Pad redistribution chip for compactness, method of manufacturing the same, and stacked package using the same
View Patent ↗A substrate includes a substrate; a number of pad redistribution chips stacked on the substrate and on one another after being rotated 90° in a predetermined direction relative to one another, the pad redistribution chips having a number of center pads positioned at the center thereof, a number of (+) edge pads positioned on an end thereof while corresponding to those of the center pads lying in (+) direction from a middle center pad located in the middle of the center pads, a number of (−) edge pads positioned on the other end thereof while corresponding to those of the center pads lying in (−) direction with symmetry to those of the center pads lying in the (+) direction, and a number of traces for electrically connecting the center pads to the corresponding (±) edge pads, respectively; a flexible PCB for electrically connecting the substrate to the pad redistribution chips; and an anisotropic dielectric film for electrically connecting the pad redistribution chips to the flexible PCB and the substrate to the flexible PCB.
1. A pad redistribution chip comprising:
a wafer, wherein a middle vertical line is referred to a line located substantially in the middle of the wafer, wherein a (+) direction is referred to as the direction perpendicular to and on the left side of the middle vertical line, wherein a (−) direction is referred to as the direction perpendicular to and on the right side of the middle vertical line, wherein four quadrants are present in the wafer such that two quadrants are present in each of the left (+) and right (−) side of the middle vertical line and such that all four quadrants meet at a middle point of the wafer;
wherein edge pads for connecting the pad redistribution chip to a substrate are formed in each of the left (+) and right (−) side of the middle vertical line, and the edge pads are formed in only one quadrant of each of the left (+) side and the right (−) side:
at least one row of center pads formed on the wafer substantially along the middle vertical line;
a row of (+) edge pads of the edge pads formed in a first quadrant of the four quadrants in the left (+) direction;
a row of (−) edge pads of the edge pads formed in a second quadrant of the four quadrants that is disposed at a diagonal from the first quadrant in the right (−) direction, such that the row of (−) edge pads and the row of (+) edge pads are diagonally symmetrical with respect to the middle point of the wafer and such that two diagonal quadrants of the four quadrants without edge pads for connecting the pad redistribution chip to the substrate exist; and
a number of traces in each of the first and second quadrants for electrically connecting each of the center pads to the corresponding one of the edge pads in the row of (+) edge pads and the row of (−) edge pads.
2. The stacked package according to claim 1 , further comprising dummy bumps positioned on each of four corners of the wafer.