Electronic device

An electronic device comprising:

• an electrically-insulative substrate having one surface and an other surface;
• a one surface side wire disposed on the one surface of the substrate;
• a one surface side land disposed on the one surface of the substrate and patterned together with the one surface side wire;
• a heat generating element mounted on the one surface of the substrate;
• an other element mounted on the one surface of the substrate;
• and
• an electrically-conductive heat dissipation path disposed to extend continuously from a one surface side of the substrate to an other surface side of the substrate in an interior of the substrate right under the heat generating element and dissipating heat generated in the heat generating element to the other surface side of the substrate, wherein:
• on the one surface of the substrate, the heat generating element is joined directly to the one surface side land with an electrically-conductive joining material, and the heat dissipation path having the one surface side land and the electrically-conductive joining material as a start point is connected directly to the heat generating element;
• the one surface side land exists over a whole area of the heat generating element projected onto the one surface of the substrate, right under the heat generating element, and a dimension of the one surface side land in a planar direction of the substrate is larger than a dimension of the heat generating element in the planar direction of the substrate;
• the other surface of the substrate is provided by an other surface side insulating layer that is disposed entirely in the planar direction of the substrate as a part of the substrate, and has an electrical insulation property;
• an electrically-conductive other surface side land is disposed on the other surface of the substrate right under the heat generating element;
• an other surface side wire is disposed on the other surface of the substrate, and the other surface side land is patterned together with the other surface side wire and is electrically independent from the other surface side wire;
• on the other surface side of the substrate, an end point of the heat dissipation path extends to the other surface side insulating layer, and the end point of the heat dissipation path is provided as an other surface side inner layer wire acting as a thermal diffusion layer;
• the other surface side insulating layer is interposed between the other surface side inner layer wire and the other surface side land, and the other surface side inner layer wire is insulated electrically from the other surface side land, so that the other surface side inner layer wire, the other surface side land, and the other surface side insulating layer interposed between the other surface side inner layer wire and the other surface side land constitute a thermal diffusion insulating section;
• and
• in the thermal diffusion insulating section, both the other surface side inner layer wire and the other surface side land exist over a whole area of the heat generating element projected onto the one surface of the substrate, right under the heat generating element, and dimensions of the other surface side inner layer wire and the other surface side land in the planar direction of the substrate are larger than the dimension of the heat generating element in the planar direction of the substrate.

An electronic device comprising:

• an electrically-insulative substrate having one surface and an other surface;
• a heat generating element mounted on the one surface of the substrate;
• an other element mounted on the one surface of the substrate;
• a one surface side wire disposed on the one surface of the substrate;
• an electrically-conductive one surface side land disposed on the one surface of the substrate and patterned together with the one surface side wire;
• an other surface side wire disposed on the other surface of the substrate;
• and
• an electrically-conductive other surface side land disposed on the other surface of the substrate, patterned together with the other surface side wire, and being electrically independent from at least a part of the other surface side wire, wherein:
• the heat generating element has a joining plane to be joined electrically to the one surface side land;
• the one surface side land has a joined plane to be joined electrically to the heat generating element;
• the joined plane exists at least in a whole projected region of the joining plane projected onto the substrate in a thickness direction of the substrate;
• the electronic device has an electrically-conductive joining material to directly join the joining plane to the joined plane in the whole projected region;
• the other surface of the substrate is provided by an other surface side insulating layer that is disposed entirely in the planar direction of the substrate as a part of the substrate, and has an electrical insulation property;
• the electronic device includes an electrically-conductive heat dissipation path having the one surface side land and the electrically-conductive joining material as a start point, being disposed to extend continuously from the one surface side of the substrate to the other surface side substrate insulating layer, and dissipating heat generated in the heat generating element to the other surface side of the substrate;
• an end point of the heat dissipation path is provided by an electrically-conductive other surface side inner layer wire disposed in an interior of the substrate;
• and
• when a region obtained by expanding a planar size of the heat generating element in the planar direction of the substrate from the heat generating element further outwardly by an extent corresponding to a thickness of the substrate at a whole periphery of the heat generating element is defined as a heat dissipation contributing region,
• the other surface side substrate insulating layer is interposed between the other surface side inner layer wire and the other surface side land in the heat dissipation contributing region and electrically insulates the other surface side inner layer wire from the other surface side land, at least a part of the other surface side inner layer wire and at least a part of the other surface side land have a total area larger than an area of the heat generating element in the planar direction of the substrate in the heat dissipation contributing region and constitute a thermal diffusion layer pair, thereby to constitute a thermal diffusion insulating section made of the other surface side inner layer wire, the other surface side land, and the other surface side substrate insulating layer, on the other surface side of the substrate.