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I know that wire wrapping was used in critical applications where reliability was a major concern because it is more reliable than PCB based assemblies. But is it still true?

The AGC (Apollo Guidance Computer) was wire wrapped but what about current designs? Are mars rovers, space telescope or critical nuclear power plants systems wire wrapped?

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    \$\begingroup\$ I've seen it as recent as last year in compact fluorescent light bulbs to connect the tube to the PCB, so yes. \$\endgroup\$ – AndrejaKo Mar 11 '13 at 14:08
  • \$\begingroup\$ But here it doesn't seems to be driven by reliability concerns. Is it an ultra low cost solution ? \$\endgroup\$ – Blup1980 Mar 11 '13 at 14:14
  • \$\begingroup\$ I guess so, since the light bulbs' internal construction left the ultra low cost feel. \$\endgroup\$ – AndrejaKo Mar 11 '13 at 14:16
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    \$\begingroup\$ Wire wrapping is very reliable, with each contact between corner of the post and wire almost equivalent to a microweld. It's also a royal PITA when you have a wire in the wrong place and it happens to be at the bottom of a stack of three wraps. \$\endgroup\$ – Scott Seidman Mar 11 '13 at 18:47
  • \$\begingroup\$ Surface Mount Technology pretty much killed wire wrapping. When everything had nice rows of pins and fitted in nice wire-wrap sockets, and PCBs were expensive and took forever to cycle, WW was great. Today, with massively integrated devices that do not come in socket friendly packages, WW is nigh impossible in many cases. \$\endgroup\$ – Trevor_G Mar 27 '17 at 20:43
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Occasionally, in some R&D lab, maybe, if they really need a one-off prototype and someone knows how to wire-wrap and has the tool and wire, and reliability isn't important. Otherwise making multi-layer PCB has just gotten too cheap and easy for everyone. Of course, multi-layer boards are much harder to fix than a rat's nest of thin wires, but with modern EDA software, are far more likely to be correct in the first place.

In some parts of the world where financial limitations and difficulty of access to markets force people to make do with whatever they have, it's no surprise to find old techniques in use. But google turned up no concrete anecdotes like that for WW. (Maybe I didn't spend enough time googling.)

More likely, WW is to be found in use by hobbyists with an itch to go retro, for example http://hackaday.com/2012/07/10/16-bit-hcmos-computer-is-a-wire-wrapping-wonderland/ where one commenter states "It’s rather zen, and an enjoyable way to burn a day – like knitting, basically."

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    \$\begingroup\$ absolutely, dead bug is fun and looks much nerdier and less sanitary than a machine assembled proto, or even just a machine printed and drilled through hole board. \$\endgroup\$ – Grady Player Mar 11 '13 at 18:01
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    \$\begingroup\$ Disagree with the reliability remark. Properly done wire wrap is very reliable. \$\endgroup\$ – gbarry Mar 11 '13 at 21:12
  • \$\begingroup\$ Yes, what I have read is that it is chosen for its reliability in place of PCBs \$\endgroup\$ – Blup1980 Mar 12 '13 at 10:29
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Wire wrap isn't used much today for a few reasons, but perhaps the most important is density. It's not possible to pack wire wrap connections much closer than the classic 0.1 inch spacing, which means you can't have as many connections on an IC or board of a given size. Applications which demand high reliability usually demand small size as well, so multilayer (often far more than 8 layers) printed wiring boards are ubiquitous.

Another consideration is the amount of skilled labor needed. A surface mount printed circuit can be assembled almost entirely by machine, while even the most automated wire wrap systems still need manual intervention. Once the printed circuit assembly line is up and running, the defects are minimal and can be monitored statistically. It's much harder to ensure quality with an army of humans holding wire wrap guns.

There is one place where wire wrap, or at least the wire used for it, hasn't died: white wire (a.k.a. green wire) fixes. The first iteration of a board often has a few design defects which get fixed in the first copies of the board by cutting incorrect traces and making a correct connection by soldering down pieces of wire wrap wire.

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I frequently use wire wrap techniques to make quick connections between eval boards and similar pre-pcb prototype setups. Most .100" headers/connectors (and even with care the 2mm variety) will take a single layer of wrapping just fine. It's cleaner and no more time consuming than soldering, and doesn't leave any residue behind when removed. Sometimes one end of the wire will end up soldered into a via or directly to an SMT pin, but the other may end up wrapped onto an available header pin.

Frankly I suspect this is why the tools and wire are still fairly widely available, even though long-pin wire wrap sockets and headers seem to be scarce.

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WW circuit boards are not common, if you read the NASA standards (all available online) they allow WW, through-hole and SMT.

However, it's still used extensively in telecomms for terminating wires on distribution frames.

Edit to add: http://nepp.nasa.gov/index.cfm/5575 - well worth a read if you've got a minute.

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imho wire wrapping is not necessary more reliable compared to a soldered PCB, but wire wrapping makes it easier to change if you need to re-route the connections, hence it is found in early telephone exchanges https://en.wikipedia.org/wiki/Wire_wrap#Manual_wire_wrap

it is also very useful for prototyping, e.g. this enterprising maker creates a cpu and computer out of basic chips http://www.bigmessowires.com/bmow1/

with arduino, beagle bone, raspberry pi, etc, electronics fads, wire wrapping is making a comeback with these diy electronics as it turns out wire wrapping is an effective and rather low cost way to connect mcu modules to breakout boards and other components and it can easily scale to very complex systems as the 2 links above show https://www.google.com.sg/search?ie=UTF-8&oe=UTF-8&q=wire+wrap&sitesearch=http://forum.arduino.cc https://www.sparkfun.com/categories/20

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In all I've seen maybe for prototyping. I had the last class in a university and we wire-wrapped an entire 8088 computer, I think I must have spent 300 hours doing that. After that I've only used it for prototyping and not even that much.

All of the aerospace hardware I've seen is all PCB's, in American space programs you have to shake your hardware in a vibe test before its sent to space (to simulate the rigors of a rocket ride, in which the payload experiences extreme g forces from turbulence). I doubt anyone today would want to do a vibe test with a wire wrapped board. The other problem with wire wrapping is, if not done correctly, wires can break. This could leave you with a dead spacecraft.

I did use wire-wrapping for to prototype a photometer trans-impedance amplifier to detect photons for an ultraviolet imager. But that was not for flight hardware, just for demonstration purposes.

PCB's are cheap and plentiful today, 40 years ago there were no computers to design PCB's, they had to be drawn by hand. Wire wrapping then would be an attractive option. Today there is no comparison for PCB's they are cost effective and take less time than wire wrapping.

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