A piston ring for an engine may include a piston ring body. The piston ring body may include a working surface, a lower surface, an upper surface, and an inner surface. An area of the working surface and/or the lower surface which is close to an outer circumferential lower edge of the piston ring body is not provided with a nitride layer, the outer circumferential lower edge is formed with a chamfer, the chamfer does not have a nitride layer, and an additional area of the piston ring has a nitride layer.

Provided is a method for manufacturing a circuit board including: (a) preparing a mixture of a metal powder, an anti-sintering agent, and an activator; (b) immersing a dielectric substrate in the mixture; (c) forming a metal-containing layer on the surface of the dielectric substrate by heating the mixture under an inert atmosphere or under a reducing atmosphere; (d) forming a first metal layer on the metal-containing layer by electroless plating and forming a second metal layer thereon by electroplating; and (e) forming a metal pattern on the dielectric substrate, wherein the first metal layer includes Cu, Ni, Co, Au, Pd, or an alloy thereof, the second metal layer includes Cu, Ni, Fe, Co, Cr, Zn, Au, Ag, Pt, Pd, Rh, or an alloy thereof, and the method further includes performing heat treatment at least once after step (c).

Provided is a method for manufacturing a circuit board including: (a) preparing a mixture of a metal powder, an anti-sintering agent, and an activator; (b) immersing a dielectric substrate in the mixture; (c) forming a metal-containing layer on the surface of the dielectric substrate by heating the mixture under an inert atmosphere or under a reducing atmosphere; (d) forming a first metal layer on the metal-containing layer by electroless plating and forming a second metal layer thereon by electroplating; and (e) forming a metal pattern on the dielectric substrate, wherein the first metal layer includes Cu, Ni, Co, Au, Pd, or an alloy thereof, the second metal layer includes Cu, Ni, Fe, Co, Cr, Zn, Au, Ag, Pt, Pd, Rh, or an alloy thereof, and the method further includes performing heat treatment at least once after step (c).

A film forming method and a film forming apparatus of a metal plating film allowing suppressing damage of a porous film. A metal plating film on a surface of a metal substrate by solid substitution-type electroless plating method. The film forming method includes preparing the film forming apparatus that includes at least a bottom wall and a sidewall surrounding the bottom wall and that is provided with a housing space, the metal substrate disposed on the bottom surface inside the housing, the porous film disposed on the surface of the metal substrate, and an electroless plating solution housed in the housing space; and using the film forming apparatus, reducing metal ions derived from the electroless plating solution contained in the porous film, and depositing the metal ions on the surface of the metal substrate to form the metal plating film on the surface of the metal substrate.

A film forming method and a film forming apparatus of a metal plating film allowing suppressing damage of a porous film. A metal plating film on a surface of a metal substrate by solid substitution-type electroless plating method. The film forming method includes preparing the film forming apparatus that includes at least a bottom wall and a sidewall surrounding the bottom wall and that is provided with a housing space, the metal substrate disposed on the bottom surface inside the housing, the porous film disposed on the surface of the metal substrate, and an electroless plating solution housed in the housing space; and using the film forming apparatus, reducing metal ions derived from the electroless plating solution contained in the porous film, and depositing the metal ions on the surface of the metal substrate to form the metal plating film on the surface of the metal substrate.

A transistor manufacturing method includes forming a source electrode and a drain electrode on a substrate, forming a layer including an insulator layer to cover the source electrode and the drain electrode, and forming a gate electrode on the layer including the insulator layer, wherein the forming the gate electrode includes forming a plating base film, forming a protection layer of the plating base film, forming a photoresist layer on the protection layer to expose the photoresist layer with desired patterning light, causing the exposed photoresist layer to come into contact with a developer to remove the photoresist layer and the protection layer until the plating base film is uncovered corresponding to the patterning light, and after depositing a metal on the uncovered plating base film, causing an electroless plating solution to come into contact with the plating base film to perform electroless plating.

A transistor manufacturing method includes forming a source electrode and a drain electrode on a substrate, forming a layer including an insulator layer to cover the source electrode and the drain electrode, and forming a gate electrode on the layer including the insulator layer, wherein the forming the gate electrode includes forming a plating base film, forming a protection layer of the plating base film, forming a photoresist layer on the protection layer to expose the photoresist layer with desired patterning light, causing the exposed photoresist layer to come into contact with a developer to remove the photoresist layer and the protection layer until the plating base film is uncovered corresponding to the patterning light, and after depositing a metal on the uncovered plating base film, causing an electroless plating solution to come into contact with the plating base film to perform electroless plating.

Provided is a method for manufacturing a circuit board including: (a) preparing a mixture of a metal powder, an anti-sintering agent, and an activator; (b) immersing a dielectric substrate in the mixture; (c) forming a metal-containing layer on the surface of the dielectric substrate by heating the mixture under an inert atmosphere or under a reducing atmosphere; (d) forming a first metal layer on the metal-containing layer by electroless plating and forming a second metal layer thereon by electroplating; and (e) forming a metal pattern on the dielectric substrate, wherein the first metal layer includes Cu, Ni, Co, Au, Pd, or an alloy thereof, the second metal layer includes Cu, Ni, Fe, Co, Cr, Zn, Au, Ag, Pt, Pd, Rh, or an alloy thereof, and the method further includes performing heat treatment at least once after step (c).

Provided is a method for manufacturing a circuit board including: (a) preparing a mixture of a metal powder, an anti-sintering agent, and an activator; (b) immersing a dielectric substrate in the mixture; (c) forming a metal-containing layer on the surface of the dielectric substrate by heating the mixture under an inert atmosphere or under a reducing atmosphere; (d) forming a first metal layer on the metal-containing layer by electroless plating and forming a second metal layer thereon by electroplating; and (e) forming a metal pattern on the dielectric substrate, wherein the first metal layer includes Cu, Ni, Co, Au, Pd, or an alloy thereof, the second metal layer includes Cu, Ni, Fe, Co, Cr, Zn, Au, Ag, Pt, Pd, Rh, or an alloy thereof, and the method further includes performing heat treatment at least once after step (c).

A catalyst solution for electroless plating is provided. The catalyst solution is printable and devoid of an amine. The catalyst solution comprises a catalytic metal salt, a solvent, and an epoxy.