Tim May was very well-known in the 1979-era for his discovery that alpha
particles (helium nuclei) caused data-read errors in then-current technology
DRAMs.
(An article from the last year or two incorrectly stated that we met; I think
that was simply a misinterpretation of the fact that I also worked for Intel
during 1980-82. But, I worked in Oregon, Aloha-3 specifically; I believe May
worked in Santa Clara. I never visited any Intel locations outside Oregon; I do
not recall that Tim May ever visited Oregon.)
One of the very minor things I did while working at Intel involved Kapton
(polyimide) 'shims' that were being experimented with to protect against such
errors caused by alpha particles. A rectangular sheet of very thin plastic was
attached over the DRAM chip. Due to the very-low penetration characteristic of
alphas, this was plenty to stop them from striking the surface of the chip. As
part of the development and evaluation process, it was occasionally necessary
to remove those shims from assembled devices. Peeling them off frequently
destroyed the chip: I used a tiny part of my Chemistry knowledge to recommend
the use of the solvent, DMF (dimethyl formamide) to assist in this removal
process, in a way which did not risk damage to the chip itself.
The reason Intel had the problem of alpha particles was its heavy use of
"cerdip" packages. http://eesemi.com/cerdip.htm (short for "ceramic dual
inline package") Cerdip looks vaguely like an Oreo cookie, with two ceramic
plates attached with a glass 'glue'. That ceramic had tiny amounts of
radioactive elements in it; not a lot, but it didn't take much to produce a
significant amount of alphas. Cerdip was used because it achieved a hermetic
seal, but it was cheaper than a different kind of ceramic packaging.
http://www.globalchipmaterials.com/visitors/products_visitors.htm
Had they packaged their DRAMs in plastic, that would have been a vast
improvement, actually virtually eliminating the problem: Production of
plastics go through chemical processes where their components (monomers) are
distilled, and so they contain virtually no radioactive atoms. But they
couldn't immediately shift to using plastic packaging, because such packages
were not hermetically sealed: Packaged in plastic, water from the environment
eventually found its way to the chip itself. The problem with that is that
this water slowly reacted with one component of the glass,
phosphorus-containing 'pyroglass'. (a related material was 'pyrox') These
phosphorus glasses slowly reacted with that moisture to generate phosphoric
acid, and in turn that slowly corroded the very thin aluminum conductors making
up interconnects in that chip.
Fixing the problem caused by alpha particles eventually required changing the
chip process so that it didn't require hermetic packaging, making plastic
packaging workable.
Jim Bell
On Saturday, December 15, 2018, 10:44:21 AM PST, John Young
<[email protected]> wrote:
This confirms Tim May's passing, by long-time cpunk, Lucky Green
Dear Friends, It is with sadness that news reaches me of the passing
of my dear friend Tim May - Cypherpunks co-Founder, Discoverer of
Radiation-Induced Single Even Upsets in Integrated Circuits, and
Uncompromising Firearms Proponent: Tweet:
https://twitter.com/luckygreen/status/1073925779304693760 Obit:
https://www.facebook.com/lucky.green.73/posts/10155498914786706 Ad
Astra, Tim! --Lucky
