Optical device cavity structure, optical device, and method for manufacturing an optical device cavity structure

An optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure comprising:

• at least three insulator layers, including a first, a second and a third insulator layer, and at least three metal layers, including a first, a second and a third metal layer, alternately layered on one another;
• a first terminal section formed on a mounting surface to be mounted on the wiring substrate so as to be electrically connected to the wiring substrate;
• and
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to the mounting surface, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer, the second insulator layer, the third metal layer and the third insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of first protruding portions and a second protruding portion protruding from the inner wall surface, wherein the first protruding portions are formed by the first insulator layer and the second metal layer, and the second protruding portion is formed by second insulator layer and the third metal layer and is protruding over a shorter distance than the first protruding portions;
• the second metal layer in each first protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• and
• a surface of the third metal layer in the second protruding portion is a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip.

An optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure comprising:

• at least two insulator layers, including a first and a second insulator layer, and at least three metal layers, including a first, a second and a third metal layer, alternately layered on one another;
• a first terminal section formed on a mounting surface to be mounted on the wiring substrate so as to be electrically connected to the wiring substrate;
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to the mounting surface;
• and
• an optical component fitting section being a depression surrounding the opening in which an optical component for transmitting therethrough light to be received by, or light emitted from, the optical element chip is to be fitted, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer and the second insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of protruding portions protruding from the inner wall surface, each protruding portion being formed by the first insulator layer and the second metal layer;
• the second metal layer in each protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• and
• a surface of the optical component fitting section generally parallel to the bottom surface of the cavity portion is a portion of the third metal layer.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, the base substrate including a first metal layer which is formed on one surface of a first insulator layer and which is to be the first terminal section, a second metal layer formed on the other surface of the first insulator layer, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of a surface of the second insulator layer and a plurality of tongue-shaped portions extending from the peripheral portion toward a central portion of the surface of the second insulator layer, and a third insulator layer formed on a surface of the third metal layer and on a portion of the second insulator layer that is not covered by the third metal layer;
• and
• a laser light irradiation step of irradiating a surface of the base substrate with laser light, thereby removing a portion of the second insulator layer that is not covered by the third metal layer, a portion of the third insulator layer where the third metal layer is absent and a portion of the third insulator layer formed over the tongue-shaped portions, while roughening a remaining portion of the third insulator layer, wherein:
• in the laser light irradiation step, as a result of the removal of the second and third insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as the optical element chip placement section;
• as a result of the removal of the third insulator layer, the tongue-shaped portions are exposed, thus forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section;
• and
• as a result of the roughening of the remaining portion of the third insulator layer, the light-transmitting member placement section is formed.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, the base substrate including a first metal layer which is formed on one surface of a first insulator layer and which is to be the first terminal section, a second metal layer formed on the other surface of the first insulator layer, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of a surface of the second insulator layer and a plurality of tongue-shaped portions extending from the peripheral portion toward a central portion of the surface of the second insulator layer, and a third insulator layer formed on a surface of the third metal layer and on a portion of the second insulator layer that is not covered by the third metal layer;
• a laser light irradiation step of irradiating a portion of a surface of the base substrate where the third metal layer is absent and portions thereof corresponding to the tongue-shaped portions with laser light, thereby removing a portion of the second insulator layer that is not covered by the third metal layer and an irradiated portion of the third insulator layer;
• and
• a step of, after the laser light irradiation step, forming a resist layer on a surface of a remaining portion of the third insulator layer, thus forming the light-transmitting member placement section, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second and third insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as an optical element chip placement section;
• and
• as a result of the removal of the third insulator layer, the tongue-shaped portions are exposed, thus forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, the base substrate including a first metal layer which is formed on one surface of a first insulator layer and which is to be the first terminal section, a second metal layer formed on the other surface of the first insulator layer, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of a surface of the second insulator layer and a plurality of tongue-shaped portions extending from the peripheral portion toward a central portion of the surface of the second insulator layer, a fourth metal layer formed on a surface of a third insulator layer formed on the third metal layer so as to be narrower than the third metal layer, and a fourth insulator layer formed on a surface of the fourth metal layer and on a portion of the third insulator layer that is not covered by the fourth metal layer;
• and
• a laser light irradiation step of irradiating a portion of a surface of the base substrate where the third metal layer is absent and portions thereof corresponding to the tongue-shaped portions and a peripheral portion of the tongue-shaped portions with laser light, thereby removing an irradiated portion of the fourth insulator layer, a portion of the third insulator layer that is not covered by the fourth metal layer and a portion of the second insulator layer that is not covered by the third metal layer, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second, third and fourth insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as the optical element chip placement section;
• as a result of the removal of the third insulator layer, the tongue-shaped portions are exposed, thus forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section;
• and
• as a result of the removal of the fourth insulator layer, at least a portion of the fourth metal layer is exposed, thereby forming a second protruding portion protruding, over a shorter distance than the first protruding portion, from each inner wall surface of the cavity portion, the second protruding portion serving as the light-transmitting member placement section.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and an optical component fitting section in which an optical component is fitted, the optical component transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, including a first metal layer which is formed on one surface of a first insulator layer and which is to be the first terminal section, a second metal layer formed on the other surface of the first insulator layer, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of a surface of the second insulator layer and a plurality of tongue-shaped portions extending from the peripheral portion toward a central portion of the surface of the second insulator layer, a fourth metal layer formed on a surface of a third insulator layer formed on the third metal layer so as to be narrower than the third metal layer, and a fourth insulator layer formed on a surface of the fourth metal layer and on a portion of the third insulator layer that is not covered by the fourth metal layer;
• and
• a laser light irradiation step of irradiating a portion of a surface of the base substrate where the third metal layer is absent and portions corresponding to the tongue-shaped portions and the fourth metal layer with laser light, thereby removing an irradiated portion of the fourth insulator layer, a portion of third insulator layer that is not covered by the fourth metal layer and a portion of the second insulator layer that is not covered by the third metal layer, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second, third and fourth insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as an optical element chip placement section;
• as a result of the removal of the third insulator layer, the tongue-shaped portions are exposed, thereby forming a plurality of first protruding portions protruding from inner wall surfaces of the cavity portion, each first protruding portion serving as the second terminal section;
• and
• as a result of the removal of the peripheral portion of the fourth insulator layer, at least a portion of the fourth metal layer is exposed, thereby forming the optical component fitting section.

An optical device cavity structure which is mounted on a wiring substrate and which receives an optical element chip thereon, the optical device cavity structure comprising:

• a plurality of insulator layers, including a first and a second insulator layer, and a plurality of metal layers, including a first, a second and a third metal layer, alternately layered on one another;
• a first terminal section formed on a mounting surface to be mounted on the wiring substrate so as to be electrically connected to the wiring substrate;
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to the mounting surface;
• and
• a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer and the second insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of protruding portions protruding from the inner wall surface, each protruding portion being formed by the first insulator layer and the second metal layer;
• the second metal layer in each protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• and
• the third metal layer is placed closer to the mounting surface than the first metal layer.

An optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure comprising:

• at least two insulator layers, including a first and a second insulator layer, and at least two metal layers, including a first and a second metal layer, alternately layered on one another;
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to a mounting surface to be mounted on the wiring substrate;
• a light-transmitting member placement section formed on the opposite surface surrounding the opening for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip;
• and
• a first terminal section electrically connected to a wire of the wiring substrate, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer and the second insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of protruding portions protruding from the inner wall surface, each protruding portion being formed by the first insulator layer and the second metal layer;
• the second metal layer in each protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• the first terminal section is protruding outwardly from an outer wall surface generally perpendicular to the mounting surface, and a lower surface and at least a portion of a side surface of the first terminal section are covered by a conductive layer;
• and
• the light-transmitting member placement section includes securing means, being a portion of the second insulator layer, for securing the light-transmitting member.

An optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure comprising:

• at least three insulator layers, including a first, a second and a third insulator layer, and at least three metal layers, including a first, a second and a third metal layer, alternately layered on one another;
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to a mounting surface to be mounted on the wiring substrate;
• and
• a first terminal section electrically connected to a wire of the wiring substrate, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer, the second insulator layer, the third metal layer and the third insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of first protruding portions and a second protruding portion protruding from the inner wall surface, wherein the first protruding portions are formed by the first insulator layer and the second metal layer, and the second protruding portion is formed by second insulator layer and the third metal layer and is protruding over a shorter distance than the first protruding portions;
• the second metal layer in each first protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• a surface of the third metal layer in the second protruding portion is a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip;
• and
• the first terminal section is protruding outwardly from an outer wall surface generally perpendicular to the mounting surface, and a lower surface and at least a portion of a side surface of the first terminal section are covered by a conductive layer.

An optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure comprising:

• at least two insulator layers, including a first and a second insulator layer, and at least three metal layers, including a first, a second and a third metal layer, alternately layered on one another;
• a cavity portion having a generally rectangular opening in a central portion of a surface opposite to a mounting surface to be mounted on the wiring substrate;
• an optical component fitting section being a depression surrounding the opening in which an optical component for transmitting therethrough light to be received by, or light emitted from, the optical element chip is to be fitted;
• and
• a first terminal section electrically connected to a wire of the wiring substrate, wherein:
• a bottom surface of the cavity portion is a portion of the first metal layer and is a chip placement section for receiving the optical element chip thereon;
• each inner wall surface of the cavity portion is formed by the first insulator layer, the second metal layer and the second insulator layer, which are layered in this order from the bottom surface toward the opening, with a plurality of protruding portions protruding from the inner wall surface, each protruding portion being formed by the first insulator layer and the second metal layer;
• the second metal layer in each protruding portion is a second terminal section which is electrically connected to the first terminal section and which is to be electrically connected to the optical element chip;
• a surface of the optical component fitting section generally parallel to the bottom surface of the cavity portion is a portion of the third metal layer;
• and
• the first terminal section is protruding outwardly from an outer wall surface generally perpendicular to the mounting surface, and a lower surface and at least a portion of a side surface of the first terminal section are covered by a conductive layer.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, the base substrate including a first metal layer formed on one surface of a first insulator layer, a second metal layer formed on the other surface of the first insulator layer and having a plurality of first tongue-shaped portions extending outwardly, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of the second insulator layer and a plurality of second tongue-shaped portions extending from the peripheral portion toward a central portion of the second insulator layer, and a third insulator layer formed on a surface of the third metal layer and on a portion of the second insulator layer that is not covered by the third metal layer;
• and
• a laser light irradiation step of irradiating a surface of the base substrate with laser light, thereby removing a portion of the second insulator layer that is not covered by the third metal layer, a portion of the third insulator layer where the third metal layer is absent, a portion of the third insulator layer that is formed on the second tongue-shaped portion, and a portion of the first insulator layer that is not covered by the second metal layer, while roughening a remaining portion of the third insulator layer, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second and third insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as an optical element chip placement section, and the first tongue-shaped portions are exposed;
• as a result of the removal of the first insulator layer, the first terminal section is formed whose upper surface is covered by the first tongue-shaped portions;
• as a result of the removal of the third insulator layer, the second tongue-shaped portions are exposed, thereby forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section;
• and
• as a result of the roughening of the remaining portion of the third insulator layer, the light-transmitting member placement section is formed.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, including a first metal layer formed on one surface of a first insulator layer, a second metal layer formed on the other surface of the first insulator layer and having a plurality of first tongue-shaped portions extending outwardly, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of the second insulator layer and a plurality of second tongue-shaped portions extending from the peripheral portion toward a central portion of the second insulator layer, and a third insulator layer formed on a surface of the third metal layer and on a portion of the second insulator layer that is not covered by the third metal layer;
• a laser light irradiation step of irradiating a portion of a surface of the base substrate where the third metal layer is absent and portions thereof corresponding to the second tongue-shaped portions with laser light, thereby removing an irradiated portion of the second insulator layer that is not covered by the third metal layer, an irradiated portion of the third insulator layer, and an irradiated portion of the first insulator layer;
• and
• a step of, after the laser light irradiation step, forming a resist layer on a surface of a remaining portion of the third insulator layer, thus forming the light-transmitting member placement section, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second and third insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as an optical element chip placement section, and the first tongue-shaped portions are exposed;
• as a result of the removal of the first insulator layer, the first terminal section is formed whose upper surface is covered by the first tongue-shaped portions;
• and
• as a result of the removal of the third insulator layer, the second tongue-shaped portions are exposed, thereby forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and a light-transmitting member placement section for receiving a light-transmitting member thereon, wherein the light-transmitting member is for transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of providing a base substrate, including a first metal layer formed on one surface of a first insulator layer, a second metal layer formed on the other surface of the first insulator layer and having a plurality of first tongue-shaped portions extending outwardly, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of the second insulator layer and a plurality of second tongue-shaped portions extending from the peripheral portion toward a central portion of the second insulator layer, a fourth metal layer formed on a surface of a third insulator layer formed on the third metal layer so as to be narrower than the third metal layer, and a fourth insulator layer formed on a surface of the fourth metal layer and on a portion of the third insulator layer that is not covered by the fourth metal layer;
• and
• a laser light irradiation step of irradiating a portion of a surface of the base substrate where the third metal layer is absent and portions thereof corresponding to the second tongue-shaped portions and a peripheral portion of the tongue-shaped portions with laser light, thereby removing an irradiated portion of the fourth insulator layer, a portion of the third insulator layer that is not covered by the fourth metal layer, a portion of the second insulator layer that is not covered by the third metal layer, and a portion of the first insulator layer, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second, third and fourth insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as the optical element chip placement section, and the first tongue-shaped portions are exposed;
• as a result of the removal of the first insulator layer, the first terminal section is formed whose upper surface is covered by the first tongue-shaped portions;
• as a result of the removal of the third insulator layer, the second tongue-shaped portions are exposed, thereby forming a plurality of protruding portions protruding from inner wall surfaces of the cavity portion, each protruding portion serving as the second terminal section;
• and
• as a result of the removal of the fourth insulator layer, at least a portion of the fourth metal layer is exposed, thereby forming a second protruding portion protruding, over a shorter distance than the first protruding portion, from each inner wall surface of the cavity portion, the second protruding portion serving as the light-transmitting member placement section.

A method for manufacturing an optical device cavity structure which receives an optical element chip thereon and which is to be mounted on a wiring substrate, the optical device cavity structure including a first terminal section electrically connected to the wiring substrate, a second terminal section electrically connected to the first terminal section, a chip placement section for receiving thereon the optical element chip electrically connected to the second terminal section, and an optical component fitting section in which an optical component is fitted, the optical component transmitting therethrough light to be received by, or light emitted from, the optical element chip, the method comprising:

• a step of forming a base substrate, including a first metal layer formed on one surface of a first insulator layer, a second metal layer formed on the other surface of the first insulator layer and having a plurality of first tongue-shaped portions extending outwardly, a second insulator layer formed on a surface of the second metal layer, a third metal layer formed on a peripheral portion of the second insulator layer and a plurality of second tongue-shaped portions extending from the peripheral portion toward a central portion of the second insulator layer, a fourth metal layer formed on a surface of a third insulator layer formed on the third metal layer so as to be narrower than the third metal layer, and a fourth insulator layer formed on a surface of the fourth metal layer and on a portion of the third insulator layer that is not covered by the fourth metal layer;
• and
• a laser light irradiation step of irradiating, a portion of a surface of the base substrate where the third metal layer is absent and portions thereof corresponding to the second tongue-shaped portions and the fourth metal layer with laser light, thereby removing an irradiated portion of the fourth insulator layer, a portion of the third insulator layer that is not covered by the fourth metal layer, a portion of the second insulator layer that is not covered by the third metal layer, and a portion of the first insulator layer, wherein:
• in the laser light irradiation step,
• as a result of the removal of the second, third and fourth insulator layers, a cavity portion having a generally rectangular opening is formed in a central portion of the surface of the base substrate;
• as a result of the removal of the second insulator layer, at least a portion of the second metal layer is exposed, thus forming a bottom surface of the cavity portion, which serves as an optical element chip placement section, and the first tongue-shaped portions are exposed;
• as a result of the removal of the first insulator layer, the first terminal section is formed whose upper surface is covered by the first tongue-shaped portions;
• as a result of the removal of the third insulator layer, the second tongue-shaped portions are exposed, thereby forming a plurality of first protruding portions protruding from inner wall surfaces of the cavity portion, each first protruding portion serving as the second terminal section;
• and
• as a result of the removal of the peripheral portion of the fourth insulator layer, at least a portion of the fourth metal layer is exposed, thereby forming the optical component fitting section.