High-pressure high-temperature polycrystalline diamond heat spreader

Abstract

This invention presents a polycrystalline diamond heat spreader useful in electronic devices for transmitting thermal energy from a high-energy thermal source, such as an IC die, into a means for dissipating thermal energy, such as a heat sink. The heat spreader comprises a bondable material that forms in situ at high pressure and high temperature a low-impedance contact surface layer on at least one its major surfaces. The contact surface layer provides a means for chemically or metallurgically bonding the heat spreader to the IC die and or to the heat sink.

What is claimed:  
     
         1 . A high-pressure high-temperature polycrystalline diamond heat spreader useful in electronic devices, comprising: 
 a. Discrete diamond crystals ranging in sizes from between 10μ and 3000μ intergrown into a unified matrix and bonded to a substrate by means of a high-pressure high-temperature sintering process;    b. The unified matrix having a major surface opposite the substrate;    c. The unified matrix further comprising at least one bondable material selected from the periodic table of elements consisting of Fe, Co, Ni, Pd, Pt, Cr, Mo, W, Nb, Ta, Hf, Zr, Ti, V, Al, Si, Ga, Au, Cd, Ag, An, Mg, Sn, and Ge, and compounds, carbides, and alloys thereof; and    d. The bondable material forming in situ, during the sintering process, a low-impedance, bondable contact-surface layer on at least a portion of the major surface opposite the substrate, said bondable surface being suitable for bonding said matrix to at least a portion of a high-energy thermal source.    
     
     
         2 . The heat spreader of  claim 1 , wherein the bondable material does not exceed the weight of the diamond matrix.  
     
     
         3 . The heat spreader of  claim 1 , wherein the bondable material does not exceed 20 weight-percent of the diamond matrix.  
     
     
         4 . The heat spreader of  claim 1 , wherein the bondable material is in the form of a foil positioned adjacent the diamond crystals prior to being subjected to the high-pressure high-temperature sintering process.  
     
     
         5 . The heat spreader of  claim 1 , wherein the bondable material is in the form of a powder positioned adjacent the diamond crystals prior to being subjected to the high-pressure high-temperature sintering process.  
     
     
         6 . The heat spreader of  claim 15 , wherein the bondable material is intermixed with the discrete diamond crystals prior to being intergrown by the high-pressure high-temperature sintering process.  
     
     
         7 . The heat spreader of  claim 1 , wherein the diamond crystals are coated with the bondable material prior to being subjected to the high-pressure high-temperature sintering process.  
     
     
         8 . The heat spreader of  claim 1 , wherein the diamond crystals are sputter coated with the bondable material prior to being subject to the high-pressure high-temperature sintering process.  
     
     
         9 . The heat spreader of  claim 1 , wherein the diamond crystals are coated with the bondable material using an ion implantation process prior to the sintering process.  
     
     
         10 . The heat spreader of  claim 1 , wherein the diamond crystals are coated with the bondable material using a milling process.  
     
     
         11 . The heat spreader of  claim 1 , wherein the substrate is adapted for bonding to a heat sink.  
     
     
         12 . The heat spreader of  claim 1 , wherein the substrate is adapted for bonding to a thermal source.  
     
     
         13 . The heat spreader of  claim 1 , wherein at least a portion of at least one major contact surface has low surface roughness.  
     
     
         14 . The heat spreader of  claim 1 , wherein at least a portion of at least one major contact surface has a non-planar topography.  
     
     
         15 . The heat spreader of  claim 1 , wherein at least a portion of the bondable surface has a non-planar topography.  
     
     
         16 . The heat spreader of  claim 1 , wherein the bondable surface layer has a cross section of 1.5 mm, but preferably less than 0.25 mm, and more preferably less than 0.025 mm.  
     
     
         17 . The heat spreader of  claim 1 , wherein at least a portion of one of the major contact surfaces are made to have high electrical resistance.  
     
     
         18 . The heat spreader of  claim 1 , wherein the diamond matrix has a cross section greater than 1 mm.