Method of manufacturing substrate and substrate and mask film

A method of manufacturing a substrate, comprising:

• providing a substrate body;
• applying solder resist ink containing a mixing resin of epoxy-based resin and acrylic-based resin on at least a surface of the substrate body to form a solder resist layer;
• irradiating the solder resist layer with ultraviolet rays through a mask film that covers the solder resist layer, and exposing the solder resist layer once;
• and
• executing a developing process after the irradiating and the exposing,
• wherein the mask film comprises:
• a first portion that transmits the ultraviolet rays with a predetermined amount of transmission;
• a second portion that transmits the ultraviolet rays with a higher amount of transmission than the predetermined amount of transmission transmitted through the first portion;
• and
• a third portion that does not transmit the ultraviolet rays,
• wherein the irradiating comprises:
• covering a predetermined portion of the solder resist layer with the first portion of the mask film and irradiating the covered predetermined portion of the solder resist layer through the first portion, wherein the first portion of the mask film reduces an amount of irradiation of the ultraviolet rays to the predetermined portion, such that the predetermined portion remains in the solder resist layer after developing to form a transparent part,
• partially covering the solder resist layer with the second portion of the mask film and irradiating the covered portion of the solder resist layer through the second portion, wherein the second portion of the mask film transmits a higher amount of irradiation of the ultraviolet rays than amount of the irradiation transmitted to the predetermined portion, such that the covered portion remains in the solder resist layer after developing to form an opaque part, and
• partially covering the solder resist layer with the third portion of the mask film to shield the covered portion of the solder resist layer from irradiation by the ultraviolet rays,
• wherein the transparent part has a shape to show information of an electronic part to be mounted on the substrate body, and
• the developing process removes the covered portion of the solder resist layer which was covered with the third portion of the mask film for mounting an electronic part to the substrate body.