Patent ID: 9686854
Date: 2017-06-20
CPC Classifications: H01L,H05K

Claim:
1. 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, the substrate is made of a resin, a molding resin is disposed on the one surface side of the substrate to seal the heat generating element, the other element, the one surface side wire, and the one surface of the substrate, the other surface of the substrate is exposed from the molding resin, a solder resist film is disposed on the other surface of the substrate to cover and protect the other surface side wire while at least a part of the other surface side land constituting the thermal diffusion insulating section is exposed, a thickness of the other surface side land constituting the thermal diffusion insulating section is smaller than a total thickness of the other surface side wire and the solder resist film covering the other surface side wire, and a portion of the substrate corresponding to the heat dissipation contributing region bends so that the one surface of the substrate is recessed and the other surface of the substrate is projected, and thereby a center of the site protrudes from a periphery thereof.