A composite circuit board includes an insulation layer, an inner circuit layer, a first conductive layer and a second conductive layer embedded in the insulation layer, a third conductive layer and a fourth conductive layer formed on opposite surfaces of the insulation layer. The third conductive layer electrically connects with the first conductive layer. The fourth conductive layer electrically connects with the second conductive layer. The inner circuit layer is in a middle portion of the insulation layer. The first conductive layer and the second conductive layer respectively forms on opposite sides of the inner circuit layer. The insulation layer forms a plurality of first through holes between the first conductive layer and the inner circuit layer, a plurality of second through holes between the second conductive layer and the inner circuit layer.

A printed circuit board, and a method of fabricating the printed circuit board is disclosed. The printed circuit board includes at least one coaxial via. A hollow via is disposed in the printed circuit board. A metal sleeve is formed around the circumference of said hollow via. An inner conductive path is disposed in the hollow via. Additionally, an insulating material is disposed in the hollow via, between the conducting path and the metal sleeve. The conductive path is used to connect signal traces disposed on two different layers of the printed circuit board. In some embodiments, these signal traces carry signals having a frequency above 1 GHz, although the disclosure is not limited to this embodiment.

The substrate for a printed circuit board according to an embodiment of the present invention includes a base film having insulating properties, and a metal layer stacked on at least one surface of the base film, in which the base film includes a portion where a transition metal in group 10 of the periodic table is present. The transition metal in group 10 is preferably nickel or palladium. The portion where the transition metal in group 10 is present preferably includes a region having an average thickness of 500 nm and extending from an interface with the metal layer.

A composite circuit board includes an insulation layer, an inner circuit layer, a first conductive layer and a second conductive layer embedded in the insulation layer, a third conductive layer and a fourth conductive layer formed on opposite surfaces of the insulation layer. The third conductive layer electrically connects with the first conductive layer. The fourth conductive layer electrically connects with the second conductive layer. The inner circuit layer is in a middle portion of the insulation layer. The first conductive layer and the second conductive layer respectively forms on opposite sides of the inner circuit layer. The insulation layer forms a plurality of first through holes between the first conductive layer and the inner circuit layer, a plurality of second through holes between the second conductive layer and the inner circuit layer.

A composite circuit board includes an insulation layer, an inner circuit layer, a first conductive layer and a second conductive layer embedded in the insulation layer, a third conductive layer and a fourth conductive layer formed on opposite surfaces of the insulation layer. The third conductive layer electrically connects with the first conductive layer. The fourth conductive layer electrically connects with the second conductive layer. The inner circuit layer is in a middle portion of the insulation layer. The first conductive layer and the second conductive layer respectively forms on opposite sides of the inner circuit layer. The insulation layer forms a plurality of first through holes between the first conductive layer and the inner circuit layer, a plurality of second through holes between the second conductive layer and the inner circuit layer.

A composite circuit board includes an insulation layer, an inner circuit layer, a first conductive layer and a second conductive layer embedded in the insulation layer, a third conductive layer and a fourth conductive layer formed on opposite surfaces of the insulation layer. The third conductive layer electrically connects with the first conductive layer. The fourth conductive layer electrically connects with the second conductive layer. The inner circuit layer is in a middle portion of the insulation layer. The first conductive layer and the second conductive layer respectively forms on opposite sides of the inner circuit layer. The insulation layer forms a plurality of first through holes between the first conductive layer and the inner circuit layer, a plurality of second through holes between the second conductive layer and the inner circuit layer.

A printed circuit board, and a method of fabricating the printed circuit board is disclosed. The printed circuit board includes at least one coaxial via. A hollow via is disposed in the printed circuit board. A metal sleeve is formed around the circumference of said hollow via. An inner conductive path is disposed in the hollow via. Additionally, an insulating material is disposed in the hollow via, between the conducting path and the metal sleeve. The conductive path is used to connect signal traces disposed on two different layers of the printed circuit board. In some embodiments, these signal traces carry signals having a frequency above 1 GHz, although the disclosure is not limited to this embodiment.

A method for forming an organic coating on a surface of nickel or nickel alloy is disclosed. The method includes contacting the nickel surface with a composition comprising a specific pyrazine derived compound to prevent corrosion of nickel without forming known gold emersion film on the surface of the nickel.

A concave part defined by a ring-shaped step is formed on the upper surface of a housing body. A first elastic member is brought into contact with a portion of an electroless nickel-plated layer, the portion being in a region inside the concave part. The first elastic member is then pressed and deformed so that the whole of an angular portion, at which the upper surface of the ring-shaped step and its side surface cross, bites into the first elastic member and that the first elastic member and the electroless nickel-plated layer on the upper surface of the ring-shaped step are separated from each other. The housing body is then immersed in a dissolving liquid that can dissolve the electroless nickel-plated layer while the first elastic member is kept deformed.

An electronic module is provided, comprising an electronic chip arranged in the electronic module and comprising an input terminal and an output terminal; a first current path electrically connected to the input terminal; a second current path electrically connected to the output terminal; and an insulation arranged between the first current path and the second current path, wherein the first current path and the second current path extend in the same direction and arranged in close proximity to each other.