Packages for semiconductor die

• US 6,329,220 B1
• Filed: 11/23/1999
• Issued: 12/11/2001
• Est. Priority Date: 11/23/1999
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Corisis, David J., Cobbley, Chad A., Bolken, Todd O., Baerlocher, Cary J.
• Primary Examiner(s): Bowers, Charles
• Assistant Examiner(s): JONES, JOSETTA I
• Application Number:
  US09/448,072
• Time in Patent Office: 749 Days
• Field of Search: 438/106, 438/127
• US Class Current: 438/106
• CPC Class Codes: H01L 21/561 Batch processing
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/3107 the device being completely enclosed
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• 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 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/1815 : Shape
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H05K 2201/10568 : Integral adaptations of a component or an auxiliary PCB for mounting, e.g. integral spacer element
• CPC Class Codes: H05K 2201/10734 : Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 2201/10977 : Encapsulated connections
• CPC Class Codes: H05K 2201/2036 : Permanent spacer or stand-off in a printed circuit or printed circuit assembly
• CPC Class Codes: H05K 3/303 : Surface mounted components, e.g. affixing before soldering, aligning means, spacing means H05K3/32 takes precedence
• CPC Class Codes: H05K 3/305 : Affixing by adhesive
• 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

Abstract

A ball grid array assembly includes a package cover that encapsulates a die and a portion of a substrate to which the die is attached, including an edge of the substrate. Encapsulation of the substrate edge by the cover reduces penetration of moisture or other contaminants into the substrate. The cover includes a rib that extends to contact a circuit board to which the ball grid array assembly is connected. With such a rib, planarity between the circuit board and the substrate is maintained during soldering.

Claims

1. A method of reducing moisture penetration into a circuit assembly, the circuit assembly including a substrate attached to a circuit board, comprising:

covering at least a portion of an edge of the substrate with an encapsulant; and

forming a rib that covers at least a portion of a first surface of the substrate and extends from a second surface of the substrate and contacts the circuit board.

2. The method of claim 1, wherein the circuit assembly includes a die and further comprising covering the die with the encapsulant.

3. The method of claim 1, wherein the rib is formed of the encapsulant.

4. A method of soldering a substrate provided with solder bumps to a circuit board, the method comprising:

contacting the circuit board with the solder bumps;

heating the solder bumps so that the solder bumps reflow to connect to the circuit board; and

providing a rib situated to maintain a separation between the substrate and the circuit board as the solder bumps reflow.

5. The method of claim 4, wherein the rib is provided at at least a portion of a perimeter of the substrate.

6. The method of claim 4, wherein the solder bumps are heated so that the rib contacts the circuit board and acts as a stop.

7. The method of claim 6, further comprising bonding the rib to the circuit board.

8. The method of claim 6, further comprising bonding the rib to the substrate.

9. The method of claim 8, further comprising bonding the rib to the circuit board.

10. The method of claim 4, further comprising encapsulating at least a portion of an edge of the substrate with the rib.

11. A method of packaging a die, comprising:

bonding the die to a first surface of a substrate;

attaching one or more solder bumps to a second surface of the substrate; and

providing an encapsulating layer that encapsulates the die and includes a rib that encapsulates at least a perimeter portion of the second surface of the substrate.

12. The method of claim 11, wherein the encapsulating layer encapsulates at least a portion of the first surface of the substrate.

13. The method of claim 12, further comprising defining the rib with a mold.

14. The method of claim 11, wherein the rib has a thickness that is at least as large as a thickness of the solder bumps.

15. A method of attaching a substrate to a circuit board, comprising:

providing a rib that covers a perimeter portion of a surface of a substrate; and

electrically connecting the substrate to the circuit board so that the separation of the substrate and the circuit board is defined by the rib.

16. A method for attaching a ball grid array packaged die to a circuit board, comprising:

providing a support band extending along at least a portion of a perimeter of a surface of the ball grid array packaged die; and

heating the packaged device to reflow solder balls provided at the surface of the ball grid array packaged die.

17. A method of making a package for a die mounted to a substrate, comprising:

contacting a first surface of the substrate with a first mold;

contacting the first mold with a second mold; and

injecting an encapsulant into a cavity defined by the first mold and the second mold, wherein one of the first mold and the second mold define a cavity for a rib.