Flip-chip packaging method for light emitting diode with eutectic layer not overlapping insulating layer

• US 7,569,420 B2
• Filed: 05/07/2008
• Issued: 08/04/2009
• Est. Priority Date: 08/08/2006
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Huga Optotech Incorporated (Ennostar, Inc.)
• Inventors: Tung, Ching-Wen
• Primary Examiner(s): Pham; Thanh V
• Application Number:
  US12/116,950
• Publication Number:
  US 20090124031A1
• Time in Patent Office: 454 Days
• Field of Search: 438/22, 438/25, 438/26, 438/48, 438/51, 438/54, 438/55, 438/108, 257/E21.503, 257/E21.511, 257/E33.057
• US Class Current: 438/108
• CPC Class Codes: H01L 2224/0554 External layer
• CPC Class Codes: H01L 2224/0555 Shape
• CPC Class Codes: H01L 2224/0556 Disposition
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05666 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/16238 the bump connector connecting to a bonding area protruding from the surface of the item
• CPC Class Codes: H01L 2224/29034 the layer connector covering only portions of the surface to be connected
• CPC Class Codes: H01L 2224/29124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/29144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32227 the layer connector connecting to a bond pad of the item
• CPC Class Codes: H01L 2224/32502 comprising an eutectic alloy
• CPC Class Codes: H01L 2224/32506 comprising an eutectic alloy
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2224/49107 : on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73203 : Bump and layer connectors
• CPC Class Codes: H01L 2224/73265 : Layer and wire connectors
• CPC Class Codes: H01L 2224/81 : using a bump connector
• CPC Class Codes: H01L 2224/81192 : wherein the bump connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81903 : by means of a layer connector
• CPC Class Codes: H01L 2224/83 : using a layer connector
• CPC Class Codes: H01L 2224/83101 : as prepeg comprising a layer connector, e.g. provided in an insulating plate member
• CPC Class Codes: H01L 2224/83192 : wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83805 : involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 2224/9211 : Parallel connecting processes
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 24/29 : of an individual layer connector
• CPC Class Codes: H01L 24/32 : of an individual layer connector
• CPC Class Codes: H01L 24/73 : Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/92 : Specific sequence of method steps
• 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 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: Y10T 225/286 : With work-abutment stop
• CPC Class Codes: Y10T 225/29 : Applied to running length work
• CPC Class Codes: Y10T 225/298 : Blades or severing devices
• CPC Class Codes: Y10T 225/30 : Breaking or tearing apparatus
• CPC Class Codes: Y10T 225/343 : Plural divergent work paths

Abstract

A packaging structure and method for a light emitting diode is provided. The present invention uses flip-chip and eutectic bonding technology to attach a LED to a thermal and electrical conducting substrate. The flip-chip packaging structure comprises a thermal and electrical conducting substrate having an insulating layer formed in an appropriate area on the top surface of the substrate and a bonding pad formed on top of the insulating layer; and a LED reversed in a flip-chip style and joined to the substrate by eutectic bonding. A first electrode of the LED is eutectically bonded to an appropriate area on the top surface of the substrate via a eutectic layer, while a second electrode of the LED is electrically connected to the bonding pad.

Claims

1. A packaging method of a LED having a first electrode and a second electrode on a top side of said LED, comprising the steps of:

(1) providing a thermal and electrical conducting substrate;

(2) forming an insulating layer in an appropriate area on the top surface of said substrate, and forming a bonding pad on top of said insulating layer;

(3) reversing said LED so that said first electrode and said second electrode face the top surface of said substrate; and

(4) eutectic bonding said LED to said substrate so that a eutectic layer is formed and bonded between said first electrode and an appropriate area not overlapping said insulating layer on the top surface of said substrate, and said second electrode electrically connected to said bonding pad.

2. The packaging method as claimed in claim 1, wherein said thermal conducting substrate made of Al.

3. The packaging method as claimed in claim 1, wherein said thermal conducting substrate is made of Cu.

4. The packaging method as claimed in claim 1, wherein said insulating layer is made of SiO₂.

5. The package method as claimed in claim 1, wherein said step (4) further comprising:

plating a metallic layer in said appropriate area not overlapping said insulating layer before conducting said eutectic bonding.

6. The packaging method as claimed in claim 5, wherein said eutectic layer is eutectic Cu/Au.

7. The packaging method as claimed in claim 5, wherein said eutectic layer is eutectic Cu/Au/Al.

8. The packaging method as claimed in claim 1, wherein said step (4) further comprising:

interposing a metallic plate between said appropriate area not overlapping said insulating layer and said first electrode before conducting said eutectic bonding.

9. The packaging method as claimed in claim 8, wherein said eutectic layer is eutectic Cu/Au.

10. The packaging method as claimed in claim 8, wherein said eutectic layer is eutectic Cu/Au/Al.