I have always had this question, but couldn't really get a good answer searching about it on the Google.
Does anyone know why these old/MIL-SPEC ICs came with gold-plated (I suppose it's plated, since it'd be ridiculously expensive to use pure gold) caps? I can somewhat understand the gold pins, but gold cap doesn't make any sense to me.
Is there any specific reason to this? or is it solely for aesthetics?
(Please refer to the attached image, for some reason the forum editor image function isn't working)