Two third-period goals less than 35 seconds apart clinched Boston University's 5-2 win over the defending champion Wisconsin Badgers in the NCAA semifinals last night at the Providence Civic Center.

Both teams came out slowly in the first period, with the Terriers having trouble clearing the puck from their own end. Wisconsin took to forechecking and drew first blood on a power play with B.U. freshman sensation Mark Fidler in the penalty box for slashing.

The Terriers responded to tie it at one-apiece at 11:29 of the first, when Dave Silk ended a scramble in the crease by pushing it past Wisconsin's All-American goalie Julian Baretta on an assist from B.U. junior co-captain Jack O'Callahan.

The locals jumped to a 2-1 lead at 7:31 of the second when winger John Bethel took a pass from Silk and O'Callahan and skated down the center to slip it behind Baretta. Tony Meagher added another at 8:47 of the second on a pass from center Marc Hetnik, to give B.U. a 3-1 edge.

Frequent whistles broke up the action in the second half of the period, as referees assessed four penalties to each side. With Theran Welsh serving two minutes for holding, Wisconsin narrowed the Terrier lead to one, on a short-handed goal by Les Grauer at 12:31.

The officials dished out severalmatching minors to calm things down as play got a little sloppy and tempers flared in the last part of the second, and the third started the same way, when Terrier Bill Cotter and Badger Tom Ulseth drew off-setting sentences.

B.U. then fired up to put the game out of reach for the Western College Hockey Association champs. Leading scorer Fidler drilled a low slapper past Baretta on a power play at 6:15 of the third period, and Silk chipped one past the netminder from right on the goal line a mere 35 seconds later.

The Terriers, who defeated Providence in a playoff last Sunday to earn their NCAA berth, will face the winner of tonight's B.C.-Bowling Green match on Saturday.