Microchips in brightfield incident light

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MicroBob · #1 Post by **MicroBob** » Sat Feb 01, 2020 9:54 am

Hi together,
a guy from the german forum cooked a lot of microchips and sold a couple for a very reasonable price.
I just-in-time received an ebay parcel with a wild mix of components and it included two "Monokel" objective holders and the H-Pl and D reflectors for my incident light condenser for the old Phomi. I have a set of nice new HD objectives that I now can start to use after a year of hunting after these reflectors. Dark field is nice for many objects but fot the chips bright field give a nicer image. The colours are interference colours resulting from the thin silicon layers on the chip. Images taken with the 40:1 0,85 objective.
A word of warning: It is easy to destroy these objectives when crashing into protruding parts of the object - much easier than on orginary slides with the cover slip as a definitive upper surface!

If you are interested in observing chips on your own: These chips were cleaned in 30 cm³ of concentrated H2SO4, in a narrow mouth Erlenmeyer flask with the mouth blocked with wet paper and then heated (don't know how high and long). At the end cooled and emptied into a bucket full of water (Never the other way round!!!). I don't recommend this for home use and for people who are not trained in the use of dangerous chemicals!!!
What works too: Simly heat the chips with a propane torch or Creme brulée torch. The plastic housing burns of with a lot of harmfully smelling vapours and che chips are left together with some residues.

General rule: The older the chip, the more likely it is that you can actually see the structures. You can try things like telephone card chips too.

Here an image of an FTDI USB cotroller chip.

Bob

PeteM · #2 Post by **PeteM** » Sat Feb 01, 2020 6:22 pm

Image seems missing, Bob?

MicroBob · #3 Post by **MicroBob** » Sat Feb 01, 2020 8:21 pm

Hi Pete,
thank you, I have added it now!

Bob

PeteM · #4 Post by **PeteM** » Sat Feb 01, 2020 10:04 pm

That's pretty cool, Bob - thanks.

FWIW for others interested in showing this minus Bob's methods of H2SO4 or torch persuasion, entire 6" wafers with a hundred or more circuits ready to be cut out, leads then soldered in place, and ready for encapsulation are sometimes available. The 6" wafers are of an early enough generation that different detail is visible all the way from 10x to higher powers.

The old UV programmable chips (with a window covered over on top) are another source.

Today's circuits, thanks to Moore's "Law" are now so small that optical microscopy is no longer suitable for quality control.

If anyone has a source of things like cell phone accelerometer chips for viewing - sure hope you'll let me know.

MicroBob · #5 Post by **MicroBob** » Sun Feb 02, 2020 1:00 am

Hi Pete,
thank you for the additional subject recommendations!
Another interesting subject are MEMS microphones: https://www.mikroskopie-forum.de/index. ... ic=35527.0
Before reading this thread I didn't even know they exist.

Bob

PeteM · #6 Post by **PeteM** » Sun Feb 02, 2020 5:21 am

Thanks for the MEMS microphone heads up, Bob. I suspect a micro tour of modern cell phone innards could be dazzling.

jb89 · #7 Post by **jb89** » Sun Feb 02, 2020 6:27 am

That's awesome!

I've been thinking of grabbing some old silicon wafer dies to look at, they normally come in sets of 50 or 100 for less than $20, if I end up grabbing some I'd offer them to the forum members for the cost of postage.

These are a few I was looking at:
https://www.ebay.com/itm/49pcs-Toshiba- ... Sw5MBc1Iro

https://www.ebay.com/itm/100pcs-Sitroni ... SwNcRdtFQj

https://www.ebay.com/itm/250pcs-Mosel-V ... oBLWxVAMBg

PeteM · #8 Post by **PeteM** » Sun Feb 02, 2020 6:58 am

I'd imagine these would look spectacular with reflected illumination, jb89. Give kids (of all ages) something to think about.

mintakax · #9 Post by **mintakax** » Mon Feb 03, 2020 5:48 pm

Fascinating !

MicroBob · #10 Post by **MicroBob** » Mon Feb 03, 2020 7:56 pm

Hi together,
one more image taken with the Phomi and a couple taken with an ROW student model incident light microscope with polarized bright field. The difference in image quality is astonishingly big.

Bob

MicroBob · #11 Post by **MicroBob** » Mon Feb 03, 2020 7:58 pm

The VALVO chip with the Hamburg flag has been made in walking distance from were I live. A friend actually made his apprenticeship as a machinist there.