It's two one-hour interviews back to back. You stay in one room and the 2 interviewers switch (4 engineers total). They are assigned technical and behavioral questions to ask you from a packet. It will be major specific: mechanical, chemistry, materials science, electrical, etc. Admit if you don't know a technical question and they will walk you through it. They alternate between technical and behavioral. Answer the behavioral questions well, that's how you get the job. You need to tell a story and set the scene about an experience you had. Be honest. Show them your personality. They ask you a statistical analysis problem in one session and troubleshooting system problem in the other. They want to see how you problem solve and think.