Whichever supervillain Iron Man was fighting in this particular issue (it may have been Midas and/or Madame Masque, but I'm not certain of that), at one point he is attacked by a whirling swarm of brightly colored disks, looking very much like polka dots. IIRC, the disks attach themselves to his armor, and begin draining energy from him. I believe the background in the story panels is all white, presumably to highlight the colored disks. Iron Man is able to thwart the devices by (again, IIRC) reversing the polarity of his armor or something like that. The disks are repulsed and possibly destroyed. In any case, ol' Shellhead lives to see another day.
This issue would have been published no later than 1980 or so, and probably in the late 1970s. That's all I can really recall here.