Electrodeposition system and method incorporating an anode having a back side capacitive element
View Patent ↗Disclosed are an electrodeposition system and method with an anode assembly comprising a capacitor comprising a first conductive plate (i.e., an anode) with a frontside having a surface exposed to a plating solution, a second conductive plate on a backside of the first conductive plate, and a dielectric layer between the two conductive plates. During a non-plating mode, a power source, having positive and negative terminals connected to the first and second conductive plates, respectively, is turned on, thereby polarizing the first conductive plate (i.e., the anode) relative to the second conductive plate to prevent degradation of the anode and/or plating solution. During an active plating mode, another power source, having positive and negative terminals connected to the first conductive plate (i.e., the anode) and a cathode, respectively, is turned on, thereby polarizing the anode relative to the cathode in order to deposit a plated layer on a workpiece.
1. An electrodeposition method comprising:
providing a container containing an anode assembly, said anode assembly comprising a capacitor comprising:
a first conductive plate having a surface;
a second conductive plate; and
a dielectric layer between said first conductive plate and said second conductive plate, said first conductive plate being electrically connected to a first positive terminal of a first power source and said second conductive plate being electrically connected to a first negative terminal of said first power source; and
during a non-plating mode when said surface is exposed to a plating solution contained in said container, turning on said first power source in order to supply a first operating current to said capacitor to prevent degradation of any one of said first conductive plate and said plating solution.
2. The electrodeposition method of claim 1 , said capacitor being held in said plating solution such that exposure of said dielectric layer and said second conductive plate to said plating solution is prevented.
3. The electrodeposition method of claim 1 , said first conductive plate comprising any one of a soluble metal and an insoluble metal.
4. The electrodeposition method of claim 1 ,
said first conductive plate further being electrically connected to a second positive terminal of a second power source,
said container further containing a cathode assembly removably placed in said container,
said cathode assembly being electrically connected to a second negative terminal of said second power source so as to form an electric circuit, and
said method further comprising, during an active plating mode, selectively turning off said first power source and turning on said second power source in order to supply a second operating current to said electric circuit so as to form a plated layer on a workpiece exposed to said plating solution at said cathode assembly.
5. The electrodeposition method of claim 4 , said first operating current being less than said second operating current.
6. The electrodeposition method of claim 4 ,
said first conductive plate comprising a soluble metal plate comprising a tin plate,
said plating solution comprising water and, dissolved in said water, methyl sulfonic acid (MSA), tin ions and silver ions,
said first operating current causing tin from said tin plate to dissolve in said plating solution and preventing silver in said plating solution from depositing on said surface, and
said second operating current causing a tin-silver plated layer to form on said workpiece.
7. The electrodeposition method of claim 4 ,
said first conductive plate comprising an insoluble metal plate comprising a platinum catalyst-coated titanium plate,
said plating solution comprising water and, dissolved in said water, methyl sulfonic acid (MSA), tin ions and silver ions,
said plating solution corroding platinum and exposing titanium of said platinum catalyst-coated titanium plate,
said first operating current preventing said titanium from said platinum catalyst-coated titanium plate from dissolving in said plating solution and further preventing tin from said plating solution from depositing on said surface, and
said second operating current causing a tin-silver plated layer to form on said workpiece.
8. A method, comprising:
providing a first power source having a first negative terminal and a first positive terminal;
providing a second power source having a second negative terminal and a second positive terminal;
providing an anode assembly comprising a first conductive plate, a second conductive plate, and a dielectric layer between said first conductive plate and said second conductive plate;
providing a cathode assembly;
electrically connecting said first conductive plate to said first positive terminal of said first power source;
electrically connecting said second conductive plate to said first negative terminal of said first power source;
electrically connecting said first conductive plate to said second positive terminal of said second power source;
electrically connecting said cathode assembly to said second negative terminal of said second power source;
disposing said anode assembly in a container containing a plating solution;
disposing said cathode assembly in said container containing said plating solution; and
performing a plating operation by energizing said second power source and de-energizing said first power source,
responsive to a non-plating operation, energizing said first power source and de-energizing said second power source.
9. The method of claim 8 , further comprising:
sealing a portion of said anode assembly to prevent exposure of said dielectric layer and said second conductive plate to said plating solution.
10. The method of claim 8 , further comprising:
attaching a workpiece to said cathode assembly.
11. The method of claim 10 ,
said first conductive plate comprising a soluble metal plate comprising a tin plate,
said plating solution comprising water and, dissolved in said water, methyl sulfonic acid (MSA), tin ions and silver ions,
said method further comprising:
said first power source applying a first operating current to said anode assembly causing tin from said tin plate to dissolve in said plating solution and preventing silver in said plating solution from depositing on an exposed surface of said first conductive plate, and
said second power source applying a second operating current causing a tin-silver plated layer to form on said workpiece.
12. The method of claim 11 , said first operating current being less than said second operating current.
13. The method of claim 10 ,
said first conductive plate comprising an insoluble metal plate comprising a platinum catalyst-coated titanium plate,
said plating solution comprising water and, dissolved in said water, methyl sulfonic acid (MSA), tin ions and silver ions,
said plating solution corroding platinum and exposing titanium of said platinum catalyst-coated titanium plate,
said first power source applying a first operating current preventing said titanium from said platinum catalyst-coated titanium plate from dissolving in said plating solution and further preventing tin from said plating solution from depositing on an exposed surface of said first conductive plate, and
said second power source applying a second operating current causing a tin-silver plated layer to form on said workpiece.
14. The method of claim 13 , said first operating current being less than said second operating current.
15. The method of claim 8 , said first conductive plate comprising any one of a soluble metal and an insoluble metal.