PURPOSE: To standardize the designing technique of a chip mounted on a lozenge package found from an arbitrary rhombus inscribing a given ellipse, to reduce the number of designing processes, to reduce the cost of the title method and to enhance the productivity of the title method.

CONSTITUTION: A first table which finds the major-axis diameter and the minor- axis diameter of a rhombus 2 inscribing an ellipse 1 decided by the mounting area of a package mounted on a printed-circuit board, a second table which finds the size of a circle A 3 inscribing the rhombus 2 and a third table which finds a polygon A 5 inscribing the circle A 3 are installed in a main storage device. The rhombus 2 inscribing the ellipse 1 given by the first table is first found, the circle A 3, in a definite size, inscribing the rhombus 2 is found by the second table, a circle B 4 which is by a prescribed ratio smaller than the circle A 3 is found, a polygon A 5 inscribing the circle B 4 is found by the third table or a polygon using the circle A 3 as a circumscribed circle is found by the third table and a polygon which is by a prescribed ratio smaller than the polygon is used as a chip. In addition, an inscribed circle for the polygon is found by a fourth table.