3D IC's

Discussion in 'General Electronics Chat' started by maxpower097, Dec 18, 2010.

  1. maxpower097

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  2. thatoneguy

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    Pretty cool.

    As long as they stay at least as large as QFP or SOIC for packages. Through Hole is going away quick lately.

    I don't think prototypers and hobbyists will all be able to transition to thousand pin packages for supercomputers the size of a sunflower seed that run on AA batteries.

    There aren't even easy breakout boards for QFN or BGA packages. It is just easier to have the board made with the parts placed.

    When they do develop multilayer silicon, I can see a big jump in processor speed, but big issues with heat removal, such as metal heatsink pads as on QFN, but on both sides of a thin package or something.
     
  3. spinnaker

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    Please don't tell me that! :) I am just getting back into this hobby after putting it on hold for about 30 years. There are a lot more cool things out there then there was 30 years ago. Including those wonderful MCUs.

    My hands are not very steady and my eyes are not good as they used to be, I doubt I could tolerate anything other then through hole.
     
  4. thatoneguy

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    I'm sure Microchip will still be producing through hole variants of their most popular PICs for quite some time. Resistors and capacitors will always have through hole variants for size and power reasons. Newer composite System on Chip and specialized controllers are only released as BGA, some as QFN, but not many other choices. :(

    A lot of stuff is just NICER when it is compact, and Larger surface mount components, such as SOIC are easier to make a PCB for and solder compared to a DIP (1/2 size roughly). You no longer have to worry about forgetting to mirror image the bottom side of the board!
     
  5. spinnaker

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    What about for a newbie with shaky hands? :) How hard is it really? I would think one big advantage is no more drilling.


    Why do DIPs still exist? Do engineers still use them in prototyping?


    Actually my hands don't shake all that much though I would never make a surgeon. My brother is far worse. He just came to visit and wow, he is getting shakier as he grows older. He would never wield a soldering iron, just a knife (he is a chef :)).
     
  6. tyblu

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    One of the profs I worked with in my undergrad is developing 3D pixels. Right now CMOS pixels (forget CCD -- those are old news) are planar -- about 1/4 of the 'pixel' is taken up by the ADC and other charge processing circuitry. He wants to be able to use 100% of the 'pixel' for light collection as well as preprocessing by putting the polysilicon collection layer on top of the circuitry, instead of beside it. Makes for interesting capabilities, like true-logarithmic image pickup, just like our eyes (except better!).
    http://www.ece.ualberta.ca/~djoseph/
     
  7. thatoneguy

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    Drilling (reduction in) is a HUGE advantage of SMD. The "Large" surface mount devices are good to go, even with mildly nervous hands, solder wick, buy a lot of it.

    DIPs are mostly around for prototyping, Simulation programs are very good, but not to the point where at least some part of it is done on a breadboard or protoboard to verify something or other.

    One off PC Boards are common for prototypes, with several locations to change component values or jumpers, then when the design is finalized, switch to the BGA packages and the sub-micro sized SMD components for machine placement, and you have a product 1/8th the size (or less) of the first PCB prototype.
     
  8. tyblu

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    DIP parts are still used advantageously by higher power dissipation devices -- ones that need to be hooked up to heat sinks, or at least need their backsides cooling off in the air instead of stuck to a copper plane. Regulators, power transistors, rectifier arrays, etc.. Could consider higher power through hole passives in this category, too, I 'suppose.
     
  9. marshallf3

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    If you look hard enough most of the essential stuff is still available as through hole and while I can deal with the 0.050 pitch SMD ICs I'd have to figure out how to build a cheap IR reflow system or buy one of those expensive irons that blows super hot air to deal with anything smaller. At least solder paste/flux is easy enough to buy nowadays as is that stuff (forget the name) that makes it easy to remove large SMD packages from a board.
     
  10. marshallf3

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    Why do DIPs still exist? Do engineers still use them in prototyping?

    I still use them as most of the things I design and sell I offer as blank PC boards, (or all the files and images needed to make one) as a complete kit of parts for self assembly or as fully assembled and tested products.

    Considering a lot of these go into the hands of hobbyists with limited experience I've got to stick with through hole or I'm going to end up with a lot of people that end up making a mess out of things, not to mention all the extra stuff they'd have to buy and all the headaches I'd end up getting about why something didn't work.

    Toner transfer is nice but most everything I design takes a double layer board with integral feedthus thus unless you solder the pin(s) on both sides it just creates another problem. Considering I sell most everything I make very near cost people usually buy the PC board or kit if they're die hards as I understand the thrill of building something yourself. Fully assembled and tested? I make a little more profit here but it all gets put back into the next project, same as Thomas Edison's strategy was.
     
  11. maxpower097

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  12. thatoneguy

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    maxpower:

    Have you held a BGA in your hand? 1mm Center to Center. A 25 pin LED controller covers half of a pinky fingernail.

    Trying to line that up perfectly is a bit of a pain without a rework station and good magnification. The slightest bump would short all the connections.

    http://www.xilinx.com/support/documentation/package_specs/fg676.pdf (They are double that pitch now, down to 0.5mm as well)

    I'll stick to ordering placed boards, since it's not that much extra if you put a price on time.
     
  13. maxpower097

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  14. tyblu

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    I would love to try some BGAs at home. I've seen many How-To's and tutorials, but am still uneasy about it. I bet there's a lot of technique that can't be covered in a simple instruction manual.
     
  15. thatoneguy

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    The biggest thing is the stencils to apply the solder paste/flux, which acts like a 'tacky glue' until it is heated. Getting the stencil lined up perfectly and the correct amount of paste laid down is one step, aligning the BGA so it doesn't smear is another, and heating it to fuse is still another.

    Yes, it can be done. The same way digital logic can still be made from discrete transistors. The logical and useful choice is to choose the in-between doable to get the project going.

    Unless you want to create a BGA board to prove it is possible.Then a multilayer board is required, with very, very tiny vias. If etching at home, you need to deal with registration issues and lamination issues as well.
     
  16. maxpower097

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  17. thatoneguy

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    The Xbox BGA are rather large spacing, about that of an AMD processor's pins. Those only need a hot air pencil or IR source to remelt, and are fairly easy to work with, comparitively. The scale difference is similar to SOIC vs TSSOP.

    Most newer ICs are coming out as the fine pitch BGA, and the pitch will only get smaller as density increases.
     
  18. maxpower097

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  19. thatoneguy

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    I never said everything was going BGA, just that through hole was vanishing for a lot of new things.

    My BGA comment was with regard to the multilayer/3D silicon. I can see thousand+ pin counts on newer creations, as well as some amazing circuits with only 8 or 16 pins.

    Consumers want everything smaller and faster, luckily, those two go together nicely. Leadless packages have almost no inductance allowing for higher digital operating speeds.

    My main statement is that I'd like most everything to at least come in SOIC, if not through hole/DIP, otherwise the hobbyists will fade again like a decade ago. I didn't mean to make it an argument about BGA, I have a strong love and hate relationship with those packages. Today, it seems to be bordering on hate.
     
  20. maxpower097

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