Light emitting device

• US 8,759,846 B2
• Filed: 08/11/2008
• Issued: 06/24/2014
• Est. Priority Date: 08/28/2007
• Status: Active Grant

• Current Assignee: Suzhou Lekin Semiconductor Company Limited
• Original Assignee: LG Innotek Company Limited (LG Corporation)
• Inventors: Park, Jun Seok
• Primary Examiner(s): Tran, Tony
• Application Number:
  US12/671,179
• Publication Number:
  US 20100193807A1
• Time in Patent Office: 2,143 Days
• Field of Search: 257/88, 257/99, 257/E33.066, 257/E33.075
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45139 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/00011 Not 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 2924/01049 Indium [In]
• CPC Class Codes: H01L 2924/207 Diameter ranges
• CPC Class Codes: H01L 33/641 characterized by the materials
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 1/0209 External configuration of printed circuit board adapted for heat dissipation, e.g. lay-out of conductors, coatings
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/09318 Core having one signal plane and one power plane
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254
• CPC Class Codes: H05K 2201/09781 Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]

Abstract

A light emitting device is provided. The light emitting device comprises a substrate, a first lead frame and a second lead frame on the substrate, a first light emitting diode, a heat conductor on the substrate, and a heat transfer pad. The first light emitting diode on the first lead frame is electrically connected to the first lead frame and the second lead frame. The heat conductor is electrically separated from the first lead frame. The heat transfer pad contacts the first lead frame and the heat conductor thermally to connect the first lead frame to the heat conductor.

Claims

1. A light emitting device comprising:

a substrate including a plurality of via holes;

a first lead frame disposed on a top surface of the substrate;

a second lead frame disposed on the top surface of the substrate and spaced from the first lead frame;

a metal layer disposed under a lower surface of the substrate;

a light emitting diode disposed on a top surface of the first lead frame and electrically connected to the first lead frame and the second lead frame, the light emitting diode vertically overlapping the first lead frame;

a heat conductive layer physically contacting the top surface of the substrate;

a heat transfer pad physically contacting the top surface of the first lead frame and a top surface of the heat conductive layer; and

a molding member directly contacting the light emitting diode and the first lead frame, the molding member not contacting the heat transfer pad,

wherein the first lead frame comprises a protruding portion protruded toward the heat conductive layer and the heat conductive layer comprises a recessed portion, the protruding portion of the first lead frame protruding into the recessed portion of the heat conductive layer,

wherein the plurality of via holes overlap the heat conductive layer and the metal layer,

wherein the heat transfer pad is made of one of a resin, a tape and paint, and does not overlap the light emitting diode,

wherein the heat conductive layer does not vertically overlap entire regions of the first lead frame, the second lead frame and the light emitting diode,

wherein the heat conductive layer is not electrically connected to the first lead frame and the second lead frame,

wherein the heat transfer pad vertically overlaps the protruding portion, a portion of the first lead frame, the recessed portion and a portion of the heat conductive layer,

wherein the heat transfer pad does not vertically overlap the plurality of via holes,

wherein the molding member does not vertically overlap an entire region of the heat conductive layer and an entire region of the heat transfer pad,

wherein the heat transfer pad has a material different from the molding member,

wherein the heat conductive layer includes a metal material, and

wherein the heat transfer pad is formed of an electrically nonconductive material;

wherein the heat transfer pad directly contacts the top surface of the first lead frame, the top surface of the heat conductive layer, and an exposed portion of the substrate between the first lead frame and the heat conductive layer.

2. The light emitting device according to claim 1, wherein the first lead frame and the light emitting diode are electrically connected to each other through a wire.

3. The light emitting device according to claim 1, wherein the second lead frame is electrically connected to the light emitting diode through a wire.

4. The light emitting device according to claim 1, wherein the recessed portion surrounds the protruding portion.

5. The light emitting device according to claim 1, wherein at least a part of a portion of the first lead frame that contacts the lower surface of the heat transfer pad is formed of a material with heat conductivity higher than that of a portion of the first lead frame that does not contact the lower surface of the heat transfer pad.

6. The light emitting device according to claim 1, wherein at least a part of a portion of the heat conductive layer that contacts the heat transfer pad is formed of a material with heat conductivity higher than that of a portion of the heat conductive layer does not contact the heat transfer pad.

7. The light emitting device according to claim 1, wherein the heat transfer pad thermally connects the second lead frame to the heat conductive layer, and

wherein a width of the heat transfer pad is greater than a width of an interval between the first lead frame and the heat conductive layer.