Light emitting diode for harsh environments

• US 8,648,356 B2
• Filed: 04/08/2013
• Issued: 02/11/2014
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Original Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Inventors: Colvin, Jason D., Colvin, Arthur E. Jr., DeHennis, Andrew, Krsmanovic, Jody L.
• Primary Examiner(s): Valentine, Jami M
• Application Number:
  US13/858,532
• Publication Number:
  US 20130328089A1
• Time in Patent Office: 309 Days
• Field of Search: 257/79, 257/98, 257/99, 257/E33.056, 257/E33.067, 438/27, 356/442
• US Class Current: 257/79
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/8507 Probe photometers, i.e. with optical measuring part dipped into fluid sample
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01087 Francium [Fr]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 31/0203 Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/125 Composite devices with photosensitive elements and electroluminescent elements within one single body
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/483 : Containers
• CPC Class Codes: H01L 33/52 : Encapsulations
• CPC Class Codes: H01L 33/54 : having a particular shape
• 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

A light emitting diode for harsh environments includes a substantially transparent substrate, a semiconductor layer deposited on a bottom surface of the substrate, several bonding pads, coupled to the semiconductor layer, formed on the bottom surface of the substrate, and a micro post, formed on each bonding pad, for electrically connecting the light emitting diode to a printed circuit board. An underfill layer may be provided between the bottom surface of the substrate and the top surface of the printed circuit board, to reduce water infiltration under the light emitting diode substrate. Additionally, a diffuser may be mounted to a top surface of the light emitting diode substrate to diffuse the light emitted through the top surface.

Claims

1. A light emitting diode for harsh environments, comprising:

a substantially transparent substrate;

a semiconductor layer deposited on a bottom surface of the substrate;

a plurality of bonding pads, coupled to the semiconductor layer, formed on the bottom surface of the substrate;

a plurality of micro posts, formed on the bonding pads, for electrically connecting the light emitting diode to a printed circuit board; and

an underfill layer, including a polymer and a filler, disposed between the bottom surface of the substrate and a top surface of the printed circuit board, to reduce water infiltration under the substrate;

wherein the filler includes a plurality of microballoons.

2. The light emitting diode of claim 1, wherein the substrate is sapphire.

3. The light emitting diode of claim 1, wherein the semiconductor layer includes at least one p-n junction.

4. The light emitting diode of claim 1, wherein the plurality of bonding pads and the plurality of micro posts are gold.

5. The light emitting diode of claim 4, wherein the plurality of micro posts are bonded to the plurality of bonding pads and to a respective plurality of gold bonding pads on the printed circuit board, one micro post to each bonding pad pair.

6. The light emitting diode of claim 5, wherein the micro posts are bonded to the bonding pads using thermocompression bonding, thermosonic bonding, ultrasonic bonding, or welding.

7. The light emitting diode of claim 1, further comprising a diffuser, mounted to a top surface of the substrate, to diffuse the light emitted through the top surface of the substrate.

8. The light emitting diode of claim 1, wherein the filler is a light-scattering filler and the polymer is an optical epoxy.

9. The light emitting diode of claim 1, wherein the underfill layer is about 70% by weight of polymer and about 30% by weight of filler.

10. The light emitting diode of claim 1, wherein each microballoon has a diameter from about 2 μ

m to about 11 μ

m.

11. The light emitting diode of claim 1, wherein each microballoon is a gas-filled sphere having a diameter of about 11 μ

m and a wall thickness of about 1 μ

m.

12. The light emitting diode of claim 7, wherein the diffuser includes titanium(IV) oxide to increase light reflectivity.

13. The light emitting diode of claim 7, wherein the diffuser includes microballoons to increase light reflectivity.

14. The light emitting diode of claim 8, wherein the light-scattering filler is titanium(IV) oxide.

15. The light emitting diode of claim 1, wherein the microballoons are pre-treated with an adhesion promoter.

16. The light emitting diode of claim 15, wherein the adhesion promoter is silane.

17. The light emitting diode of claim 7, wherein the diffuser is a substantially transparent, hemispherical diffuser.

18. A semiconductor device for harsh environments, comprising:

a printed circuit board having a top surface with a plurality of bonding pads;

a light emitting diode, including;

a substantially transparent substrate,

a semiconductor layer deposited on a bottom surface of the substrate,

a plurality of bonding pads, coupled to the semiconductor layer, formed on the bottom surface of the substrate, and

a plurality of micro posts, formed on the bonding pads, bonded to the bonding pads of the printed circuit board;

an underfill layer, including a polymer and a filler, disposed between the bottom surface of the substrate and the top surface of the printed circuit board, to reduce water infiltration under the light emitting diode substrate; and

a substantially transparent, hemispherical diffuser, mounted to a top surface of the substrate, to diffuse the light emitted through the top surface of the substrate;

wherein the filler includes a plurality of gas-filled, glass microballoons.

19. The semiconductor device of claim 18, wherein the underfill layer is about 70% by weight of epoxy and about 30% by weight of filler.

20. The semiconductor device of claim 18, wherein each microballoon has a diameter from about 2 μ

m to about 11 μ

m, and a wall thickness of about 1 μ

m.

21. The semiconductor device of claim 18, wherein the filler is a light-scattering filler and the polymer is an optical epoxy.

22. The semiconductor device of claim 21, wherein the light-scattering filler is titanium(IV) oxide.

23. The semiconductor device of claim 18, wherein the micro posts are bonded to the bonding pads using thermocompression bonding, thermosonic bonding, ultrasonic bonding, or welding.

24. The semiconductor device of claim 18, wherein the microballoons are pre-treated with an adhesion promoter.

25. The semiconductor device of claim 24, wherein the adhesion promoter is silane.

26. The semiconductor device of claim 18, wherein the plurality of bonding pads and the plurality of micro posts are gold.