Accurate Alignment of an LED Assembly

• US 20070117273A1
• Filed: 01/23/2007
• Published: 05/24/2007
• Est. Priority Date: 01/16/2003
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Martin, Paul, Aziz, Zainul, Elpedes, Cresente
• Granted Patent: US 7,795,051 B2
• Time in Patent Office: Days
• US Class Current: 438/123
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/642 characterized by the shape

Abstract

An LED assembly includes a heat sink and a submount. The heat sink has a top mating surface that is solder wettable, and the submount has a bottom mating surface that is solder wettable. The top and the bottom mating surfaces have substantially the same shape and area. The submount is soldered atop the heat sink. During solder reflow, the molten solder causes the submount to align with the top mating surface of the heat sink. The LED assembly may further include a substrate having a top mating surface, and the heat sink may further include a bottom mating surface. The top and bottom mating surfaces have substantially the same shape and area. The heat sink is soldered atop the substrate. During solder reflow, the molten solder causes the heat sink to align with the top mating surface of the substrate.

Claims

1. A method for assembling LED components, comprising:

mounting an LED die on a submount;

applying a first solder between a bottom mating surface of the submount and a top mating surface of a heat sink, wherein the bottom mating surface and the top mating surface have substantially the same shape and area; and

reflowing the first solder, whereby the submount and the heat sink are aligned and bonded together during reflowing.

2. The method of claim 1, wherein said applying a first solder comprises:

applying the first solder to the top mating surface of the heat sink; and

placing the bottom mating surface of the submount on the first solder atop the top mating surface of the heat sink.

3. The method of claim 1, further comprising:

applying a second solder between a second bottom mating surface of the heat sink and a second top mating surface of a substrate, wherein the second bottom mating surface and the second top mating surface have substantially the same shape and area; and

reflowing the second solder, whereby the heat sink and the substrate are aligned and bonded together during reflowing.

4. The method of claim 3, wherein said applying a second solder comprises:

applying the second solder to the second top mating surface of the substrate; and

placing the second bottom mating surface of the heat sink on the second solder

atop the second top mating surface of the substrate.

5. The method of claim 3, wherein said reflowing the first solder occurs at a higher temperature than said reflowing the second solder.

6. The method of claim 3, wherein said mounting an LED die on a submount comprises:

applying a third solder between the LED die and the submount; and

reflowing the third solder, whereby the LED die and the submount are bonded together during reflowing.

7. The method of claim 6, wherein said reflowing the third solder occurs at a higher temperature than said reflowing the first solder.

8. The method of claim 1, wherein the bottom mating surface and the top mating surface have a hexagon shape.

9. The method of claim 3, wherein the second bottom mating surface and the second top mating surface have a hexagon shape.

10. The method of claim 3, wherein the heat sink is a thermally conducting slug.

11. The method of claim 1, wherein the top and the bottom mating surfaces have substantially the same shape and area when one circumference is at least 50% of another circumference.

12. The method of claim 1, wherein the top and bottom mating surfaces have substantially the same shape and area when the first solder aligns the top and bottom mating surfaces with an accuracy of at least 20 microns.