Radiation emitter device having an encapsulant with different zones of thermal conductivity

• US 6,521,916 B2
• Filed: 04/13/2001
• Issued: 02/18/2003
• Est. Priority Date: 03/15/1999
• Status: Expired due to Term

• Current Assignee: Everlight Electronics Company Limited
• Original Assignee: Gentex Corporation
• Inventors: Roberts, John K., Reese, Spencer D.
• Primary Examiner(s): Abraham, Fetsum
• Assistant Examiner(s): Andujar, Leonardo
• Application Number:
  US09/835,278
• Publication Number:
  US 20010026011A1
• Time in Patent Office: 676 Days
• Field of Search: 257/678, 257/98, 257/100, 257/99
• US Class Current: 257/100
• CPC Class Codes: B60Q 1/2665 on rear-view mirrors lighting devices for vehicle interior on or for rear-view mirrors B60Q3/258
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/4823 connecting the wire to a pin of the item
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/48599 Principal constituent of the connecting portion of the wire connector being Gold (Au)
• CPC Class Codes: H01L 2224/48699 Principal constituent of the connecting portion of the wire connector being Aluminium (Al)
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/49562 for devices being provided for in H01L29/00
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 24/97 : the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/10336 : Aluminium gallium arsenide [AlGaAs]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12044 : OLED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/351 : Thermal stress
• 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 33/483 : Containers
• CPC Class Codes: H01L 33/50 : Wavelength conversion elements
• 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 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/641 : characterized by the materials
• CPC Class Codes: H01L 33/642 : characterized by the shape
• CPC Class Codes: H01L 33/647 : the elements conducting electric current to or from the semiconductor body
• CPC Class Codes: H10K 50/84 : Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/85 : Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/87 : Arrangements for heating or cooling

Abstract

A radiation emitting device of the present invention includes at least one radiation emitter, first and second electrical leads electrically coupled to the radiation emitter, and an integral encapsulant configured to encapsulate the radiation emitter and a portion of the first and second electrical leads. The encapsulant has at least a first zone and a second zone, where the second zone exhibits at least one different characteristic from the first zone. Such different characteristics may be a physical, structural, and/or compositional characteristic. Preferably, the at least one different characteristic includes at least one of the following: mechanical strength, thermal conductivity, thermal capacity, coefficient of thermal expansion, specific heat, oxygen and moisture impermeability, adhesion, and transmittance with respect to radiation emitted from the radiation emitter. The radiation emitter may be in a form of an emitter, and is preferably an LED.

Claims

1. A radiation emitting device comprising:

at least one radiation emitter;

first and second electrical leads electrically coupled to said radiation emitter; and

an integral encapsulant configured to encapsulate said radiation emitter and a portion of said first and second electrical leads, said encapsulant having at least a first zone and a second zone, the second zone exhibiting at least one different characteristic from the first zone, wherein said at least one different characteristic is that said second zone has a higher thermal conductivity than said first zone, and wherein, in both said zones, said encapsulant is made of a material with a relatively high electrical resistivity.

2. The radiation emitting device of claim 1, wherein said at least one different characteristic is a physical characteristic.

3. The radiation emitting device of claim 1, wherein said at least one different characteristic is an optical characteristic.

4. The radiation emitting device of claim 3, wherein said at least one different optical characteristic is transparency.

5. The radiation emitting device of claim 3, wherein said at least one different optical characteristic is diffusivity.

6. The radiation emitting device of claim 1, wherein said at least one different characteristic is a thermal characteristic.

7. The radiation emitting device of claim 6, wherein said at least one different thermal characteristic is thermal expansion coefficient.

8. The radiation emitting device of claim 6, wherein said at least one different thermal characteristic is specific heat.

9. The radiation emitting device of claim 6, wherein said at least one different thermal characteristic is glass transition temperature.

10. The radiation emitting device of claim 1, wherein said at least one different characteristic is a structural characteristic.

11. The radiation emitting device of claim 10, wherein said at least one different characteristic includes at least one of tensile strength and compression strength.

12. The radiation emitting device of claim 1, wherein said at least one different characteristic is a compositional characteristic.

13. The radiation emitting device of claim 1, wherein said radiation emitter is mounted on one of said first and second electrical leads.

14. The radiation emitting device of claim 1 and further including a wire bond extending from one of said first and second electrical leads to said radiation emitter.

15. The radiation emitting device of claim 1, wherein the at cast one different characteristic includes at least one of the following:

mechanical strength, thermal capacity, specific heat, coefficient of thermal expansion, adhesion, oxygen impermeability, moisture impermeability, and transmittance for radiation emitted from said radiation emitter.

16. The radiation emitting device of claim 1, wherein one of said zones is at least partially transparent to radiation emitted from said radiation emitter.

17. The radiation emitting device of claim 1, wherein a region of said encapsulant is configured to function as a lens.

18. The radiation emitting device of claim 1, wherein a region of said first zone of said encapsulant is configured to function as a lens.

19. The radiation emitting device of claim 18, wherein said second zone of said encapsulant is configured to retain said electrical leads.

20. The radiation emitting device of claim 19, wherein said lens is formed on a side of said encapsulant different from any sides from which said electrical leads extend.

21. The radiation emitting device of claim 20, wherein the side on which said lens is formed is opposite a side from which said electrical leads extend.

22. The radiation emitting device of claim 20, wherein the side on which said lens is formed is adjacent sides from which said electrical leads extend.

23. The radiation emitting device of claim 1, wherein said electrical leads are wave-solderable.

24. The radiation emitting device of claim 1, wherein said radiation emitter is an LED chip.

25. The radiation emitting device of claim 1, wherein said radiation emitter is a PLED.

26. The radiation emitting device of claim 1, wherein said radiation emitter is an OLED.

27. The radiation emitting device of claim 1, wherein said radiation emitter is an LEP.

28. The radiation emitting device of claim 1, wherein said radiation emitter is a semiconductor optical radiation emitter.

29. The radiation emiting device of claim 1, wherein said at least one radiation emitter includes a first radiation emitter and said device further comprises a second radiation emitter, both of said first and second radiation emitters are encapsulated by said encapsulant.

30. The radiation emitting device of claim 29, wherein said second radiation emitter is an LED chip.

31. The radiation emitting device of claim 29, wherein said second radiation emitter is a photoluminescent emitter.

32. The radiation emitting device of claim 29, wherein the first radiation emitter is an LED chip and said second radiation emitter is a photoluminescent emitter.

33. The radiation emitting device of claim 1, wherein said first zone of said encapsulant is optically transparent and extends from said radiation emitter to a light output surface of said encapsulant.

34. The radiation emitting device of claim 1, wherein said second zone has a higher thermal capacity than said first zone.

35. The radiation emitting device of claim 1, wherein said second zone has a greater mechanical strength than said first zone.

36. The radiation emitting device of claim 1, wherein said second zone has a lower coefficient of thermal expansion than said first zone.

37. The radiation emitting device of claim 1, wherein said second zone has a greater adhesion strength than said first zone with respect to said electrical leads.

38. The radiation emitting device of claim 1, wherein said second zone has lower oxygen permeability than said first zone.

39. The radiation emitting device of claim 1, wherein said second zone has lower moisture permeability than said first zone.

40. The radiation emitting device of claim 1, wherein said second zone has a higher specific heat than said first zone.

41. The radiation emitting device of claim 1, wherein said first and second zones of said encapsulant are cohesively bonded.

42. The radiation emitting device of claim 1, wherein said integral encapsulant is heterogeneous.

43. The radiation emitting device of claim 1, wherein said electrical leads extend from said encapsulant substantially non-perpendicular to the optical axis of the device.

44. The radiation emitting device of claim 1, wherein said first and second zones are made of different compositions and wherein a gradient mix of the different compositions exists between said zones.

45. The radiation emitting device of claim 1, wherein both said zones of said encapsulant are made of a thermoset material.

46. The radiation emitting device of claim 1, wherein said encapsulant is integrally molded.

47. The radiation emitting device of claim 1 and further including a glob-top disposed over said radiation emitter.

48. The radiation emitting device of claim 47, wherein said glob-top includes a photoluminescent material.

49. The radiation emitting device of claim 1, wherein, in said second zone, said encapsulant physically contacts said electrical leads.

50. The radiation emitting device of claim 1, wherein, in said second zone, said encapsulant is an epoxy.

51. An optical radiation emitting device comprising:

an optical radiation emitter;

first and second electrical leads electrically coupled to said optical radiation emitter; and

an integrally molded encapsulant configured to encapsulate said optical radiation emitter and a portion of said first and second electrical leads, said encapsulant being made of a first composition that is substantially optically transparent to radiation emitted by said radiation emitter, and a second composition having different properties than said first composition including a higher thermal conductivity than said first composition, wherein said encapsulant is made of a material with a relatively high electrical resistivity.

52. The radiation emitting device of claim 51, wherein said first and second compositions are substantially segregated into different regions of said encapsulant.

53. The radiation emitting device of claim 51, wherein said second composition is substantially opaque.

54. The radiation emitting device of claim 51, wherein said first composition is substantially transparent.

55. The radiation emitting device of claim 51, wherein said second composition has a higher thermal capacity than said first composition.

56. The radiation emitting device of claim 51, wherein said second composition has a greater mechanical strength than said first composition.

57. The radiation emitting device of claim 51, wherein said second composition has a lower coefficient of thermal expansion than said first composition.

58. The radiation emitting device of claim 51, wherein said second composition has a greater adhesion strength than said first composition with respect to said electrical leads.

59. The radiation emitting device of claim 51, wherein said second composition has lower oxygen permeability than said first composition.

60. The radiation emitting device of claim 51, wherein said second composition has lower moisture permeability than said first composition.

61. The radiation emitting device of claim 51, wherein said second composition has a higher specific heat than said first composition.

62. The radiation emitting device of claim 51, wherein said first and second compositions are substantially segregated into different zones of said encapsulant and are cohesively bonded at an interface of those zones.

63. The radiation emitting device of claim 51, wherein said optical radiation emitter is mounted on one of said first and second electrical leads.

64. The radiation emitting device of claim 51, wherein said radiation emitter is an LED chip.

65. The radiation emitting device of claim 51, wherein said radiation emitter is a semiconductor optical radiation emitter.

66. The radiation emitting device of claim 51 and further including a glob-top disposed over said optical radiation emitter.

67. The radiation emitting device of claim 66, wherein said glob-top includes a photoluminescent material.

68. The radiation emitting device of claim 51, wherein said second composition physically contacts said electrical leads.

69. The radiation emitting device of claim 51, wherein said second composition is an epoxy.

70. A light emitting device comprising:

at lean one LED chip;

first and second electrical leads electrically coupled to said LED chip; and

an integral encapsulant configured to encapsulate said LED chip and a portion of said first and second electrical leads, said encapsulant having at least a transparent first zone and a second zone, the second zone having a higher thermal conductivity than said first zone, wherein, in both said zones, said encapsulant is made of a material with a relatively high electrical resistivity.

71. The light emitting device of claim 70, wherein, in said second zone, said encapsulant physically contacts said electrical leads.

72. The light emitting device of claim 70, wherein, in said second zone, said encapsulant is an epoxy.