An embodiment of the present invention provides a copper foil which comprises a copper layer and an anticorrosive film placed on the copper layer, and has a Young's modulus of 3800 to 4600 kgf/mm.sup.2 and a modulus bias factor (MBF) less than 0.12, wherein the modulus bias factor (MBF) is obtained by formula 1 below.
MBF=(maximum Young's modulus−minimum Young's modulus)/(average Young's modulus)  [Formula 1]

Provided is a liquid mixture for filling blind holes in copper foil, relating to the technical field of electroplating hole filling. The liquid mixture comprises copper sulfate pentahydrate 210-240 g/L, citric acid 40-50 g/L, tartaric acid 10-20 g/L, chloride ion 40-70 ppm, accelerator 0.5-2 g/L, leveling agent 5-15 g/L, inhibitor 5-10 g/L, and sulfonate ion liquid 50-180 g/L. The leveling agent comprises tetranitro blue tetrazolium blue and triazolyl acetyl hydrazide.

Systems and processes for recycling printed circuit boards, wherein precious metals may be reclaimed. The system generally includes a number of modules to systematically remove materials from the printed circuit boards and to separate the precious metals from the materials.

Substrate assemblies having adhesion promotor layers and related methods are disclosed. An example apparatus includes a substrate, a dielectric layer, a first copper layer between the substrate and the dielectric layer, and a film between the dielectric layer and the first copper layer. The film including silicon and nitrogen and being substantially free of hydrogen. A via in the dielectric layer is to provide access to the first copper layer. A portion of the first copper layer uncovered in the via, a wall of the via and the portion of the first copper layer to be substantially free of fluorine. A seed copper layer positioned on the dielectric layer. The via wall and the portion of the first copper layer. The seed copper layer and the first copper layer define an undercut at an interface between the seed copper layer and the first copper layer.

An etch chemistry solution for treating metallic surfaces in which the etch chemistry solution includes an oxidizing agent and gluconic acid. The etch chemistry solution may also include an oxidizing agent and a short-chained polyethylene polymer glycol or a short-chained polyethylene copolymer glycol. The metallic surfaces are usually used in circuits such as flexible circuits.

An etch chemistry solution for treating metallic surfaces in which the etch chemistry solution includes an oxidizing agent and gluconic acid. The etch chemistry solution may also include an oxidizing agent and a short-chained polyethylene polymer glycol or a short-chained polyethylene copolymer glycol. The metallic surfaces are usually used in circuits such as flexible circuits.

An embodiment of the present invention provides a copper foil which comprises a copper layer and an anticorrosive film placed on the copper layer, and has a Young's modulus of 3800 to 4600 kgf/mm.sup.2 and a modulus bias factor (MBF) less than 0.12, wherein the modulus bias factor (MBF) is obtained by formula 1 below.

MBF=(maximum Young's modulus-minimum Young's modulus)/(average Young's modulus)[Formula 1]

An etch chemistry solution for treating metallic surfaces in which the etch chemistry solution includes an oxidizing agent and gluconic acid. The etch chemistry solution may also include an oxidizing agent and a short-chained polyethylene polymer glycol or a short-chained polyethylene copolymer glycol. The metallic surfaces are usually used in circuits such as flexible circuits.

To provide a wiring substrate having excellent transmission characteristics, of which initial failure of a plating layer formed on an inner wall surface of a hole is suppressed regardless of the type of the pre-treatment applied to the inner wall surface of the hole, and of which the plating layer has favorable heat resistance, and a process for producing it. A wiring substrate 10 comprising an electrical insulator layer 20, a first conductor layer 32 formed on a first surface of the electrical insulator layer 20, a second conductor layer 34 formed on a second surface of the electrical insulator layer 20, and a plating layer 42 provided on an inner wall surface of a hole 40 which opens from the first conductor layer 32 through the second conductor layer 34; wherein the electrical insulator layer 20 has a heat resistant resin layer 22 containing a heat resistant resin and a resin powder; the resin powder is formed from a resin material containing a melt-formable fluororesin having a functional group such as a carbonyl group-containing group; the content of the resin powder is from 5 to 70 mass % to the heat resistant resin layer 22; and the electrical insulator layer 20 has a dielectric constant of from 2.0 to 3.5.

To provide a wiring substrate having excellent transmission characteristics, of which initial failure of a plating layer formed on an inner wall surface of a hole is suppressed regardless of the type of the pre-treatment applied to the inner wall surface of the hole, and of which the plating layer has favorable heat resistance, and a process for producing it.

A wiring substrate 10 comprising an electrical insulator layer 20, a first conductor layer 32 formed on a first surface of the electrical insulator layer 20, a second conductor layer 34 formed on a second surface of the electrical insulator layer 20, and a plating layer 42 provided on an inner wall surface of a hole 40 which opens from the first conductor layer 32 through the second conductor layer 34; wherein the electrical insulator layer 20 has a heat resistant resin layer 22 containing a heat resistant resin and a resin powder; the resin powder is formed from a resin material containing a melt-formable fluororesin having a functional group such as a carbonyl group-containing group; the content of the resin powder is from 5 to 70 mass % to the heat resistant resin layer 22; and the electrical insulator layer 20 has a dielectric constant of from 2.0 to 3.5.