How to take die photos
In this section, I explain how I got the photos of the 8008 die.
The first step is to open the chip package to expose the die.
Most chips come in epoxy packages, which can be dissolved with dangerous acids.
The 8008 microprocessor in a ceramic package
Since I would rather avoid boiling nitric acid, I took a simpler approach. The 8008 is also available in a ceramic package (above), which I got on eBay. Tapping the chip along the seam with a chisel pops the two ceramic layers apart.
The photo below shows the lower half of the ceramic package, with the die exposed.
Most of the metal pins have been removed, but their positions in the package are visible. To the right of the die is a small square; this connects ground (Vcc) to the substrate.
A couple of the tiny bond wires are still visible, connected to the die.
Inside the package of the 8008 microprocessor, the silicon die is visible.
Once the die is exposed, a microscope can be used to take photographs.
A standard microscope shines the light from below, which doesn’t work well for die photographs.
Instead, I used a metallurgical microscope, which shines the light from above to illuminate the chip.
I took 48 photographs through the microscope and then used the Hugin stitching software to combine them into one high-resolution image.
Finally, I adjusted the image contrast to make the chip’s structures more visible. The original image (which is approximately what you see through the microscope) is below for comparison.
Die photograph of the 8008 microprocessor
