Microelectronic connections with liquid conductive elements

• US 6,774,306 B2
• Filed: 02/21/2003
• Issued: 08/10/2004
• 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): Reichard, Dean A.
• Assistant Examiner(s): OLIVA, CARMELO B
• Application Number:
  US10/371,324
• Publication Number:
  US 20030150635A1
• Time in Patent Office: 536 Days
• Field of Search: 174/52.2, 174/52.3, 174/52.4, 361/704, 361/707, 361/709, 361/717, 361/718, 361/719, 361/720, 361/749, 257/706, 257/707, 257/712, 257/713, 257/737, 257/738
• US Class Current: 174/541
• 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 structure for making a microelectronic assembly comprising:

a layer of a matrix material having top and bottom surfaces extending in lateral directions;

one or more individual masses of a fusible conductive material dispersed in said layer of matrix material so that said individual conductive masses are spaced apart from one another in said lateral directions and separated from one another by said matrix material, said conductive masses having a melting temperature below about 150°

C.; and

a removable release layer overlying at least one of said surfaces and said one or more individual masses, whereby upon removal of said release layer said at least one of said surfaces is adapted to be adhered to a microelectronic element, wherein said matrix material is selected from the group consisting of (a) compliant materials having degradation temperature higher than the melting temperature of said conductive masses and (b) flowable, curable precursor materials.

2. A structure as claimed in claim 1, further comprising a second removable release layer overlying the other one of said surfaces.

3. A structure as claimed in claim 1, further comprising one or more microelectronic elements in engagement with one of said surfaces devoid of said release layer.

4. A structure as claimed in claim 3, wherein said one or more microelectronic elements include one or more semiconductor chips, each said chip having a surface in engagement with said one of said surfaces of said layer of said matrix material.

5. A structure as claimed in claim 3, wherein said one or more microelectronic elements include one or more thermally conductive package elements in engagement with said one of said surfaces of said layer.

6. A structure as claimed in claim 1, wherein said fusible conductive material includes one or more metals.

7. A structure as claimed in claim 1, wherein said fusible conductive material has a melting temperature below about 65°

C.

8. A structure as claimed in claim 1, wherein at least some of said one or more individual masses of a fusible conductive material extend over a major portion of the distance between said top and bottom surfaces of said layer of matrix material.

9. A structure as claimed in claim 1, wherein at least some of said one or more individual masses of a fusible conductive material extend from said top surface to said bottom surface of said layer of matrix material to provide a continuous conduction path from the top surface of said layer of matrix material to the bottom surface of said layer of matrix material.

10. A structure as claimed in claim 1, further comprising an adhesive on at least one of said top and bottom surfaces of said layer of said matrix material.