The first contact was through a conference. A skype call was initially scheduled before the application, which lasted about 1 hr and was with 3 persons. Then, I applied for the job position and the response was immediate (after 1 week) and before the closing date. I was invited to their site in Livermore (all expenses covered). The interview was scheduled about a month after their positive response to my application. All the travelling (from Europe) procedure was smooth and well planned. I was really very satisfied.
The interview lasted 1 whole day. Be prepared, because even though it was a very pleasant experience (I would do it again), you will get tired (especially considering the long journey that you may have made 1-2 days ago, if you do not live in the surroundings). It was started at 9 am and ended at 6 pm with a lunch break approximately 1.5 hr, when I went out with other postdoc researchers, in order to inform me how the living in Livermore and the working at Sandia is. The whole experience ended with a dinner with the employer and other team colleagues.
The process involved a 45 min presentation of my phd and my research activities. All team members were attending (for me there were more than 10 people watching) and questions follow. The questions are about your work. Then, I had almost 10 interviews (1:1 person) with all team members. Each interview lasted almost half an hour (there was a detailed program for the entire day given to me upon my arrival in Sandia). In the 1:1 interviews, they first introduced themselves and then a discussion was made mainly regarding my work experience and scientific skills. Only, one person asked more HR questions, e.g. how do you manage deadlines, if I have worked in teams, etc.
They had also arrange a site tour (including visiting their experimental facility) .
Finally, before the interviews and the presentation, I also met with a HR person, who gave me general information in a very friendly manner. In general, all were really friendly and kind and gave me the impression of a healthy working environment.
After a month after my return, I had the positive response for the hiring. However, some months later and before the official offer from the HR, I was informed that the position was unfortunately cancelled (funding issues) and not filled at this time.