Abstract: A masking tape for EMI shielding applications comprising an adhesive layer, a metal foil layer adhered to the top of the adhesive layer, two or more adhesive strips running parallel to the edges of the tape and extending the length of the foil along the strips are preferably inset from the outer edges of the foil so as to form a stepped or notch-like configuration. A mask layer is attached to the top of the strips. The mask alone or the mask and strips are designed to be removed after use. The tape is applied to a substrate such as a computer cabinet, the cabinet is then sprayed with a paint or finish coat and the mask is removed to reveal a conductive metal foil surface to which a conductive EMI shield can be mounted.

Abstract: A tractor for feeding perforated webs, such as perforated paper in a computer printer, typewriter or the like has a frame which locates a sprocket and a belt having pins projecting from the belt and lugs driven by the sprocket. To provide precision feeding of the web the lid is arranged with respect to the frame so that the web is maintained substantially at the pitch line of the belt where the pins enter, are engaged by and leave the perforations. The distance between the surface of the lid which faces the belt and the belt surface is limited such that the perforations contact the pin surface below a critical position where the web clings to the pins. This is the position where the angle between the surface of the belt and a line from the position of repose perpendicular to a tangent to pin surface which intersects the belt surface is equal to the art tangent of the coefficient of friction between the web and pin materials.