Methods of preparing an electrode

Abstract

Methods of preparing an electrode are provided. A metal lead wire is pre-treated to facilitate bonding of the lead wire to a metal powder during subsequent de-oxidation sintering. A connection region can be formed by directly contacting the metal lead wire with a liquid reactive metal. After removal of resultant oxides, an additional metal powder can be de-oxidation sintered onto the connection region to form the electrode. The oxides formed during the de-oxidation sintering are then removed from the electrode.

1 . A method of preparing an electrode for a medical device comprising:
 a. pre-treating a region of an electrically conductive lead wire by contacting the region with a liquid of a reactive metal;   b. removing reactive metal oxides formed on the lead wire due to the contacting with the liquid of the reactive metal;   c. embedding the lead wire in a metal powder compact;   d. de-oxidation sintering the metal powder compact and lead wire in the presence of a vapor of the reactive metal; and   e. removing reactive metal oxides formed during the de-oxidation sintering process.   
     
     
         2 . The method of  claim 1 , wherein the contacting of the region of the lead wire with the liquid of the reactive metal comprises immersing the region of the lead wire in the liquid of the reactive metal. 
     
     
         3 . The method of  claim 1 , wherein pre-treating the lead wire further comprises removing the reactive metal oxides formed prior to embedding the lead wire in the metal powder compact. 
     
     
         4 . The method of  claim 1 , wherein the reactive metal has a higher oxygen affinity than the metal powder. 
     
     
         5 . The method of  claim 1 , wherein the reactive metal is selected from the group consisting of magnesium and calcium. 
     
     
         6 . The method of  claim 1 , further comprising conducting the de-oxidation sintering at a temperature greater than 1100 degrees C. 
     
     
         7 . The method of  claim 1 , wherein removing oxides from the electrode comprises leaching the oxides in an acid bath. 
     
     
         8 . The method of  claim 1 , wherein the metal powder comprises tantalum powder. 
     
     
         9 . The method of  claim 1 , wherein the electrode comprises a capacitor anode. 
     
     
         10 . A valve metal capacitor anode comprising:
 a valve metal lead wire embedded within a metal powder compact, wherein the valve metal lead wire and metal powder compact are bonded together during a de-oxidation sintering process in the presence of a vapor of a reactive metal, and   wherein at least a portion of the valve metal lead wire has been pre-treated with a liquid of the reactive metal to improve bonding to the metal powder compact during the de-oxidation sintering process.   
     
     
         11 . The valve metal capacitor anode of  claim 10 , wherein pre-treatment of the lead wire comprises a de-oxidation of the lead wire wherein at least the portion of the lead wire is in direct contact with the liquid of the reactive metal and a removal of the reactive metal oxides formed prior to embedding the lead wire in the metal powder compact. 
     
     
         12 . The valve metal capacitor anode of  claim 10 , wherein the reactive metal has a higher oxygen affinity than the metal powder. 
     
     
         13 . The valve metal capacitor anode of  claim 10 , wherein the reactive metal is selected from the group consisting of magnesium and calcium. 
     
     
         14 . The valve metal capacitor anode of  claim 10 , wherein the metal powder comprises tantalum powder. 
     
     
         15 . A method of use of an anode comprising:
 a. preparing a capacitor anode comprising:
 i. exposing at least a portion of a tantalum lead wire to a liquid of a reactive metal to pre-treat the lead wire to facilitate bonding of the lead wire to tantalum metal powder; 
 ii. embedding the pre-treated tantalum lead wire into a pressed compact of tantalum metal powder; 
 iii. de-oxidation sintering the embedded lead wire and pressed compact of tantalum metal powder; 
 iv. removing oxides from the embedded lead wire and pressed compact of tantalum metal powder by leaching in an inorganic acid bath; and 
 v. anodically forming an oxide layer on the anode to provide capacitance; 
   b. incorporating the anode into a capacitor;   c. connecting the capacitor to a medical device; and   d. administering a therapy from the medical device to a patient.   
     
     
         16 . The method of  claim 15  further comprising exposing the capacitor to a voltage of from between 150 to 375 volts. 
     
     
         17 . The method of  claim 15  wherein the medical device comprises a defibrillator. 
     
     
         18 . The method of  claim 15 , wherein the device comprises a medical device for a space-critical application. 
     
     
         19 . The method of  claim 15 , wherein the reactive metal has a higher oxygen affinity than the metal powder. 
     
     
         20 . The method of  claim 15 , wherein the reactive metal is selected from the group consisting of magnesium and calcium.