Mounting Board and Circuit Device Using the Same

A mounting board comprising:

• a core layer made of an insulating resin;
• a first conductive pattern including at least a first island, a second island, a first electrode, a second electrode and wiring, the first conductive pattern provided on a front side of the core layer;
• a second conductive pattern being an external electrode, the second conductive pattern provided on a back side of the core layer;
• and
• a via provided between the first electrode and the external electrode provided so as to correspond to the first electrode,
• the first conductive pattern and the second conductive pattern having the same film thickness,
• the via is set at a resistance value lower than a resistance value of the first conductive pattern so that a current flowing from a power transistor, which is to be mounted on the first island, or a current flowing into the power transistor flows to the external electrode through the via.

A mounting board comprising:

• a core layer made of an insulating resin;
• a first conductive pattern provided on a front side of the core layer;
• a second conductive pattern having a film thickness greater than a film thickness of the first conductive pattern, the second conductive pattern provided on a back side of the core layer;
• a first electrode for a high current including at least one of the first conductive patterns;
• an external electrode including at least one of the second conductive patterns, the external electrode provided so as to correspond to the first electrode;
• and
• a via provided between the first electrode and the external electrode,
• the via is set at a resistance value lower than a resistance value of the first conductive pattern so that the high current flows to the external electrode through the via.