| 摘要 |
A multi-layer circuit board having a decreased number of circuit boards for mounting an electronic part that has connection electrodes arranged in the form of an area array, featuring a high yield and improved reliability. In the multi-layer circuit board, circuit patterns formed on a first circuit board on the surface of the side where said electronic part is mounted, are connected to every land positioned on the outermost side of the lands arranged in the form of an area array, and are connected to the lands alternatingly selected from the lands of the second sequence and the third sequence of the inner side; circuit patterns formed on a second circuit board are connected to every via electrically connected to the lands of the second sequence to which the circuit pattern is not connected on the first circuit board, and to the vias electrically connected to all of the lands of the fourth sequence and the fifth sequence on the first circuit board; circuit patterns formed on a third circuit board are connected to every via electrically connected to the lands of the third sequence to which the circuit pattern is not connected on the first circuit board, and to the vias electrically connected to all of the lands of the sixth sequence and the seventh sequence on the first circuit board; and circuit patterns formed on a fourth circuit board are connected to every via electrically connected to the lands of the eighth sequence and the ninth sequence on the first circuit board.
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