Flip chip with integrated flux and underfill

• US 20010003058A1
• Filed: 12/06/2000
• Published: 06/07/2001
• Est. Priority Date: 03/10/1999
• Status: Abandoned Application

• Current Assignee: Fry's Metals Incorporated (Element Solutions Inc)
• Original Assignee: Fry's Metals Incorporated (Element Solutions Inc)
• Inventors: Blumel, David, Gilleo, Kenneth Burton
• Application Number:
  US09/730,995
• Publication Number:
  US 20010003058A1
• Time in Patent Office: Days
• US Class Current: 438/612
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/274 by blanket deposition of the material of the layer connector
• CPC Class Codes: H01L 2224/73104 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 2224/81191 wherein the bump connectors are disposed only on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83191 wherein the layer connectors are disposed only on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83856 Pre-cured adhesive, i.e. B-stage adhesive
• CPC Class Codes: H01L 24/29 of an individual layer connector
• 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 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01023 Vanadium [V]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01074 Tungsten [W]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H03F 2200/504 : the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H05K 2201/10977 : Encapsulated connections
• 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 3/3489 : Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 428/12569 : Synthetic resin
• CPC Class Codes: Y10T 428/24917 : including metal layer
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A flip chip having solder bumps and an integrated flux and underfill, as well as methods for making such a device, is described. The resulting device is well suited for a simple one-step application to a printed circuit board, thereby simplifying flip chip manufacturing processes which heretofore have required separate fluxing and underfilling steps.

Claims

1. An integrated circuit assembly which comprises:

a) a substrate having a plurality of solderable contact sites on a surface thereof;

b) a plurality of solder bumps positioned on the substrate such that each of the solderable contact sites has one solder bump associated therewith, the solder bumps being affixed to the solderable contact sites; and

c) an underfill material applied to the surface of the substrate, the underfill material at least occupying a space defined between each of the solder bumps and characterized in that, upon heating to a solder reflow temperature, at least a portion of the underfill material acts as a solder flux.

2. The integrated circuit assembly of

claim 1

wherein the substrate comprises a semiconductor wafer.

3. The integrated circuit assembly of

claim 2

wherein the substrate comprises a semiconductor chip.

4. The integrated circuit assembly of

claim 3

wherein the substrate comprises a flip chip.

5. The integrated circuit assembly of

claim 1

wherein the underfill material covers substantially all of each solder bump.

6. The integrated circuit assembly of

claim 1

wherein the underfill material comprises an epoxy resin and a material selected from the group consisting of carboxylic acids, anhydrides and combinations thereof.

7. The integrated circuit assembly of

claim 6

wherein the underfill material comprises an epoxy resin and a material selected from the group consisting of adipic acids and cyclohexane dicarboxylic acids.

8. The integrated circuit assembly of

claim 1

wherein the underfill material is reworkable.

9. The integrated circuit assembly of

claim 8

wherein the underfill material comprises a thermoplastic material.

10. The integrated circuit assembly of

claim 9

wherein the thermoplastic material is selected from the group consisting of phenoxy resins, acrylic resins, methacrylic resins, polycarbonate resins, polyamide resins, polybutene resins, polyester resins, polyolefin resins and mixtures thereof.

11. A method for making an integrated circuit assembly which comprises:

a) providing a substrate having a plurality of solderable contact sites on a surface thereof;

b) positioning a plurality of solder bumps on the substrate such that each of the solderable contact sites has one solder bump associated therewith;

c) affixing each solder bump to its associated contact site; and

d) applying an underfill material to the surface of the substrate in a manner such that it at least occupies a space defined between each of the solder bumps and is characterized in that, upon heating to a solder reflow temperature, at least a portion of the underfill material acts as a solder flux.

12. The method for making an integrated circuit assembly of

claim 11

wherein the substrate comprises a semiconductor wafer.

13. The method for making an integrated circuit assembly of

claim 12

wherein the substrate comprises a semiconductor chip.

14. The method for making an integrated circuit assembly of

claim 13

wherein the substrate comprises a flip chip.

15. The method for making an integrated circuit assembly of

claim 11

wherein the underfill material covers substantially all of each solder bump.

16. The method for making an integrated circuit assembly of

claim 11

wherein the underfill material comprises an epoxy resin and a material selected from the group consisting of carboxylic acids, anhydrides and combinations thereof.

17. The method for making an integrated circuit assembly of

claim 16

wherein the underfill material comprises an epoxy resin and a material selected from the group consisting of adipic acids and cyclohexane dicarboxylic acids.

18. The method for making an integrated circuit assembly of

claim 11

wherein the underfill material is reworkable.

19. The method for making an integrated circuit assembly of

claim 18

wherein the underfill material comprises a thermoplastic material.

20. The method for making an integrated circuit assembly of

claim 19

wherein the thermoplastic material is selected from the group consisting of phenoxy resins, acrylic resins, methacrylic resins, polycarbonate resins, polyamide resins, polybutene resins, polyester resins, polyolefin resins and mixtures thereof.

21. A method for affixing a flip chip to a circuit board which comprises the steps of:

a) providing a printed circuit board having a plurality of solderable contact sites on a surface thereof;

b) providing an integrated circuit chip having a plurality of solderable contact sites on a surface thereof, each solderable contact site on the integrated circuit chip having a corresponding solderable contact site on the surface of the printed circuit board, the integrated circuit chip further characterized in that it includes;

1) a plurality of solder bumps positioned on the integrated circuit chip such that each of the solderable contact sites located on the surface of the integrated circuit chip has one solder bump associated therewith, the solder bumps being affixed to the solderable contact sites; and

2) an underfill material applied to the surface of the substrate, the underfill material at least occupying a space defined between each of the solder bumps and characterized in that, upon heating to a solder reflow temperature, at least a portion of the underfill material acts as a solder flux;

c) positioning the integrated circuit chip relative to the printed circuit board such that each solder bump is in contact with a solderable contact site on the printed circuit board;

d) heating the integrated circuit chip to a temperature sufficiently high to melt the solder and the underfill material; and

e) allowing the solder and underfill material to solidify.

22. An integrated circuit assembly which comprises:

a) a substrate having a plurality of solderable contact sites on a surface thereof;

b) a plurality of solder bumps positioned on the substrate such that each of the solderable contact sites has one solder bump associated therewith, the solder bumps being affixed to the solderable contact sites; and

c) an underfill material applied to the surface of the substrate, the underfill material occupying a space defined between each of the solder bumps and characterized in that, upon heating to a solder reflow temperature, at least a portion of the underfill material acts as a solder flux.