Epoxy molding compounds with resistance to UV light and heat

• US 20040063840A1
• Filed: 09/22/2003
• Published: 04/01/2004
• Est. Priority Date: 06/06/2001
• Status: Active Grant

• Current Assignee: Henkel Corporation (Henkel AG & Co KGaA)
• Original Assignee: Henkel Loctite Corporation (Henkel AG & Co KGaA)
• Inventors: Starkey, Dale
• Granted Patent: US 7,125,917 B2
• Time in Patent Office: Days
• US Class Current: 524/442
• CPC Class Codes: C08G 59/3245 containing only nitrogen as a heteroatom
• CPC Class Codes: C08G 59/4215 cycloaliphatic
• CPC Class Codes: C09K 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/08 containing inorganic luminescent materials
• 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 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 33/501 characterised by the materials, e.g. binder

Abstract

A molding compound is provided for use in encapsulating electronic packages which include an optoelectronic component, such as an LED. The molding compound includes a partially cured epoxy composition, an antioxidant, and, optionally, a phosphor material substantially uniformly distributed throughout the epoxy composition. The optional phosphor material may be suspended within the epoxy composition by pre-reacting a portion of the epoxy composition prior to B-staging of the molding compound. As such, the optional phosphor material is suspended within the epoxy composition, thereby preventing settling of the phosphor material during B-staging, as well as during curing of the molding compound in the encapsulation process.

Claims

1. A composition, comprising:

a) an epoxy composition comprising the reaction product of;

i) an epoxy component, and

ii) an anhydride component;

b) an antioxidant material; and

c) a visible light-emitting phosphor material substantially uniformly distributed throughout said composition.

2. A composition as in claim 1, wherein the epoxy component comprises epoxy monomers within structures I and II represented as:

3. A composition as in claim 1, wherein said epoxy component comprises materials within the structure represented by:

4. A composition as in claim 1, wherein the epoxy component comprises materials within the structure represented by:

5. A composition as in claim 1, wherein the epoxy component comprises materials within the structure represented by:

6. A composition as in claim 1, wherein the epoxy component comprises materials within the structure represented by:

7. A composition as in claim 1, wherein said epoxy component comprises triglycidyl isocyanurate.

8. A composition as in claim 1, wherein said anhydride component comprises a cycloaliphatic anhydride.

9. A composition as in claim 8, wherein said anhydride component comprises methyl hexahydrophthalic anhydride.

10. A composition as in claim 1, wherein said epoxy composition further comprises a polyol for promoting reaction of said epoxy component and said anhydride component.

11. A composition as in claim 10, wherein said polyol is selected from the group consisting of glycerol, trimethylol propane, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, and mixtures thereof.

12. A composition as in claim 1, wherein said antioxidant material comprises an alkyl salt of propionic acid.

13. A composition as in claim 12, wherein said antioxidant material comprises a thiodialkylpropionate.

14. A composition as in claim 13, wherein said antioxidant material comprises a thiodiethylenepropionate.

15. A composition as in claim 14, wherein said antioxidant material comprises thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

16. A composition as in claim 1, wherein said phosphor material is capable of converting ultraviolet and blue light into visible white light.

17. A composition as in claim 1, wherein said phosphor comprises yttrium aluminum garnet.

18. A composition as in claim 1, wherein said epoxy component comprises from about 20 weight percent to about 75 weight percent of said composition based on the total weight of the composition.

19. A composition as in claim 1, wherein said anhydride component comprises from about 20 weight percent to about 75 weight percent of said composition based on the total weight of the composition.

20. A composition as in claim 1, wherein said antioxidant material comprises from about 0.01 weight percent to about 5 weight percent of said composition based on the total weight of the composition.

21. A composition as in claim 1, wherein said phosphor material comprises from about 0.5 weight percent to about 35 weight percent of said composition based on the total weight of the composition.

22. A molding compound comprising the composition of claim 1.

23. A composition, comprising:

a) an epoxy composition comprising the reaction product of;

i) an epoxy component, and

ii) an anhydride component; and

b) an antioxidant material.

24. A composition as in claim 23, wherein said antioxidant material comprises an alkyl salt of propionic acid.

25. A composition as in claim 24, wherein said antioxidant material comprises thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

26. A molding compound comprising the composition of claim 23.

27. An encapsulant material for electronic components comprising a molding compound comprising a reaction product of a partially cured epoxy component and an anhydride component having an antioxidant material and, optionally, a phosphor material substantially uniformly distributed therethrough.

28. An encapsulant material as in claim 27, wherein said antioxidant material comprises an alkyl salt of propionic acid.

29. An encapsulant material as in claim 28, wherein said antioxidant material comprises a thiodialkylpropionate.

30. An encapsulant material as in claim 29, wherein said antioxidant material comprises thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

31. An encapsulant material as in claim 27, wherein the epoxy component comprises epoxy monomers within structures I and II represented as:

32. An encapsulant material as claimed in claim 27, wherein said epoxy component comprises materials within the structure represented by:

33. A method of preparing a molding compound, comprising:

a) providing an epoxy composition;

b) mixing an antioxidant material with said epoxy composition to provide a homogeneous mixture;

c) increasing the viscosity of said homogeneous mixture to form a pre-reacted intermediate; and

d) partially curing said epoxy composition of said pre-reacted intermediate, thereby forming said molding compound.

34. A method as in claim 33, further comprising:

mixing a visible light-emitting phosphor material with said epoxy composition to provide a homogeneous mixture with said phosphor material suspended within said epoxy composition; and

increasing the viscosity of said homogeneous mixture while maintaining said phosphor material suspended within said epoxy composition to form the pre-reacted intermediate.

35. A method of encapsulating an optoelectronic device, comprising:

a) providing an optoelectronic device;

b) providing a molding compound comprising a partially cured epoxy composition including an antioxidant material;

c) encapsulating said optoelectronic device with said molding compound; and

d) fully curing said epoxy composition.

36. A method as in claim 35, wherein said molding compound further comprises a light-emitting phosphor material homogeneously mixed therethrough.

37. A method as in claim 36, wherein said optoelectronic device is a light-emitting diode.

38. An optoelectronic device comprising a light-emitting diode having an encapsulant surrounding said light-emitting diode, said encapsulant comprising a reaction product of a cured epoxy composition including an antioxidant material and, optionally, a phosphor material.