Bulk metallic glass solder material

Abstract

High strength, reliable bulk metallic glass (BMG) solder materials formed from alloys possessing deep eutectics with asymmetric liquidous slopes. BMG solder materials are stronger and have a higher elastic modulus than, and therefore are less likely than crystalline solder materials to damage fragile low k interlayer dielectric (ILD) materials due to thermal stress in materials with different coefficients of thermal expansion (CTE). BMG solder materials may physically, electrically, or thermally couple a feature to another feature, or any combination thereof. For example, in an embodiment of the invention, a BMG solder material may physically and electrically couple an electronic component to a printed circuit board. In another embodiment of the invention, a BMG solder material may physically and thermally couple an integrated heat sink to a semiconductor device.

1 . A solder material, comprising:
 an alloy, the alloy being of a composition which forms a bulk metallic glass material when heated at least to a first temperature and cooled to at least a second temperature.   
   
   
       2 . The solder material of  claim 1 , wherein the first temperature is at or above the melting temperature (Tm) of the alloy. 
   
   
       3 . The solder material of  claim 2 , wherein the second temperature is at or below the glass transition temperature (Tg) of the alloy. 
   
   
       4 . The solder material of  claim 1 , wherein the solder alloy comprises a composition which undergoes glass formation when the solder material is cooled from at or above the alloy melting temperature (Tm) to at or below the alloy glass transition temperature (Tg) at a cooling rate below approximately 10 2 ° C./second. 
   
   
       5 . The solder material of  claim 4 , wherein the alloy comprises a binary alloy including at least one of tin-indium including 45-60 wt. % tin, tin-zinc including 80-92 wt. % tin, tin-nickel including 95-99.9 wt. % tin, tin-copper including 95-99.9 wt. % tin, tin-silver including 90-98 wt. % tin, tin-aluminum including 95-99.9 wt. % tin, tin-arsenic including 95-99.9 wt. % tin, tin-gold including 80-95 wt. % tin, tin-cadmium including 60-70 wt. % tin, tin-dysprosium including 95-99 wt. % tin, tin-magnesium including 80-90 wt. % tin, tin-lead including 55-70 wt. % tin, tin-thallium including 50-65 wt. % tin, indium-bismuth including 60-70 wt. % indium, indium-zinc including 97-99 wt. % indium, indium-nickel including >99 wt % indium, indium-copper including >99 wt % indium, indium-silver including 95-99 wt. % indium, and indium-gold including >99 wt % indium, indium-cadmium including 60-70 wt. % indium, and indium-gallium including 20-30 wt. % indium. 
   
   
       6 . The solder material of  claim 4 , wherein the alloy has a deep eutectic that is at least 25% lower than the melting temperature, and wherein the alloy has asymmetric liquidous slopes. 
   
   
       7 . The solder material of  claim 4 , wherein the alloy comprises a ternary alloy including at least one of tin (Sn) and indium (In). 
   
   
       8 . The solder material of  claim 7 , wherein the alloy further comprises two of bismuth (Bi), zinc (Zn), nickel (Ni), copper (Cu), and silver (Ag). 
   
   
       9 . The solder material of  claim 4 , wherein the alloy takes the form of at least one of a liquid, a sphere, a pellet, a paste, a powder, a thick film, a thin film, a ribbon, a bar, and a flexible wire. 
   
   
       10 . The solder material of  claim 4 , wherein the solder alloy has an elastic strain limit of at least 2%. 
   
   
       11 . A solder material, comprising:
 an alloy comprising a composition which undergoes glass formation when the solder material is cooled from at or above the melting temperature (Tm) to at or below the glass transition temperature (Tg) at a cooling rate below approximately 10 2 ° C./second, and the solder alloy comprising a binary alloy including at least one of tin-indium including 45-60 wt. % tin, tin-zinc including 80-92 wt. % tin, tin-nickel including 95-99.9 wt. % tin, tin-copper including 95-99.9 wt. % tin, tin-silver including 90-98 wt. % tin, tin-aluminum including 95-99.9 wt. % tin, tin-arsenic including 95-99.9 wt. % tin, tin-gold including 80-95 wt. % tin, tin-cadmium including 60-70 wt. % tin, tin-dysprosium including 95-99 wt. % tin, tin-magnesium including 80-90 wt. % tin, tin-lead including 55-70 wt. % tin, tin-thallium including 50-65 wt. % tin, indium-bismuth including 60-70 wt. % indium, indium-zinc including 97-99 wt. % indium, indium-nickel including >99 wt % indium, indium-copper including >99 wt % indium, indium-silver including 95-99 wt. % indium, and indium-gold including >99 wt % indium, indium-cadmium including 60-70 wt. % indium, and indium-gallium including 20-30 wt. % indium.   
   
   
       12 . The solder material of  claim 11 , wherein the solder alloy has an elastic strain limit of at least 2%. 
   
   
       13 . The solder material of  claim 11 , wherein the alloy takes the form of at least one of a liquid, a sphere, a pellet, a paste, a powder, a thick film, a thin film, a ribbon, a bar, and a flexible wire. 
   
   
       14 . The solder material of  claim 11 , wherein the alloy has a deep eutectic that is at least 25% lower than the melting temperature, and wherein the alloy has asymmetric liquidous slopes. 
   
   
       15 . A solder material, comprising:
 an alloy comprising a composition which undergoes glass formation when the solder material is cooled from at or above the melting temperature (Tm) to at or below the glass transition temperature (Tg) at a cooling rate below approximately 10 2 ° C./second, and the solder alloy comprising a ternary alloy including at least one of tin (Sn) and indium (In).   
   
   
       16 . The solder material of  claim 15 , wherein the alloy further comprises two of bismuth (Bi), zinc (Zn), nickel (Ni), copper (Cu), and silver (Ag). 
   
   
       17 . The solder material of  claim 15 , wherein the alloy takes the form of at least one of a liquid, a sphere, a pellet, a paste, a powder, a thick film, a thin film, a ribbon, a bar, and a flexible wire. 
   
   
       18 . The solder material of  claim 15 , wherein the solder alloy has an elastic strain limit of at least 2%.