This topic will be difficult to accompany with a sufficient amount of text, because the main content falls, of course, on video. Although it looks like an advertisement, all the same, the production process of the Nokia N9’s flagship smartphone — assemblies, assembly, etc. — is shown in some detail. In general, it is better to watch.
UPD: The slash80 habrauser comment relates to my mistake, which I corrected after his comment.