Abstract: A heat-dissipating metal bar to be imbedded in a molded body of plastic material, together with a punched metal foil forming an array of conductor strips to be soldered to a silicon chip, has a large exposed surface and is provided on its opposite surface with projections passing through cutouts in the foil. Upon the molding of the resinous body around the bar, portions of the foil and the silicon chip, one of the mold halves bears upon these projections while the other mold half comes to rest against the exposed bar surface which is thereby pressed into firm contact with that mold half to prevent the intrusion of any resin therebetween. The mold-closing pressure deforms the tips of the projections to help anchor the bar to the resinous body.