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Ken Shirriff

Silicon-on-sapphire got its start in 1963. Instead of starting with a silicon wafer, silicon circuits are built on top of a synthetic sapphire base. The sapphire provides insulation between the transistors, improving performance and making the chip resistant to radiation. 2/9

6 comments
Ken Shirriff

HP made a lot of silicon-on-sapphire chips: processors, calculators, and this PHI interface chip. First was the MCΒ² 16-bit processor. This cover photo from HP Journal shows the transparency of that chip. 3/9

Ken Shirriff

The package is unusual: the die is mounted on a flat ceramic substrate with a ceramic cap glued on. We heated the package to soften the glue. twitter.com/TubeTimeUS poked the cap with an X-Acto knife, but instead of sliding off, the cap violently flew off with a loud "pow"! 4/9

Alexey Merz

@kenshirriff So the interface was under mechanical strain?

πŸ‡ΊπŸ‡¦ haxadecimal

@kenshirriff Motorola experimented with that package design in the late 1980s, e.g. with their DSP56001, and called it the "SLAM" package. Maybe their's more than one reason for that name.
:-)

photos of Motorola chip and a socket:
flickr.com/gp/_brouhaha_/r2459

Sebastiaan Dammann

@kenshirriff Is the defect in the chip visible through the die shot?

Infinity

@kenshirriff You can also find Tube Time on Mastodon at @tubetime πŸ˜ƒ.

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