Microelectronics unit mounting with multiple lead bonding

• US 5,794,330 A
• Filed: 05/08/1995
• Issued: 08/18/1998
• Est. Priority Date: 02/01/1994
• Status: Expired due to Term

• Current Assignee: Tessera, Inc. (Adeia, Inc.)
• Original Assignee: Tessera, Inc. (Adeia, Inc.)
• Inventors: Distefano, Thomas H., Smith, John W. Jr.
• Primary Examiner(s): VO, PETER DUNG BA
• Application Number:
  US08/436,649
• Time in Patent Office: 1,198 Days
• Field of Search: 29/830, 29/840, 29/876, 228/180.1, 228/180.21, 228/180.22, 439/66, 439/67, 439/91
• US Class Current: 29/840
• CPC Class Codes: H01L 21/486 Via connections through the substrate with or without pins
• CPC Class Codes: H01L 21/4885 Wire-like parts or pins wire ball formation B23K20/00; methods related to connecting semiconductor or other solid state bodies H01L24/00
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/78301 Capillary
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 2224/85205 Ultrasonic bonding
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• 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 24/81 using a 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01032 Germanium [Ge]
• 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 2924/0105 : Tin [Sn]
• 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 2924/01322 : 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 2924/12042 : LASER
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: Y10T 29/49126 : Assembling bases
• CPC Class Codes: Y10T 29/49144 : by metal fusion
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.
• CPC Class Codes: Y10T 29/49208 : by assembling plural parts

Abstract

A component for mounting semiconductor chips or other microelectronic units includes a flexible top sheet with an array of terminals on it, and with flexible leads extending downwardly from the terminals. A compliant dielectric support layer surrounds the leads, holding the lead tips in precise locations. The leads are desirably formed from wire such as gold wire, and have eutectic bonding alloy on their tips. The component can be laminated to a chip or other unit under heat and pressure to form a complete subassembly with no need for individual bonding to the contacts of the chip. The subassembly can be tested readily and provides compensation for thermal expansion.

Claims

1. A method of making a microelectronic unit subassembly comprising the steps of:

(a) providing a connection component having a dielectric structure, having an array of terminals on a top surface of the dielectric structure and having flexible leads connected to said terminals and extending through said dielectric structure to bottom ends at a bottom surface of said dielectric structure; and

(b) engaging the bottom surface of said connection component dielectric structure with a front surface of a microelectronic unit having an array of contacts thereon while subjecting said connection component and microelectronic unit to heat and pressure so that the bottom surface of the dielectric layer forms a sealed interface with the front surface of the microelectronic unit and so that the bottom ends of the flexible leads on the connection component bond with the contacts on the unit so as to form electrical connections therebetween, wherein said dielectric structure includes a compliant layer and said leads extend through said compliant layer, and wherein at least some of said flexible leads extending through said compliant layer are bent during said engaging step.

2. The method as claimed in claim 1 wherein said leads and contacts are metallic, and wherein said heat is sufficient to form a liquid metal phase at the juncture of each lead and contact.

3. The method as claimed in claim 2 wherein said leads and contacts include one or more structural metals and a bonding metal is provided at the juncture of each said lead and contact, said bonding metal forming a low-melting alloy with at least one said structural metal, said liquid phase including said alloy.

4. The method as claimed in claim 3 wherein said bonding metal is disposed on said bottom ends of said leads prior to said engaging step.

5. The method as claimed in claim 1 wherein said dielectric structure includes a sealant on said bottom surface, said sealant forming said sealed interface with the front surface of the microelectronic unit.

6. The method as claimed in claim 5 wherein said sealant momentarily forms a flowable phase at the interface between the bottom surface of said dielectric structure and the front surface of said microelectronic unit during said engaging step, and wherein said flowable phase is cured to form an adhesive bond between said dielectric structure and said unit.

7. A method as claimed in claim 1 wherein said compliant layer is elastomeric.

8. The method as claimed in claim 1 wherein said microelectronic unit is a semiconductor chip.

9. The method as claimed in claim 1 wherein said microelectronic unit includes a substrate having a plurality of semiconductor chips thereon.

10. The method as claimed in claim 1 further comprising the step of engaging a multiplicity of said terminals simultaneously with a test fixture after bonding the connection component to the microelectronic unit and electrically testing the microelectronic unit through said test fixture.

11. A method of making connections to a microelectronic unit comprising the steps of:

(a) providing a connection component including a flexible dielectric top sheet, a plurality of terminals on said top sheet and a plurality of electrically conductive, elongated flexible leads connected to said terminals and extending side-by-side downwardly from said terminals away from said top sheet to bottom ends remote from the top sheet; and

(b) engaging said connection component structure with a front surface of a microelectronic unit having an array of contacts thereon while subjecting said connection component and unit to heat and pressure so that bottom ends of the leads on the connection component remote from the top sheet bond with the contacts on the unit to form electrical connections therewith, said connection component including a support layer which surrounds and supports said leads prior to and during said engaging step, said support layer being compliant and at least some of said leads being bent during said engaging step.

12. The method as claimed in claim 11 wherein said engaging step includes the step of supporting a top surface of said top sheet on a platen so that said leads extend away from said platen and urging said microelectronic unit towards said platen into engagement with said bottom ends of said leads.

13. The method as claimed in claim 11 further comprising the step of removing said support layer after said engaging step.

14. The method as claimed in claim 13 wherein said removing step includes the step of exposing said assembled microelectronic unit and connection component to a solvent so as to dissolve said support layer.

15. The method as claimed in claim 14 further comprising the step of forming a compliant layer between the microelectronic unit and the top sheet by injecting a curable liquid therebetween and then curing said liquid to form a compliant material.

16. A method of making a connection component for a microelectronic unit, the method comprising the steps of:

(a) providing a top sheet having an array of terminals thereon;

(b) attaching a lead to each said terminal so that said leads extend generally side-by-side and downwardly away from said top sheet and so that a bottom end of each lead is remote from the top sheet; and

(c) injecting a flowable, curable dielectric matieral so that said flowable material surrounds said leads and then curing said flowable material to form a support layer,

the method further comprising the step of engaging a first fixture with the bottom ends of the leads so that the fixture is spaced apart from the top sheet, said step of injecting a flowable material being conducted while said fixture is engaged with said bottom ends so that said flowable material is injected between said fixture and said top sheet.

17. The method as claimed in claim 16 further comprising the step of engaging a second fixture with a top side of said top sheet remote from said first fixture, whereby said top sheet and leads are engaged between said fixtures, and deforming said leads to bring said bottom ends of said leads to a predetermined distance from said top sheet by forcing said fixtures toward one another.

18. The method as claimed in claim 17 wherein said first fixture has a lead-engaging surface with an array of pockets at preselected locations thereon, the bottom end of each said lead being engaged in one said pocket prior to said deforming step, whereby said bottom ends of said leads will be brought to preselected locations during said deforming step.

19. The method as claimed in claim 18 wherein said deforming step is performed so as to buckle each said lead.

20. The method as claimed in claim 19 wherein said step of attaching said leads includes the step of bonding a wire to each said terminal so that said wire extends downwardly from the terminal and then severing the wire so that the severed end of the wire forms the bottom end of the lead.

21. The method as claimed in claim 20 wherein said severing step is performed by heating the wire to melt the wire and thereby form a bulbous portion at the severed bottom end.

22. The method as claimed in claim 16 further comprising the step of applying a bonding metal to the bottom ends of the leads.

23. The method as claimed in claim 16 further comprising the step of applying an sealant to the bottom surface of the support layer, remote from said top sheet.

24. The method as claimed in claim 16 wherein said flowable material is cured to form a compliant layer.