binder clip vs clipboard

binder clip

noun
  • A simple device for binding a few to many sheets of paper, leaving the sheets intact; a strip of spring steel bent into the shape of an isosceles triangle with loops at the apex. 

clipboard

noun
  • A flat piece of rigid material, such as card or plastic, with a clip at one end under which papers can be held. 

  • A buffer in memory where the user can store data temporarily while transferring it from one place within an application to another or between applications. 

How often have the words binder clip and clipboard occurred in a corpus of books? (source: Google Ngram Viewer )