The ornamental design for a boardframe, as shown and described.
FIG. 1 is an isometric view of a board frame holding a board showing our new design.
FIG. 2 is a back perspective view of the board frame holding the board.
FIG. 3 is an isometric view of the board frame.
FIG. 4 is a back perspective view thereof.
FIG. 5 is a front view thereof.
FIG. 6 is a back view thereof.
FIG. 7 is a side view thereof.
FIG. 8 is a top view thereof; and,
FIG. 9 is a bottom view thereof.
The broken lines shown in the Figures are directed to environment forming no part of the claimed design. The shade lines in the Figures show contour and do not claim surface ornamentation or treatment.