An electrosurgical vessel sealing instrument having a first and a second opposing jaw member at a distal end thereof, wherein each jaw member includes a jaw housing, an inner tissue engaging surface, and an insulating layer disposed therebetween. The instrument includes the ability to move the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue. The jaws include a tissue-contacting seal plate having obverse and reverse surfaces. A series of ribs extend from the reverse surface of the seal plate into an insulating layer, which, in turn, is affixed to a jaw housing. The ribbed structure of the seal plate reduces thermal spread and edge cutting during vessel sealing procedures, leading to improved surgical outcomes.