US2004065954A1PendingUtilityA1

Semiconductor packages; lead-containing solders and anodes; and methods of removing alpha-emitters from materials

48
Priority: Oct 8, 2002Filed: Sep 26, 2003Published: Apr 8, 2004
Est. expiryOct 8, 2022(expired)· nominal 20-yr term from priority
Inventors:Martin WeiserNancy DeanBrett M. ClarkMichael J. BossioRonald H. FlemingJames Flint
C25C 1/18B23K 35/268B23K 35/26B23K 35/025C22B 13/06H10W 72/90H10W 72/9415H10W 90/724H10W 72/252H10W 72/251H10W 90/701H10W 74/117H10W 72/20H05K 3/346H05K 3/3485
48
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Claims

Abstract

The invention includes solder materials having low concentrations of alpha particle emitters, and includes methods of purification of materials to reduce a concentration of alpha particle emitters within the materials. The invention includes methods of reducing alpha particle flux in various lead-containing and lead-free materials through purification of the materials. The invention also includes methods of estimating the fractionation of a low concentration of one or more alpha particle emitters during purification of a material.

Claims

exact text as granted — not AI-modified
The invention claimed is:  
     
         1 . A semiconductor package comprising a solder having an alpha flux of less than 0.001 cts/cm 2 /hr.  
     
     
         2 . The semiconductor package of  claim 1  wherein the solder predominately comprises Ag, Bi, Cu, In, Pb or Sn.  
     
     
         3 . The semiconductor package of  claim 1  wherein the solder predominately comprises Ag.  
     
     
         4 . The semiconductor package of  claim 1  wherein the solder predominately comprises Sn.  
     
     
         5 . The semiconductor package of  claim 1  wherein the solder is substantially lead-free.  
     
     
         6 . The semiconductor package of  claim 1  wherein the solder is lead-containing solder that is at least 99 weight % lead.  
     
     
         7 . The semiconductor package of  claim 6  wherein the lead-containing solder has an alpha flux of less than 0.0005 cts/cm 2 /hr.  
     
     
         8 . The semiconductor package of  claim 6  wherein the lead-containing solder has an alpha flux of less than 0.0002 cts/cm 2 /hr.  
     
     
         9 . The semiconductor package of  claim 6  wherein the lead-containing solder has an alpha flux of less than 0.0001 cts/cm 2 /hr.  
     
     
         10 . A lead-containing anode having an alpha flux of less than 0.001 cts/cm 2 /hr, the lead-containing anode comprising at least about 50 weight % lead.  
     
     
         11 . The lead-containing anode of  claim 10  having an alpha flux of less than 0.0005 cts/cm 2 /hr.  
     
     
         12 . The lead-containing anode of  claim 10  having an alpha flux of less than 0.0002 cts/cm 2 /hr.  
     
     
         13 . The lead-containing anode of  claim 10  having an alpha flux of less than 0.0001 cts/cm 2 /hr.  
     
     
         14 . A lead-containing solder bump having an alpha flux of less than 0.001 cts/cm 2 /hr, the lead-containing solder bump comprising at least about 50 weight % lead.  
     
     
         15 . The lead-containing solder bump of  claim 14  having an alpha flux of less than 0.0005 cts/cm 2 /hr.  
     
     
         16 . The lead-containing solder bump of  claim 14  having an alpha flux of less than 0.0002 cts/cm 2 /hr.  
     
     
         17 . The lead-containing solder bump of  claim 14  having an alpha flux of less than 0.0001 cts/cm 2 /hr.  
     
     
         18 . A lead-containing solder paste having an alpha flux of less than 0.001 cts/cm 2 /hr, the lead-containing solder paste comprising at least about 50 weight % lead.  
     
     
         19 . The solder paste of  claim 18  having an alpha flux of less than 0.0005 cts/cm 2 /hr.  
     
     
         20 . The solder paste of  claim 18  having an alpha flux of less than 0.0002 cts/cm 2 /hr.  
     
     
         21 . The solder paste of  claim 18  having an alpha flux of less than 0.0001 cts/cm 2 /hr.  
     
     
         22 . A method of refining a lead-containing material, comprising: 
 providing an initial composition of the lead-containing material, the initial composition having an alpha flux of greater than or equal to 0.002 cts/cm 2 /hr; and    purifying the lead-containing material to form a second composition of the lead-containing material, the second composition having an alpha flux of less than 0.001 cts/cm 2 /hr.    
     
     
         23 . The method of  claim 22  wherein the purifying comprises one or more of electro-refining, zone refining and chemical refining.  
     
     
         24 . The method of  claim 22  wherein the purifying comprises electro-refining utilizing a bath comprising nitric acid and water, with the nitric acid being present at a concentration of from about 2% to about 50%, by volume.  
     
     
         25 . The method of  claim 22  wherein the purifying comprises electro-refining utilizing a bath consisting essentially of nitric acid and water, with the nitric acid being present at a concentration of from about 2% to about 50%, by volume.  
     
     
         26 . The method of  claim 22  wherein the lead-containing material of the second composition is at least 99.99% lead by weight.  
     
     
         27 . The method of  claim 22  wherein the second composition has an alpha flux of less than 0.0005 cts/cm 2 /hr.  
     
     
         28 . The method of  claim 22  wherein the second composition has an alpha flux of less than 0.0002 cts/cm 2 /hr.  
     
     
         29 . The method of  claim 22  wherein the second composition has an alpha flux of less than 0.0001 cts/cm 2 /hr.

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