More than likely, the small ants at your place are odorous house ants, Tapinoma sessile. They are very common in the northwest and, when they periodically invade homes, even those which are as free of crumbs as is possible, the ants drive the residents nuts with their persistence.
They will take baits, but you must be persistent in your efforts. Keep fresh bait available until they stop coming, perhaps 3 weeks or so. (Sometimes they'll leave within days, other times not.)
If (actually, when) they return, put out more fresh bait.
The most useful baits contain borates (e.g Terro, a liquid) or indoxacarb, the latter often available as a gel.
Be certain to protect the baits from children and/or inquisitive pets.
Unfortunately, you cannot get rid of them permanently. The key to success is to learn to live in spite of them. Always have effective baits on hand to set out at a moment's notice.