Methods For Providing Composite Asperities

Abstract

Novel methods for providing asperities (sometimes referred to as asperates) on interposer contacts. The asperities comprise low electrical resistant particles such as titanium carbide that are bonded or plated in conjunction with nickel or other matrices on metallic substrate pads. An electroplating bath that has the low electrical resistant particles dispersed in solution is used at low current densities to electrolytically plate a composite electrically low resistant abrasive surface. The composite bond between the particles and the substrate can then be further reinforced with a standard metallic electroplate, if desired.

1 . A method for providing asperities on a conductive contact region of a circuit panel, comprising:
 providing a circuit panel having at least one conductive contact region;   exposing the circuit panel to a first electroplating solution comprising a first conductive metal and a plurality of metal ceramic particles, wherein the first conductive metal is selected from the group consisting of nickel, aluminum, copper, gold, iridium, palladium, platinum, rhodium, ruthenium, silver, titanium, and alloys of these metals, and wherein the metal ceramic particles have an electrical resistance less than about 10 milliohms; and   supplying a low density current to the first electroplating solution for a period of time sufficient to co-deposit the first conductive metal and the metal ceramic particles as a first conductive layer on the surface of the at least one conductive contact region, wherein said low density current is less than 8 amps per square foot (ASF).   
   
   
       2 . The method of  claim 1 , further comprising, prior to said exposure step, roughening the surface of said at least one conductive contact region. 
   
   
       3 . The method of  claim 1 , further comprising, after said supplying step:
 exposing the circuit panel to a second electroplating solution comprising a second conductive metal, and   supplying current to the second electroplating solution for a period of time sufficient to deposit the second conductive metal as a second conductive layer on top of the first conductive layer, wherein said second conductive metal is selected from the group consisting of gold, iridium, osmium, palladium, platinum, rhodium, ruthenium, silver, and alloys and combinations thereof.   
   
   
       4 . The method of  claim 1 , further comprising, after said supplying step:
 exposing the at least one conductive contact region to a second electroplating solution comprising the first conductive metal; and   supplying a current to the second electroplating solution for a period of time sufficient to induce growth of the first conductive layer.   
   
   
       5 . The method of  claim 1 , wherein said first electroplating solution is agitated at a rate between 0.5 and 5 meters per second during said period of time. 
   
   
       6 . The method of  claim 1 , wherein the first conductive metal is selected from the group consisting of nickel, silver, copper, gold and alloys of these metals. 
   
   
       7 . The method of  claim 1 , wherein the metal ceramic is a Group IV or Group V metal carbide. 
   
   
       8 . The method of  claim 7 , wherein the metal ceramic is titanium carbide. 
   
   
       9 . The method of  claim 8 , wherein the first conductive metal is nickel. 
   
   
       10 . A method for providing asperities on a conductive contact region of a substrate for forming an electrical connection with a contact location on a semiconductor die, comprising:
 providing a substrate having at least one conductive contact region;   exposing the at least one conductive contact region of the substrate to a first electroplating solution comprising a first conductive metal and a plurality of metal ceramic particles, wherein the first conductive metal is selected from the group consisting of nickel, silver, copper, gold, and alloys of these metals, and wherein the metal ceramic particles are ceramics of a Group IV metal, a Group V metal, or a Group VI metal and wherein the metal ceramic particles have an electrical resistance less than about 25 milliohms; and   supplying a low density current to the first electroplating solution for a period of time sufficient to co-deposit a layer of the first conductive metal and the metal ceramic particles as a first conductive layer on the surface of the at least one conductive contact region, wherein said low density current is less than 8 amps per square foot and wherein said first electroplating solution is vigorously agitated during said period of time.   
   
   
       11 . The method of  claim 10 , wherein the substrate is an interposer flex panel. 
   
   
       12 . The method of  claim 10 , wherein said agitation is provided by a slurry pump. 
   
   
       13 . The method of  claim 10 , wherein said agitation is provided by air agitation. 
   
   
       14 . The method of  claim 10 , wherein said first conductive metal is nickel, and said first electroplating solution further comprises nickel sulfamate. 
   
   
       15 . The method of  claim 10 , further comprising, after said supplying step:
 exposing the at least one conductive contact region to a second electroplating solution comprising the first conductive metal; and   supplying a current to the second electroplating solution for a period of time sufficient to induce growth of the first conductive layer.   
   
   
       16 . A method for providing asperities on a conductive contact region of a substrate for forming an electrical connection with a contact location on a semiconductor die, comprising:
 providing a substrate having at least one conductive contact region;   exposing the at least one conductive contact region of the substrate to a first electroplating solution comprising a first conductive metal and a plurality of metal ceramic particles, wherein the first conductive metal is selected from the group consisting of nickel, silver, copper, gold, and alloys of these metals, and wherein the metal ceramic particles are ceramics of a Group IV metal, a Group V metal, or a Group VI metal and wherein the metal ceramic particles have an electrical resistance less than about 15 milliohms;   supplying a low density current to the first electroplating solution for a period of time sufficient to co-deposit a layer of the first conductive metal and the metal ceramic particles as a first conductive layer on the surface of the at least one conductive contact region, wherein said low density current is less than 5 amps per square foot (ASF) and wherein said first electroplating solution is vigorously agitated during said period of time;   exposing the at least one conductive contact region of the substrate to a second electroplating solution comprising the first conductive metal; and   supplying a current to the second electroplating solution for a period of time sufficient to induce growth of the first conductive layer.   
   
   
       17 . The method of  claim 16 , further comprising, after said second supplying step:
 exposing the circuit panel to a third electroplating solution comprising a second conductive metal, and   supplying current to the third electroplating solution for a period of time sufficient to deposit the second conductive metal as a second conductive layer on top of the first conductive layer, wherein said second conductive metal is selected from the group consisting of gold, iridium, osmium, palladium, platinum, rhodium, ruthenium, silver, and alloys and combinations thereof.   
   
   
       18 . The method of  claim 17 , wherein said first conductive metal is nickel or copper, and said second conductive metal is gold or rhodium. 
   
   
       19 . The method of  claim 16 , wherein said first conductive metal is nickel or copper, and said metal ceramic is a Group IV or Group V metal carbide. 
   
   
       20 . The method of  claim 19 , wherein said metal carbide is titanium carbide, vanadium carbide, or hafnium carbide.