Method of producing an article comprising a multichip assembly

• US 4,954,453 A
• Filed: 02/24/1989
• Issued: 09/04/1990
• Est. Priority Date: 02/24/1989
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Venutolo, John H.
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): Griffis, Andrew
• Application Number:
  US07/316,050
• Time in Patent Office: 557 Days
• Field of Search: 437/209, 437/8, 29/847, 29/762, 29/742
• US Class Current: 29/592
• CPC Class Codes: B23K 1/018 Unsoldering; Removal of melted solder or other residues
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/75 Apparatus for connecting with bump connectors or layer connectors
• CPC Class Codes: H01L 2224/75251 in the lower part of the bonding apparatus, e.g. in the apparatus chuck
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 24/75 Apparatus for connecting with bump connectors or layer connectors
• 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 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01075 Rhenium [Re]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• CPC Class Codes: H01L 2924/014 Solder alloys
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H05K 13/0486 : Replacement and removal of components
• CPC Class Codes: H05K 2203/162 : Testing a finished product, e.g. heat cycle testing of solder joints
• CPC Class Codes: H05K 2203/176 : Removing, replacing or disconnecting component; Easily removable component
• 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: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49 : Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49156 : with selective destruction of conductive paths
• CPC Class Codes: Y10T 29/53187 : Multiple station assembly apparatus
• CPC Class Codes: Y10T 29/53274 : Means to disassemble electrical device
• CPC Class Codes: Y10T 29/53552 : Valve applying or removing

Abstract

In methods of producing an article that comprises a multichip assembly, in which the (typically electronic but not excluding opto-electronic) chips are bonded to a substrate by means of spaced-apart localized solder regions (frequently referred to as "solder bumps"), it is frequently desirable to be able to remove a given chip from the substrate and to replace it with another chip. According to the invention, such chip removal is accomplished by a technique that comprises heating the solder bumps between the given chip and the substrate to a temperature below the solidus temperature of the solder in a manner such that a temperature gradient exists across the solder bumps, and applying to the given chip simultaneously a torque and a lifting force sufficient to cause separation of the given chip from the substrate. The technique can be carried out such that the solder bumps remaining on the substrate after chip removal are of substantially uniform height, facilitating attachment of the replacement chip.

Claims

1. Method of producing an article comprising a multichip assembly that comprises a substrate with a multiplicity of electronic subassemblies thereon, a given subassembly attached to the substrate by means of a multiplicity of localized solder regions, the subassemblies to be referred to as "chips" and the localized solder regions to be referred to as "solder bumps";

the method comprising

(a) producing multichip assemblies;

(b) testing at least some of the multichip assemblies;

(c) if the testing indicates that a given assembly does not meet predetermined criteria due to a fault associated with a given chip or chips then the given chip or chips are removed from the substrate, and a replacement chip or chips are attached to the substrate; and

the method further comprises

(d) completing producing the article;

CHARACTERIZED IN THAT step (c) comprises

(e) heating at least the solder bumps between the given chip and the substrate to a temperature Tr, such that T_r <

T_m, where T_m is the absolute solidus temperature of the solder, the heating carried out such that a temperature gradient exists across the solder bumps; and

(f) applying to the given chip a combination of a torque and a lifting force, the combination being sufficient to cause separation of the given chip from the substrate.

2. Method of claim 1, wherein T_r is in the range 0.85-0.95 T_m.

3. Method of claim 2, wherein the solder comprises about 95% by weight Pb, the remainder comprising Sn, and wherein T_r is in the range 240°

-260°

C.

4. Method of claim 1, wherein the torque and lifting force result in a lifting motion in the range 5-50 μ

m/degree rotation.

5. Method of claim 1, wherein the article is the multichip assembly.