Connor Tava chipped in 13 points, eight rebounds and five assists for the Broncos, who shot an efficient 58.9 percent from the field and were 10 of 16 on 3-pointers.
Richie was 10 of 11 overall and went a perfect 5 of 5 from the perimeter. Brown was 8 for 10 and hit four from deep.
Western Michigan opened the game with a 16-2 run sparked by two 3-pointers from Brown. Aquinas pulled within five midway but the Broncos countered, closing the first half with a 26-9 surge. They led 48-26 at half and coasted in the final 20 minutes.
Aquinas was held to 19-of-55 shooting (34.5 percent) and got out-rebounded 41-21. Anthony Williams led the Saints with 17 points and Jake Bullock added 11.