Heatsink-less electronic unit

1. A heatsink-less electronic unit comprising:

a metal coreless electronic substrate; and

a heatsink-less microcomputer and various semiconductor relays which are mounted on the metal coreless electronic substrate,

wherein the heatsink-less microcomputer is arranged on a front face of the metal coreless electronic substrate;

wherein among the various semiconductor relays, a plurality of wiper relays which reach the highest temperatures of the semiconductor relays are separated a longest distance from a location where the heatsink-less microcomputer is arranged, and the wiper relays are arranged on a front face of the metal coreless electronic substrate so as to be separated from one another, the front face being opposite to a rear face;

wherein among the various semiconductor relays, a plurality of head lamp relays are arranged on the rear face of the metal coreless electronic substrate so as to be separated from one another;

wherein the metal coreless electronic substrate has a rectangular shape including a long side and a sort side,

wherein the heatsink-less microcomputer is arranged at a region away from a center region of the metal coreless electronic substrate in a longitudinal direction of the metal coreless electronic substrate,

wherein a plurality of first semiconductor relays from among the various semiconductor relays are arranged on one end on the front face of the metal coreless electronic substrate in the longitudinal direction, the one end on the front face does not overlap the region, and the first semiconductor relays are aligned along the longitudinal direction in the one end on the front face, and

wherein a plurality of second semiconductor relays from among the various semiconductor relays are arranged on a region on the rear face corresponding to a region on the front face between the heatsink-less microcomputer and the one end on the front face of the metal coreless electronic substrate in a lateral direction, and the second semiconductor relays are aligned along the lateral direction in the region on the rear face.

2. A heatsink-less electronic unit comprising:

a metal coreless electronic substrate which is provided with three or more layers of copper foil conductive patterns, the metal coreless electronic substrate having a rectangular shape including a long side and a short side; and

a heatsink-less microcomputer and various semiconductor relays which are mounted on the metal coreless electronic substrate,

wherein a through hole is formed in an end portion of the metal coreless electronic substrate, passes through from the copper foil conductive pattern of a front face of the metal coreless electronic substrate to the copper foil conductive pattern of a rear face of the metal coreless electronic substrate, and is connected to the copper foil conductive pattern of each layer of the metal coreless electronic substrate, and the through hole being arranged in at least one of both end portions in a longitudinal direction of the metal coreless electronic substrate; and

wherein the heatsink-less microcomputer is arranged at a center region on the front face of the metal coreless electronic substrate;

wherein a plurality of first semiconductor relays from among the various semiconductor relays are arranged on both ends on the front face of the metal coreless electronic substrate in the longitudinal direction, the both ends on the front face do not overlap the center region, and the first semiconductor relays are aligned along a lateral direction of the metal coreless electronic substrate in the both ends on the front face; and

wherein a plurality of second semiconductor relays from among the various semiconductor relays are arranged on both ends on the rear face of the metal coreless electronic substrate in the lateral direction, and the second semiconductor relays are aligned along the longitudinal direction in the both ends on the rear face.

3. The heatsink-less electronic unit according to claim 1 , wherein the various semiconductor relays include two or more among a wiper relay, a head lamp relay and a fog lamp relay.

4. The heatsink-less electronic unit according to claim 2 , wherein the various semiconductor relays include two or more among a wiper relay, a head lamp relay and a fog lamp relay.

5. The heatsink-less electronic unit according to claim 2 , wherein the heatsink-less microcomputer and the various semiconductor relays are arranged respectively in end portions of a first layer of the metal coreless electronic substrate,

wherein a copper foil, provided in the end portions of the first layer of the metal coreless electronic substrate and connected to the various semiconductor relays, is connected to a copper foil of another layer of the metal coreless electronic substrate other than the first layer via a through hole of the first layer, and

wherein a copper foil, provided on a center area of the first layer of the metal coreless electronic substrate, is not connected to copper foils of another layer of the metal coreless electronic substrate other than the first layer.