Training for part of words (well ... abbreviations)?

I have certain things I want to filter on (abbreviations), those are part of other words.
eg if I filter say DA I think it will filter out all subjects that have that in it so say “Davinci new version released” but I want those I just don’t was the “DA” by itself (eg “The DA gets a new start time”). If there some sort of regex I should use or a way to do this better?
I had it set to filter the short abbreviation but if I recall I was missing a lot.