US-20260128233-A1 - FABRICATION OF CAPACITORS AND RECOVERY OF CAPACITOR FABRICATION MATERIALS

US20260128233A1US 20260128233 A1US20260128233 A1US 20260128233A1US-20260128233-A1

Abstract

Fabricating a capacitor includes using a first etching solution to etch a first sheet of material so as to generate a spent etchant. At least one chemical component is recovered from the spent etchant. A second etching solution is used to etch a second sheet of material. The second etchant includes at least one of the chemical components that was recovered from the spent etchant.

Inventors

Ralph Hemphill
Henry Buser, III
Shelley M. Smith
Brian Smith
Debbie Uselman

Assignees

PACESETTER, INC.

Dates

Publication Date: 20260507
Application Date: 20251230

Claims (17)

1 . A method of fabricating a capacitor, comprising: using a first etching solution to etch a first sheet of material so as to generate a spent etchant, wherein the first etching solution includes at least one chemical component selected from the group consisting of hydrochloric acid, sulfuric acid, sodium perchlorate, and potassium perfluorobutane sulfonic acid (KFBS); recovering the at least one chemical component from the spent etchant; and using a second etching solution to etch a second sheet of material, the second etchant including the at least one chemical component that was recovered from the spent etchant, wherein the at least one chemical component in the second etching solution is not quantified before using the second etching solution.
2 . The method of claim 1 , further comprising: fabricating a capacitor with an electrode that includes a portion of the first sheet of material.
3 . The method of claim 1 , wherein the recovered chemical component includes sodium perchlorate.
4 . The method of claim 1 , wherein the spent etching solution that includes metal ions from the first sheet of material; and wherein recovering the at least one chemical component includes adding a precipitant to the spent etching solution so as to cause precipitation of a compound in a precipitation solution, the compound including the metal ions from the sheet of material.
5 . A method of fabricating a capacitor electrode, comprising: exposing a sheet of material to an etching solution so as to generate a spent etching solution that includes metal ions from the sheet of material, wherein the etching solution includes at least one chemical component selected from the group consisting of hydrochloric acid, sulfuric acid, sodium perchlorate, and potassium perfluorobutane sulfonic acid (KFBS); adding a precipitant to the spent etching solution so as to cause precipitation of a compound in a precipitation solution, the compound including the metal ions from the sheet of material, the precipitant being disassociated in the precipitation solution such that the precipitation solution includes cations from the precipitant; removing from the precipitation solution at least a portion of the cations from the precipitant; and removing the cations from the precipitation solution so as to generate a recovery solution; wherein the at least one chemical component in the recovery solution is not quantified.
6 . The method of claim 5 , wherein the etching solution includes sodium perchlorate.
7 . The method of claim 5 , wherein the etching solution includes hydrochloric acid, sulfuric acid, sodium perchlorate, and potassium perfluorobutane sulfonic acid (KFBS).
8 . The method of claim 5 , wherein the sheet of material includes aluminum and the spent etching solution includes aluminum ions.
9 . The method of claim 5 , wherein removing the cations from the precipitation solution includes performing a cation exchange on the precipitation solution.
10 . The method of claim 5 , wherein the precipitant is a base.
11 . The method of claim 5 , wherein the cations from the precipitant are a base cation.
12 . The method of claim 5 , wherein adding the precipitant to the spent etching solution increases a pH of the precipitation solution above the pH of the spent etching solution.
13 . The method of claim 5 , wherein the precipitant is added to the spent etching solution so as to maintain a pH of the precipitation solution in a range of 5.5 to 7.0 during the precipitation of the compound.
14 . The method of claim 5 , wherein a molar amount of each one of one or more of the chemical components in the recovery solution is more than 30 wt % of the chemical components that were originally included in the etching solution and are not water.
15 . The method of claim 5 , wherein one or more adjustment solutions are added to the recovery solution so as to generate a recovered etchant that includes at least a portion of the chemical components at a concentration that is within the concentration of that component in the etching solution +/−0.5 wt %.
16 . The method of claim 15 , wherein the one or more chemical components include hydrochloric acid, sulfuric acid, sodium perchlorate, and potassium perfluorobutane sulfonic acid (KFBS).
17 . The method of claim 15 , wherein the one or more chemical components include sodium perchlorate and the recovered etchant includes the sodium perchlorate at a concentration that is within the concentration of the sodium perchlorate in the etching solution +/−2 wt %.

Description

RELATED APPLICATIONS This application is a Continuation of U.S. patent application Ser. No. 17/539,171, filed on Nov. 30, 2021, and incorporated herein in its entirety; and U.S. patent application Ser. No. 17/539,171 is a Divisional of U.S. patent application Ser. No. 16/785,594, filed on Feb. 8, 2020, and incorporated herein in its entirety; and U.S. patent application Ser. No. 16/785,594 claims the benefit of U.S. Patent application Ser. No. 62/804,055, filed on Feb. 11, 2019, and incorporated herein in its entirety and U.S. patent application Ser. No. 16/785,594 also claims the benefit of U.S. Patent application Ser. No. 62/804,060, filed on Feb. 11, 2019, and incorporated herein in its entirety. FIELD The invention relates to electrochemical devices. In particular, the invention relates to capacitors. BACKGROUND Electrodes for capacitors are often fabricated by etching tunnels in a sheet of material that includes an anode metal. An oxide of the anode metal is then formed on the exposed anode metal. In order to prevent clogging of the tunnels by the oxide, the tunnels are generally widened before the oxide is formed in the tunnels. After the formation of the oxide, the sheet of material generally becomes brittle. The electrode is removed from the sheet of material using mechanical cutting techniques or other cutting techniques such as laser cutting. During fabrication of the capacitor, one or more electrical conductors are generally connected to the electrode in order to provide electrical communication between the electrode and a terminal of the capacitor. Welding is often used to make this connection, however, welding is hampered by the composite nature of the electrode. In order to overcome this problem, the welded region of the electrode is masked during the etching of the tunnels and during the formation of the oxide. This masking prevents the tunnels from being formed under the mask. As a result, the final electrode includes an inactive region where the sheet of material excludes the tunnels. In some instances, the inactive region also excludes the oxide. An electrical conductor is then connected to the inactive region of the electrode. While masking the welded region solves the problem of welding the electrode, it has the unwanted side effect of contributing to mechanical waviness across the surface of the electrode formation of the oxide. The waviness can be caused by etching and/or oxide formation reducing the size of the unmasked portion of the electrode and producing a strain in regions of the electrode where an etched region is interfaced with an inactive region. As a result, there is a need for improved capacitor electrode construction. Additionally, etching the tunnels in the anode of a capacitor can be done with processes such as electrochemical etching or electrochemical drilling. In electrochemical etching and/or electrochemical drilling, a sheet of a material is at least partially immersed in a bath of etching solution. In some instances, the etching solution includes one or more acids and sodium perchlorate. The etching process leaves material from the sheet of material dissolved in spent etching solution. For instance, when the sheet of material is aluminum, the etching process results dissolved aluminum being present in the spent etching solution. However, high levels of dissolved aluminum causes tunnel initiation to drop and the pH of the bath to increase. As a result, fresh etching solution is added to the etch bath to control pH and aluminum concentration. The spent etching solution cannot be discharged to POTW (Publicly Owned Treatment Work) and accordingly requires costly waste disposal. Additionally, sodium perchlorate is expensive and, highly stable thermally, and does not break down quickly in the environment. As a result, there is a need to recover spent one or more compounds from spent etching solution. SUMMARY A capacitor includes an electrode with a first active region that includes tunnels extending into an electrode metal. The electrode also has a first inactive region that includes the electrode metal but does not include the tunnels extending into the electrode metal. The first inactive region has a first shape that includes multiple first projections that each projects from a perimeter of a first semicircle. In some instances, the electrode has a second inactive region that includes the electrode metal but does not include the tunnels extending into the electrode metal. The second inactive region has a second shape that includes multiple second projections that each projects from a perimeter of a second semicircle. A first side of the electrode is opposite from a second side of the electrode. The first active region and the first inactive region are on the first side of the electrode and the second active region and the second inactive region are on the second side of the electrode. The first semicircle can be aligned with the second semicircle in that a first line c