Tin in solder or some other meals can form spiky crystals when under stress. These whiskers can form short circuits if not properly insulated or not alloyed with other metals.
this post was submitted on 20 Jul 2024
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You're misunderstanding me.
For instance, electrons always move the same speed in a given metal. Which of couse isn't even 'true' because temperature affects mobility.
There are multiple mechanisms for metal to migrate, grow whiskers, or whatever you like to call the individual growth on an object. I mentioned that in the case if ICs, we are concerned with one we call electromigration. I'm not saying all metal migration is due to electromigration.
You're being pedantic when all I'm saying is, I deal with these sorts of concerns in my job.
Tiger I think you're being pedantic, they linked to Whiskers (metallurgy) not Whiskers (electromigration). There is a difference! But it's not super clear cut, which is why I took the time to write about it.
Electrons do not always move at the same speed in a given metal. A lot of things affects mobility, but the E field is very important too. Both things combine so that electrons do not always move at the same speed in a given metal. But you can simplify in an IC world because there you're riding the saturation velocity basically always, which is why I assume you keep claiming that.
I want you to know that your experiences from your education and job are valid - you do deal with whiskers in ICs, not denying that; the fact is that whiskers due to stresses and strains aren't called electromigration which is what the original comment says.
"A similar thing also called whiskers can happen inside ICs and has been a known failure mode for high frequency processors for many years. I work in chip design, and we use software tools to simulate it. It’s due to electromigration and doesn't rely on stresses but instead high current densities."
Metal whiskering is a phenomenon that occurs in electrical devices when metals form long whisker-like projections over time.
That's what the article says. EM is a subset of metal whiskering. It's not a similar thing, it's an example of it.
Tiger, you’re very similar to many of the semiconductor EEs I know :) and I mean that in a teasing-but-you-know-cause-you-work-in-the-industry way. Yeah, we only really care about whiskering in the context of electrical devices. That’s what it’s saying. Read the “Mechanics” section, it tells you nothing about actual electromigration doing it; they describe an E field encouraging metal ions in a fluid to make a reaching whisker and link to electromigration because it technically is “electromigration” making the targeted whisker occur. But IC-style electromigration is not causing the whisker, clearly cause no currents are flowing, which is why I took the time to write the explanation in the first place.
But just because the semiconductor community called it whiskers so it shares the name with the Big Whiskers, does not make the process anywhere close to similar. The current densities that cause absolutely not present for the stress ones, which the wiki article is about.