USRE45923EExpiredUtility

High solids HBN slurry, HBN paste, spherical HBN powder, and methods of making and using them

48
Assignee: PUJARI VIMAL KPriority: Aug 7, 2001Filed: Nov 3, 2005Granted: Mar 15, 2016
Est. expiryAug 7, 2021(expired)· nominal 20-yr term from priority
Inventors:Vimal K. PujariWilliam T. CollinsJeffrey J. KutschThomas M. ClereEugene Anthony Pruss
H10W 40/251C04B 35/62625C04B 35/634C04B 2235/3225Y10T428/25C04B 2235/658C08K 3/38C01B 21/064C04B 35/6303C04B 2235/3895C04B 2235/6581C04B 2235/5292C04B 35/62655C04B 2235/6027C04B 35/6263Y10T428/252C04B 35/6264C04B 2235/5427C04B 35/63C04B 2235/528C09K 5/14C04B 2235/5436C04B 2235/5409C01P 2006/22C01P 2002/77C08K 2003/385C04B 2235/421C04B 35/632C01P 2004/32Y10T428/2982C04B 2235/3804C01P 2004/50C04B 2235/386C01P 2006/12C01B 21/0648C04B 2235/767C04B 2235/449C01P 2004/20
48
PatentIndex Score
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Cited by
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References
59
Claims

Abstract

The present invention relates to a method for making a hexagonal boron nitride slurry and the resulting slurry. The method involves mixing from about 0.5 wt. % to about 5 wt. % surfactant with about 30 wt. % to about 50 wt. % hexagonal boron nitride powder in a medium under conditions effective to produce a hexagonal boron nitride slurry. The present invention also relates to a method for making a spherical boron nitride powder and a method for making a hexagonal boron nitride paste using a hexagonal boron nitride slurry. Another aspect of the present invention relates to a hexagonal boron nitride paste including from about 60 wt. % to about 80 wt. % solid hexagonal boron nitride. Yet another aspect of the present invention relates to a spherical boron nitride powder, a polymer blend including a polymer and the spherical hexagonal boron nitride powder, and a system including such a polymer blend.

Claims

exact text as granted — not AI-modified
What is claimed: 
     
       1. A method for making spherical boron nitride powder comprising:
 providing a hexagonal boron nitride slurry; 
 spray drying the slurry under conditions effective to produce spherical boron nitride powder comprising spherical agglomerates of boron nitride platelets; and 
 sintering the spherical boron nitride powder. 
 
     
     
       2. The method according to  claim 1 , wherein the hexagonal boron nitride slurry comprises from about 30 wt. % to about 50 wt. % hexagonal boron nitride powder. 
     
     
       3. The method according to  claim 1 , wherein the spherical boron nitride powder has a tap density of about 0.4 g/cc to about 0.7 g/cc. 
     
     
       4. The method according to  claim 1 , wherein the sintering is carried out at a temperature of from about 1800° C. to about 2400° C. 
     
     
       5. The method according to  claim 1 , wherein the spherical agglomerates of boron nitride platelets have an average agglomerate diameter of from about 10 microns to about 500 microns. 
     
     
       6. The method according to  claim 5 , wherein the majority of boron nitride agglomerates have an average diameter of from about 30 microns to about 150 microns. 
     
     
       7. The method according to  claim 1  further comprising;
 classifying the spherical boron nitride powder under conditions effective to obtain a desired agglomerate size distribution. 
 
     
     
       8. The method according to  claim 7 , wherein the classifying is selected from the group consisting of screening, air classifying, and elutriation. 
     
     
       9. A spherical boron nitride powder comprising sintered spherical agglomerates of boron nitride platelets having an average agglomerate diameter of from about 10 microns to about 500 microns. 
     
     
       10. The spherical boron nitride powder according to  claim 9 , wherein the spherical boron nitride powder has a tap density of about 0.4 g/cc to about 0.7 g/cc. 
     
     
       11. The spherical boron nitride powder according to  claim 9 , wherein the spherical agglomerates of boron nitride platelets have an average agglomerate diameter of from about 10 150 microns to about 500 microns. 
     
     
       12. The spherical boron nitride powder according to  claim 11 , wherein the majority of boron nitride agglomerates have an average diameter of from about 30 microns to about 150 microns. 
     
     
       13. A method for making a hexagonal boron nitride paste comprising:
 providing a hexagonal boron nitride slurry and   treating the slurry under conditions effective to produce a hexagonal boron nitride paste comprising from about 60 wt. % to about 80 wt. % solid hexagonal boron nitride.   
     
     
       14. The method according to  claim 13 , wherein the hexagonal boron nitride slurry comprises from about 30 wt. % to about 50 wt. % hexagonal boron nitride solids loading. 
     
     
       15. The method according to  claim 13 , wherein said treating comprises placing the slurry in a plaster mold. 
     
     
       16. The method according to  claim 13 , wherein said treating comprises vacuum filtration. 
     
     
       17. A hexagonal boron nitride paste comprising from about 60 wt. % to about 80 wt. % solid hexagonal boron nitride in a medium. 
     
     
       18. The hexagonal boron nitride paste according to  claim 17 , wherein the medium is an aqueous medium. 
     
     
       19. The hexagonal boron nitride paste according to  claim 18 , wherein the medium is a non-aqueous medium selected from the group consisting of isopropyl alcohol, methanol, and ethanol. 
     
     
       20. A polymer blend comprising:
 a polymer, and   a powder phase comprising spherical agglomerates of hexagonal boron nitride platelets, wherein the powder phase is distributed homogeneously within the polymer.   
     
     
       21. The polymer blend according to  claim 20 , wherein the powder phase has a tap density of about 0.4 g/cc to about 0.7 g/cc. 
     
     
       22. The polymer blend according to  claim 20 , wherein the polymer is selected from the group consisting of melt-processable polymers, polyesters, phenolics, silicone polymers, acrylics, waxes, thermoplastic polymers, low molecular weight fluids, and epoxy molding compounds. 
     
     
       23. The polymer blend according to  claim 20 , wherein the polymer blend comprises from about 30 wt. % to about 80 wt. % spherical boron nitride powder. 
     
     
       24. The polymer blend according to  claim 20 , wherein the polymer blend has a thermal conductivity of from about 1 W/mK to about 15 W/mK. 
     
     
       25. The polymer blend according to  claim 20 , wherein the spherical agglomerates of hexagonal boron nitride platelets have an average agglomerate diameter of from about 10 microns to about 500 microns. 
     
     
       26. The polymer blend according to  claim 25 , wherein the majority of spherical agglomerates have an average diameter of from about 30 microns to about 150 microns. 
     
     
       27. A system comprising:
 a heat source;   a heat sink; and   a thermally conductive material connecting the heat source to the heat sink, wherein the thermally conductive material comprises a powder phase comprising spherical agglomerates of hexagonal boron nitride platelets.   
     
     
       28. The system according to  claim 27 , wherein the powder phase has a tap density of about 0.4 g/cc to about 0.7 g/cc. 
     
     
       29. The system according to  claim 27 , wherein the heat source is an integrated circuit chip, power module or transformer. 
     
     
       30. The system according to  claim 27 , wherein the heat sink is finned aluminum, copper, berilium or diamond. 
     
     
       31. The system according to  claim 27 , wherein the thermally conductive material comprises from about 30 wt. % to about 80 wt. % spherical boron nitride powder. 
     
     
       32. The system according to  claim 27 , wherein the thermally conductive material has a thermal conductivity of from about 1 W/mK to about 15 W/mK. 
     
     
       33. The system according to  claim 27 , wherein the spherical agglomerates of hexagonal boron nitride platelets have an average agglomerate diameter of from about 10 microns to about 500 microns. 
     
     
       34. The system according to  claim 33 , wherein the majority of spherical agglomerates have an average diameter of from about 30 microns to about 150 microns. 
     
     
       35. The system according to  claim 27 , wherein the thermally conductive material is a polymer. 
     
     
       36. The system according to  claim 35 , wherein the polymer is selected from the group consisting of melt-processable polymers, polyesters, phenolics, silicone polymers, acrylics, waxes, thermoplastic polymers, low molecular weight fluids, and epoxy molding compounds. 
     
     
       37. A polymer blend comprising:
 a polymer; and   a powder phase comprising sintered spherical agglomerates of boron nitride having an average diameter of from about 10 microns to about 500 microns.    
     
     
       38. The polymer blend according to claim 37, wherein the sintered spherical agglomerates of boron nitride have an average agglomerate diameter of from about 150 microns to about 500 microns.  
     
     
       39. The polymer blend according to claims 37 or 50 or 59, wherein the polymer is selected from the group consisting of melt-processable polymers, polyesters, phenolics, silicone polymers, acrylics, waxes, thermoplastic polymers, low molecular weight fluids, and epoxy molding compounds.  
     
     
       40. The polymer blend according to claims 37 or 50 or 59, wherein the polymer blend comprises from about 30 wt. % to about 80 wt. % of the powder phase.  
     
     
       41. The polymer blend according to claim 40, wherein the polymer blend comprises from about 50 wt. % to about 80 wt. % of the powder phase.  
     
     
       42. The polymer blend according to claims 37 or 50 or 59, wherein the polymer blend has a thermal conductivity of from about 1 W/mK to about 15 W/mK.  
     
     
       43. The method according to claim 2, wherein the hexagonal boron nitride slurry comprises from about 40 wt. % to about 50 wt. % hexagonal boron nitride powder.  
     
     
       44. A spherical boron nitride powder comprising sintered spherical agglomerates of boron nitride platelets, wherein the spherical agglomerates have been sintered at a temperature of at least about 1800° C.  
     
     
       45. The spherical boron nitride powder according to claim 44, wherein the spherical agglomerates have been sintered at a temperature of from about 2000° C. to about 2400° C.  
     
     
       46. The spherical boron nitride powder according to claim 44, wherein the spherical boron nitride powder has a tap density of about 0.4 g/cc to about 0.7 g/cc.  
     
     
       47. The spherical boron nitride powder according to claim 44, wherein the spherical agglomerates of boron nitride platelets have an average agglomerate diameter of from about 10 microns to about 500 microns.  
     
     
       48. The spherical boron nitride powder according to claim 47, wherein a majority of boron nitride agglomerates have an average diameter of from about 30 microns to about 150 microns.  
     
     
       49. The spherical boron nitride powder according to claim 44, wherein the spherical agglomerates of boron nitride platelets have an average agglomerate diameter of from about 150 microns to about 500 microns.  
     
     
       50. A polymer blend comprising:
 a polymer; and   a powder phase comprising sintered spherical agglomerates of boron nitride, wherein the spherical agglomerates have been sintered at a temperature of at least about 1800° C.    
     
     
       51. The polymer blend according to claim 50, wherein the spherical agglomerates have been sintered at a temperature of from about 2000° C. to about 2400° C.  
     
     
       52. The polymer blend according to claim 50, wherein a majority of boron nitride agglomerates have an average agglomerate diameter of from about 10 microns to about 500 microns.  
     
     
       53. The polymer blend according to claim 52, wherein a majority of boron nitride agglomerates have an average diameter of from about 30 microns to about 150 microns.  
     
     
       54. The polymer blend according to claim 50, wherein the spherical agglomerates of boron nitride platelets have an average agglomerate diameter of from about 150 microns to about 500 microns.  
     
     
       55. A spherical boron nitride powder comprising sintered spherical agglomerates of boron nitride platelets having an average agglomerate diameter of from about 30 microns to about 125 microns.  
     
     
       56. A polymer blend comprising:
 a polymer; and   a powder phase comprising sintered spherical agglomerates of boron nitride having an average diameter of from about 30 microns to about 125 microns.    
     
     
       57. A spherical boron nitride powder comprising sintered spherical agglomerates of hexagonal boron nitride platelets having a crystallization index of at least 0.12.  
     
     
       58. The spherical boron nitride powder according to claim 57, wherein the spherical boron nitride powder has a tap density of about 0.4 g/cc to about 0.7 g/cc.  
     
     
       59. A polymer blend comprising:
 a polymer; and   a power phase comprising sintered spherical agglomerates of boron nitride.

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