Thermally improved PCB for semiconductor power die connected by via technique and assembly using such PCB

Power module comprising:

• a power semiconductor die;
• and
• at least one substrate comprising an insulating layer in contact with a metallized connection surface of said die and at least one conductive path on a conductive layer on a face of the insulating layer opposite to the metallized connection surface of the die, wherein
• said insulating layer comprises vias filled with conductive material to provide connecting pads between said metallized connection surface of said die and said conductive path, and
• said vias are arranged with a decreasing density from at least one hot spot position of said metallized connection surface when the die is in operation to a peripheral area of said metallized connection surface, said vias providing a mechanical, electrical, and thermal joining layer between said die and said conductive path of said conductive layer in said module,
• wherein said vias are arranged as a peripheral area around at least one cavity of a length and width greater than the diameter of the vias in said insulating layer, said vias and said cavity being filled with conductive material to form respectively connecting pads and a connecting block joining said metallized connection surface and said conductive path, said connecting pads and said connecting block providing a mechanical, electrical and thermal joining layer of said die and said conductive path of said conductive layer in said module, and
• a distribution of said vias and size of said cavity are defined to decrease the thermal resistance RTH of the connecting layer in higher die temperature areas of said metallized connection surface and increase the thermal resistance of the joining layer in lower temperature areas of said connection surface thus increasing homogeneity of the temperature of said joining layer and connection surface during operation of the power module.

A manufacturing method of a power module including a power semiconductor die, and at least one substrate comprising an insulating layer in contact with a metallized connection surface of said die and at least one conductive path on a conductive layer on a face of the insulating layer opposite to the metallized connection surface of the die, wherein said insulating layer comprises vias filled with conductive material to provide connecting pads between said metallized connection surface of said die and said conductive path, and said vias are arranged with a decreasing density from at least one hot spot position of said metallized connection surface when the die is in operation to a peripheral area of said metallized connection surface, said vias providing a mechanical, electrical, and thermal joining layer between said die and said conductive path of said conductive layer in said module,

• wherein said vias are arranged as a peripheral area around at least one cavity of a length and width greater than the diameter of the vias in said insulating layer, said vias and said cavity being filled with conductive material to form respectively connecting pads and a connecting block joining said metallized connection surface and said conductive path, said connecting pads and said connecting block providing a mechanical, electrical and thermal joining layer of said die and said conductive path of said conductive layer in said module, and
• wherein the insulating layer is a PCB insulating layer having at least one cut cavity filled with conductive material to provide said connecting block or wherein a distribution of said vias and size of said cavity are defined to decrease the thermal resistance RTH of the connecting layer in higher die temperature areas of said metallized connection surface and increase the thermal resistance of the joining layer in lower temperature areas of said connection surface thus increasing homogeneity of the temperature of said joining layer and connection surface during operation of the power module, the method comprising:
• providing at least one conductive path on a side of an insulating layer of the substrate opposite to said metallized connection surface of said die;
• drilling holes in said insulating layer to form said vias with a decreasing density from a center of said metallized connection surface to a peripheral area of said metallized connection surface;
• and
• filling said vias with conductive material thus providing connecting pads providing an electrical connection between said metallized connection surface and said conductive path.