Heat sink having a restrictive region

A semiconductor structure, comprising:

• a heat sink having:
• a first major surface and a second major surface opposite the first major surface, wherein the first major surface includes a thermal contact area surrounded by a semiconductor die perimeter;
• a first sidewall surface between the first and second major surfaces;
• and
• a through-opening extending from each of the first major surface and the first sidewall surface, through the heat sink, to the second major surface, and having a first inflow region, a second inflow region, a restrictive region, and an outflow region, wherein the outflow region extends from the restrictive region to the second major surface and has an outflow surface opening at the second major surface, the first inflow region extends from the first sidewall surface to the restrictive region and has a first inflow surface opening at the first sidewall surface, and the second inflow region extends from the first major surface to the restrictive region and has a second inflow surface opening at the first major surface, wherein a cross-sectional area of the restrictive region is less than an area of the first inflow surface opening, less than an area of the second inflow surface opening, and less than an area of the outflow surface opening.

A semiconductor structure, comprising:

• a heat sink having:
• a first major surface and a second major surface opposite the first major surface;
• a first sidewall surface between the first and second major surfaces;
• and
• a through-opening extending from one of the first sidewall surface or the first major surface of the heat sink to the second major surface of the heat sink, wherein the through-opening has an inflow region, a restrictive region, and an outflow region, the restrictive region located between the inflow region and the outflow region, wherein the inflow region has an inflow surface opening at the one of the first sidewall or the first major surface, and the outflow region has an outflow surface opening at the second major surface, wherein a cross-sectional area of the restrictive region is less than an area of the inflow surface opening and less than an area of the outflow surface opening;
• and
• a semiconductor die, wherein the first major surface of the heat sink is attached to the semiconductor die with a thermal interface material, and wherein the restrictive region overlaps a perimeter of the semiconductor die.