A method and apparatus are provided for mounting circuit elements on a printed wiring board, wherein an integrated circuit having terminals with a first interterminal pitch are mounted onto a first surface of a terminal density. conversion board which converts the first interterminal pitch of the integrated circuit to terminals with a second interterminal pitch larger than the first interterminal pitch on a second surface of the terminal density conversion board; and the terminals on the second surface of the terminal density conversion board with the second interterminal pitch are mounted onto the printed wiring board.