Package-on-package structure including a thermal isolation material

A package comprising:

• a first package component comprising:
• a first package substrate;
• a first device die over and bonded to the first package substrate;
• a second package component comprising:
• a second package substrate;
• a second device die over and bonded to the second package substrate;
• a plurality of solder regions bonding the first package substrate to the second package substrate;
• a thermal isolation region between and contacting the first device die and the second package substrate, wherein the thermal isolation region comprises:
• a thermal insulation material forming a ring, wherein the thermal insulation material is a dielectric material;
• and
• an air gap or a vacuumed region encircled by the ring;
• and
• a molding compound between and in contact with the first package substrate and the second package substrate, wherein the thermal isolation region is in physical contact with the molding compound, and has a first thermal conductivity lower than a second thermal conductivity of the molding compound.

A package comprising:

• a bottom package component comprising:
• a bottom substrate;
• and
• a bottom die over and bonded to the bottom substrate;
• a top package component over and bonded to the bottom package component;
• a thermal isolation material attached to the bottom die, wherein the thermal isolation material comprises a seal ring having air or vacuum therein;
• and
• a molding compound encircling the thermal isolation material, the molding compound comprising a material different from the thermal isolation material, and wherein the molding compound contacts outer sidewalls of the seal ring to form vertical interfaces.