Electronic unit and method of making the same

An electronic unit comprising:

• a substrate;
• a heat-generating electronic component mounted on the substrate;
• a heat sink disposed on the heat-generating electronic component;
• and
• a hot-melt resin layer disposed on the substrate,
• wherein the heat sink includes an upper part that serves as a radiating portion and a lower part that has a recess facing downward and that includes a peripheral wall surrounding the recess and having an end face and a side face, the recess of the heat sink covering the heat-generating electronic component, and the end face of the peripheral wall of the heat sink placed on a surface of the substrate,
• wherein the hot-melt resin layer covers at least part of the surface of the substrate and at least part of the side face of the peripheral wall of the heat sink, and
• wherein the peripheral wall separates the heat-generating electronic component from the hot-melt resin layer.