Microelectronic connections with liquid conductive elements

• US 5,808,874 A
• Filed: 05/02/1996
• Issued: 09/15/1998
• Est. Priority Date: 05/02/1996
• Status: Expired due to Term

• Current Assignee: Tessera, Inc. (Adeia, Inc.)
• Original Assignee: Tessera, Inc. (Adeia, Inc.)
• Inventors: Smith, John W.
• Primary Examiner(s): SPARKS, DONALD ALAN
• Application Number:
  US08/641,698
• Time in Patent Office: 866 Days
• Field of Search: 174/255, 174/260, 174/261, 257/723, 257/724, 257/700, 361/760, 361/782, 361/783, 361/767-771, 361/784, 361/785, 361/749, 361/787, 361/789, 361/790, 361/803, 361/774, 361/776, 361/779, 439/66, 439/69, 439/91, 439/179, 439/876, 439/591, 228/121, 228/180.21, 228/180.22, 228/175, 228/187
• US Class Current: 361/769
• 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 2224/02333 being a bump
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• 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 2224/14181 On opposite sides of the body
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/17051 Bump connectors having different shapes
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 2224/8192 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 23/055 the leads having a passage through the base H01L23/057 takes precedence
• CPC Class Codes: H01L 23/48 Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• 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 2924/00013 : Fully indexed content
• 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 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• 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 2924/01087 : Francium [Fr]
• 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 2924/15174 : in different layers of the multilayer substrate
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16152 : Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/16195 : Flat cap [not enclosing an internal cavity]
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19105 : in a side-by-side arrangement on a common die mounting substrate
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: Y10T 29/49126 : Assembling bases
• CPC Class Codes: Y10T 29/49135 : and shaping, e.g., cutting or bending, etc.
• CPC Class Codes: Y10T 29/49144 : by metal fusion
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

A microelectronic assembly including elements such as a semiconductor chip and substrate has electrical connections between the elements incorporating fusible conductive metal masses. The fusible masses are surrounded and contained by a compliant material such as an elastomer or gel. The fusible material may melt during operation or processing of the device to relieve thermal cycling stress in the electrical connections.

Claims

1. A microelectronic assembly comprising first and second microelectronic elements having confronting surfaces and contacts disposed on said confronting surfaces, a compliant dielectric material including a layer of a compliant dielectric material having cavities therein disposed between the confronting surfaces of said microelectronic elements and masses of a liquid conductive material disposed in said cavities so that masses of said liquid conductive material are electrically connected between said contacts on said first microelectronic element and said contacts on said second microelectronic element, said second element including a flexible but substantially inextensible dielectric sheet having an interior surface facing toward said first element, said sheet also having an exterior surface facing away from the first element, the dielectric sheet having conductive terminals disposed thereon, said conductive terminals being electrically connected to the contacts of the second element, said compliant dielectric material electrically insulating said masses of said liquid conductive material from one another and containing said liquid conductive material.

13. An assembly as claimed in claim 1 or claim 2 further comprising leads connected between said elements in series with said masses so that each said lead is connected to at least one of said elements by at least one said mass.

14. An assembly as claimed in claim 1 or claim 2 wherein said conductive material in each said mass is contiguous with contacts on both said microelectronic elements and contained by both said microelectronic elements.

15. An assembly as claimed in claim 1 or claim 2 wherein each said mass of said conductive material is connected between one contact on said first element and one contact on said second element.

16. An assembly as claimed in claim 15 wherein each said contact on said first microelectronic element is substantially aligned with one said contact on said second microelectronic element to form a pair of aligned contacts and each pair of aligned contacts is connected with one another by one said mass of said conductive material.

17. An assembly as claimed in claim 1 or claim 2 wherein said conductive terminals are disposed on said exterior surface of said flexible dielectric sheet.

18. An assembly as claimed in claim 1 or claim 2 wherein each said terminal includes an electrically conductive bonding material.

19. An assembly as claimed in claim 1 or claim 2 further comprising a substrate having contact pads thereon, each such contact pad being electrically and physically connected to one said terminal on an exterior surface of said second element.

20. An assembly as claimed in claim 1 or claim 2 wherein said first element includes one or more semiconductor chips.

21. An assembly as claimed in claim 1 or claim 2 wherein said second element includes a plurality of metallic terminal assemblies disposed on said sheet, each said terminal assembly forming one said contact and one said terminal of said second element.

22. An assembly as claimed in claim 1 or claim 2 wherein said first element includes one or more semiconductor chips and said second element includes a rigid substrate, said compliant layer mechanically connecting said one or more chips to said substrate.

2. A microelectronic assembly comprising first and second microelectronic elements having confronting surfaces and contacts disposed on said confronting surfaces, a compliant dielectric material including a layer of a compliant dielectric material having cavities therein disposed between the confronting surfaces of said microelectronic elements and masses of a fusible conductive material disposed in said cavities so that masses of said fusible conductive material are electrically connected between said contacts on said first microelectronic element and said contacts on said second microelectronic element, said fusible conductive material having a melting temperature below about 125°

C., said second element including a flexible but substantially inextensible dielectric sheet having an interior surface facing toward said first element, said sheet also having a exterior surface facing away from the first element, the dielectric sheet having conductive terminals disposed thereon, said conductive terminals being electrically connected to the contacts of the second element, said compliant dielectric material electrically insulating said masses of said fusible conductive material from one another, said compliant dielectric material being adapted to contain said fusible conductive material when said conductive material is in a liquid state.

3. An assembly as claimed in claim 2 wherein said fusible conductive material has a melting temperature below about 100°

C.

4. An assembly as claimed in claim 2 wherein said fusible conductive material has a melting temperature below about 65°

C.

5. An assembly as claimed in claim 2 wherein said fusible conductive material has a melting temperature between about 25°

C. and about 65°

C.

6. An assembly as claimed in claim 2 wherein said conductive material consists essentially of one or more metals.

7. An assembly as claimed in claim 6 wherein said conductive material includes a metal alloy.

8. An assembly as claimed in claim 2 wherein said elements of said assembly are adapted to operate in a range of operating temperatures above the melting temperature of said fusible conductive material.

9. A microelectronic assembly comprising:

(a) a first microelectronic element having a surface with contacts thereon;

(b) a layer of a compliant material having a layer of a compliant dielectric material having cavities therein overlying said surface of said microelectronic element so that a first side of said layer of compliant material faces toward said first microelectronic element and a second side of the layer faces away from the first microelectronic element;

(c) masses of a fusible conductive material having a melting temperature below about 125°

C. disposed in said cavities, said compliant material electrically insulating said masses from one another;

(d) terminal assemblies disposed on said second side of said layer, said terminal assemblies being connected to said contacts on said first microelectronic element by said fusible conductive materials; and

(e) a second element disposed on said second side of said compliant layer, said second element including a flexible dielectric sheet overlying said second side of said compliant layer, said terminal assemblies being attached to said flexible dielectric sheet.

10. An assembly as claimed in claim 9 wherein said first microelectronic element is adapted to operate in a range of operating temperatures above the melting temperature of said fusible conductive material.

11. An assembly as claimed in claim 9 wherein said second element includes a rigid microelectronic element having contact pads thereon, said terminal assemblies being bonded to the contact pads of said rigid microelectronic element.

12. An assembly as claimed in claim 9, said dielectric sheet having an interior surface facing toward said first element and an exterior surface facing away from said first element, each said terminal assembly providing one terminal on said exterior surface for connecting to a further microelectronic element and another terminal on said of said second element on said interior surface of said dielectric sheet in engagement with one said mass of fusible conductive material.