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William Blair
Joined: 06 Nov 2005
Posts: 68
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 Posted: Wed Nov 09, 2005 9:15 pm Post subject: Removing CPU die lids & CPU die macro/micro photography |
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I want to take macro photographs of CPU dies like the excellent ones found here (under Posters SHOP):
http://logout.sh.cvut.cz/%7Eastro/index.htm
Anyone know any other web sources for photos like these?
Through web research, I've discovered that the CPU die lids on ceramic packages are affixed in place using either a high-temperature gold solder or epoxy. Has anyone found a way to remove the lid without damaging the ceramic case or the CPU die? The only way I've thought of is to mill away the cover along its edges. Unfortunately, I don't have a milling machine.
BTW, here's a fascinating article about how data was extracted from a _very_ damaged EEPROM (the die lid was off, leads to the die had been broken, everything had been exposed to saltwater, etc.) from the flight control computer of an airliner that had crashed. Amazing. I found it while doing a Google search for "IC die lid" during my research for a way to remove these lids:
http://www.chipworks.com/resources/whitepapers/SwissAir.PDF
Last edited by William Blair on Sat Nov 12, 2005 4:51 pm; edited 1 time in total |
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metalmaker
Joined: 06 Dec 2004
Posts: 161
Location: St. Louis, MO, USA
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| Posted: Thu Nov 10, 2005 12:00 am Post subject: |
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see this link at CPUshack's site http://www.cpushack.net/DiePhotos.html for some good die pictures. He has some more good ones in the PA-Risc ID page too.
As for removing lids all you need is a hot air gun like is used for removing paint - buy one at your local hardware store - looks like a hair dryer. It gets hot enough to melt the solder, but not the ceramic or the silicon as long as you don't blast it too long. Great for removing soldered chips from boards too.
Does anyone else here remember who (the link?) did the "cooking with pentium pro" demo where the lid was removed from a pentium with a blow torch and then the chip put back in the motherboard and it still worked? I think I remember seeing it on a CPU-world member website - but forget who? My google search did not turn it up within the first couple pages.
MM
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| Posted: Thu Nov 10, 2005 1:16 am Post subject: |
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| metalmaker wrote: | see this link at CPUshack's site http://www.cpushack.net/DiePhotos.html for some good die pictures. He has some more good ones in the PA-Risc ID page too.
As for removing lids all you need is a hot air gun like is used for removing paint - buy one at your local hardware store - looks like a hair dryer. It gets hot enough to melt the solder, but not the ceramic or the silicon as long as you don't blast it too long. Great for removing soldered chips from boards too.
Does anyone else here remember who (the link?) did the "cooking with pentium pro" demo where the lid was removed from a pentium with a blow torch and then the chip put back in the motherboard and it still worked? I think I remember seeing it on a CPU-world member website - but forget who? My google search did not turn it up within the first couple pages.
MM |
I have a small butane torch that produces enough heat to soften the single-edged razor blade (held in needle-nose pliers) that I was using to attempt to pry up the lid while heating it. I tried using it last night before posting this question today. No dice, the lid didn't budge (MC6800L). If it had, I fully expected the leads between the die and the package to have vaporized in the tiny instant between the departure of the lid and my removal of the torch flame. That wouldn't be acceptable because I want the leads there for the photos.
After the failure of my mini-torch, I didn't even try my 1000F electric heatgun. |
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Simmayor
Joined: 23 Apr 2003
Posts: 328
Location: Deventer Ov, The Netherlands
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metalmaker
Joined: 06 Dec 2004
Posts: 161
Location: St. Louis, MO, USA
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| Posted: Thu Nov 10, 2005 1:35 pm Post subject: |
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Thats the one!
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William Blair
Joined: 06 Nov 2005
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| Posted: Thu Nov 10, 2005 2:02 pm Post subject: |
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Ah, now I get it! Thanks, gents! It's possible to heat the entire IC (without having it shatter due to thermal stress) up to the point where the lid will begin to slide. The secret of avoiding destruction of the leads to the die due to flame impingment is to remove the flame and _then_ slide the die lid off. The entire IC (not just the lid) must remain hot enough to allow this. However, I'm still amazed that the tiny leads to the die don't instantly oxidize to aluminum oxide the instant they are exposed to air. Perhaps they are so thin that they radiate their heat away nearly instantly after the heat source is removed even while the ceramic IC case remains extremely hot.
I note that the lids on these CPUs were soldered in place with what looks like lead-based solder, probably a non-eutectic alloy that melts at a moderately higher temperature that the solder used during the wave soldering of circuit boards (don't want IC lids sliding off during the manufacturing process, I guess). Or, perhaps, it was silver solder which would melt at an even higher temperature and have the same benefit. Anyway, the IC I was attempting to remove the lid of very obviously used a gold-based solder which would have an even higher melting point than silver solder. Anyway, I'm gonna' try burnin' that same MC6800L some more tonight! I love the smell of ICs in the evening. It's the smell of... technology.
Thanks again. |
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William Blair
Joined: 06 Nov 2005
Posts: 68
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| Posted: Fri Nov 11, 2005 5:30 pm Post subject: |
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| I finally got the die lid off pretty easily thanks to your help. The MC6800L die is tiny and I don't have anything remotely approaching a proper macro photography setup (to be corrected next year when the new batch of digital SLRs come out), so I've found a truly sharp focus and good depth-of-field to be impossible. Anyway, here it is with a little photo-editing to remove the (ugly) solder-covered die attachment lip on the ceramic DIP. |
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William Blair
Joined: 06 Nov 2005
Posts: 68
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| Posted: Fri Nov 11, 2005 8:17 pm Post subject: |
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| Here's a composite of the original CPU DIP and a second macro image I took. |
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wepwawet
Joined: 18 Mar 2004
Posts: 3019
Location: Seligenstadt - Germany
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| Posted: Sat Nov 12, 2005 10:46 am Post subject: |
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Nice work.
Try some light effects, the lid can be very colourful then.
btw, most lids I removed I used a extremely hard needle and a small hammer. Makes also good results (one little scratch instead of all the solder risk)
br, Michael |
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William Blair
Joined: 06 Nov 2005
Posts: 68
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| Posted: Sat Nov 12, 2005 2:26 pm Post subject: |
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| wepwawet wrote: | Nice work.
Try some light effects, the lid can be very colourful then.
btw, most lids I removed I used a extremely hard needle and a small hammer. Makes also good results (one little scratch instead of all the solder risk)
br, Michael |
Thanks, Michael. I'll have to try your lid removal method.
About the lighting, I'm having thoughts about creating tiny, high-intensity illuminators using high-output white LEDs. They'd be like little desk lamps with flexible necks and with bases created using PVC pipe end caps filled with lead shot and epoxy for weight. I'm now trying to think of a clever way to allow the temporary attachment of color filters in front of the LEDs. Any ideas?
Using my inexpensive Fuji S5100/5500 4MP camera and a cheap (but glass and optically coated, not plastic) $14 set of closeup lenses I just received via mail, I've managed to finally take an almost decent closeup of the MC6800L die. Focus still isn't perfect and there are chromatic aberations due to the closeup lens, but it's far better than what I had. I have to use auto-focus since the camera's LCD screen and electronic viewfinder don't have adequate resolution to allow the determination of perfect focus when focusing manually on an object with such incredibly fine features (like the die to package leads). However, the autofocus is still doing very well in its difficult task. I've attached here a reduced-size copy of the image.
As always, any inputs on anything related to photographing ICs and IC dies will be greatly appreciated. |
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CPUShack
Joined: 16 Jun 2003
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Location: State of Jefferson, USA
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William Blair
Joined: 06 Nov 2005
Posts: 68
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| Posted: Sun Nov 13, 2005 2:15 pm Post subject: |
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If anyone has CPUs with removable die compartment lids that they'd like to donate to me to photograph for them, please send me a PM. I'd be willing to pay the postage to get them to me. I'm after stuff that isn't otherwise a prime item for collectors due to badly bent or missing pins, badly scratched or cracked ceramic cases, etc. As long as the die compartment is in good shape, it'll be fine for our purposes.
I plan to come up with a homebrew closeup lens setup (found on the web) to get even better at this until I upgrade my camera next year (THE year for buying a digital SLR because of all of the new players coming into the digital SLR market in 2006). I'd be re-photography everything then with the newer and better equipment.
Thanks,
Bill Blair
Colorado, USA |
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