ENCAPSULANT FOR OPTO-ELECTRONIC DEVICES AND METHOD FOR MAKING IT

• US 20040248337A1
• Filed: 06/04/2003
• Published: 12/09/2004
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Yan, Yongan, Raychaudhuri, Satyabrata, Morris, Mark Allen, Meyers, Douglas Evan, Meixner, D. Laurence
• Granted Patent: US 6,841,888 B2
• Time in Patent Office: Days
• US Class Current: 438/64
• CPC Class Codes: C08K 3/40 Glass
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: H01L 23/293 Organic, e.g. plastic
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 428/31511 Of epoxy ether

Abstract

An encapsulant for use with opto-electronic devices and optical components incorporates a filler made from a glass that has been processed into particle form and heated to a predetermined temperature for a predetermined time, along with an epoxy having an index of refraction matched to that of the glass and heated to a predetermined temperature for a predetermined time, to prevent settling of the filler particles after mixing the filler particles with the epoxy, and thereby obtaining uniform dispersion of the particles within the epoxy. The encapsulant provides for high light transmittance, and its coefficient of thermal expansion can be varied by varying the amount of filler without substantially altering the optical properties of the encapsulant. The coefficient of thermal expansion variation within the encapsulant preferably is less than 30%, due to uniform dispersion of the filler particles within the epoxy.

Claims

1. An encapsulant for an opto-electronic (device or optical component, the encapsulant characterized by a coefficient of thermal expansion and an optical transmittance, the encapsulant comprising:

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1) a filler consisting essentially of glass particles having diameters in the range of 1 μ

m to 500 μ

m, the glass particles formed from a glass essentially free of titania and characterized by a glass refractive index having a value in the range of 1.48 to 1.60 and a variance of less than about 0.001, wherein the filler is characterized by a filler refractive index; and

2) an epoxy, characterized by an epoxy refractive index;

wherein the coefficient of thermal expansion of the encapsulant has an average value of less than 50 ppm/°

C. with a variation of less than ±

30%, and

wherein the filler refractive index and the epoxy refractive index have values sufficiently similar such that the optical transmittance of the encapsulant is at least 65% when measured at a wavelength in the range of 300 nm to 800 nm at an encapsulant thickness of about 1 mm.

2. An encapsulant as defined in claim 1, wherein the coefficient of thermal expansion of the encapsulant has an average value of less than 40 ppm/°

C.

4. An encapsulant as defined in claim 1, wherein the coefficient of thermal expansion of the encapsulant has a variation of less than ±

10%.

5. An encapsulant as defined in claim 1, wherein the optical transmittance of the encapsulant is at least 75% when measured at a wavelength in the range of 300 nm to 800 nm at an encapsulant thickness of about 1 mm.

6. An encapsulant as defined in claim 5, wherein optical transmittance of the encapsulant is at least 80% when measured at a wavelength in the range of 300 nm to 800 nm at an encapsulant thickness of about 1 mm

7. An encapsulant as defined in claim 1, wherein the optical transmittance of the encapsulant is at least 65% when measured at a wavelength in the range of 600 nm to 700 nm at an encapsulant thickness of about 1 mm.

8. An encapsulant as defined in claim 7, wherein the optical transmittance of the encapsulant is at least 75% when measured at a wavelength in the range of 600 nm to 700 nm at an encapsulant thickness of about 1 mm.

9. An encapsulant as defined in claim 8, wherein the optical transmittance of the encapsulant is at least 80% when measured at a wavelength in the range of 600 nm to 700 nm at an encapsulant thickness of about 1 mm.

10. An encapsulant as defined in claim 1, wherein the optical transmittance of the encapsulant is at least 65% when measured at a wavelength of about 650 nm at an encapsulant thickness of about 1 mm.

11. An encapsulant as defined in claim 10, wherein the optical transmittance of the encapsulant is at least 75% when measured at a wavelength of about 650 nm at an encapsulant thickness of about 1 mm.

13. An encapsulant as defined in claim 1, wherein the glass particles are essentially free of alkali.

14. An encapsulant as defined in claim 1, wherein the glass particles consist essentially of borosilicate.

15. An opto-electronic device substantially encased in an encapsulant as defined in claim 14.

16. An encapsulant as defined in claim 14, wherein the glass refractive index has a value of about 1.526.

17. An encapsulant as defined in claim 1, wherein the glass particles have diameters in the range of 1 μ

m to 250 μ

m.

18. An encapsulant as defined in claim 17, wherein the glass particles have diameters in the range of 10 μ

m to 250 μ

m.

19. An encapsulant as defined in claim 1, wherein less than 60 volume percent of the filler comprises glass particles having diameters smaller than 10 μ

m.

20. An encapsulant as defined in claim 19, wherein less than 20 volume percent of the filler comprises glass particles having diameters smaller than 10 μ

m.

21. An encapsulant as defined in claim 20, wherein less than 10 volume percent of the filler comprises glass particles having diameters smaller than 10 μ

m.

22. An encapsulant as defined in claim 1, wherein the filler comprises between 5 volume percent and 60 volume percent of the total volume of encapsulant.

23. An encapsulant as defined in claim 22, wherein the filler comprises between 10 volume percent and 50 volume percent of the total volume of encapsulant.

24. An encapsulant as defined in claim 23, wherein the filler comprises between 15 volume percent and 40 volume percent of the total volume of encapsulant.

25. An encapsulant as defined in claim 1, wherein the filler has been heat treated at a heat treatment temperature for at least about 1 hour, wherein the heat treatment temperature is about the strain point of the glass or less.

26. An encapsulant as defined in claim 25, wherein the heat treatment temperature is between 20°

C. and the strain point of the glass.

27. An encapsulant as defined in claim 15, wherein the filler has been heat treated at a heat treatment temperature for at least about 1 hour, wherein the heat treatment temperature is about 627°

C. or less.

28. An encapsulant as defined in claim 27, wherein the heat treatment temperature is between 20°

C. and 627°

C.

29. An encapsulant as defined in claim 28, wherein the heat treatment temperature is between 450°

C. and 550°

C.

30. An encapsulant as defined in claim 25, wherein the filler has been heat treated at a heat treatment temperature for between 5 hours and 50 hours

31. An encapsulant as defined in claim 30, wherein the filler has been heat treated at a heat treatment temperature for between 30 hours and 40 hours.

32. An encapsulant as defined in claim 25, wherein the filler has been heat treated in an oxygen-containing atmosphere.

33. An encapsulant as defined in claim 32, wherein the oxygen-containing atmosphere is dry air.

34. An encapsulant as defined in claim 1, wherein the filler is reacted with a silane coupling agent selected from the group consisting of aminopropyltriethoxysilane, vinyltrimethoxysilane, methacryloxy propyltriethoxysilane, gylcidoxypropyltrimethoxysilane, and mixtures thereof.

35. An encapsulant as defined in claim 34, wherein the silane coupling agent is aminopropyltriethoxysilane.

36. An encapsulant as defined in claim 1, wherein the epoxy is prepared from a composition comprising:

a) diglycidyl ether of bisphenol-A

b) cyclo-aliphatic epoxy resin;

c) a hardener; and

d) an accelerator.

37. An encapsulant as defined in claim 36, wherein the ratio by weight of diglycidyl ether of bisphenol-A resin to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.20 to 0.54.

38. An encapsulant as defined in claim 37, wherein the ratio by weight of diglycidyl ether of bisphenol-A resin to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.30 to 0.50.

39. An encapsulant as defined in claim 36, wherein the ratio by weight of hardener to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.30 to 0.80.

40. An encapsulant as defined in claim 39, wherein the ratio by weight of hardener to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.50 to 0.70.

41. An encapsulant as defined in claim 36, wherein the ratio by weight of accelerator to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.001 and 0.05.

42. An encapsulant as defined in claim 41, wherein the ratio by weight of accelerator to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.005 and 0.03.

3. (canceled)

12. An encapsulant as defined in claim 107 wherein the optical transmittance of the encapsulant is at least 80% when measured at a wavelength of about 650 nm at an encapsulant thickness of about 1 mm.

43. An encapsulant for an opto-electronic device or optical component, the encapsulant characterized by a coefficient of thermal expansion and an optical transmittance, the encapsulant comprising:

1) between 15 volume percent and 40 volume percent of a filler, the filler consisting essentially of glass particles formed from an alkali-free borosilicate glass that has been silylated with aminopropyltriethoxysilane, the particles having diameters in the range of 1 μ

m to 250 μ

m, of which particles less than 10 percent by volume have diameters less than 10 μ

m, wherein the glass is characterized by a glass refractive index having a value of about 1.526 and a variance of less than about 0.001, and wherein the filler has been heated in an oxygen-containing atmosphere at a temperature in the range of 450°

C. to 550°

C. for a duration in the range of 30 hours to 40 hours; and

2) between 60 volume percent and 85 volume percent of an epoxy, wherein the epoxy is prepared from a composition comprising diglycidyl ether of bisphenol-A resin, cyclo-aliphatic epoxy resin, a hardener, and an accelerator, wherein the ratio by weight of diglycidyl ether of bisphenol-A resin to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.30 to 0.50, the ratio by weight of hardener to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.50 to 0.70, and the ratio by weight of accelerator to combined weight of diglycidyl ether of bisphenol-A resin and cyclo-aliphatic epoxy resin has a value in the range of 0.005 and 0.03,

and wherein the coefficient of thermal expansion of the encapsulant has an average value of less than about 40 ppm/C and a variation of less than about ±

10%, and the optical transmittance of the encapsulant is at least 80% when measured at a wavelength of 650 nm at an encapsulant thickness of 1 mm.