Connor Scott scored a game and career high 24 points for the Warriors and Brandan Gartland added 14.
Schroeder led by seven at the half and built the lead to 41-25 late in the third quarter. A 10-1 Aquinas run in the fourth quarter got the Lil' Irish within seven, but Schroeder began a parade to the free throw line that closed the game out.
Melvin Grayson led Aquinas with 16 points.
Schroeder will face top-seeded Athena in Wednesday's semifinals at Blue Cross Arena. Athena fought off (8)Kearney 71-62 Saturday afternoon.
The game is the last of three at the Big House. It's slated for an 8:45pm tip, but will likely begin later.