[HN Gopher] "Space age electronics": Inside a GE thin-film paper...
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       "Space age electronics": Inside a GE thin-film paperweight from the
       1960s
        
       Author : parsecs
       Score  : 58 points
       Date   : 2021-07-02 19:37 UTC (3 hours ago)
        
 (HTM) web link (www.righto.com)
 (TXT) w3m dump (www.righto.com)
        
       | jtchang wrote:
       | Why gold wires instead of copper?
        
         | syntaxing wrote:
         | A lot of high performance chips like hybrids (the chip, not
         | cars) are gold bonded. Mainly because its a good conductor and
         | super inert (metal behave funny in contact in space, oxygen is
         | earth's "memory" after all).
        
           | AnimalMuppet wrote:
           | > oxygen is earth's "memory" after all
           | 
           | Could you explain what you mean by this?
        
             | LaMarseillaise wrote:
             | They may be referring to 'cold welding'. Oxygen lets metals
             | 'remember' what they are connected to. References:
             | 
             | - https://en.wikipedia.org/wiki/Cold_welding
             | 
             | - https://youtube.com/watch?v=Y2nQ8isf55s
        
           | canadianfella wrote:
           | > metal behave funny
           | 
           | *behaves
        
         | [deleted]
        
         | kens wrote:
         | Gold wires were used for bonding in integrated circuits too. I
         | think because gold is much more ductile, so you can make thin
         | wires that won't break. It's also more resistant to corrosion,
         | which is a problem with copper wire.
        
           | pfdietz wrote:
           | Doesn't copper interact badly with silicon?
        
             | kens wrote:
             | I don't know about copper-silicon interactions, but
             | normally you'd bond to a metal pad, not to silicon
             | directly. For a while, the "purple plague" was a problem
             | when gold bond wires reacted badly with aluminum bond pads,
             | forming a purple compound. https://en.wikipedia.org/wiki/Go
             | ld%E2%80%93aluminium_interme...
        
           | jacquesm wrote:
           | The fact that it is more ductile probably also helps with the
           | welding process.
        
       | kens wrote:
       | Author here if anyone has questions...
        
         | mustacheemperor wrote:
         | Thanks for the great write up!
         | 
         | Any chance this thing still works? I imagine it may require
         | some modification either way because of the oldschool battery.
        
           | kens wrote:
           | The paperweight worked after I fixed a broken wire and
           | powered it from a power supply, and it generated the beeping
           | sound. However, after I re-assembled it, it switched to an
           | annoying fast-beep. I don't know if a component failed or I
           | messed something up during assembly.
           | 
           | You can hear the beeping here:
           | https://twitter.com/kenshirriff/status/1411032440534028289
        
         | betamaxthetape wrote:
         | A great "tear down" of a really interesting device. I'd be
         | curious how you ended up with this?
         | 
         | I'm sceptical that the satellite is Ariel 1 or Ariel 2 for two
         | reasons: (a) Ariel was the British satellite programme, and I
         | think that General Electric would have based the design on an
         | American satellite. (b) Ariel 2 was build by Westinghouse, a
         | rival to GE. My guess would be that it's a generic design, but
         | I would love to hear an update if you find out for sure.
         | 
         | (I'm interested in the Ariel satellites, particularly Ariel 3,
         | since I've ended up with a few of the original Ariel 3
         | telemetry tapes from the STADAN tracking stations. Still trying
         | to work out a viable way to read / understand them...)
        
           | kens wrote:
           | The paperweight was loaned to me for analysis.
           | 
           | It's pretty cool that you have Ariel 3 telemetry tapes. I
           | agree that the satellite in the paperweight isn't Ariel, but
           | Ariel was the most similar satellite I could find. I'm hoping
           | someone will find a satellite that is a better match. But it
           | could be some obscure proposed satellite that was never
           | built.
        
           | jacquesm wrote:
           | What kind of physical format do those tapes have?
        
         | Cerium wrote:
         | I love that it is a literal paperweight and not simply a relic.
         | Thank you for the fun read.
        
         | ipsum2 wrote:
         | Could you record a clip of the sound?
        
           | kens wrote:
           | You can hear the beeping here:
           | https://twitter.com/kenshirriff/status/1411032440534028289
        
       | sensorsbroken wrote:
       | Makes you wonder what's possible in 2021 in the age of light
       | sails and uncommoditized nanoelectronics.
       | 
       | What is SOTA for 2D semiconductors (e.g. MoS2 with bismuth) in
       | production?
        
       | jacquesm wrote:
       | Impressive how little that battery leaked over all those years.
       | And funny how the transistors have an extra wire coming out of
       | them, but those are all paired and run to the same terminal, I
       | wonder what's up with that.
       | 
       | The beeper is one of those crystal (piezo) earphones with part of
       | the bit that you would stick in your ear cut off.
        
         | kens wrote:
         | The two wires are probably for reliability and/or current
         | capacity.
        
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       (page generated 2021-07-02 23:00 UTC)