Claims
- 1. A method comprising:
providing a dielectric layer having a via; exposing a portion of a conductive layer through the via in the dielectric layer; and adding a conductive material to the conductive layer to create a nonplanar interface which is exposed through the via.
- 2. The method of claim 1 wherein the nonplanar interface is discontinuous.
- 3. The method of claim 1 wherein the conductive layer is planar.
- 4. The method of claim 1 wherein the nonplanar interface has a larger surface area than the conductive layer exposed through the via.
- 5. The method of claim 1 wherein the nonplanar interface includes the conductive material and an exposed portion of the conductive layer not covered by the conductive material.
- 6. The method of claim 1 wherein the adding step completely covers the portion of the conductive layer exposed through the via.
- 7. The method of claim 1 comprising the step of seating a conductive ball on the nonplanar interface.
- 8. The method of claim 7 wherein the nonplanar interface prevents a crack from propagating substantially planarly through the conductive ball.
- 9. The method of claim 7 wherein the conductive ball couples a printed circuit board to a integrated circuit package.
- 10. The method of claim 7 comprising directly contacting the conductive ball with a portion of the conductive layer.
- 11. The method of claim 1 wherein the adding step is carried out by plating up copper directly on the conductive layer.
- 12. The method of claim 1 wherein the adding step is carried out with a mask and photoresist.
- 13. The method of claim 1 further comprising etching away a portion of the nonplanar interface.
- 14. The method of claim 13 wherein the etching step is carried out through photolithography.
- 15. The method of claim 1 wherein the via is formed by mechanically punching the dielectric layer.
- 16. The method of claim 1 wherein the via is formed by chemically etching the dielectric layer.
- 17. The method of claim 1 wherein the conductive material is a different material than the conductive layer.
- 18. The method of claim 1 wherein the via extends away from the conductive layer at an angle.
- 19. The method of claim 1 wherein the nonplanar interface is discontinuous, a step, dome, a hemisphere, or a cylinder.
- 20. The method of claim 1 further comprising plating at least one of the conductive layer and the conductive material with a layer of gold, nickel, or silver.
- 21. A method of engaging a conductive lead comprising:
defining a land area on a substrate; and adding material to the land area to create a nonplanar interface between the conductive lead and the land area.
- 22. The method of claim 21 wherein the land area without the added material defines a first surface area and the nonplanar interface defines a second surface area that is larger than the first surface area.
- 23. The method of claim 21 wherein the land area without the added material defines a first shear plane, and the land area with the added material defines a second shear plane that is larger than the first shear plane.
- 24. A method of fabricating a substrate comprising:
adding a conductive structure to a surface of a conductive ball pad; applying a coat of photoresist to the conductive structure; masking a desired portion of the photoresist; exposing the photoresist to a light source; developing the photoresist to remove an unwanted portion of the photoresist; etching away an unwanted portion of the conductive structure; and removing the remaining photoresist.
- 25. A method comprising:
providing a dielectric material having a first surface, a second surface, and a first thickness between the first and second surfaces, wherein the dielectric material has a via to a ball bonding pad; and forming at the ball bonding pad a nonplanar locking structure electrically coupled to the ball bonding pad, wherein a conductive ball coupled to the ball bonding pad without the locking structure defines a shear plane, and the conductive ball coupled to the ball bonding pad having the nonplanar locking structure defines a shear interface which has a larger area than the shear plane.
- 26. The method of claim 25 wherein the conductive ball locking structure extends from the conductive ball bonding pad through the via in a direction from the first surface to the second surface.
- 27. The method of claim 25 wherein the conductive ball locking structure extends from the conductive ball bonding pad through the via a second thickness which is less than the first thickness.
- 28. The method of claim 25 wherein the conductive ball locking structure is formed by electroplating a conductive material to the ball bonding pad.
- 29. The method of claim 25 wherein the forming step is carried out by defining the conductive ball locking structure using lithography.
- 30. A method comprising:
providing a printed circuit board and an integrated circuit package having a ball bond pad which has a ball locking structure, the ball locking structure having an exposed surface which limits the movement of a fatigue crack across the interface between the ball bond pad and a conductive ball; and interlocking the conductive ball between the printed circuit board and the integrated circuit package.
- 31. The method of claim 30 wherein the interlocking step is carried out by increasing the area of the shear plane of the conductive ball.
- 32. The method of claim 30 wherein the conductive ball locking structure is formed by adding material to the ball bond pad.
- 33. The method of claim 30 wherein the interlocking step is carried out by preventing a crack from propagating planarly across the conductive ball.
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application Ser. No. 09/517,799, filed Mar. 2, 2000; which claims priority to U.S. Provisional Patent Application No. 60/126,234, filed Mar. 24, 1999, which are incorporated by reference.
[0002] This application is also related to U.S. Provisional Patent Application No. 60/123,116, filed Mar. 5, 1999, and U.S. Nonprovisional Patent Application No. 09/517,345, filed Mar. 2, 2000, which are incorporated by reference.
Provisional Applications (2)
|
Number |
Date |
Country |
|
60126234 |
Mar 1999 |
US |
|
60123116 |
Mar 1999 |
US |
Divisions (1)
|
Number |
Date |
Country |
Parent |
09517799 |
Mar 2000 |
US |
Child |
10219173 |
Aug 2002 |
US |