IEEE’s database, called IEEE Xplore, covers electrical and computer engineering, nanotechnology, bioengineering, robotics, and more, with the full text of articles, conferences, and standards from 1988 to the present.
If you search for IEEE items through IEEE Xplore, that’s fine. If you use Compendex, which is a very broad engineering database with citations to much of IEEE’s materials, that’s fine, too.
However, if you hope to find IEEE material through Google Scholar or even Google, you might not get the results you deserve.
What happened? IEEE has told subscribers that Google eliminated IEEE’s article records and decided to completely rebuild IEEE’s index of over 2.5 million records. (No, Google didn’t say why.)
So if you’re searching for engineering information, consider using Compendex (which has 9 million records) or IEEE Xplore, rather than any of the Googles, at least until this problem is fixed.