
Electro-Migration in a Xerox Alto - coldnose
https://engblg.livingcomputers.org/index.php/2019/01/21/xerox-alto-interesting-issue/
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londons_explore
Electromigration is a major cause for failures of silicon components.

Over many years, metal in the very tiny vias between metal layers in the chip
fail.

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tedsanders
Indeed, this is one the largest challenges in semiconductor fabrication today.
The narrower our wires become, the more susceptible they are to tiny voids
formed by electromigration.

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mrguyorama
The article seems to imply that the effect is highly dependent on the "amount"
of electricity going through a connection. With that in mind, how much does
this occur on the scale of a CPU where the connection is only a few tens of
atoms across but the power is measured in only a couple volts?

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philipkglass
In microelectronics the voltage is low but the current density can be quite
high, and that makes electromigration a more severe problem than in higher
voltage macroscopic devices like motors.

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mrguyorama
Are you familiar with the field or have links to resources I can read?
Basically what I want to know is how long will a modern core-i5 last before
some transistor bridges and it dies? 10 years? 50?

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philipkglass
This "Fundamentals of Electromigration-Aware Integrated Circuit Design"
appears to be a decent starting point:

[https://www.ifte.de/books/em/](https://www.ifte.de/books/em/)

[https://www.ifte.de/books/em/em_chap1_figs.pdf](https://www.ifte.de/books/em/em_chap1_figs.pdf)

[https://www.ifte.de/books/em/em_chap2.pdf](https://www.ifte.de/books/em/em_chap2.pdf)

It won't answer your question directly (especially if you just read the free
material instead of obtaining the whole book) but it should orient you for
further reading. Note that electromigration is sensitive to temperature.
Running cooler can extend the lifetime non-linearly, whether achieved via
lower duty cycles or more effective cooling methods. You need to know how many
years at what temperature the processor will run, not just the dimensions of
the conductors.

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white-flame
Tangential, but is the spelling "buss rail" used in any widespread sense? Buss
is affection, bus is shared transport.

