[OK, this is try number 3. I don't know what's blocking my mail.] Steve Weir wrote: > Stefan, Dr. Photoelectric is a lot more concerned with photons that > dancing > molecules. Translation: I think what you're saying (in your strange way) is that opaque packages are best, so that light doesn't reach the die, where photo-electric effects would otherwise occur and disturb the electronics. (Yes, it happens, I've seen it.) My guess is that's one of the big reasons, but others like cost and mechanical considerations are there too. And then there's radiation (Alpha particles), but I think that mostly comes from the metal in the solder, leadframe, or pins. Years ago there were some white IC packages. I think they may have been ceramic, not plastic. They were opaque too, or at least reasonably so. Regards, Andy ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu