Tim May's Passing Confirmed

John Young jya at pipeline.com
Sat Dec 15 13:19:48 PST 2018

Excllent post, Jim, thanks.

At 02:47 PM 12/15/2018, you wrote:
>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>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 
>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 
><jya at pipeline.com> 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:
>Astra, Tim! --Lucky

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