Microelectronic connections with liquid conductive elements

• US 6,437,240 B2
• Filed: 01/10/2001
• Issued: 08/20/2002
• 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:
  US09/757,897
• Publication Number:
  US 20010001989A1
• Time in Patent Office: 587 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 method of making a microelectronic assembly includes providing a first microelectronic element and a second microelectronic element with confronting, spaced-apart surfaces defining a space therebetween and providing one or more masses of a fusible conductive material having a melting temperature below about 150° C. in said space, whereby the fusible conductive masses connect the first and second microelectronic elements to one another. Next, a flowable material is introduced between the confronting surfaces of the first and second microelectronic elements and around the one or more fusible conductive masses and the flowable material is then cured to provide a compliant layer disposed between said confronting surfaces and intimately surrounding each fusible conductive mass. The fusible conductive masses are capable of electrically interconnecting the contacts on microelectronic elements confronting one another and/or conducting heat between confronting microelectronic elements.

Claims

1. A microelectronic package comprising:

(a) a first microelectronic element having a front surface including contacts and a rear surface, said first microelectronic element being operable in a range of operating temperatures;

(b) a package element having a surface confronting the rear surface of said microelectronic element;

(c) a first layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first microelectronic element and said package element;

(d) one or more masses of a thermally conductive material dispersed in said first compliant layer so that said thermally conductive masses are spaced apart from one another in lateral directions, said thermally conductive masses having a melting temperature within or below the range of operating temperatures of said first microelectronic element, each said thermally conductive mass being adjacent to said confronting surfaces of said first microelectronic element and said package element for transferring heat therebetween during operation of said first microelectronic element; and

(e) a second microelectronic element overlying said front surface of said first microelectronic element so that said first microelectronic element is disposed between said package element and said second microelectronic element, said second microelectronic element being electrically connected to said first microelectronic element.

2. A package as claimed in claim 1, wherein said second microelectronic element has a contact bearing surface confronting the contact bearing front surface of said first microelectronic element;

, the package further comprising;

a second layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first and second microelectronic elements;

one or more masses of a fusible electrically conductive material dispersed in said second compliant layer so that said electrically conductive masses are spaced apart from one another and extend between contacts of said first and second microelectronic elements, said electrically conductive masses having a melting temperature within or below said range of operating temperatures.

3. A package as claimed in claim 2, wherein said first and second compliant layers are contiguous with one another.

4. A package as claimed in claim 2, wherein said thermally conductive material and said electrically conductive material comprise one or more metals.

5. A package as claimed in claim 1, wherein said second microelectronic element includes a flexible dielectric sheet having a first surface confronting the contact bearing front surface of said first microelectronic element and a second surface facing away from said first microelectronic element, said flexible dielectric sheet including conductive terminals and accessible at said second surface, the package further comprising flexible leads electrically connected between said conductive terminals said contacts of said first microelectronic element for electrically interconnecting said first and second microelectronic elements.

6. A package as claimed in claim 5 further comprising:

a second layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first and second microelectronic elements;

one or more masses of a thermally conductive fusible material dispersed in said second compliant layer so that said thermally conductive masses are spaced apart from one another in lateral directions, said thermally conductive masses having a melting temperature within or below the range of operating temperatures of said first and second microelectronic elements, each said mass of thermally conductive material having opposite ends adjacent to said confronting surfaces of said first and second microelectronic elements for conducting heat therebetween.

7. A package as claimed in claim 1, wherein said first microelectronic element includes one or more semiconductor chips.

8. A package as claimed in claim 1, wherein said package element includes a heat sink.