How appreciably do electrons in live wires, like in computers and generators, erode them? Do they erode like water and silt erode pipes and streams?
"The pros and cons of leaving your computer on" made me wonder about this.
The ganglions in your brain erode, obviously.
w.
"Helmut Wabnig" wrote in message news: snipped-for-privacy@4ax.com...
lowering daily salt intake can delay such erosion.
Too many electrons in the wires can cause overheating of the wire, if they are moving, or they can cause a large spark.
There's electromigration, which causes metal atoms to be displaced when the current density is high like 10^7 amps/cm^2. Electromigration is manifest as wire failure after a certain number of months or years of cumulative usage.
For ac current, this effect is not so bad since the current moves one way and then the opposite way, "fixing" the previous damage.
However, digital electronics uses DC, so it's important to use small current pulses in the tiny chips.
Aluminum house wiring looked like a good idea - cheaper than copper, low mass for the conductivity, limp for pulling through conduit. Even
5 amp currents at 110 VAC will cause aluminum wire to wriggle out of screw connections at sockets over a decade or two.Aluminum microwiring in CPUs was replaced by copper. CPUs are now sucking 70 (AMD) to nearly 100 (Intel) amps/core. Low mass atoms, especially in Intel frypans, electromigrate.
Ever hear of the electric power generating operations being stopped because the generators have been operating too many hours and the wires are deteriorating?
A light bulb with over 800,000 hours *continuous* service (over 101 years!)
IOW, there ain't no such thing as erosion of wires by electric current.
There are *many* other things that can happen which will affect the integrity of the circuit elements: heating, chemical reactions, vibration, etc.
Tom Davidson Richmond, VA
Does a toaster die from the current? Of course not, the element reacts chemically with the oxygen causes by the heat.
Speed does not kill people. Deceleration does. Don't stop.
Androcles.
Research is not the same as shooting off one's mouth.
Electromigration
FC knew what he was talking about.
One of the primary concerns in the manufacture of advanced microelectronic devices is to ensure that metallic contacts and interconnects do not fail by electromigration or stress-induced voiding. This article discusses the possibility of implementing two kinds of beneficial treatments within normal manufacturing processes?treatments that modify grain structure to minimize failures through diffusional flux divergence and treatments that control solute and precipitate distributions in order to avoid undesirable, overaged microstructures at the end of manufacturing.
Electromigration is generally considered to be the result of momentum transfer from the electrons, which move in the applied electric field, to the ions which make up the lattice of the interconnect material.
Modern semiconducting chips include a dense array of narrow, thin-film metallic conductors that serve to transport current between the various devises on the chip. These metallic conductors are called interconnects.
As integrated circuits become progressively more complex, the individual components must become increasingly more reliable if the reliability of the whole is to be acceptable. However, due to continuing miniaturization of very large scale integrated (VLSI) circuits, thin-film metallic conductors or interconnects are subject to increasingly high current densities. Under these conditions, electromigration can lead to the electrical failure of interconnects in relatively short times, reducing the circuit lifetime to an unacceptable level . It is therefore of great technological importance to understand and control electromigration failure in thin film interconnects.
The lifetime is high but there are two considerations. First lifetime is a statistical parameter, so you will have a distribution of lifetimes for the same batch of bulbs, for example. This bulb is clearly the exceptional 99.9% case. And then again the current is pretty low for this light bulb, like 3.3 mA (4W/120 V) and is AC. The wire diameter looks pretty thick (much more than 100 nm). All helping to suppress the current density below electromigration onset.
On the other hand, a 3.3 mA DC current pulse going through a 100 nm wide wire or contact in a chip will cut the device lifetime short, maybe on the order of years.
The usually quoted limit for top-level wiring on an IC is 10**6 A/cm^^2, and that's a DC average. Bulk copper has an electrical resistivity of about 1.7e-8 ohm cm at room temperature, so the power dissipation density in a wire at 1e6 A/cm**2 is 17 kW/cubic centimetre--it's the small size and excellent cooling of chip wiring that makes this possible. Pretty toasty for #14 house wiring!
Cheers,
Phil Hobbs
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