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Comment by kens | Hacker News Reader

Author here for all your CT scanning questions :-)

This isn't about CT scanning, but about the chip itself.

Since the bond wires are just hanging out in air, does this mean that a chip like this could be ruined by dropping it which might cause the bond wires to move enough to short something?

Thanks for all your hard work!

I'm not an expert in this area but I'd expect that the bond wires' mass is low enough relative to their stiffness that any shock sufficient to bend them would also shatter the ceramic package.

If the chip is subjected to a few thousand g's of shock the wires can bend and short.

This failure mode is quite low on the list among others, but it is something that people did investigate. For example: "Swing Touch Risk Assessment of Bonding Wires in High-Density Package Under Mechanical Shock Condition" https://asmedigitalcollection.asme.org/electronicpackaging/a...

Yes, that can be a problem. Story from one of my professors who worked on instrumentation and telemetry for a defense lab. They built a data recorder for artillery shells. In the early "flight" tests, the recorders failed and nobody could figure out why. They worked before and after. Then someone realized the high acceleration bent some of the bond wires in the chips, causing them to touch and short. The fix was surprisingly simple: make sure all chips face top down.

Genuine question: the website doesn't work in Russia. Did you restrict the access or is it my ISP doing that? Someone tries to prevent me from studying of very niche info on ancient Intel CPUs. Thanks! P.S. Big fan of your work!

One word: VPN

That's three words

I’m upvoting you.

ya'r good boy

Or is it 5

Some smaller sites ban ips from countries that continually try to hack into your server or just make a ton of requests, it happens to be that traffic is often from Russia and China. Could just be that.

I block Russia, China, and Iran from my sites. They represent 0% of the revenue, and 99% of the login attempts.

Yeah. In the same vein I also don't distribute my app in the Play Store in certain countries. I realize it completely sucks for them, but it's purely a business decision. Certain countries are just very vocal in terms of negative reviews, simply swap 5 star and 1 stars due to cultural differences, and also bring in almost zero revenue. The net result of distributing in these countries is literally negative: they hurt my ratings and reviews and don't make up for that in terms of money.

I did find that, while running a financial startup, I was able to significantly reduce attacks on the server by disabling access from Russia and China. Not saying that's happening here, just my experience. That was a while ago so I'm sure things have changed since then.

Thanks for your reply! I hope this is the real reason of blocking. If that's not the case, that's at least not effective. Less effective than idk placing a banner in the header or whatever.

I mean I eventually read the article. Sorry for that. But we're at "Hacker News", sporting hackers ethics, aren't we?

Opposing the invasion of Ukraine and the biggest existential threat Europe's faced in a couple generations seems pretty ethical to me.

We should be jamming American media down Russias throats like we did during the Cold War.

Radio Free Europe and Radio Liberty were one of the very first things that the Trump presidency stopped.

By preventing some computer history enthusiast in Russia from reading an article on a processor from 1985? Really?

That is it was more financially effective to block an entire country, than analyzing attack patterns and blocking by ASNs or IP-ranges. Correct?

Startups don't have enough free time to analyze individual ASNs, because they don't have enough people for that.

That and financial businesses usually don't operate outside their host country anyway. Though you do want your customers to see their accounts when they're traveling.

Yes. Multiple countries.

In all fairness, this isn’t a good use of that technique. But most websites are of no interest outside a handful of countries.

It is your ISP. (don't ask me how I know but please research this before posting)

It could be this: https://blog.cloudflare.com/russian-internet-users-are-unabl...

Because the author is the opportunistic racist:

> kens on April 10, 2022

> Are you trying to access from Russia? Russia is currently blocked.

https://news.ycombinator.com/item?id=30974444

> kens on Dec 3, 2022

> Unfortunately there are also many people in Ukraine who didn't personally do anything to deserve what's happening. Consider the country filter a small reminder of the ongoing war and a suggestion that you might find better opportunities outside Russia.

https://news.ycombinator.com/item?id=33846782

Yet he doesn't consider to 'find better opportunities outside of the USA' despite the actions of the USA government in the last 30 years.

Probably your ISP, or more precisely, the ТСПУ box they were required to install. You can use this tool to test your connectivity to these hosting providers that the government dislikes: https://hyperion-cs.github.io/dpi-checkers/ru/tcp-16-20/

Ken himself did block access to his website from Russia for a while after 24/02/2022, but right now it loads for me after a CF captcha.

What kVp/mAs do you use for this? How are you avoiding the artifacts seen from medical imaging? Curious, in school for CT in the medical field.

Lumafield does all the work; I just get the images :-) The data says 130 kV, 123µA. The whole scan took 21 hours: 1200 projections of 60 seconds each. I assume that they avoid artifacts by using a whole lot more radiation than medical imaging would permit.

I’m assuming each image was taken with 123 microamperes? Or is that total dosage over the 21 hours? If it’s total that’s much less than medical dosage, but if it’s per image that’s a lot more!

Thanks for the info, how interesting!

(for those who don’t know, mAs = mA • seconds = milliampere seconds. It’s how Radiographers measure how much x-ray photos are being produced by the tungsten filament in an X-ray tube. kVp is kiloVoltage potential and it’s how we measure the speed and thus the penetration power of the X-rays. 130kvp is slightly more than the 120kvp used for an avg human chest radiograph)

Any rational argument to use mAs instead of mC?

I asked Jon Bruner at Lumafield for details:

The scan was performed on our Neptune Microfocus scanner, configured with a 130 kV source. Current varies on this source depending on scan settings; in this case 123 µA. Each voxel in this scan is 12.8 microns; for smaller parts that we're able to move even closer to the X-ray source we can achieve 3-6 micron voxels.

Compared to medical CT scans, this is much higher resolution--medical CT scans have voxels on the order of 0.5 to 1 mm! This is possible because we're able to apply much higher X-ray doses in industrial scans. Medical CT scans are typically on the order of 120 kV, at higher current but for much less time--perhaps a few seconds compared with minutes to hours for an industrial CT scan.

Does it look like the almost connected pins could have been purposely severed during production? ie: could they have been connected and then using a calculated pulse of power, disconnected?

If they installed wire bonds and removed them, there would be visible remnants on the die, which aren't there.

Is the CPU destroyed by the process or did you reassemble this particular specimen?

I took the metal lid off the chip to improve the scan quality. If I had left the chip intact, it would probably be fine. (I assume the X-ray levels are low enough to avoid damage, but I haven't confirmed that.)

Also 386s are very resistant to radiation, I believe they still use them on the ISS for that reason (a radiation-hardened version but still)

What is the last node/cpu that had the smallest features visible at optical microscope scales?

With a good scope we could inspect 0.35um chips just fine. I honestly didn't look at die photos much after that until we started getting SEM images of 32nm and smaller chips

What CT scanner was used? The images are surprisingly detailed for something so small, while we are used to coarser scales of human anatomy.

It's a Lumafield scanner, but I don't know the specific model.

What is your CPU's yearly deductible?

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