A method for manufacturing the circuit board comprises following steps of forming a silver layer on each of two opposite surfaces of an insulating substrate, and forming a copper layer on each silver layer, thereby obtaining a middle structure; defining at least one through-hole on the middle structure, and each through-hole extending through each copper layer; forming a copper wiring layer on the copper layers to cover each through-hole and a portion region of the copper layers, the copper wiring layer comprising a copper conductive structure passing through each through-hole, the copper conductive structure connecting the copper layers; removing the copper layers not covered by the copper wiring layer; and etching the silver layers to form a silver wiring layer corresponding to the copper wiring layer, wherein a first etching liquid, which does not etch the copper wiring layer, is used for etching the silver layers.

A material removal method comprises receiving a component that includes a component body and a coating on the component body, the component body comprising metallic first material, and the coating comprising a second material that is different from the first material, wherein the component is a component of an item of rotational equipment. The method also includes receiving a solution comprising nitric acid and hydrogen peroxide and subjecting at least a portion of the coating to the solution in supercritical condition in order to remove at least some of the second material from the component, wherein a chemistry of the solution is selected such that the solution is substantially non-reactive with the first material.

A material removal method comprises receiving a component that includes a component body and a coating on the component body, the component body comprising metallic first material, and the coating comprising a second material that is different from the first material, wherein the component is a component of an item of rotational equipment. The method also includes receiving a solution comprising nitric acid and hydrogen peroxide and subjecting at least a portion of the coating to the solution in supercritical condition in order to remove at least some of the second material from the component, wherein a chemistry of the solution is selected such that the solution is substantially non-reactive with the first material.

An etchant composition of an embodiment includes a persulfate, a four-nitrogen ring compound, a two-chlorine compound, a fluorine compound and water, and has a weight ratio of the four-nitrogen ring compound and the two-chlorine compound of about 1:0.5 to about 1:4. The etchant composition may etch a multilayer metal substrate of titanium/copper and may be used for manufacturing a multilayer metal pattern and an array substrate having excellent properties of etched patterns.

According to one embodiment, a method for manufacturing a ceramic circuit board is disclosed. The ceramic circuit board includes a copper plate bonded to at least one surface of a ceramic substrate via a brazing material layer including Ag, Cu, and a reactive metal. The method includes: preparing a ceramic circuit board in which a copper plate is bonded on a ceramic substrate via a brazing material layer, and a portion of the brazing material layer is exposed between a pattern shape of the copper plate; a first chemical polishing process of chemically polishing the portion of the brazing material layer; and a first brazing material etching process of etching the chemically polished portion of the brazing material layer by using an etchant having a pH of 6 or less and including one type or two types selected from hydrogen peroxide and ammonium peroxodisulfate.

A method for manufacturing the circuit board comprises following steps of providing an insulating substrate, and defining at least one through-hole on the insulating substrate to extending through two opposite surfaces of the insulating substrate; forming a silver layer on each of the two opposite surfaces, and forming a silver conductive structure in each through-hole connecting the silver layers; forming a copper wiring layer on the silver layers to cover each silver conductive structure and a portion region of the silver layers; and etching the silver layers to form a silver wiring layer corresponding to the copper wiring layer, wherein a first etching liquid, which does not etch the copper wiring layer, is used for etching the silver layers.

A method for manufacturing the circuit board comprises following steps of providing an insulating substrate, and defining at least one through-hole on the insulating substrate to extending through two opposite surfaces of the insulating substrate; forming a silver layer on each of the two opposite surfaces, and forming a silver conductive structure in each through-hole connecting the silver layers; forming a copper wiring layer on the silver layers to cover each silver conductive structure and a portion region of the silver layers; and etching the silver layers to form a silver wiring layer corresponding to the copper wiring layer, wherein a first etching liquid, which does not etch the copper wiring layer, is used for etching the silver layers.

An etchant includes about 8 wt % to about 12 wt % of nitric acid, about 3 wt % to about 8 wt % of alkylsulfonic acid, about 7 wt % to about 12 wt % of a sulfate, about 40 wt % to about 55 wt % of an organic acid, about 0.5 wt % to about 5 wt % of an organic acid salt, and a balance of water.

An etchant includes about 8 wt % to about 12 wt % of nitric acid, about 3 wt % to about 8 wt % of alkylsulfonic acid, about 7 wt % to about 12 wt % of a sulfate, about 40 wt % to about 55 wt % of an organic acid, about 0.5 wt % to about 5 wt % of an organic acid salt, and a balance of water.

An etchant includes about 8 wt % to about 12 wt % of nitric acid, about 3 wt % to about 8 wt % of alkylsulfonic acid, about 7 wt % to about 12 wt % of a sulfate, about 40 wt % to about 55 wt % of an organic acid, about 0.5 wt % to about 5 wt % of an organic acid salt, and a balance of water.