Water resistant surface mount device package

• US 9,831,393 B2
• Filed: 07/27/2011
• Issued: 11/28/2017
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Hong Kong Limited (Wolfspeed, Inc.)
• Inventors: Chan, Alex Chi Keung, Pang, Charles Chak Hau
• Primary Examiner(s): Warren, Matthew E
• Application Number:
  US13/192,293
• Publication Number:
  US 20120025227A1
• Time in Patent Office: 2,316 Days
• Field of Search: 257 89, 257 99, 257100
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• 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 2224/73265 Layer and wire connectors
• 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 25/0753 the devices being arranged next to each other
• 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 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• 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

The present invention is directed to LED packages and LED displays utilizing water resistant packages with improved structural integrity and customizable attributes. In some embodiments, the improved structural integrity is provided by various features in the lead frame that the casing material encompasses to improve the adhesion between the lead frame and the casing for a stronger, water resistant package. Moreover, in some embodiments the improved structural integrity and water resistance is further provided by cavity features that improve adhesion between the cavity and a protective encapsulant. Some embodiments also provide for packages with a greater overall height than the length of their side-exposed solder pins, which improves gel coverage of the side-exposed solder pins between adjacent packages.

Claims

1. An emitter package, comprising:

a casing comprising a cavity extending into an interior of the casing from a top surface of the casing;

an electrically conductive lead frame coupled to the casing and comprising a plurality of leads, each lead of the plurality of leads comprising a package mounting portion in a first plane, a device mounting portion in a plane other than the first plane, and an intermediate portion between the first plane and the second plane, at least one lead in the plurality of leads having a first surface, and a second surface opposite the first surface, in which the plurality of leads comprises a plurality of electrically conductive cathode parts and a plurality of electrically conductive anode parts, in which the plurality of electrically conductive anode parts are separated by a gap from the plurality of electrically conductive cathode parts;

at least one lead of the plurality of leads comprising at least one feature in a first portion of the electrically conductive lead frame, wherein the at least one feature comprises at least one of a through-hole, a cut, a spot punch, a U-bend, a projection, and an indentation, in which a material of the casing contacts the at least one feature, wherein the at least one feature is distinct from the gap and in at least the first surface and the second surface, in which a portion of the first surface and a portion of the second surface comprising the at least one feature is entirely inside the casing; and

a plurality of light emitting devices coupled to the electrically conductive lead frame, in which the plurality of light emitting devices and at least a second portion of the electrically conductive lead frame distinct from the first portion of the electrically conductive lead frame are exposed through the cavity.

2. The emitter package of claim 1, wherein the at least one feature comprises at least one through-hole;

wherein a shape of the at least one through-hole is a circle, a star, a polygon, a cross, an oval, a triangle, a square, a hexagon, a polygon, a diamond, or a rectangle.

3. The emitter package of claim 2, wherein said at least one through-hole comprises one or more steps.

4. The emitter package of claim 1, wherein at least one part in of the plurality of electrically conductive cathode parts and the plurality of electrically conductive anode parts is coupled to at least one of the light emitting devices, and each part in the plurality of electrically conductive anode parts and the plurality of electrically conductive cathode parts is electrically connected to one of the light emitting devices.

5. The emitter package of claim 1, wherein said light emitting devices are adapted to be energized to produce, in combination, all colors of the visible spectrum.

6. The emitter package of claim 4, wherein each of said light emitting devices comprises at least a first contact and a second contact, the first contact being electrically coupled to at least one part in the plurality of electrically conductive cathode parts, and the second contact is electrically coupled to at least one part in the plurality of electrically conductive anode parts.

7. The emitter package of claim 4, wherein:

the light emitting devices are arranged in a linear array extending in a first direction;

the plurality of electrically conductive anode parts are in a parallel relationship with each other; and

the plurality of electrically conductive cathode parts in parallel relationship with each other;

wherein the plurality of electrically conductive anode parts and the plurality of electrically conductive cathode parts extend in a second direction orthogonal to said first direction.

8. The emitter package of claim 1, wherein the electrically conductive lead frame comprises an electrically conductive metal or metal alloy.

9. The emitter package of claim 1, wherein the plurality of light emitting devices emit a plurality of colors.

10. The emitter package of claim 4, wherein each of the light emitting devices is attached to one part in the pluralities of electrically conductive cathode parts and electrically conductive anode parts via a wire bond and a respective part in the pluralities of electrically conductive cathode parts and electrically conductive anode parts via solder.

11. The emitter package of claim 1, wherein said casing is comprised of a plastic or resin.

12. The emitter package of claim 1, wherein a shape of a bottom of the cavity is different than a shape of a top of the cavity.

13. The emitter package of claim 1, further comprising a reflector in said cavity.

14. The emitter package of claim 1, wherein a shape of the electrically conductive lead frame is an L-leg configuration, a U-leg configuration, or an S-leg configuration.

15. The emitter package of claim 14, wherein the U-leg configuration and the S-leg configuration comprise a plurality of solder pins exposed on an outside of an end surface of the emitter package.

16. The emitter package of claim 1, wherein said features increase a surface area of said lead frame such that adhesion reliability between said casing and said lead frame is enhanced.

17. The emitter package of claim 1, wherein a first feature is on a vertical plane of the lead frame and a second feature is on a horizontal plane of the electrically conductive lead frame.

18. The emitter package of claim 17, wherein the second feature on the horizontal plane comprises a stepped portion along the electrically conductive lead frame.

19. The emitter package of claim 17, wherein the second feature on the horizontal plane comprises an indentation along the electrically conductive lead frame.

20. An emitter package, comprising:

a casing comprising a cavity extending into the interior of the casing from a top surface of the casing;

an electrically conductive lead frame comprising a package mounting portion at a first level and a device mounting portion at a level other than the first level, and a first surface and a second surface opposite the first surface, the electrically conductive lead frame being coupled to said casing, wherein the electrically conductive lead frame comprises an S-leg configuration or comprises an L-leg configuration in which the electrically conductive lead frame extends outside of the casing only at a bottom surface of the casing, and wherein a portion of the electrically conductive lead frame inside the casing comprises one or more bends, wherein a portion of said lead frame inside said casing comprises one or more U-bends, at least one of said U-bends being entirely in said casing; and

a plurality of light emitting devices coupled to the electrically conductive lead frame, the plurality of light emitting devices and portions of the electrically conductive lead frame exposed through the cavity;

wherein the electrically conductive lead frame comprises a plurality of electrically conductive cathode parts and a plurality of electrically conductive anode parts, in which the plurality of electrically conductive anode parts are separated by a gap from the plurality of electrically conductive cathode parts;

the electrically conductive lead frame comprising at least one feature in at least the first surface and the second surface such that a portion of the first surface and a portion of the second surface comprising the at least one feature is entirely encased by the casing.

21. The emitter package of claim 20, wherein the electrically conductive lead frame further comprises a plurality of solder pins which are exposed outside of an end surface of the casing.