I spoke to 3M at my school's career fair and was contacted close to two months later for an interview. I don't believe that is the standard time frame, I got the impression that they were somewhat disorganized this year. The man interviewing me was nice and somewhat casual compared to other interviews I have had; he stated in the email to dress business casual and that it was not necessary to wear a suit.

Behavioral interview with regular questions. Good to know technical specifications of role. Two people on call, one recruiter, one person on the team for which they are hiring. Overall great experience