Method and structure for an organic package with improved BGA life

• US 20020137256A1
• Filed: 03/26/2001
• Published: 09/26/2002
• Est. Priority Date: 03/26/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Knickerbocker, John U., Markovich, Voya R., Miller, Thomas R., Rudik, William J.
• Granted Patent: US 7,148,566 B2
• Time in Patent Office: Days
• US Class Current: 438/107
• CPC Class Codes: H01L 23/49866 characterised by the materials materials of the substrates H01L23/14, of the lead-frames H01L23/49579
• 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 1/0271 Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion
• CPC Class Codes: H05K 1/111 Pads for surface mounting, e.g. lay-out
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2203/0307 Providing micro- or nanometer scale roughness on a metal surface, e.g. by plating of nodules or dendrites
• CPC Class Codes: H05K 2203/1152 Replicating the surface structure of a sacrificial layer, e.g. for roughening
• CPC Class Codes: H05K 3/384 by plating
• CPC Class Codes: H05K 3/4092 Integral conductive tabs, i.e. conductive parts partly detached from the substrate

Abstract

Ball Grid Array packages having decreased adhesion of the BGA pad to the laminate surface and methods for producing same are provided.

Claims

1. An electronic package having selectively controlled contact pad-laminate surface adhesion comprising:

a dielectric substrate having a major surface;

a conductive foil laminated to said major surface wherein said foil has at least one side having a smooth portion thereof, and wherein said smooth portion contacts said major surface of said dielectric substrate.

2. An electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 1, wherein said conductive foil comprises any conductive material selected from the group consisting of copper, aluminum, gold, silver, nickel, and chrome.

3. An electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 1, wherein said conductive foil comprises any material having high electrical conductivity.

5. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 2, wherein said conductive foil comprises any conductive material selected from the group consisting of copper, aluminum, gold, silver, nickel, and chrome.

6. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 2, wherein said conductive foil comprises any material having high electrical conductivity.

7. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 2, wherein said smooth portion has a surface roughness less than about 1.0 micron.

8. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 2, wherein said smooth side has a surface roughness about 0.01 micron.

9. An electronic package having selectively controlled contact pad-laminate surface adhesion, fabricated by the method of claim 2.

4. A method of fabricating an electronic package having selectively controlled contact pad laminate surface adhesion comprising:

providing a dielectric substrate having a major surface;

providing a conductive foil wherein said foil has at least one side having a smooth portion thereof;

laminating said conductive foil to said major surface wherein said smooth portion contacts said major surface;

applying a negative acting resist to said conductive foil;

developing said resist forming openings;

etching exposed conductive foil, wherein said etching forms a connection pad.

10. An electronic package having selectively controlled contact pad-laminate surface adhesion comprising:

a dielectric substrate having a major surface;

a conductive foil laminated to said major surface wherein said foil has a smooth side and a dendritic side, and wherein said dendritic side contacts said major surface of said dielectric substrate.

11. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion comprising:

providing a dielectric substrate having a major surface;

providing conductive foil having a least one dendritic side;

laminating said conductive foil to said major surface wherein said at least one dendritic side contacts and imparts a dendritic topology to said major surface;

Masking said conductive foil;

exposing said dendritic topology by etching said conductive foil;

smoothing said dendritic topology;

applying a first metallization layer to said major surface; and

plating at least a second metallization layer on said first metallization layer.

12. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 11, wherein said first metallization layer is a catalyst seed layer.

13. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 11, wherein said first metallization layer comprises a catalyst selected from the group consisting of pailladium, palladium/tin, and other similar catalysts.

14. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 11, wherein said first metallization layer comprises a thin sputter or electrodeposited metal layer.

15. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion, according to claim 11, wherein smoothing said dendritic topology comprises techniques selected from the group consisting of plasma, vapor, chemical, and mechanical attack.

16. A method of fabricating an electronic package having selectively controlled contact pad-laminate surface adhesion fabricated by the method of claim 11.

18. A springboard contact pad-laminate surface contact structure, according to claim 17, wherein said mask layer is a soldermask.

19. A springboard contact pad-laminate surface contact structure, according to claim 17, wherein said mechanically compliant layers comprises dielectric materials selected from the group consisting of photoresist, photoimageable dielectrics and prepreg.

20. A springboard contact pad-laminate surface contact structure, according to claim 17, wherein said electrical contact pads comprise highly conductive material selected from the group consisting of copper, copper foil, plated copper foil, and other suitable materials.

21. A springboard contact pad-laminate surface contact structure, according to claim 17, wherein said electrical contact pads comprise highly conductive material selected from the group consisting of aluminum, gold, silver, nickel, and chrome.

34. A springboard contact pad-laminate surface contact structure fabricated according to the method of claim 13.

17. A springboard contact pad-laminate surface contact structure comprising:

a semiconductor substrate having a major surface;

a first mechanically compliant dielectric layer formed over said major surface of said substrate and having at least one first opening formed therethrough;

a first electrical contact pad formed in said first opening and in electrical contact with said substrate;

a second mechanically compliant dielectric layer formed over said first compliant layer and having at least one second opening formed therethrough wherein said second opening is substantially offset from said first opening;

a second electrical contact pad formed in said second opening and in electrical contact with said first electrical contact pad;

a mask layer formed over said second compliant layer and having a third opening therethrough in communication with said second electrical contact pad; and

a solder ball solderably connected to said second electrical contact pad and extending through said third opening.

22. A method of fabricating a springboard contact pad - laminate surface contact structure comprising the steps of:

providing a semiconductor substrate having a major surface;

forming a first electrical contact pad on said major surface of said semiconductor substrate;

forming a first mechanically compliant dielectric layer over said major surface of said substrate wherein the upper surface of said first dielectric layer is coplanar with the upper surface of said first electrical contact pad and wherein said upper surface of said first electrical contact pad is exposed through said first dielectric layer;

forming a second mechanically compliant dielectric layer over said first dielectric layer and having at least one opening formed therethrough wherein said opening is substantially offset from said first electrical contact pad and wherein said second opening exposes a target surface;

forming a second electrical contact pad on said target surface;

forming a mask layer over said second dielectric layer wherein said mask has an opening through to said second electrical pad; and

soldering a solder ball to said second electrical pad wherein said solder ball extends through said third opening.

23. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein forming said first electrical contact pad comprises the steps of:

laminating said semiconductor substrate with metallic foil;

optionally,

plating said foil with a second metallization; and

appropriately masking and etching said second metallization and said foil through to said substrate.

24. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said foil comprises copper.

25. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said second metallization comprises copper plating.

26. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said first and said second mechanically compliant layers comprise dielectric materials selected from the group consisting of photoresist, photoimageable dielectrics and prepreg.

27. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said target surface comprises an edge portion of the upper surface of said first electrical contact pad and a portion of the upper surface of said first compliant layer.

28. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein forming said second electrical contact pad comprises the steps of:

providing the target surface with a catalyst seed layer; and

plating a second metallization over said seed layer.

29. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said catalyst seed layer comprises a catalyst selected from the group consisting of palladium, palladium/tin, and other similar catalysts.

30. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said second metallization comprises copper.

31. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein said second metallization comprises any conductive material selected from the group consisting of copper, aluminum, gold, silver, nickel, and chrome.

32. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein forming said second electrical contact pad comprises the steps of:

forming a layer of conductive paste on the upper surface of said first electrical contact pad and on the upper surface of said first compliant layer;

laminating an upper layer of metallic foil over said paste layer wherein said metallic foil mechanically bonds with said first electrical contact pad;

masking and etching said upper metallic layer leaving a second electrical contact pad in electrical contact with and substantially offset from said first electrical contact pad.

33. A method of fabricating a springboard contact pad-laminate surface contact structure, according to claim 22, wherein forming said second electrical contact pad comprises the steps of:

plating a layer a layer of wirebondable gold on the upper surface of said first electrical contact pad;

laminating an upper layer of copper foil over said gold layer;

masking and etching said upper copper layer leaving a second electrical contact pad in electrical contact with and substantially offset from said first electrical contact pad.