Mounting substrate and manufacturing method thereof, light-emitting module and illumination device

A manufacturing method of a mounting substrate on which a semiconductor light-emitting element is to be mounted, the method comprising:

• forming a reflective film on a back surface of a substrate that includes a front surface on which the semiconductor light-emitting element is to be mounted and transmits light from the semiconductor light-emitting element;
• and
• forming an electrode on the front surface of the substrate,
• wherein the forming of the reflective film includes:
• forming a first film that includes metal oxide microparticles and a glass frit and reflects the light, which is emitted from the semiconductor light-emitting element and is transmitted through the substrate, toward the front surface of the substrate, by applying a first paste obtained by kneading first materials containing the metal oxide microparticles that reflect the light from the semiconductor light-emitting element and glass powders to the back surface of the substrate and then, heating the first paste;
• and
• forming a second film including the glass frit by applying a second paste obtained by kneading second materials containing the glass powders to a surface of the first film on an opposite side to the substrate and then, heating the second paste, and
• a second volume concentration of the glass frit in the second film is larger than a first volume concentration of the glass frit in the first film.

A light-emitting module, comprising:

• a mounting substrate including a substrate and a reflective film on a back surface of the substrate;
• a wiring pattern on the front surface of the substrate;
• and
• a semiconductor light-emitting element on a front surface of the substrate,
• wherein the substrate transmits light from the semiconductor light-emitting element,
• the reflective film is a multilayer film,
• the multilayer film includes a first film that reflects the light, which is emitted from the semiconductor light-emitting element and is transmitted through the substrate, toward the front surface of the substrate and a second film on the first film on an opposite side to the substrate,
• the first film includes metal oxide microparticles that reflect the light from the semiconductor light-emitting element and a first glass frit,
• the second film includes a second glass frit, and
• a second volume concentration of the second glass frit in the second film is larger than a first volume concentration of the first glass frit in the first film.