Abstract: A feedthrough for an implantable medical electronic device that has a housing and a header. The feedthrough having an insulator that has a housing-side surface and a header-side surface opposite it, a feedthrough flange surrounding the insulator, and at least one primary connection element penetrating the insulator and for connection of an electrical or electronic component of the device. This electrical or electronic component is arranged in the housing. The connection element is fastened by a hard solder connection, so that it is fluid-tight in a passage of the insulator. The primary connection element has a housing-side end that is essentially even with the housing-side surface of the insulator or is recessed into the insulator with respect to this surface.

Abstract: A method for subcutaneously treating pain in a patient includes first providing a neurostimulator with an IPG body and at least a primary integral lead with electrodes disposed thereon. A primary incision is opened to expose the subcutaneous region below the dermis in a selected portion of the body. A pocket is then opened for the IPG through the primary incision and the primary integral lead is inserted through the primary incision and routed subcutaneously to a first desired nerve region along a first desired path. The IPG is disposed in the pocket through the primary incision. The primary incision is then closed and the IPG and the electrodes activated to provide localized stimulation to the desired nerve region and at least one of the nerves associated therewith to achieve a desired pain reduction response from the patient.

Abstract: According to aspects of the present disclosure, an implantable pulse generator includes a housing, a header, and a retainer device. The housing includes circuitry and a battery. The header is coupled to the housing and includes a bore configured to receive an end of a lead, and a passage disposed transverse to the bore and extending between an exterior surface of the header and an anchor cavity that extends into the header from the bore. The header supports at least one electrical contact within the bore coupled to the circuitry. The retainer device includes a looped member arranged within the bore, a proximal end extending at least partially into the passage, and anchored at a distal end by the anchor cavity.

Abstract: Disclosed are systems for wireless energy transfer including transcutaneous energy transfer. Embodiments are disclosed for electrical connections between an implanted wireless receiver and an implanted medical device powered by the receiver. Methods for manufacturing and using the devices and system are also disclosed.

Abstract: Aspects of the present disclosure are directed toward methods, systems, and apparatuses that include an insertion tool configured to removeably secure to an implantable lead. The implantable lead may be connected to an implantable medical device by applying longitudinal force to the insertion tool. The insertion tool may subsequently be removed.

Abstract: Connector enclosure assemblies for medical devices provide an angled lead passageway. The lead passageway which is defined by electrical connectors and intervening seals within the connector enclosure assembly establishes the angle relative to a base plane of the connector enclosure assembly. Various other aspects may be included in conjunction with the angled lead passageway, including an angled housing of the connector enclosure assembly, feedthrough pins that extend to the electrical connectors where the feedthrough pins may include angled sections, and a set screw passageway set at an angle relative to the lead passageway to provide fixation of a lead within the lead passageway.

Abstract: A hermetically sealed feedthrough subassembly attachable to an active implantable medical device includes a first conductive leadwire extending from a first end to a second end, the first conductive leadwire first end disposed past a device side of an insulator body. A feedthrough filter capacitor is disposed on the device side. A second conductive leadwire is disposed on the device side having a second conductive leadwire first end at least partially disposed within a first passageway of the feedthrough filter capacitor and having a second conductive leadwire second end disposed past the feedthrough filter capacitor configured to be connectable to AIMD internal electronics. The second conductive leadwire first end is at, near or adjacent to the first conductive leadwire first end. A first electrically conductive material forms a three-way electrical connection electrically connecting the second conductive leadwire first end, the first conductive leadwire first end and a capacitor internal metallization.

Abstract: A pass-through assembly including a first wall having oppositely-directed inner and outer sides, the first wall defining a first opening extending from the inner side to the outer side; an elongated structure extending into the opening from the outer side of the first wall; a first material contacting the first wall and the elongated structure so as to at least partially seal the opening, and a second material different from the first material, the second material overlying the first material on the outer side of the wall, the second material adhering to the elongated structure and the first wall, the second material having at least one physical property different than a corresponding physical property of the first material.

Abstract: An optical stimulation lead includes a lead body including a distal end, a distal portion, and a proximal portion; and an optical assembly attached to the distal end of the lead body. The optical assembly includes a light emitter; a feedthrough assembly including at least one ceramic block, at least one feedthrough pin extending through the at least one ceramic block and electrically coupled to the light emitter, and a metal housing attached to the at least one ceramic block; a metal tube attached to the feedthrough assembly and disposed around the light emitter; and an emitter cover disposed over the light emitter and coupled to the metal tube.

Abstract: Connector enclosure assemblies for medical devices provide an angled lead passageway. The lead passageway which is defined by electrical connectors and intervening seals within the connector enclosure assembly establishes the angle relative to a base plane of the connector enclosure assembly. Various other aspects may be included in conjunction with the angled lead passageway, including an angled housing of the connector enclosure assembly, feedthrough pins that extend to the electrical connectors where the feedthrough pins may include angled sections, and a set screw passageway set at an angle relative to the lead passageway to provide fixation of a lead within the lead passageway.

Abstract: An electrical connector for detachably connecting an electrical lead to an implantable medical device includes a conductive housing and a plurality of spring contacts. The conductive housing extends from a proximal end to a distal end. The conductive housing has an interior surface forming a hollow cylinder. The plurality of spring contacts projects from the interior surface of the conductive housing and toward the proximal end. The plurality of spring contacts is at least partially contained within the conductive housing and configured to form an electrical connection to an electrical lead inserted within the conductive housing. The conductive housing and the plurality of spring contacts are integrally formed by an additive manufacturing process such that the electrical connector is a unitary structure.

Abstract: Medical devices include deformable structures that contact a lead upon being compressed. A grip that a clinician may grasp and manipulate is engaged with a nose structure of a header block of the medical device, and manipulation of the grip causes compression of the deformable structure to ultimately create fixation of the lead within the header block.

Abstract: An implantable connector assembly (14) for communicating an element to an implantable device (12) within a patient (20) comprises a plug (16), a receptacle (18), and a pair of communication structures (72, 108). The plug (16) includes a plunger body (64). The receptacle (18) includes a sleeve (98) and a stopper (114). The sleeve (98) defines an opening (104), and the stopper (114) is resiliently mounted within the sleeve (98) to cover and fluidly seal the opening (104). The pair of communication structures (72, 108) is positioned respectively on the plunger body (64) and the sleeve (98). One of the communication structures (72, 108) connects to a source and the other communication structure (108, 72) connects to the implantable device (12). The plunger body (64) inserts into the sleeve (98) to displace the stopper (114) and couple the pair of communication structures (72, 108) for communication of the element therebetween.

Abstract: A pass-through assembly including a first wall 110d having oppositely-directed inner and outer sides, 112, 114, the first wall 110d defining a first opening 116 extending from the inner side 112 to the outer side 114; an elongated structure 118 extending into the opening 116 from the outer side 114 of the first wall 110d; a first material 130 contacting the first wall 110d and the elongated structure 118 so as to at least partially seal the opening 116, and a second material 140 different from the first material 130, the second material 140 overlying the first material 130 on the outer side 114 of the wall 110d, the second material 140 adhering to the elongated structure 118 and the first wall 110d, the second material 140 having at least one physical property different than a corresponding physical property of the first material 130.

Abstract: Implantable medical devices include connector enclosure assemblies that utilize conductors that are electrically coupled to feedthrough pins and that extend into a can where electrical circuitry is housed. The conductors may be coupled to the feedthrough pins and to capacitor plates within a filter capacitor by an electrically conductive bonding material and as a single bonding event during manufacturing. The base plate of the connector enclosure assembly may also include a ground pin. Ground capacitor plates may be present at a ground aperture of the filter capacitor where the ground pin passes through so that the ground pin, a ground conductor, and the ground capacitor plate may be coupled. A protective cover may be provided for the connector enclosure assembly to enclose the conductors intended to extend into the can prior to the assembly being joined to the can. Conductors may be attached to a common tab that is subsequently removed.

Abstract: Various embodiments of a hermetically-sealed package and methods of forming such packages are disclosed. In one or more embodiments, the hermetically-sealed package can include a housing and a feedthrough assembly that forms a part of the housing. The feedthrough assembly can include a non-conductive substrate and a feedthrough. The feedthrough can include a via from an outer surface to an inner surface of the non-conductive substrate, a conductive material disposed in the via, and an external contact disposed over the via on the outer surface of the non-conductive substrate. The external contact can be electrically coupled to the conductive material disposed in the via. Further, the external contact can be hermetically sealed to the outer surface of the non-conductive substrate by a laser bond surrounding the via.

Abstract: Implantable medical devices include header structures with conductive paths from the feedthrough conductors that may be located on one side of the device to electrical connectors that may be located on an opposite side of the device. The conductive paths may include conductive interconnect pins and lead frame conductors. The conductive interconnect pins may be located in holes present in a header body where the conductive interconnect pins are attached to the feedthrough conductors on one end and are attached to the lead frame conductors on the opposite end. The lead frame conductors then extend to the corresponding electrical connectors. The header body may provide cavities on each side to allow for the insertion of stack assemblies that include the electrical connectors and lead frame conductors.

Abstract: A monitor device having a sensor interface includes a connector portion configured to mechanically interface with one or more sensors of a pre-defined type. A hardware interface layer is configured to determine a sensor type and establish a communication interface with the sensor type. A hardware abstraction layer is configured to store a plurality of protocols corresponding with the one or more sensors of a pre-defined type. The hardware abstraction layer communicates with the sensor using a selected protocol for that type through the communication interface to permit interaction between the device and the sensor type.

Abstract: An implantable active medical device includes a hermetic housing defining an exterior surface and a hermetic cavity of an implantable active medical device. An elongate lead connector extends into the hermetic cavity. The elongate lead connector includes a closed end, an open end extending through and hermetically joined to the hermetic housing, an outer surface at least partially defining the hermetic cavity, and an inner surface defining a lead aperture.

Abstract: An implantable electrical medical device system includes a device body portion having a plurality of contacts operably coupled to discrete channels of electronics. One or more swappable headers may be attached to the device body portion by an end user, such as an implanting physician, to operably couple internal lead receptacle contacts in the header to the contacts of the device body portion. The swappable headers may have lead receptacles configured to receive differing types or combinations of leads, allowing an end user to select one or more appropriate headers as desired.

Abstract: Implantable medical devices include header structures with conductive paths from the feedthrough conductors that may be located on one side of the device to electrical connectors that may be located on an opposite side of the device. The conductive paths may include conductive interconnect pins and lead frame conductors. The conductive interconnect pins may be located in holes present in a header body where the conductive interconnect pins are attached to the feedthrough conductors on one end and are attached to the lead frame conductors on the opposite end. The lead frame conductors then extend to the corresponding electrical connectors. The header body may provide cavities on each side to allow for the insertion of stack assemblies that include the electrical connectors and lead frame conductors.

Abstract: A header for use in implantable pulse generator devices. The header is part of electrical connector assembly having one or more openings designed to receive the terminal pin of an electrical lead wire or electrode. The header is designed to provide and sustain long-term electrical and mechanical lead wire connections between the electrodes of a terminal pin and the implantable pulse generator device.

Abstract: An implantable pulse generator includes a device housing containing pulse generator circuitry and a header molded to the device housing. The header can be formed of an epoxy header material. A header component can have a first part molded in the header material to fix the header component to the header at a surface of the header and a second part extending out of the header material.

Abstract: A connector for an implantable medical device includes a lumen extending from a port defined along a length of a connector housing. Axially-spaced-apart connector couplers are disposed along the lumen and are configured to couple to a proximal end of an inserted lead or lead extension. Each of the connector couplers includes a plurality of circumferentially-spaced-apart coupling members and at least one elastic member. The plurality of circumferentially-spaced-apart coupling members each have inner surfaces and outer surfaces. The inner surfaces of the coupling members are configured and arranged to couple to the proximal end of the lead or lead extension when the proximal end of the lead or lead extension is inserted into the lumen. The at least one elastic member couples the coupling members to one another such that a distance between the coupling members is expandable.

Abstract: Implementations of the present disclosure may take the form of an implantable electronic device such as an implantable pulse generator for administering electrotherapy via an implantable medical lead configured to couple with the implantable pulse generator, or an implantable cardiac monitor. The implantable electronic device includes a housing, a header connector assembly and a sealing member. The header connector assembly includes a connector assembly and a header enclosing the connector assembly. The sealing member is sandwiched between the header connector assembly and the housing.

Abstract: An operating-room-cable assembly includes a lead connector with a lead-connector housing for receiving a lead. The lead-connector housing includes a first housing element and a second housing element that slide relative to one another to transition the lead-connector housing between an open position and a closed position. A connector port is defined in the lead-connector housing and includes a first surface formed by the first housing element and a second surface formed by the second housing element. A lead retainer is disposed along the second surface and receives the lead when the lead-connector housing is in the open position. Connector contacts are disposed along the first surface. The connector contacts couple to terminals disposed along the lead when the lead is received by the lead retainer and the lead-connector housing is in the closed position. Operating-room-cable conductors are coupled to the connector contacts and extend along the elongated body.

Abstract: In general, techniques are described for labeling an implantable medical device (IMD). In one example, an IMD can include a housing including electronic circuitry. The IMD can include a header coupled to the housing and includes a core. The core can define a bore and include a first metal label positioned adjacent to the at least one bore. The IMD includes a lead assembly including at least one lead having a distal end and a proximal end, the at least one lead including a second metal label, the distal end including at least one electrode and the proximal end received within the bore.

Abstract: A positionally sensitive spinal cord stimulation apparatus and method using near-infrared (NIR) reflectometry are provided for automatic adjustments of spinal cord stimulation. The system comprises an electrode assembly with an integrated optical fiber sensor for sensing spinal cord position. The integrated optical fiber sensor, comprising a pair of optical elements for emitting light from an IR emitter and for collecting reflected light into a photodetector, determines a set of measured photocurrents. As the spinal cord changes position, the angles of incidence for light from the IR emitter and the measured optical intensities change. Electrode pulse characteristics are adjusted in real time, based on the set of measured optical intensities, to minimize changes in stimulation perceived by the patient during motion. The system includes automatic calibration of the optical fiber sensor when the patient is at rest, and a patient orientation detection.

Abstract: A system includes a medical device lead including a connector at a proximal end of the lead, a conductor electrically connected to the connector at a proximal end of the conductor, and at least one electrode coupled to a distal end of the conductor. The system further includes a device securable to the proximal end of the lead including an inductive element. The device includes a port configured to receive the connector and position the inductive element around at least a portion of the connector.

Abstract: One aspect provides a method of securing a feedthrough to a metal housing for an implantable medical device. The feedthrough is provided comprising an insulating section and at least one conductive section extending through the insulating section. At least a portion of the insulating section is metalized and the metalized feedthrough is placed within an opening in the metal housing of the implantable medical device. The feedthrough and metal housing are positioning within an ultrasonic welding system and the ultrasonic welding system is energized such that sonic energy welds the feedthrough directly to the metal housing. The temperature of the metal housing is not raised above the ?-transus temperature of the metal housing during the ultrasonic welding.

Abstract: An implantable medical device includes a housing; at least one module enclosed within the housing and configured to at least one of generate an electrical stimulation therapy for delivery to a patient or monitor a physiological parameter of the patient; one or more feedthroughs extending through the housing; a header assembly including one or more electrical connectors electrically coupled to the module via the feedthroughs; and a preformed gasket compressed between the housing and the header assembly forming a seal to electrically isolate the feedthroughs from an external environment.

Abstract: This disclosure includes techniques for securing the proximal ends of a medical lead to the connector block of an IMD with a fastener device that incorporates a flexible clamp. A fastener device for a medical device comprising a flexible clamp forming a clamp aperture, wherein the flexible clamp includes a clamp protrusion configured to facilitate actuation of the flexible clamp, a rigid body, wherein the rigid body connects to and surrounds the flexible clamp, and an actuator configured to actuate on the clamp protrusion to change a perimeter of the clamp aperture, wherein the change of the perimeter of the clamp aperture by the actuator is configured to apply a compressive force about a perimeter of an electrical contact of a medical lead in the clamp aperture to electrically and mechanically connect the medical lead to the fastener device.

Abstract: An implantable medical device (IMD) includes an electrode that forms a first snap-fit attachment area and an insulator that forms a through-hole, a second snap-fit attachment area and a third snap-fit attachment area. The second snap-fit attachment area mates with the first snap-fit attachment area of the electrode. The IMD further includes a body including an elongated conductive housing and a feedthrough wire extending therefrom. The body forms a fourth snap-fit attachment area on one end that mates with the third snap-fit attachment area of the insulator such that the feedthrough wire extends through the through-hole of the insulator. The housing encloses at least one of a battery, a sensor, and an electronic circuit. The insulator functions to electrically isolate the electrode from the housing of the body.

Abstract: Devices, systems, and methods for implanting and testing multi-conductor electrical leads are disclosed. An illustrative implant tool for use with an implantable lead includes a main body, a plurality of spring contact members, and a knob mechanism. The main body of the implant tool includes a distal clamping mechanism with an opening adapted to frictionally receive a terminal boot of the implantable lead. The spring contact members are configured to provide an interface for connecting electrical connectors from a Pacing System Analyzer (PSA) or other testing device to the terminal contacts on the implantable lead. A knob mechanism coupled to the main body can be actuated to engage a terminal pin of the implantable lead, allowing an implanting physician to engage a fixation helix into body tissue by rotating the mechanism.

Abstract: An implantable active medical device includes a hermetic housing defining an exterior surface and a hermetic cavity of an implantable active medical device. The hermetic housing has a first major surface, an opposing second major surface and a side surface extending between them. An elongate lead connector is recessed into the first major surface. The elongate lead connector has a top surface and a bottom surface and a side surface extending between them. The top surface forms only a portion of the first major surface.

Abstract: Molded headers, implantable signal generators having molded headers, and associated systems and methods are disclosed herein. An implantable signal generator in accordance with a particular embodiment includes a can having a shell and a battery positioned at least partially within the shell. An output terminal can be operably coupled to the battery and positioned to provide electrical power to a signal delivery device. A pre-molded header having a plurality of openings can be coupled to the can, and the output terminal can be positioned at least partially within an individual opening.

Abstract: An implantable monitoring device includes a flexible lead body that includes at least one sensing element. The device also includes a rigid main body connected to the flexible lead body at an attachment point. The rigid main body is generally centered about a longitudinal axis defined by the flexible lead body when the lead body is unflexed. The device further includes a measurement circuit, which is housed within the rigid main body and electrically coupled to the at least one sensing element of the flexible lead body and at least another sensing element on an outside surface of the rigid main body. The measurement circuit is configured to measure a potential difference between the at least one sensing element of the flexible lead body and the at least another sensing element of the main body.

Abstract: A connector is described herein that includes a plurality of layers patterned in two dimensions and joined in a stack with a bore there through. At least a subset of the plurality of layers are contact layers that include deflectable members (e.g., springs) that deflect in plane or out of plane upon insertion of a lead into the bore through the connector. The deflectable members form redundant electrical connections with the lead when the lead is inserted into the bore. For example, the connector can be incorporated into an implantable medical device (e.g., IPG). Moreover, methods of manufacturing a connector are set forth herein.

Abstract: A reinforced medical electrical lead for neurological applications has a reinforced construction for resisting the detachment of electrodes and lead connection terminals, thereby improving the robustness of the lead and extending the life of the lead by reducing the likelihood that a further surgical procedure will be required to remove the lead for repair or replacement thereof. The present reinforced lead construction maintains the integrity of the electrical connection between the conductor and the respective electrode and lead connection terminal by incorporating several reinforcing features in the lead construction in contrast to conventional lead constructions where it is possible to pull the electrodes and lead connection terminals away from their contact points with relatively little force.

Abstract: A paddle lead assembly for providing electrical stimulation of patient tissue includes a paddle body having a longitudinal axis and a lateral axis transverse to the longitudinal axis. The paddle body includes a plurality of electrodes disposed into at least four columns extending parallel with the longitudinal axis. The at least four columns include two lateral columns and at least two medial columns disposed therebetween. The electrodes of the at least two medial columns are arranged into rows aligned along the transverse axis. The electrodes of the two lateral columns are each longitudinally offset from the rows of electrodes of the at least two medial columns. An array of terminals are disposed on each of at least one lead body coupled to the paddle body. A plurality of conductive wires couple each of the electrodes to at least one terminal of the terminal arrays.

Abstract: A micro electronic component structure includes an insulating body, at least one conductive through hole, at least one conductive material, and at least one micro terminal. The insulating body has a top surface and a bottom surface. The conductive through hole penetrates the top surface and the bottom surface. The conductive material is formed in the conductive through hole. The micro terminal is disposed above the conductive material.

Abstract: A contact block for electrically connecting a medical device to a conductive pin using improved electrical contact components. More specifically, an electrical contact block for achieving electrical contact with a conductive portion of an in-line IPG pin by utilizing a plurality of spherical conductive contact structures arranged in a ring around the conductive portion of the pin and biased toward the pin and held in place using a compliant o-ring.

Abstract: One aspect relates to an electrical bushing for use in a housing of an active implantable medical device. The electrical bushing includes an electrically insulating base body and an electrical conducting element. The conducting element is set up to establish, through the base body, an electrically conducting connection between an internal space of the housing and an external space. The conducting element is hermetically sealed with respect to the base body, and the conducting element includes a cermet.

Abstract: A connector assembly of an implantable medical electrical lead includes insulation and conductor segments, which may be formed together in a molded subassembly. The insulation segment includes at least one sealing surface, and the conductor segment includes at least one contact surface and a shank electrically common therewith. The shank has a smaller diameter than a uniform outer diameter of the assembly, which is defined by the sealing and contact surfaces, and the smaller diameter is sized to receive a coiled proximal end of a lead conductor mounted thereabout. The connector assembly may include another conductor segment that has a third contact surface, active or inactive, extending between third and fourth sealing surfaces of another insulation segment of the assembly; if active, a distal shank of the segment is electrically common with the third contact surface, and sized to receive a coiled proximal end of another lead conductor mounted thereabout.

Abstract: A header for use in implantable pulse generator devices. The header is part of electrical connector assembly having one or more openings designed to receive the terminal pin of an electrical lead wire or electrode. The header is designed to provide and sustain long-term electrical and mechanical lead wire connections between the electrodes of a terminal pin and the implantable pulse generator device.

Abstract: An implantable lead includes a flexible lead body, a plurality of conductor wires and a plurality of electrodes. The implantable lead also includes a terminal connector assembly coupled with a proximal end of the lead body. The terminal connector assembly is sized to be inserted into and received by a connector port of a pulse generator header. The terminal connector assembly includes a plurality of axially spaced terminal ring elements each electrically coupled to at least one of the conductor wires. The terminal ring elements are separated from one another by an electrically insulating material. Each of the terminal ring elements includes an outer surface having a first portion and a second portion, the first portion being electrically conductive and the second portion being electrically non-conductive.

Abstract: One aspect relates to a housing for an active implantable medical device, whereby the housing, at least parts thereof, includes an electrically insulating ceramic material, and has at least one electrically conductive conducting element, whereby the at least one conducting element is set up to establish at least one electrically conductive connection between an internal space of the housing and an external space. One aspect provides the at least one conducting element to include at least one cermet, whereby the housing and the at least one conducting element are connected in a firmly bonded manner.

Abstract: A system to increase the reliability of the electrical connections between the stimulating electrodes and the battery/controlling electronics of an electrical stimulating device as DBS (Deep Brain Stimulator), heart pacemakers and the like. We disclose a redundant male/female connector and/or a set of redundant wires to improve the reliability of the electrical connections. The redundant male/female connector serves as a backup for a potential loss of electrical continuity due to the adverse effect of body fluids, and the redundant wires serve as a backup for potential loss of electrical continuity due to repetitive muscle movement causing wire movement, stress and breaking. DBS connecting wires, that ran down the neck of the patient, are subjected to repetitive stresses due to neck twisting and therefore at high risk of breaking.

Abstract: A low-insertion force electrical connector for implantable medical devices includes a housing with a pair of opposing sidewalls each with center openings oriented generally concentrically around a center axis. An inner coil is located in a recess with a coil axis generally co-linear with the center axis of the center openings. The inner coil includes an outer diameter less than a recess diameter, and an inner diameter greater than a center opening diameter. An outer coil is threaded onto the inner coil. The outer coil has an outer diameter less than the recess diameter, and an inner diameter less than the center opening diameter. The outer coil is radially expanded within the recess in response to engagement with contact rings on the implantable medical device, such that the outer diameter of the outer coil is at least equal to the recess diameter.

Abstract: A medical device lead includes a lead body having a proximal end and a distal end. The proximal end is configured for connection to a pulse generator. One or more electrodes are at a distal end of the lead body, and a lead conductor extends through the lead body and is electrically coupled to at least one of the one or more electrodes. The conductor is configured to deliver electrical signals between the proximal end and the at least one of the one or more electrodes. A sacrificial conductor extends through the lead body adjacent to lead conductor and is configured to fail at a lower stress than the lead conductor.