Ball grid array formed on printed circuit board

1. A ball grid array, formed on a printed circuit board, comprising:

a first ballout module, comprising a plurality of first solder balls arranged as an array, wherein two among the first solder balls are grounded and remaining of the first solder balls are disposed within a shielding area defined by the two grounded first solder balls, wherein a first row of the first ballout module faces a first direction, a first column of the first ball module faces a second direction, the first direction is perpendicular to the second direction, and the two grounded first solder balls are disposed at a third row of the first ballout module; and

a second ballout module, disposed adjacent to the first ballout module and comprising a plurality of second solder balls, wherein two among the second solder balls are grounded and remaining of the second solder balls are disposed within a shielding area defined by the two grounded second solder balls;

wherein the first ballout module and the second ballout module deploy substantially a same ballout arrangement associated with relative positions of the two grounded solder balls and the remaining solder balls that are not grounded in each ballout module;

wherein the ball grid array renders at most two grounded soldier balls in every five columns of solder balls.

2. The ball grid array according to claim 1 , wherein the ballout arrangement comprises two grounded first solder balls for the first ballout module.

3. The ball grid array according to claim 1 , wherein a number of the second solder balls of the second ballout module equals a number of the first solder balls of the first ballout module, and positions of the two grounded second solder balls in the second ballout module are identical to positions of the two grounded first solder balls in the first ballout module.

4. The ball grid array according to claim 1 , further comprising:

a third ballout module, arranged next to the first ballout module, comprising a plurality of third solder balls; wherein two of the third solder balls are grounded, and remaining of the third solder balls are disposed within a shielding area defined by the two grounded third solder balls;

wherein, the third ballout module deploys the substantially same ballout arrangement as that of the first ballout module and the second ballout module.

5. The ball grid array according to claim 4 , wherein maximum numbers of the first solder balls, the second solder balls and the third solder balls are twenty respectively.

6. The ball grid array according to claim 4 , wherein quantity of the third solder balls equals quantity of the first and the second solder balls; and positions of the two grounded third solder balls in the third ballout module are identical to the positions of the two grounded first solder balls in the first ballout module, as well as the positions of the two grounded second solder balls in the second ballout module.

7. The ball grid array according to claim 1 , being applied to a double-data-rate (DDR) dynamic random access memory (DRAM).

8. A wiring method for a multi-layer printed circuit board, comprising:

providing one at least two-layer printed circuit, a plurality of signal wires and a plurality grounding wires;

disposing a first ballout module and a second ballout module on one layer of the two-layer printed circuit board;

wherein the first ballout module comprises a plurality of first solder balls arranged as an array, two of the first solder balls are grounded and remaining of the first solder balls are disposed within a shielding area defined by the two grounded first solder balls, wherein a first row of the first ballout module faces a first direction, a first column of the first ball module faces a second direction, the first direction is perpendicular to the second direction, and the two grounded first solder balls are disposed at a third row of the first ballout module;

wherein the second ballout module is adjacent to the first ballout module and comprising a plurality of second solder balls, wherein two of the second solder balls are grounded and remaining of the second solder balls are within a shielding area defined by the two grounded second solder balls;

wherein the first ballout module and the second ballout module deploy substantially a same ballout arrangement associated with relative positions of the rounded solder balls and the remaining ungrounded solder balls; and

wherein the ballout arrangement renders at most two rounded soldier balls in every five columns of solder balls; and

providing a plurality of vias on one other layer of the two-layer printed circuit board, wherein the signal wires pass through a part of the vias to connect to the solder balls of the first ballout module, the grounding wires pass through a part of the vias to connect to the two grounded solder balls of the first and second ballout modules, in a way that one side of each of the signal wires is adjacent to one of the grounding wire.

9. The ball grid array according to claim 1 , wherein said array comprises at least four rows and at least five columns.

10. The wiring method according to claim 8 , wherein said array comprises at least four rows and at least five columns.

11. The ball grid array according to claim 1 , wherein a last column of the first ballout module is adjacent to a first column of the second ballout module.

12. The wiring method according to claim 8 , wherein a last column of the first ballout module is adjacent to a first column of the second ballout module.