Ball-out for differential signals

• US 9,089,060 B1
• Filed: 10/18/2011
• Issued: 07/21/2015
• Est. Priority Date: 10/19/2010
• Status: Active Grant

• Current Assignee: Marvell Israel Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell Israel Limited (Marvell Technology Group Limited)
• Inventors: Azeroual, Dan, Ben Artsi, Liav
• Primary Examiner(s): Semenenko, Yuriy
• Application Number:
  US13/275,588
• Time in Patent Office: 1,372 Days
• Field of Search: 174/250, 174/255, 174/260, 361/790, 361/803, 361/767, 361/768, 361/783, 297/40, 297/39, 297/41, 438/108, 257/692, 257/698, 257/690
• US Class Current: 1/1
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 23/50 for integrated circuit devices, e.g. power bus, number of leadsH01L23/482 - H01L23/498 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 1/0245 Lay-out of balanced signal pairs, e.g. differential lines or twisted lines
• CPC Class Codes: H05K 1/0298 Multilayer circuits
• CPC Class Codes: H05K 1/112 directly combined with via connections
• CPC Class Codes: H05K 1/114 Pad being close to via, but not surrounding the via
• CPC Class Codes: H05K 2201/09227 Layout details of a plurality of traces, e.g. escape layout for Ball Grid Array [BGA] mounting
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array

Abstract

Aspects of the disclosure provide a ball grid array (BGA) package. The ball grid array (BGA) package includes an integrated circuit (IC) packaged in the BGA package, first solder ball, a second solder ball and a third solder ball to transmit a first signal, a second signal, and a third signal. The first signal and the second signal are a pair of differential signals. The third solder ball has a substantially equal distance from the first solder ball and the second solder ball, and thus the first solder ball and the second solder ball are in symmetry with regard to the third solder ball.

Claims

1. A ball grid array (BGA) package, comprising:

an integrated circuit (IC) packaged in the BGA package configured to process a first signal, a second signal, a third signal, and a fourth signal, the first signal and the second signal being a first pair of differential signals and the third signal and the fourth signal being a second pair of differential signals;

a first solder ball configured to conduct the first signal disposed on a surface of the BGA package;

a second solder ball configured to conduct the second signal disposed on the surface of the BGA package;

a third solder ball configured to conduct the third signal disposed on the surface of the BGA package;

a fourth solder ball configured to conduct the fourth signal disposed on the surface of the BGA package, wherein the third solder ball has a first equal distance from the first solder ball and the second solder ball, the fourth solder ball has a second equal distance from the first solder ball and the second solder ball, and the first solder ball and the second solder ball are in symmetry with regard to the third solder ball; and

a plurality of grounded solder balls coupled to the IC for ground connections including a first grounded solder ball, a second grounded solder ball, a third grounded solder ball, and a fourth grounded solder ball, wherein the first grounded solder ball is disposed adjacent to the first solder ball, the second grounded solder ball is disposed adjacent to the second solder ball, the third grounded solder ball is disposed adjacent to the third solder ball, the fourth grounded solder ball is disposed adjacent to the third solder ball, the first and the third grounded solder balls are disposed on a line that intersects the first and the third solder balls, and the second and the fourth grounded solder balls are disposed on a line that intersects the second and the third solder balls.

2. The BGA package of claim 1, wherein the IC comprises a serializer/deserializer (SERDES) that is electrically coupled to the first solder ball and the second solder ball configured to transmit the first pair of differential signals or receives the first pair of differential signals.

3. The BGA package of claim 1, wherein the first equal distance is equal to the second equal distance.

4. The BGA package of claim 3, wherein the first equal distance and the second equal distance are smaller than a distance between the first solder ball and the second solder ball.

5. The BGA package of claim 4, wherein the IC comprises:

a first serializer/deserializer (SERDES) that is electrically coupled to the first solder ball and the second solder ball configured to transmit the first pair of differential signals or receives the first pair of differential signals; and

a second serializer/deserializer (SERDES) that is electrically coupled to the third solder ball and the fourth solder ball configured to transmit the second pair of differential signals or receives the second pair of differential signals.

6. The BGA package of claim 1, wherein

the plurality of grounded solder balls are configured to collectively cause an equal electro-magnetic coupling field to the first solder ball and the second solder ball.

7. The BGA package of claim 1, wherein the plurality of grounded solder balls further includes a fifth grounded solder ball, a sixth grounded solder ball, a seventh grounded solder ball, and an eighth grounded solder ball, the fifth grounded solder ball is disposed adjacent to the fourth solder ball, the sixth grounded solder ball is disposed adjacent to the fourth solder ball, the seventh grounded solder ball is disposed adjacent to the second solder ball, the eighth grounded solder ball is disposed adjacent to the first solder ball, the fifth and the seventh grounded solder balls are disposed on a line that intersects the second and the fourth solder balls, and the sixth and the eighth grounded solder balls are disposed on a line that intersects the first and the fourth solder balls.

8. A method, comprising:

forming a first solder ball for transmitting a first signal on a surface of a ball grid array (BGA) package;

forming a second solder ball for transmitting a second signal on the surface of the BGA package;

forming a third solder ball for transmitting a third signal on the surface of the BGA package;

forming a fourth solder ball for transmitting a fourth signal on the surface of the BGA package, wherein the first signal and the second signal are a first pair of differential signals, the third signal and the fourth signal are a second pair of differential signals, the third solder ball has a first equal distance to the first solder ball and the second solder ball, the fourth solder ball has a second equal distance to the first solder ball and the second solder ball, and the first solder ball and the second solder ball are in symmetry with regard to the third solder ball; and

forming a plurality of grounded solder balls on the surface of the BGA package including a first grounded solder ball, a second grounded solder ball, a third grounded solder ball, and a fourth grounded solder ball, wherein the first grounded solder ball is disposed adjacent to the first solder ball, the second grounded solder ball is disposed adjacent to the second solder ball, the third grounded solder ball is disposed adjacent to the third solder ball, the fourth grounded solder ball is disposed adjacent to the third solder ball, the first and the third grounded solder balls are disposed on a line that intersects the first and the third solder balls, and the second and the fourth grounded solder balls are disposed on a line that intersects the second and the third solder balls.

9. The method of claim 8, wherein the first equal distance is equal to the second equal distance.

10. The method of claim 9, wherein the first equal distance and the second equal distance are smaller than a distance between the first solder ball and the second solder ball.

11. A method, comprising:

forming a first conductive unit on a PCB to transmit a first signal, the first conductive unit including a first land that matches a first solder ball on a surface of a ball grid array (BGA) package, and a first via electrically connected to the first land;

forming a second conductive unit on the PCB to transmit a second signal, the second conductive unit including a second land that matches a second solder ball on the surface of BGA package, and a second via electrically connected to the second land;

forming a third conductive unit on the PCB to transmit a third signal, the third conductive unit including a third land that matches a third solder ball on the surface of the BGA package, and a third via electrically connected to the third land;

forming a fourth conductive unit on the PCB to transmit a fourth signal, the fourth conductive unit including a fourth land that matches a fourth solder ball on the surface of the BGA package, and a fourth via electrically connected to the fourth land, wherein the first signal and the second signal are a pair of differential signals, the third signal and the fourth signal being a second pair of differential signals, the third via has a first equal distance to the first via and the second via, the fourth via has a second equal distance to the first via and the second via, thus the first via and the second via are in symmetry with regard to the third via; and

forming a plurality of grounded conductive units including a first grounded conductive unit including a first grounded land that matches a first grounded solder ball on the surface of the BGA package and a first grounded via electrically connected to the first grounded land, a second grounded conductive unit including a second grounded land that matches a second grounded solder ball on the surface of the BGA package and a second grounded via electrically connected to the second grounded land, a third grounded conductive unit including a third grounded land that matches a third grounded solder ball on the surface of the BGA package and a third grounded via electrically connected to the third grounded land, and a fourth grounded conductive unit including a fourth grounded land that matches a fourth grounded solder ball on the surface of the BGA package and a fourth grounded via electrically connected to the fourth grounded land, wherein the first grounded via is disposed adjacent to the first via, the second grounded via is disposed adjacent to the second via, the third grounded via is disposed adjacent to the third via, the fourth grounded via is disposed adjacent to the third via, the first and the third grounded vias are disposed on a line that intersects the first and the third vias, and the second and the fourth grounded vias are disposed on a line that intersects the second and the third vias.

12. The method of claim 11, wherein the first via and the second via in are symmetry with regard to the third via and the fourth via, and the third via and the fourth via are in symmetry with regard to the first via and the second via.

13. The method of claim 11, further comprising:

assembling the BGA package on the PCB.

14. A printed circuit board (PCB), comprising:

a first conductive unit configured to make electrical connection with a first solder ball of a ball grid array (BGA) package to conduct a first signal, the first conductive unit including a first land and a first via on the PCB;

a second conductive unit configured to make electrical connection with a second solder ball of the BGA package to conduct a second signal, the second conductive unit including a second land and a second via on the PCB, the first signal and the second signal being a first pair of differential signals;

a third conductive unit configured to make electrical connection with a third solder ball of the BGA package to conduct a third signal, the third conductive unit including a third land and a third via on the PCB;

a fourth conductive unit configured to make electrical connection with a fourth solder ball of the BGA package to conduct a fourth signal, the fourth conductive unit including a fourth land and a fourth via on the PCB, the third signal and the fourth signal being a second pair of differential signals, wherein the third via has a first equal distance from the first via and the second via, the fourth via has a second equal distance to the first via and the second via, thus the first via and the second via are in symmetry with regard to the third via; and

a plurality of grounded conductive units including a first grounded conductive unit configured to make electrical connection with a first grounded solder ball of the BGA package and including a first grounded land and a first grounded via on the PCB, a second grounded conductive unit configured to make electrical connection with a second grounded solder ball of the BGA package and including a second grounded land and a second grounded via on the PCB, a third grounded conductive unit configured to make electrical connection with a third grounded solder ball of the BGA package and including a third grounded land and a third grounded via on the PCB, and a fourth grounded conductive unit configured to make electrical connection with a fourth grounded solder ball of the BGA package and including a fourth grounded land and a fourth grounded via on the PCB, wherein the first grounded via is disposed adjacent to the first via, the second grounded via is disposed adjacent to the second via, the third grounded via is disposed adjacent to the third via, the fourth grounded via is disposed adjacent to the third via, the first and the third grounded vias are disposed on a line that intersects the first and the third vias, and the second and the fourth grounded vias are disposed on a line that intersects the second and the third vias.

15. The PCB of claim 14, wherein the second equal distance is the same as the first equal distance.

16. The PCB of claim 15, wherein the first equal distance is less than a distance between the first via and the second via.

17. The PCB of claim 14, wherein the first via, the second via, the third via and the fourth via respectively shift from the first land, the second land, the third land and the fourth land in a same shift direction and by a same shift distance.

18. The PCB of claim 14, further comprising:

the BGA package assembled on the PCB.

19. The PCB of claim 14, wherein the first grounded via, the second grounded via, the third grounded via, and the fourth grounded via are configured to collectively cause an equal electro-magnetic coupling field to the first via and the second via.