Apparatus and methods are provided for integrated circuit packages having a low z-height. In an example, a method can include mounting a first integrated circuit sub-package to a first package substrate wherein the sub-package substrate spans an opening of the first package substrate, mounting a second integrated circuit package to a second package substrate, and mounting the first package substrate with the second package substrate wherein the mounting includes locating a portion of the second integrated circuit package within the opening of the first package substrate.