Method of forming pre-fabricated wavelength converting elements for semiconductor light emitting devices

• US 7,553,683 B2
• Filed: 06/09/2004
• Issued: 06/30/2009
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Mueller-Mach, Regina B., Martin, Paul S., Mueller, Gerd O., Tichy, Ladislav, Ticha, Helena
• Primary Examiner(s): Huynh; Andy
• Application Number:
  US10/863,980
• Publication Number:
  US 20050274967A1
• Time in Patent Office: 1,847 Days
• Field of Search: 438/22, 438/24, 438/29, 438/35, 438/69, 257/88, 257/98, 257/794, 257/E33.061, 257/E33.063
• US Class Current: 438/29
• CPC Class Codes: C03C 14/004 the non-glass component being in the form of particles or flakes
• CPC Class Codes: C03C 2214/04 Particles; Flakes
• CPC Class Codes: C03C 2214/16 Microcrystallites, e.g. of optically or electrically active material
• CPC Class Codes: C03C 3/12 Silica-free oxide glass compositions
• CPC Class Codes: C03C 8/10 containing lead
• CPC Class Codes: C09K 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder

Abstract

A semiconductor light emitting device is provided with a separately fabricated wavelength converting element. The wavelength converting element, of e.g., phosphor and glass, is produced in a sheet that is separated into individual wavelength converting elements, which are bonded to light emitting devices. The wavelength converting elements may be grouped and stored according to their wavelength converting properties. The wavelength converting elements may be selectively matched with a semiconductor light emitting device, to produce a desired mixture of primary and secondary light.

Claims

1. A method comprising:

producing a sheet of an inorganic binder and embedded wavelength converting material; and

producing a plurality of separate individual wavelength converting elements from the sheet;

wherein the inorganic binder is a glass and wherein producing a sheet of an inorganic binder and embedded wavelength converting material comprises;

providing a mixture of wavelength converting material and powdered glass;

inserting the mixture in a crucible;

inserting the crucible into a furnace that is heated to produce a melt;

homogenizing the melt;

pouring the homogenized melt onto a plate; and

pressing the melt on the plate to produce the sheet.

2. The method of claim 1, wherein the glass is formed from material selected from the group consisting of GeO2, TeO2, PbO, CaO, and B203.

3. The method of claim 1, wherein the inorganic binder has an index of refraction that is greater than approximately 1.6.

4. The method of claim 1, wherein the inorganic binder has an index of refraction that is greater than approximately 1.8.

5. The method of claim 1, wherein the inorganic binder has a glass softening temperature of less than approximately 400°

C.

6. The method of claim 1, wherein the wavelength converting material is phosphor.

7. The method of claim 6, wherein the phosphor is YAG:

Ce.

8. The method of claim 1, further comprising bonding one of the plurality of wavelength converting elements to a semiconductor light emitting device die.

9. The method of claim 8, wherein the semiconductor light emitting device die has a flip-chip architecture.

10. The method of claim 8, wherein bonding one of the plurality of wavelength converting elements to a semiconductor light emitting device die comprises:

elevating a temperature of the wavelength converting element and the semiconductor light emitting device die; and

applying a pressure to press the wavelength converting element and the semiconductor light emitting device die together.

11. The method of claim 10, further comprising disposing a layer of bonding material between the wavelength converting element and the semiconductor light emitting device die.

12. The method of claim 8, further comprising bonding an optical component to the wavelength converting element.

13. The method of claim 8, further comprising shaping the wavelength converting element into a lens.

14. The method of claim 8 further comprising roughening the top surface of the wavelength converting element.

15. The method of claim 14, wherein roughening is performed through at least one of a mechanical process and a chemical process.

16. The method of claim 8, further comprising roughening the bottom surface of the wavelength converting element prior to bonding the wavelength converting element to the semiconductor light emitting device die.

17. The method of claim 8, further comprising:

providing an encapsulant over the bonded wavelength converting element and the semiconductor light emitting device die; and

roughening a top surface of the encapsulant.

18. The method of claim 8, further comprising:

measuring light conversion properties of the plurality of wavelength converting elements;

measuring a range of wavelengths emitted by the semiconductor light emitting device die; and

selecting the wavelength converting element to be bonded to the semiconductor light emitting device die based on the range of wavelengths emitted by the semiconductor light emitting device die, the light conversion properties of the wavelength converting element.

19. The method of claim 8, further comprising:

measuring light conversion properties of the plurality of wavelength converting elements;

grouping and storing the wavelength converting elements based on the light conversion properties.

20. A method comprising:

producing a sheet of an inorganic binder and embedded wavelength converting material;

producing a plurality of separate individual wavelength converting elements from the sheet;

wherein the inorganic binder is a glass and wherein producing a sheet of an inorganic binder and embedded wavelength converting material comprises;

providing a mixture of wavelength converting material and powdered glass;

inserting the mixture in a crucible;

inserting the crucible into a furnace heated between 800°

C. and 950°

C. to produce a melt;

homogenizing the melt in the furnace;

pouring the homogenized melt onto a plate; and

pressing the melt on the plate to produce the sheet.

21. A method comprising:

producing a sheet of an inorganic binder and embedded wavelength converting material; and

producing a plurality of separate individual wavelength converting elements from the sheet; and

bonding one of the plurality of wavelength converting elements to a semiconductor light emitting device die;

wherein the wavelength converting element has an indentation, the method further comprising fitting the semiconductor light emitting device die into the indentation of the wavelength converting element.

22. A method comprising:

producing a sheet of a binder and embedded wavelength converting material;

producing a plurality of separate individual wavelength converting elements from the sheet;

measuring light conversion properties of the plurality of wavelength converting elements; and

grouping and storing the wavelength converting elements based on the light conversion properties.

23. The method of claim 22, further comprising:

providing a semiconductor light emitting device die;

measuring a range of wavelengths emitted by the semiconductor light emitting device die; and

selecting one of the plurality of wavelength converting elements based on the range of wavelengths emitted by the semiconductor light emitting device die and the light conversion properties of the wavelength converting element.

24. The method of claim 23, further comprising bonding the selected wavelength converting element to the semiconductor light emitting device die.

25. The method of claim 24, wherein bonding the selected wavelength converting element to the semiconductor light emitting device die comprises:

elevating a temperature of the wavelength converting element and the semiconductor light emitting device die; and

applying a pressure to press the wavelength converting element and the semiconductor light emitting device die together.

26. The method of claim 24, further comprising disposing a layer of bonding material between the wavelength converting element and the semiconductor light emitting device die.

27. The method of claim 24, further comprising bonding an optical component to the wavelength converting element.

28. The method of claim 24, further comprising shaping the wavelength converting element into a lens.

29. The method of claim 22, wherein the sheet of binder and embedded wavelength converting material is a sheet of glass with embedded phosphor.

30. A method comprising:

producing a sheet of a binder and embedded wavelength converting material;

producing a plurality of separate individual wavelength converting elements from the sheet;

measuring the light conversion properties of the plurality of wavelength converting elements;

grouping and storing the wavelength converting elements based on the light conversion properties;

providing a semiconductor light emitting device die;

measuring the range of wavelengths emitted by the semiconductor light emitting device die;

selecting one of the plurality of wavelength converting elements based on the range of wavelengths emitted by the semiconductor light emitting device die and the light conversion properties of the wavelength converting element; and

bonding the selected wavelength converting element to the semiconductor light emitting device die;

wherein the wavelength converting element has an indentation, the method further comprising fitting the semiconductor light emitting device die into the indentation of the wavelength converting element.