Printed wiring board, printed circuit board, and method for manufacturing printed circuit board

A printed wiring board comprising:

• a first surface layer on which an electronic component is to be mounted, wherein a heat transfer pattern is formed in an area of the first surface on which the electronic component is to be mounted;
• a second surface layer positioned on a side of the printed wiring board, opposite to the first surface layer;
• and
• at least one through hole penetrating the printed wiring board in a thickness direction thereof, wherein the through hole is formed in the area in which the heat transfer pattern is formed, the heat transfer pattern and a through hole conductor thermally connected to the conductive pattern are formed within the through hole, wherein
• the heat transfer pattern is covered with a solder resist, and is exposed from the solder resist to form a plurality of connecting lands, and wherein
• the plurality of connecting lands comprises a first land group including a plurality of first lands, and a second land group including a plurality of second lands, each of the first lands is arranged adjacent to the through hole, and the each of the second lands is arranged distant from the through hole rather than the first land.

A printed circuit board comprising

• a printed wiring board, wherein the printed wiring board comprises a first surface layer on which an electronic component is mounted, wherein a heat transfer pattern is formed in an area of the first surface on which the electronic component is mounted, a second surface layer positioned on a side of the printed wiring board, opposite to the first surface layer, and a through hole penetrating the printed wiring board in a thickness direction thereof, wherein the through hole is formed in the area in which the heat transfer pattern is formed, the heat transfer pattern and at least one through hole conductor thermally connected to the conductive pattern are formed within the through hole;
• an electronic component having a heat sink mounted on the first surface layer of the printed wiring board;
• and
• a solder joint portion arranged between the heat sink of the electronic component and the heat transfer pattern of the printed wiring board, wherein
• the heat transfer pattern is covered with a solder resist, and is exposed from the solder resist to form a plurality of connecting lands, wherein
• the plurality of connecting lands comprises a first land group including a plurality of first lands, and a second land group including a plurality of second lands, each of the first lands is arranged adjacent to the through hole, and the each of the second lands is not arranged adjacent to the through hole, and wherein
• at least one of the first lands is not connected through the solder joint portion to the heat sink, the second lands are connected through the solder joint portion to the heat sink, the solder is solidified within the at least one of the through holes.