Rabbi Shimon Eider's book, Student Edition of Halachos of Tefillin, dates to 1985. In it (section Ⅲ D 7), he writes:
Some Poskim hold that one should sit while putting on the Shel Yad and stand while putting on the Shel Rosh; this is the minhag of Sefardim. Other Poskim hold that one should stand while putting on both the Shel Yad and Shel Rosh; this is the minhag of Ashkenazim.
The claim that Sephardic Jews customarily sit, and Ashkenazic Jews customarily stand, while donning the hand-t'filin accords also with what I have always understood to be the case (for what it's worth). There's a little more information on this practice elsewhere on Mi Yodeya.
However, in the past year or so, I have seen three or four Sephardic Jews in Ashkenazic synagogues donning the hand-t'filin while standing. While it's certainly possible that they are ignorant of the common practice or have decided on their own to ignore it in an Ashkenazic synagogue in order to act like those around them (an idea with halachic basis in some contexts), I wonder whether there is more to it than that. Specifically:
Are there any Sephardic communities that have always had the custom of standing to don hand-t'filin? Which?