Abstract: An active device with a heat sink and low mechanical stress comprises a heat-producing substrate having a first thermal expansion coefficient; a heat sink having a second thermal expansion coefficient, wherein the first and second thermal expansion coefficients are different; and an interface between the heat-producing substrate and the heat sink formed so that, when the heat-producing substrate is operating at a predetermined temperature, a mechanical stress between the heat-producing substrate and the heat sink is substantially minimized. The heat sink has a yield strength that is lower than a yield strength of the heat-producing substrate and has been plastically deformed during fabrication to minimize the stress between the heat-producing substrate and the heat sink. Methods for fabricating the device are also disclosed.