Abstract: The invention provides a lead structure having a lead of low resistance material disposed within a surrounding sleeve or collar of low expansion material which is bonded at one end to the lead. The sleeve or collar is bonded on its outer surface to an insulating wall through which the lead structure extends. The lead is preferably copper and the sleeve or collar is preferably a nickel-alloy. The lead is hermetically sealed to the surrounding sleeve, and the sleeve is hermetically sealed to the insulating wall to provide a hermetic structure which does not detract from the use of high conductivity electrical lead materials which are often not employable in conventional hermetic sealed leads or packages. A plurality of lead structures can be employed in one or more walls of a circuit package.