certain leakage. Cores and caches could be disabled and the list of potential yield increasing tooling is always increasing when wafers nowadays costs thousands of dollars.
notjoemama 2y ago
I’ll add chip designers add redundancy. When errors are detected in testing, they can disable sections of the chip by lasering fuses. That allows routing the circuit through a higher quality area. Quality is measured by not only that the circuit produces correct data but also within tolerances of timing and voltage. IIRC RAM is approximately 10% redundant. A good quality chip will use what meets the spec and leave good transistors unused. A poor quality chip will disable bad ones and only use the ones that meet spec.

exe34 2y ago

if you could print transistors, you could make computers the way Wozniak made them - a bunch of chips with a ton of wiring.

chongli 2y ago
You can do that easily and cheaply today without a fancy transistor printer. You can find Apple II schematics easily enough online. All the chips are common, off-the-shelf parts still available today. You can send the KiCAD drawings (also available) to a company like PCBWay and have PCBs made very cheaply and in small quantity. Then all you have to do is solder in the chips and other components and connect the board to a power supply.
- exe34 2y ago
  I think the appeal is the you can print out a couple of pages of chips and wire them up, not send out for chips and PCBs.
  - chongli 2y ago
    You can order a whole batch of chips and wire them up on breadboards without sending away to have a PCB made. The PCB step is the last one when you want to finalize your computer and package it up. Ben Eater actually has a free course on YouTube [1] all about building a breadboard computer! [1] https://youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565dvjafglHU https://youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565d...
    - fc417fc802 2y ago
      There's just a different emotional sense between manufacturing the lego bricks yourself versus mail ordering the magic blocks that you can assemble into a finished product.
      - chongli 2y ago
        Lego bricks is an apt analogy. I don't know how many people would actually care to manufacture their own Lego bricks but millions of people enjoy putting Lego together. Sam Zeloof [1] actually went through the exercise of making his own semiconductors from scratch. It's a lot of chemistry and experimentation and quite interesting as an exercise, but not at all practical for building your own computer. Printable transistors would take away the nasty chemistry bits that Sam had to deal with but otherwise wouldn't help much with making practical devices. Computers have a lot of very standard, "Lego brick" or jellybean components. Stuff like muxes/demuxes, shift registers, adders, and the like. These are the components you can buy off the shelf to build your own computer. Building these yourself on giant sheets of paper with a printer might be interesting but you'd get a far less practical, usable computer out of the deal. [1] https://www.youtube.com/@SamZeloof/videos https://www.youtube.com/@SamZeloof/videos