Bump and method of forming bump

• US 20030101584A1
• Filed: 01/16/2003
• Published: 06/05/2003
• Est. Priority Date: 06/09/1998
• Status: Active Grant

• Current Assignee: Shigeru Matsumura
• Original Assignee: Shigeru Matsumura
• Inventors: Matsumura, Shigeru
• Granted Patent: US 7,084,657 B2
• Time in Patent Office: Days
• US Class Current: 29/840
• CPC Class Codes: H01L 2224/1134 Stud bumping, i.e. using a wire-bonding apparatus
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2924/00013 Fully indexed content
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H01R 11/18 End pieces terminating in a probe
• CPC Class Codes: H01R 43/0214 Resistance welding H01R43/0228 takes precedence
• CPC Class Codes: H05K 3/4015 using auxiliary conductive elements, e.g. pieces of metal foil, metallic spheres
• CPC Class Codes: Y10T 29/49144 by metal fusion
• CPC Class Codes: Y10T 29/49149 by metal fusion bonding

Abstract

A bump used for electric contact with an electric part is formed by arranging on a conductor a conductive material including a substantially same electric characteristic as the bump by fusing, and forming the arranged conductive material into a desired shape by die pressing with a bump forming die in which a recess having a given shape is defined.

Such a bump formed on a conductor and used for electric contact with an electric part, comprises a lower portion fusedly arranged on the conductor and a upper portion taperedly formed by die pressing in such a fashion that a cross section of the bump closer to a tip thereof is smaller.

A probe card used for establishing electric contact with an electric part to inspect an electric characteristic thereof, comprises a plurality of conductors each transmitting a signal used for inspection, and a plurality of bumps each formed on one of the plurality of conductors used for establishing mechanical contact with the electric part. Each bump includes a lower portion fusedly arranged on the conductor and an upper portion taperedly formed in such a fashion that a cross section of the bump closer to a tip thereof is smaller.

Claims

1. A method of forming on a conductor a bump used for electric contact with an electric part, comprising:

arranging on said conductor a conductive material including a substantially same electric characteristic as said bump by fusing; and

forming said arranged conductive material into a desired shape by die pressing with a bump forming die in which a recess having a given shape is defined.

2. A method as set forth in claim 1, wherein

said desired shape is a tapered shape that a cross section of said bump closer to a tip thereof is smaller than a cross section further from said tip.

3. A method as set forth in claim 2, wherein

said tapered shape is a conical shape.

4. A method as set forth in claim 1, wherein

said forming includes retaining a distance between said conductor and a peripheral portion of said recess larger than half of a depth of said recess.

5. A method as set forth in claim 1, wherein

said bump forming die includes in a peripheral portion of said recess, a concave recess shallower than said recess to prevent a surplus of said conductive material from expanding.

6. A method as set forth in claim 1, wherein

said forming includes plating said formed bump with a hard material having a hardness higher than that of said conductive material.

7. A method as set forth in claim 6, wherein

said hard material comprises nickel or palladium nickel.

8. A method as set forth in claim 6, further comprising

plating said plated bump with gold.

9. A method as set forth in claim 1, wherein

said arranging includes

fusing a tip of a wire having a substantially same electric characteristic as said conductive material by discharging;

positioning said fused tip on said conductor;

holding said wire with said tip being in contact with said conductor for a given period of time to arrange said tip on said conductor; and

cutting said wire with said tip remaining on said conductor by separating said wire from said conductor.

10. A method as set forth in claim 1, wherein

said arranging includes

transferring a ball-shaped material having said conductive material onto said conductor using suction;

fusing said transferred ball-shaped material by reflowing; and

solidifying said fused ball-shaped material by cooling.

11. A bump formed on a conductor used for electric contact with an electric part, comprising:

a lower portion fusedly arranged on said conductor; and

a upper portion taperedly formed by die pressing in such a fashion that a cross section of said bump closer to a tip thereof is smaller than a cross section further from said tip.

12. A bump as set forth in claim 11, wherein

said tapered shape is a conical shape.

13. A bump as set forth in claim 11, wherein

said upper portion has a length larger than 20 microns.

14. A bump as set forth in claim 11, wherein

said bump is plated with a hard material having a hardness higher than that of said upper portion.

15. A bump as set forth in claim 14, wherein

said hard material comprises nickel or palladium nickel.

16. A bump as set forth in claim 14, wherein

said hard material on said bump is plated with gold.

17. A probe card used for establishing electric contact with an electric part to inspect an electric characteristic thereof, comprising:

a plurality of conductors each transmitting a signal used for inspection; and

a plurality of bumps each formed on one of the plurality of conductors used for establishing mechanical contact with said electric part, wherein each bump includes a lower portion fusedly arranged on said conductor and an upper portion taperedly formed in such a fashion that a cross section of said bump closer to a tip thereof is smaller than a cross section further from said tip.

18. A probe card as set forth in claim 17, further comprising

a plurality of elastic members each pressing one of said plurality of bumps to said electric part.

19. A probe card as set forth in claim 18, further comprising

a flexible board on which said conductors are arranged;

wherein said flexible board is pressed by the elastic body to allow said bumps on said conductors to come in contact with said electric part.

20. A probe card as set forth in claim 18, wherein

said elastic members are arranged for said plurality of conductors, respectively.

21. A probe card as set forth in claim 20, wherein

said conductors are unified with said respective elastic members.

22. A probe card as set forth in claim 17, wherein

said tapered shape is a conical shape.

23. A probe card as set forth in claim 17, wherein

said bumps are formed to have a uniform height by die pressing.

24. A probe card as set forth in claim 17, wherein

said upper portion of said bump is more than 20 microns in height.

25. A probe card as set forth in claim 17, wherein

said bump is plated with a hard material having a hardness higher than that of said upper portion.