PRINTED CIRCUIT BOARD BALL GRID ARRAY SYSTEM HAVING IMPROVED MECHANICAL STRENGTH

• US 20100018763A1
• Filed: 07/24/2008
• Published: 01/28/2010
• Est. Priority Date: 07/24/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: BARRY, ALAN L.
• Granted Patent: US 8,173,910 B2
• Time in Patent Office: Days
• US Class Current: 174/263
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H05K 1/111 Pads for surface mounting, e.g. lay-out
• CPC Class Codes: H05K 1/116 Lands, clearance holes or other lay-out details concerning the surrounding of a via
• CPC Class Codes: H05K 2201/0949 Pad close to a hole, not surrounding the hole
• CPC Class Codes: H05K 2201/099 Coating over pads, e.g. solder resist partly over pads
• CPC Class Codes: H05K 3/3436 having an array of bottom contacts, e.g. pad grid array or ball grid array components
• CPC Class Codes: H05K 3/3452 Solder masks
• CPC Class Codes: H05K 3/42 Plated through-holes or plated via connections

Abstract

A printed circuit board (PCB) ball grid array (BGA) system is provided. In one embodiment, the PCB BGA system includes a PCB, a PCB BGA pad formed on the PCB, a plated through-hole via disposed at least partially through the PCB proximate the PCB BGA pad, and a soldermask disposed over the PCB. The soldermask includes: (i) a BGA pad opening through which the PCB BGA pad is exposed, and (ii) a via opening through which a central portion of the plated through-hole via is exposed. The via opening has an inner diameter that is less than the outer diameter of the plated through-hole via.

Claims

1. A printed circuit board (PCB) ball grid array (BGA) system, comprising:

a PCB;

a PCB BGA pad formed on the PCB;

a plated through-hole via disposed at least partially through the PCB proximate the PCB BGA pad; and

a soldermask disposed over the PCB, the soldermask comprising;

a BGA pad opening through which the PCB BGA pad is exposed; and

a via opening through which a central portion of the plated through-hole via is exposed, the via opening having an inner diameter that is less than the outer diameter of the plated through-hole via.

2. A PCB BGA system according to claim 1 wherein the inner diameter of the via opening is approximately 0.41 millimeter to approximately 0.45 millimeter.

3. A PCB BGA system according to claim 2 wherein the inner diameter of the BGA pad opening is approximately 0.07 millimeter to approximately 0.135 millimeter greater than the outer diameter of the PCB BGA pad.

4. A PCB BGA system according to claim 1 wherein the outer diameter of the plated through-hole via is approximately 0.05 millimeter to approximately 0.11 millimeter greater than the inner diameter of the via opening.

5. A PCB BGA system according to claim 1 wherein the BGA pad opening is substantially concentric with the PCB BGA pad.

6. A PCB BGA system according to claim 5 wherein the via opening is substantially concentric with the plated through-hole via.

7. A PCB BGA system according to claim 6 wherein the BGA pad opening and the via opening each have a generally circular planform shape.

8. A PCB BGA system according to claim 1 further comprising a reflowed solder ball disposed over and circumferentially adhering to the PCB BGA pad.

9. A PCB BGA system according to claim 8 wherein the reflowed solder ball substantially circumscribes the PCB BGA pad.

10. A PCB BGA system according to claim 1 further comprising a plating disposed over the plated through-hole via, the plating comprising at least one of tin and lead.

11. A printed circuit board (PCB) ball grid array (BGA) system, comprising:

a PCB;

a PCB BGA pad disposed on the PCB;

a plated through-hole via disposed at least partially through the PCB proximate the PCB BGA pad; and

a soldermask disposed over the PCB, the soldermask encroaching the plated through-hole via such that;

(i) an outer portion of the upper surface of the plated through-hole via is covered by the soldermask, and (ii) a central portion of the plated through-hole via is exposed through the soldermask.

12. A PCB BGA system according to claim 11 wherein the soldermask encroaches approximately 0.025 millimeter to approximately 0.055 millimeter over the outer circumferential edge of the plated through-hole via.

13. A PCB BGA system according to claim 11 wherein the soldermask has a BGA pad opening therethrough, the PCB BGA pad residing within the BGA pad opening and offset therefrom by a circumferential clearance.

14. A PCB BGA system according to claim 13 wherein the radial width of the circumferential clearance is approximately 0.045 millimeter to approximately 0.05 millimeter.

15. A PCB BGA system according to claim 14 further comprising a reflowed solder ball contacting the PCB BGA pad and residing at least partially within the circumferential clearance.

16. A PCB BGA system according to claim 15 wherein the reflowed solder ball fills a majority of the circumferential clearance.

17. A PCB BGA system according to claim 13 wherein the BGA pad opening is substantially concentric with the PCB BGA pad.

18. A printed circuit board (PCB) ball grid array (BGA) system for use in conjunction with an electronic component, the electronic component including a component BGA pad thereon, the PCB BGA system comprising:

a PCB;

a PCB BGA pad disposed on the PCB and having an outer diameter that is greater than the outer diameter of the component BGA pad;

a plated through-hole via disposed at least partially through the PCB proximate the PCB BGA pad;

a soldermask disposed over the PCB;

a BGA pad opening formed through the soldermask and exposing the PCB BGA pad, the BGA pad opening having an inner diameter that is greater than the outer diameter of the PCB BGA pad;

a via opening formed through the soldermask and partially exposing the plated through-hole via, the via opening having an inner diameter that is less than the outer diameter of the plated through-hole via; and

a reflowed solder ball cooperating with the PCB BGA pad and the component BGA pad to form a solder joint, the reflowed solder ball circumferentially engaging the PCB BGA pad.

19. A PCB BGA system according to claim 18 wherein the inner diameter of the BGA pad opening is approximately 0.07 millimeter to approximately 0.135 millimeter greater than the outer diameter of the PCB BGA pad.

20. A PCB BGA system according to claim 19 wherein the inner diameter of the via opening is approximately 0.05 millimeter to approximately 0.11 millimeter less than the outer diameter of the plated through-hole via.