Transient liquid phase bonding compositions and power electronics assemblies incorporating the same

Abstract

A transient liquid phase (TLP) composition includes a plurality of first high melting temperature (HMT) particles, a plurality of second HMT particles, and a plurality of low melting temperature (LMT) particles. Each of the plurality of first HMT particles have a core-shell structure with a core formed from a first high HMT material and a shell formed from a second HMT material that is different than the first HMT material. The plurality of second HMT particles are formed from a third HMT material that is different than the second HMT material and the plurality of LMT particles are formed from a LMT material. The LMT particles have a melting temperature less than a TLP sintering temperature of the TLP composition and the first, second, and third HMT materials have a melting point greater than the TLP sintering temperature.

What is claimed is: 
     
         1 . A transient liquid phase (TLP) composition comprising:
 a plurality of first high melting temperature (HMT) particles, wherein each of the plurality of first HMT particles comprise a core-shell structure with a core formed from a first HMT material and a shell formed from a second HMT material;   a plurality of second HMT particles, wherein each of the plurality of second HMT particles are formed from a third HMT material;   a plurality of low melting temperature (LMT) particles, wherein each of the plurality of LMT particles are formed from a LMT material;   wherein the first HMT material, the second HMT material, and the third HMT material have a melting point greater than a TLP sintering temperature of the TLP composition and the plurality of LMT particles have a melting point less than the TLP sintering temperature.   
     
     
         2 . The TLP composition of  claim 1 , wherein the first HMT material is nickel, silver, copper, aluminum, or an alloy thereof. 
     
     
         3 . The TLP composition of  claim 1 , wherein the second HMT material is nickel, silver copper or an alloy thereof. 
     
     
         4 . The TLP composition of  claim 1 , wherein the third HMT material is nickel, silver, copper, aluminum, or an alloy thereof. 
     
     
         5 . The TLP composition of  claim 1 , wherein the LMT material is tin, indium, or an alloy thereof. 
     
     
         6 . The TLP composition of  claim 1 , wherein a concentration of the LMT material in the TLP composition is between about 25 weight % and about 75 weight %. 
     
     
         7 . The TLP composition of  claim 1 , wherein the core of the plurality of first HMT particles comprise a graded average diameter along a thickness of a TLP bonding layer formed from the TLP composition. 
     
     
         8 . A power electronics assembly comprising:
 a semiconductor device extending across a metal substrate; and   a transient liquid phase (TLP) bond layer disposed between the semiconductor device and the metal substrate, the TLP bond layer comprising a plurality of first high melting temperature (HMT) particles, a plurality of second HMT particles, and a TLP intermetallic layer positioned between and TLP bonding together the plurality of first HMT particles, the plurality of second HMT particles, the semiconductor device and the metal substrate, wherein:
 each of the plurality of first HMT particles comprise a core formed from a first HMT material and a shell formed from a second HMT material; 
 each of the plurality of second HMT particles is formed from a third HMT material; 
 the first HMT material, the second HMT material, the third HMT material and the TLP intermetallic layer have a melting point greater than a TLP sintering temperature for the TLP bond layer. 
   
     
     
         9 . The power electronics assembly of  claim 8 , wherein the TLP bond layer has a graded stiffness along a thickness of the TLP bond layer. 
     
     
         10 . The power electronics assembly of  claim 8 , further comprising localized stiffness variations at locations where the plurality of first HMT particles are positioned within the TLP bond layer. 
     
     
         11 . The power electronics assembly of  claim 8 , wherein the plurality of first HMT particles within the TLP bond layer have a graded average diameter along a thickness of the TLP bond layer. 
     
     
         12 . The power electronics assembly of  claim 8 , wherein the TLP bond layer has a graded density of the plurality of first HMT particles along a thickness of the TLP bond layer. 
     
     
         13 . The power electronics assembly of  claim 8 , wherein the first HMT material is nickel, silver, copper, aluminum, or an alloy thereof. 
     
     
         14 . The power electronics assembly of  claim 8 , wherein the second HMT material is nickel, copper, silver or an alloy thereof. 
     
     
         15 . The power electronics assembly of  claim 8 , wherein the third HMT material is nickel, silver, copper, aluminum, or an alloy thereof. 
     
     
         16 . The power electronics assembly of  claim 8 , wherein the TLP intermetallic layer comprises tin. 
     
     
         17 . The power electronics assembly of  claim 8 , wherein an average diameter of the core of the plurality of first HMT particles is between about 10.0 μm and about 50.0 μm, an average thickness of the shell of the plurality of first HMT particles is between about 0.5 μm and about 15 μm, and an average diameter of the plurality of second HMT particles is between about 5μm and 50 μm. 
     
     
         18 . A process for manufacturing a power electronics assembly comprising:
 positioning a transient liquid phase (TLP) bonding layer between a metal substrate and a semiconductor device to provide a metal substrate/semiconductor device assembly, the TLP bonding layer comprising a plurality of first high melting temperature (HMT) particles, a plurality of second HMT particles, and a plurality of low melting temperature (LMT) particles, wherein:
 each of the plurality of first HMT particles comprise a core-shell structure with a core formed from a first HMT material and a shell formed from a second HMT material; 
 each of the plurality of second HMT particles is formed from a third HMT material; 
 each of the plurality of LMT particles is formed from a LMT material; 
   heating the metal substrate/semiconductor device assembly to a TLP sintering temperature and forming a TLP bond layer between the metal substrate and the semiconductor device, wherein:
 the first HMT material, the second HMT material and the third HMT material have a melting point above the TLP sintering temperature; and 
 the LMT material has a melting point below the TLP sintering temperature such that the plurality of LMT particles at least partially melt and form a TLP intermetallic layer between the plurality of first HMT particles, the plurality of second HMT particles, the metal substrate, and the semiconductor device. 
   
     
     
         19 . The process of  claim 18 , wherein the TLP bond layer comprises a graded stiffness between the metal substrate and the semiconductor device. 
     
     
         20 . The process of  claim 18 , wherein the plurality of first HMT particles within the TLP bond layer have a graded average diameter along a thickness of the TLP bond layer.