LED PACKAGE WITH SURFACE TEXTURES AND METHODS OF FORMATION

• US 20160247984A1
• Filed: 02/20/2015
• Published: 08/25/2016
• Est. Priority Date: 02/20/2015
• Status: Active Grant

• Current Assignee: Luminus, Inc.
• Original Assignee: Luminus, Inc.
• Inventors: Liu, Saijin, Ma, Hongtao, Tong, Tao
• Granted Patent: US 11,217,735 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 having a particular shape
• 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 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Methods and apparatus are provided for LED packages with surface textures. In one novel aspect, microstructures are formed on surfaces of the LED package such that light extract efficiency is improved. In one embodiment, the LED package has a silicone-encapsulating layer scattered with phosphors. In another embodiment, the LED package has a leadframe substrate. The microstructure can be micro lens, micro dents, micro pillars, micro cones, or other shapes. The microstructures can be periodically arranged or randomly arranged. In one novel aspect, the compression molding process is used to form rough surfaces. The molding block or the release film is modified with microstructures. In another novel aspect, sandblasting process is used. In one embodiment, microstructures are formed on sidewalls using the sandblasting process. The hardness, the angle, and/or the size of the blasting media are selected to improve the efficiency of the LED package.

Claims

1. A light emitting devices (LED) package, comprising:

a substrate having a top surface;

one or more LEDs attaching to the top surface of the leadframe substrate;

a silicone encapsulating layer covering the LEDs and a substantial area of the substrate, wherein the silicone encapsulating layer is scattered with phosphor particles; and

microstructures on a top surface of the silicone-encapsulating layer.

2. The LED package of claim 1, wherein the substrate is a leadframe substrate.

3. The LED package of claim 1, wherein the silicone-encapsulating layer is cube shaped.

4. The LED package of claim 3, further comprising microstructures on side surfaces of the silicone-encapsulating layer.

5. The LED package of claim 1, wherein the microstructures are of one or more shapes comprising:

micro lens, micro dents, micro pillars, and micro cones.

6. The LED package of claim 1, wherein the microstructures are randomly arranged.

7. The LED package of claim 1, wherein the microstructures are periodically arranged with a selected pattern, and wherein the pattern is selected to increase an efficiency of the LED package.

8. The LED package of claim 7, wherein the microstructures are micro lens with diameters about 2 μ

m to 20 μ

m.

9. A method, comprising:

attaching one or more light emitting devices (LEDs) to a substrate;

depositing an adequate amount of silicone mixed with phosphor particles into a molding cavity, wherein the top surface of the molding cavity has a modified molding structure with microstructures;

compression molding the substrate with the one or more LEDs to form a LED package such that the LED package has microstructures on its top surface transferred from the modified molding structure.

10. The method of claim 9, wherein the substrate is a leadframe substrate.

11. The method of claim 9, wherein the modified molding structure is a molding block with microstructures on the top surface.

12. The method of claim 9, wherein the modified molding structure is a release film with microstructures placed on the top surface of the molding cavity.

13. The method of claim 9, wherein the microstructures are of one or more shapes comprising:

micro lens, micro dents, micro pillars, and micro cones.

14. The method of claim 9, wherein the microstructures are randomly arranged.

15. The method of claim 9, wherein the microstructures are periodically arranged.

16. A method, comprising:

placing a light emitting device (LED) surface mount technology (SMT) package in a soundblasting chamber by mounting the LED SMT package on a base, wherein the LED SMT package has a silicone-encapsulating layer scattered with phosphor particles;

selecting a blasting media that is harder than silicone and softer than the phosphor particles such that only the silicone are removed without attacking the phosphors;

sandblasting the LED package such that surfaces of the LED package contains microstructures.

17. The method of claim 16, wherein the LED SMT package has a leadframe substrate.

18. The method of claim 16, further comprising:

selecting the size of the sandblasting media based on a size-selection criterion such that the efficiency of the LED SMT package is increased.

19. The method of claim 16, further comprising:

selecting an angle of a blasting direction based on an angle-selection criterion such that the efficiency of the LED SMT package is increased.

20. The method of claim 16, further comprising:

tilting the base such that side surfaces of the LED SMT package contains microstructures.