Solder joint reliability by changing solder pad surface from flat to convex shape

• US 20040099716A1
• Filed: 11/27/2002
• Published: 05/27/2004
• Est. Priority Date: 11/27/2002
• Status: Abandoned Application

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yuan, Yuan, Carpenter, Burton J.
• Application Number:
  US10/306,626
• Publication Number:
  US 20040099716A1
• Time in Patent Office: Days
• US Class Current: 228/246
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05541 Structure
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05557 comprising protrusions or indentations
• CPC Class Codes: H01L 2224/05559 non conformal layer on a patterned surface
• CPC Class Codes: H01L 2224/05571 the external layer being disposed in a recess of the surface
• CPC Class Codes: H01L 2224/05611 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05639 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05684 Tungsten [W] as principal constituent
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/13022 the bump connector being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/81805 involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/10 Bump connectors bumps on insulating substrates, e.g. chip carriers, H01L23/49816; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/13 of an individual bump connector
• 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 2924/00011 : Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H05K 1/111 : Pads for surface mounting, e.g. lay-out
• CPC Class Codes: H05K 2201/0367 : Metallic bump or raised conductor not used as solder bump solder materials or compositions and methods of application thereof H05K3/3457
• CPC Class Codes: H05K 2201/10992 : Using different connection materials, e.g. different solders, for the same connection
• 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 3/3463 : Solder compositions in relation to features of the printed circuit board or the mounting process
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

A device (61) is provided herein which comprises a semiconductor substrate (63) having a solder pad (65) disposed thereon. The solder pad (65) has a convex surface (67) upon which is disposed a solder (75). The solder joints formed with this type of solder pad are found to exhibit reduced stress and improved reliability.

Claims

1. A device, comprising:

a first device component having a first solder pad disposed thereon, said first solder pad having a first convex surface; and

a portion of solder disposed on said first convex surface.

2. The device of claim 1, further comprising a second device component having a second solder pad disposed thereon, said second solder pad having a second surface, and wherein said first and second surfaces are connected by the portion of solder.

3. The device of claim 2, wherein said first and second device components are selected from the group consisting of die, packages, packaging substrates, and PCBs.

4. The device of claim 3, wherein said second surface is also convex.

5. The device of claim 1, wherein said first solder pad has a normalized solder pad thickness within the range of about 20 to about 150.

6. The device of claim 1, wherein said first solder pad has a normalized solder pad thickness within the range of about 60 to about 125.

7. The device of claim 1, wherein said first solder pad has a normalized solder pad thickness within the range of about 90 to about 110.

8. The device of claim 1, wherein the first solder pad has a first portion comprising a first metal and a second portion comprising a second metal, and wherein said first and second metals are diverse.

9. The device of claim 8, wherein said second portion is in contact with the solder, and wherein said second metal has a higher Young'"'"'s modulus than the solder.

10. The device of claim 9, wherein T₂ is the highest melting temperature of the solder, wherein T₁ is the lowest melting temperature of the second metal, and wherein T₁- T₂ is at least about 25°

C.

11. The device of claim 10, wherein T₁- T₂ is at least about 50°

C.

12. The device of claim 1, wherein the elastic modulus E₁ of the solder pad material and the elastic modulus E₂ of the solder at a strain of 0.02 are such that E₁-E₂ is at least about 30,000 MPa.

13. The device of claim 1, wherein the elastic modulus E₁ of the solder pad material and the elastic modulus E₂ of the solder at a strain of 0.02 are such that E₁-E₂ is at least about 55,000 MPa.

14. The device of claim 1, wherein the elastic modulus E₁ of the solder pad material and the elastic modulus E₂ of the solder at a strain of 0.02 are such that E₁-E₂ is at least about 70,000 MPa.

15. A method for forming a solder joint, comprising the steps of:

providing a solder pad having a convex surface; and

disposing a portion of solder onto said convex surface.

16. The method of claim 15, wherein the step of providing a solder pad having a convex surface comprises the steps of providing a first portion of a solder pad comprising a first metal, and forming a second portion of a solder pad on the first portion, said second portion having a convex surface and comprising a second metal diverse from the first metal.

17. The method of claim 16, wherein the first portion of the solder pad has a flat surface.

18. The device of claim 15, wherein said solder pad has a normalized solder pad thickness within the range of about 20 to about 150.

19. The device of claim 15, wherein said solder pad has a normalized solder pad thickness within the range of about 60 to about 125.

20. The device of claim 15, wherein said solder pad has a normalized solder pad thickness within the range of about 90 to about 110.

21. A method for forming a solder joint, comprising the steps of:

providing a substrate;

creating a first portion of a solder pad on the substrate, said first portion comprising a first metal;

creating a second portion of a solder pad on the first portion, said second portion having a convex surface and comprising a second metal distinct from the first metal;

disposing a portion of solder onto said convex surface; and

reflowing the solder.

22. The method of claim 21, wherein the first portion of the solder pad has a flat surface.

23. The device of claim 21, wherein said solder pad has a normalized solder pad thickness within the range of about 20 to about 150.

24. The device of claim 21, wherein said solder pad has a normalized solder pad thickness within the range of about 60 to about 125.

25. The device of claim 21, wherein said solder pad has a normalized solder pad thickness within the range of about 90 to about 110.

26. A device, comprising:

a solder pad having a convex surface; and

a portion of solder joined to said solder pad across said convex surface.

27. The device of claim 26, wherein said solder pad has a normalized solder pad thickness within the range of about 20 to about 150.

28. The device of claim 26, wherein said solder pad has a normalized solder pad thickness within the range of about 60 to about 125.

29. The device of claim 26, wherein said solder pad has a normalized solder pad thickness within the range of about 90 to about 110.