Device package, a printed wiring board, and an electronic apparatus with efficiently spaced bottom electrodes including intervals between bottom electrodes of different lengths
A device package, such as a BGA, to be mounted on a printed wiring board (PWB) is disclosed. The bottom electrodes of the device package are arranged in an array such that intervals between the edges of the bottom electrodes become different from place to place. The intervals may be set wider at the peripheral positions of the bottom electrodes. The PWB includes pads that are located at positions corresponding to the bottom electrodes.
1. A device package to be mounted on the surface of a printed wiring board, comprising:
a plurality of bottom electrodes arranged in a first row, which is an outermost row of the package, and a second row parallel and adjacent to the first row and, sizes of which bottom electrodes are different from place to place such that intervals between edges of the bottom electrodes in a section of the first row progressively increase in length from an end of the section of the first row toward a center of the first row such that an interval between a first electrode disposed at an end of the section of the first row and a second electrode in the first row, which is a next electrode closer to the center of the first row after the first electrode, is shorter than an interval between the second electrode and a third electrode, which is a next electrode after the second electrode within the first row, wherein
the interval between the second electrode and third electrode is shorter than an interval between the third electrode and a fourth electrode, which is a next electrode after the third electrode within the first row, and
the fourth electrode is closer to the center than is the third electrode.
2. The device package as claimed in claim 1 , wherein a first second-row electrode is located in the second row and aligned with the first electrode in a direction perpendicular to the first row, and an interval between the first second-row electrode and a second second-row electrode, which is a next electrode closer to the center of the second row after the first second-row electrode, is shorter than the interval between the first electrode and the second electrode.
3. The device package as claimed in claim 2 , wherein a center of the second electrode is not aligned with a center of the second second-row electrode in the direction perpendicular to the first row.
4. The device package as claimed in claim 2 further comprising a third row parallel to the first row and including
a first third-row electrode aligned with the first electrode in a direction perpendicular to the first row, and
a second third-row electrode, which is a next electrode closer to a center of the third row after the first third-row electrode, positioned such that an interval between the first third-row electrode and the second third-row electrode is shorter than the interval between the first electrode and the second electrode.
5. The device package as claimed in claim 4 , wherein the interval between the first third-row electrode and second third-row electrode is shorter than the interval between the first second-row electrode and the second second-row electrode.