[sdiy] LEDs history and age?

[Peter Blackett]

Dear Paul, and list ,
I was looking for some other info this morning [ data on the icl7101 ic
] and found the following web page that does give some info /history
about led's 
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1883

regards Peter 
BTW I have had to replace a LDR in an electronic organ sweel pedal 
recently , it had gone low resisttance ! 

 > I have some CLM6000 that I bought from a surplus guy, old stock from
when
> they first came out.
> About 20% seemed to be 'out of spec', as though not enough output from
> the led (and I can't imagine any kind of amorphous semi going high in
> resistance with age).
> I vaguely remember reading once that early leds sometimes had
> bodies that allowed warer vapor to diffuse in slowly, with resulting
> decreasing light output.
> No idea whether this is true or not, but it seems a plausible mechanism..
> what do the semi fabrication experts here think?
 
> paul perry melb australia