In an embodiment, a device includes: a package component including an integrated circuit die and conductive connectors connected to the integrated circuit die, the conductive connectors disposed at a front-side of the package component, the integrated circuit die exposed at a back-side of the package component; a heat dissipation layer on the back-side of the package component and on sidewalls of the package component; an adhesive layer on a back-side of the heat dissipation layer, a portion of a sidewall of the heat dissipation layer being free from the adhesive layer; and a package substrate connected to the conductive connectors.