Circuit board capable of efficiently conducting heat through an inside thereof using thermal lands surrounding through-hole connections

Claim 1

A circuit board apparatus comprising: a mother board including a ground or power supply layer having a ground or power supply potential-defining plane; at least one circuit board including at least one ground or power supply layer having a ground or power supply potential-defining plane, the circuit board being mounted on the mother board in such a manner that the at least one ground or power supply layer of the circuit board is contacted respectively to the corresponding ground or power supply layer of the mother board; and an electronic circuit unit mounted on the circuit board and having at least one terminal connected to the circuit board, the electronic circuit unit being adapted to generate heat upon operation thereof; wherein a thermal resistance of connection of the ground or power supply layer of the circuit board with the terminal of the electronic circuit unit is adjusted to be a low level to conduct therethrough an excess part, other than a part removed from surface of the electronic circuit unit, of heat generated from the electronic circuit unit, and wherein the ground or power supply layer in the circuit board is thick enough to conduct therethrough the excess part of heat to be diffused over an area wide enough to be removed, a part of the diffused heat over the ground or power supply layer of the circuit board being removed therefrom by fluid which flows along a surface of the circuit board, an other part of the diffused heat over the ground or power supply layer of the circuit board being further conducted from the ground or power supply layer of the circuit board to the ground or power supply layer of the mother board to be further diffused to be removed therefrom.