Patent Description:
One type of implantable medical lead includes an IS4/DF4 lead connector, which is a standardized lead connector having an injection molded, reaction injection molded (RIM) or potted, cylindrical body (typically of a thermoplastic, or thermoset material). The connector body has a proximal end configured to connect into a header of an active implantable device of some type, and a distal end configured to connect to the conductors/coils within the main lead. Such lead connectors have multiple electrical contacts in the form of contact rings which are spaced along and are flush with a surface of the connector body. Lead connectors may also include a pin contact extending from the proximal end. A conductor typically extends through the lead body from each contact ring and projects from the distal end of the molded body so as to provide a connection point for the conductors of the main lead. Similarly, a main body pin may extend along a central axis of the lead connector from the pin contact at the proximal end and also project from the distal end of the molded body.

Conventional practices for the manufacture of lead connectors include an injection molding process, or a reaction injection molding process, or liquid silicone molding process, or a potting process wherein the ring connectors, conductive pins, and the central pin/pin contact (if being employed) are arranged within a mold cavity. A thermoplastic material, or other suitable material, is then injected into the mold cavity to over-mold the conductive pins, ring connectors, and main body pin to form the cylindrical body of the lead connector.

<CIT> discloses an implantable lead connector assembly including contact rings, and bulk of insulation, which includes sealing surfaces and a shank defining a distal end of the bulk. One or more conductor pins extend within the bulk and have distal ends protruding distally therefrom to be exposed alongside the shank; and an inner surface of each contact ring may have a proximal end of a corresponding conductor pin coupled thereto. <CIT> relates to a method for constructing a plug for an electrical connection to a multipolar lead for an active implantable medical device. A method of manufacturing a lead connector for an implantable medical device is described in <CIT>. <CIT> concerns a lead end containing a slotted member, which can have a plurality of slots extending along at least a portion of the length of the slotted member, each of the slots having a respective positioning feature, the plurality of slots having a plurality of positioning features at different longitudinal positions along the length of the slotted member.

Tight tolerances are required for the safe and effective performance of lead connectors, including IS4/DF4 connectors. However, the injection molding process presents many challenges and shortcomings that make maintenance of such tight tolerance difficult to meet and which can result in high production costs and low manufacturing yields. For these and other reasons, there is a need for the present embodiments.

According to the present invention a method of manufacturing a lead connector <NUM> for an implantable device as defined in claim <NUM> is provided. According to a further aspect of the present invention a lead connector <NUM> for an implantable device as defined in claim <NUM> is provided. According to still a further aspect of the present invention a ring-pin assembly <NUM> as defined in claim <NUM> is provided.

<FIG> is a perspective view, and <FIG> is a side view of an example of a lead connector <NUM> for an implantable medical device. Lead connector <NUM> can be any of a variety of implantable leads, including, for example, an IS4/DF4 lead connector. Lead connector <NUM> includes a cylindrical body <NUM> having a proximal end <NUM> and a distal end <NUM> according to one embodiment.

In one embodiment, lead connector <NUM> includes first-third ring contacts 38a, 38b, 38c, disposed in a spaced-apart fashion along a longitudinal dimension of body <NUM>, and a central pin <NUM> axially extending from proximal end <NUM> having a pin contact <NUM>. First-third ring contacts 38a-38c are imbedded in and have a same outer diameter as body <NUM> so as to provide cylindrical body <NUM> with a uniform circumferential surface. Body <NUM> may be formed of an electrically non-conductive polymer material (e.g. polyurethane, polyetheretherketone (PEEK), polysulfone, etc.), epoxy, liquid silicone rubber, or any other suitable type of electrically non-conductive material.

In one embodiment, first-third conductive pins 48a, 48b, and 48c axially extend through body <NUM> respectively from first-third ring contacts 38a, 38b and 38c, and project from distal end <NUM> of body <NUM>. In one embodiment, first-third conductive pins 48a-48c are generally rigid wires that form first-third conductive pins 48a-48c. Similarly, central pin <NUM> extends axially through body <NUM> and projects from distal end <NUM>, with central pin <NUM> defining a central lumen <NUM>. In other embodiments, central pin <NUM> may extend axially through body <NUM>, but project from distal end <NUM> on the outer periphery, such as with first-third conductive pins 48a-48c.

In one embodiment, lead connector <NUM> is configured to be coupled to a flexible implantable lead. For example, lead connector <NUM> can be coupled at its distal end <NUM> to a flexible implantable lead <NUM> (illustrated in dashed lines in <FIG>). In one embodiment, first-third conductive pins 48a-48c serve as a contact point to which conductors 52a, 52b, and 52c of flexible implantable lead <NUM> are electrically and mechanically connected, such as by laser welding, for example, to thereby place lead conductors 52a-52c in electrical communication with first-third ring contacts 38a-38c. Lead <NUM> may also include a central conductor <NUM> which is in electrical communication with pin contact <NUM> via central lumen <NUM>. In one embodiment, conductors 52a-52c and central conductor <NUM> extend through lead <NUM> to corresponding coil or sensor.

In one embodiment, lead connector <NUM> is configured at its proximal end <NUM> to be coupled to a device. For example, in one embodiment, lead connector <NUM> is configured to be inserted into a receptacle or bore of <NUM> of header of a pulse generator <NUM> (illustrated in dashed lines in <FIG>) of some type, such as a pacemaker or implantable cardioverter defibrillator ("ICD"), for example. Complementary contacts within pulse generator contact ring contacts 38a-38c and pin contact <NUM>, thereby placing pulse generator <NUM> in electrical communication with sensors and/or coils associated with lead <NUM>.

It is noted that while lead connector <NUM> has been described with an example primarily in the context of an IS4/DF4 lead connector, one skilled in the art understands that the use of an assembly frame described below, as well as manufacturing techniques described herein, are applicable to other types of lead connectors as well. Accordingly, the features of lead connector <NUM>, including as assembly frame, and methods of manufacture described, herein should not be interpreted as being limited to only IS4/DF4 lead connectors.

<FIG> and <FIG> are respective perspective and side views illustrating portions of lead connector <NUM>, prior to being over-molded to form body <NUM>, according to one embodiment. As illustrated, prior to the molding process for forming body <NUM>, first-third conductive pins 48a, 48b, and 48c are respectively connected to an inner surface of corresponding first-third ring contact 38a, 38b, 38c, such as by laser welding, or soldering, for example, to form first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c.

In one embodiment, each of first-third conductive pins 48a, 48b, and 48c respectively have proximal ends 46a, 46b, and 46c and distal ends 47a, 47b, and 47b. In one embodiment, the proximal ends 46a, 46b, and 46c are respectively fixed to ring contacts 38a, 38b, 38c, while the distal ends 47a, 47b, and 47b each extend back toward the distal end <NUM> of lead connector <NUM>.

In one embodiment, first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c are configured for "nesting", such that first conductive pin 48a extends from its proximal end 46a at first ring 38a back through second and third rings 38b and 38c toward the distal end <NUM> of lead connector <NUM>. Similarly, second conductive pin 48b extends from its proximal end 46b at second ring 38b back through third ring 38c toward the distal end <NUM> of lead connector <NUM>. Third conductive pin 48c extends from its proximal end 46c at third ring 38c back toward the distal end <NUM> of lead connector <NUM>. In one embodiment, central pin <NUM> is also arranged so as to extend through all three ring contacts 38a-38c from proximal end <NUM> to distal end <NUM>.

In one embodiment, it is important that conductive pins extending through rings to which they are not coupled do not inadvertently make contact with these rings. For example, while first conductive pin 48a is coupled to first ring 38a, it cannot make contact with second and third rings 38b and 38c as it extends toward the distal end <NUM> of lead connector <NUM>. Touching another ring can cause an electrical short. Even getting too near a ring can leave the device susceptibility to electrical arcing.

In some designs, an insulative coating is added to each conductive pin or wire and it exends through adjacent rings in order to avoid inadvertant electrical contact with rings. Similarly, an insulating sleeve can be added to each wire or pin. Both processes, however, add complexity and cost to the manufacturing of a lead connector. For example, a coated wire must be ablated on each of the proximal and distal ends to provide electrical conductivity where it is needed (at connection points). Furthermore, adding individual insulating tubing to each wire is time consuming and adds multiple parts. All of this adds to manufacturing time and cost.

<FIG> illustrate various perspective views and an end view of assembly frame <NUM> of lead connector <NUM> in accordance with one embodiment. In one embodiment, assembly frame <NUM> includes first-third steps 62a, 62b and 62c. In one embodiment, assembly frame <NUM> includes first-fourth openings 68a, 68b, 68c, and 68d, each extending the length of the assembly frame <NUM>. In one embodiment, first-fourth openings 68a, 68b, 68c, and 68d, are configured as cylindrical lumens with a diameter that accommodates conductive pins 48a, 48b, and 48c. Proximal end <NUM> and distal end <NUM> of assembly frame <NUM> correlate with that of lead connector <NUM>. In one embodiment, assembly frame <NUM> assists in the assembly of lead connector <NUM> and overcomes many of the disadvantages of prior systems.

In one embodiment, during the assembly of lead connector <NUM>, each first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c are individually assembled onto assembly frame <NUM> to form a ring-pin assembly <NUM>. <FIG> illustrates an exploded view of a partially assembled ring-pin assembly <NUM> for forming lead connector <NUM>, where each of first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c are adjacent assembly frame <NUM>.

In one embodiment, third ring-pin subassembly 38c/48c is placed over assembly frame <NUM> by sliding third conductive pin 48c into third opening 68c (not visible in <FIG>, but illustrated in <FIG>) and sliding third ring 38c over assembly frame <NUM> until it engages third step 62c (not visible in <FIG>, but illustrated in <FIG>). Next, second ring-pin subassembly 38b/48b is placed over assembly frame <NUM> by sliding second conductive pin 48b into second opening 68b and sliding second ring 38b over assembly frame <NUM> until it engages second step 62b. Finally, first ring-pin subassembly 38a/48a is placed over assembly frame <NUM> by sliding first conductive pin 48a into first opening 68a and sliding first ring 38a over assembly frame <NUM> until it engages first step 62a. In one embodiment, central pin <NUM> is inserted through fourth opening 68d so that it extends out of assembly frame <NUM> on both proximal end <NUM> and distal end <NUM>. Fully assembled ring-pin assembly <NUM> is illustrated in <FIG>.

In one embodiment, assembly frame <NUM> is configured with first-third steps 62a, 62b and 62c being spaced along its longitudinal dimension such that when a respective ring 38a-48c is placed adjacent the step, the ring will be situated in a desired longitudinal location relative to the final lead connector <NUM>. The longitudinal spaces between steps can be adjusted and tailored to any particular application or standard to ensure proper spacing between rings. Similarly, first-fourth openings 68a, 68b, 68c, and 68d are configured to ensure that respective conductive pins 48a, 48b, 48c, and 48d are located properly to ensure conductive contact with appropriate rings and avoid inadvertent contact with the other rings and other conductors.

In one embodiment, first-third openings 68a, 68b, 68c, and thus, first-third conductive pins 48a, 48b, 48c, are arranged generally on the outer perimeter of assembly frame <NUM>, such as viewed from the end illustrated in <FIG>. In one embodiment, conductive pins 48a, 48b, 48c are spaced apart around the perimeter to ensure no one conductor is too close to another, or too close to a ring to which it is not coupled.

In one embodiment, once first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c are individually placed on to assembly frame <NUM>, the combined ring-pin assembly <NUM>, illustrated in <FIG>, is then placed into a mold for over-molding to produce a completed lead connector <NUM>, such as illustrated by <FIG> and <FIG>. Generally, the conductive pins and central pin/pin contact are positioned within the mold cavity with their ends extending through corresponding exit holes formed in the mold tool steel. A thermoplastic material, or other suitable material, is then injected under pressure into the cavity to over-mold the subassemblies and main contact pin to form the cylindrical body of the lead connector.

<FIG> generally illustrates ring-pin assembly <NUM> placed in an injection molding system <NUM> for over-molding to form body <NUM>, and thereby form completed lead connector <NUM>. Molding system <NUM> includes a mold cavity <NUM> configured to receive a ring-pin assembly <NUM>. According to one embodiment, mold cavity <NUM> is substantially tubular or cylindrical in shape, and has an inside diameter equal to that of the outside diameter of body <NUM> of lead connector <NUM>. Mold cavity <NUM> includes an opening <NUM> at one end through which the proximal end of central pin <NUM>, including pin contact <NUM>, extends. Mold cavity <NUM> includes an opening <NUM> at an opposing end through which portions of the distal end of ring-pin assembly <NUM> extend, including the portions of conductive pins 38a-38c and central pin <NUM>. Mold system <NUM> can also include a block <NUM> configured to retain a portion for connecting to pins 38a-38c.

In one embodiment, assembly frame <NUM> obviates the need for an assembly operator to carefully load each ring-pin subassembly into the mold cavity <NUM> and to carefully position them to ensure proper spacing and alignment. Traditional manufacturing process requires that each ring-pin subassembly must be nested and inserted individually into the mold tool, such that each ring and each conductor is precisely located to ensure proper spacing, thereby requiring skill and extra time during the assembly process.

After ring-pin assembly <NUM> is loaded into mold cavity <NUM>, mold material is injected into mold cavity <NUM> to over-mold those portions of ring-pin assembly <NUM> within mold cavity <NUM> and form connector body <NUM>. After removal from the mold cavity, assembly frame <NUM> is integral with body <NUM> and forms a portion of the finished lead connector <NUM>. The resulting finished lead connector <NUM> (as illustrated by <FIG> and <FIG>) is then removed from mold system <NUM>.

In one embodiment, assembly frame <NUM> is made of a material that is the same as the mold material injected into mold cavity <NUM>. Since the mold material flows in hot, some or all portions of assembly frame <NUM> may melt and mix with the injected mold material. In other embodiments, assembly frame <NUM> is made of a material that is the different than the mold material injected into mold cavity <NUM>. For example the materials may have different durometers and/or meting points, such that in some circumstances, the material of assembly frame <NUM> will remain relatively intact, but fully surrounded by the molding material in the final lead connector <NUM>.

In one embodiment, the rigid structure of assembly frame <NUM>, combined with a secure fit of first-third conductive pins 48a, 48b, 48c with first-third openings 68a, 68b, 68c, prevents the forces of mold material injected into the mold cavity <NUM> from moving and misaligning conductive pins 48a, 48b, 48c and rings 38a, 38b, 38c. In traditional manufacturing process, the ring-pin subassemblies are free-standing during molding. High injection pressure used in the injection molding process can cause the conductive pins and central pin to move within the mold cavity, thereby causing the electrical characteristics to potentially vary between lead connectors, and even causing shorting issues should the conductive pins be moved into contact with one another or other conductive elements within the lead connector. Forces created inside the mold cavity subject the pins to potential movement and bowing (forcing curvature) during the molding process. For example, during traditional manufacturing process, there are opportunities for electrical shorts or arcing between conductor paths. During the nesting process and the molding process it is imperative that the pin from one ring does not touch or come too near another ring or pin. Assembly frame <NUM> ensures such faults are avoided.

<FIG> is flow diagram illustrating a process <NUM> for forming a lead connector, such as lead connector <NUM>, according to one embodiment. Process <NUM> begins at <NUM> where conductive pins, such as conductive pins 48a-48c are joined (e.g. by laser welding) to ring contacts, such as ring contacts 38a-38c, to form ring-pin sub-assemblies.

At <NUM>, the ring-pin sub-assemblies are arranged onto the assembly frame to form a ring-pin assembly. For example, according to one embodiment as illustrated by <FIG>, third ring-pin subassembly 38c/48c is arranged over assembly frame <NUM> by sliding third conductive pin 48c into third opening 68c and sliding third ring 38c over assembly frame <NUM> until it engages third step 62c, second ring-pin subassembly 38b/48b is arranged over assembly frame <NUM> by sliding second conductive pin 48b into second opening 68b and sliding second ring 38b over assembly frame <NUM> until it engages second step 62b, and first ring-pin subassembly 38a/48a is arranged over assembly frame <NUM> by sliding first conductive pin 48a into first opening 68a and sliding first ring 38a over assembly frame <NUM> until it engages first step 62a.

At <NUM>, the ring-pin assembly, such as ring-pin assembly <NUM>, is loaded into a mold cavity of an injection molding system, such as mold cavity <NUM> of molding system <NUM> (see <FIG>). Mold material is injected into the mold cavity to over-mold the portions of ring-pin assembly <NUM> within the mold cavity <NUM>.

At <NUM>, the finished lead connector, such as lead connector <NUM>, is removed from the mold. At <NUM>, if required, post mold secondary processing is performed, such as annealing, plasma treatment, machining, trimming or cleaning. For example, some thermoplastics require annealing in order to meet dimensional specification. Machining can be done to add a feature on an inner diameter or outer diameter of the lead connector that cannot be effectively formed via injection molding.

<FIG> illustrate an assembly frame <NUM> in accordance with one embodiment. Assembly frame <NUM> is configured for use similar to that described above relative to assembly frame <NUM>. For example, a plurality of ring-pin subassemblies, such as for example, first-third ring-pin subassemblies 38a/48a, 38b/48b, 38c/48c, can be arranged over assembly frame <NUM> to form a ring-pin assembly, which can then be overmolded to form a lead connector. Whereas assembly frame <NUM> illustrated in previous embodiments had a substantially square-shaped outer surface, especially when viewed from its distal end <NUM> (<FIG>), assembly frame <NUM> has an outer surface that is hexagonal. As is evident to one skilled in the art, an assembly frame can have an outer surface with any of a variety of shapes.

Also, whereas assembly frame <NUM> illustrated in previous embodiments had <NUM> openings around its perimeter and <NUM> steps spaced along its length, assembly frame <NUM> has <NUM> openings around its perimeter and <NUM> steps spaced along its length. In this way, assembly frame <NUM> can accommodate <NUM> ring-pin subassemblies, ensuring proper spacing between each ring and between each conductor in the ring-pin assemblies. Like assembly frame <NUM>, assembly frame <NUM> can also be provided with a center opening to accommodate a center pin or other center conductor or the like. As is evident to one skilled in the art, an assembly frame can have any number of steps and openings to accommodate any number of ring-pin subassemblies.

<FIG> illustrates an exploded view of a partially assembled ring-pin assembly <NUM> for forming lead connector <NUM>, where each of first-third ring-pin subassemblies 238a/248a, 238b/248b, 238c/248c are adjacent assembly frame <NUM>. In one embodiment, third ring-pin subassembly 238c/248c is placed over assembly frame <NUM> by sliding third conductive pin 248c into third opening 268c and sliding third ring 238c over assembly frame <NUM> until it engages third step 262c. Next, second ring-pin subassembly 238b/248b is placed over assembly frame <NUM> by sliding second conductive pin 248b into second opening 268b and sliding second ring 238b over assembly frame <NUM> until it engages second step 262b. Finally, first ring-pin subassembly 238a/248a is placed over assembly frame <NUM> by sliding first conductive pin 248a into first opening 268a and sliding first ring 238a over assembly frame <NUM> until it engages first step 262a. In one embodiment, central pin <NUM> is inserted through fourth opening 268d so that it extends out of assembly frame <NUM> at both its ends. Once fully assembled, the ring-pin assembly is placed in a mold cavity and overmolded into a lead connector as previously described.

<FIG> illustrates an exploded view of a partially assembled ring-pin assembly <NUM> for forming lead connector <NUM>, where each of first-sixth ring-pin subassemblies 338a/348a, 338b/348b, 338c/348c, 338d/348d, 338e/348e, 338f/348f are adjacent assembly frame <NUM>. In one embodiment, sixth ring-pin subassembly 338f/348f is placed over assembly frame <NUM> by sliding sixth conductive pin 348f into sixth opening 368f and sliding sixth ring 338f over assembly frame <NUM> until it engages sixth step 362f. Next, fifth ring-pin subassembly 338b/348e is placed over assembly frame <NUM> by sliding fifth conductive pin 348e into fifth opening 368e and sliding fifth ring 338e over assembly frame <NUM> until it engages fifth step 362e. Next, fourth ring-pin subassembly 338d/348d is placed over assembly frame <NUM> by sliding fourth conductive pin 348d into fourth opening 368d and sliding fourth ring 338d over assembly frame <NUM> until it engages fourth step 362d. Next, third ring-pin subassembly 338c/348c is placed over assembly frame <NUM> by sliding third conductive pin 348c into third opening 368c and sliding third ring 338c over assembly frame <NUM> until it engages third step 362c. Next, second ring-pin subassembly 338b/348b is placed over assembly frame <NUM> by sliding second conductive pin 348b into second opening 368b and sliding second ring 338b over assembly frame <NUM> until it engages second step 362b. Finally, first ring-pin subassembly 338a/348a is placed over assembly frame <NUM> by sliding first conductive pin 348a into first opening 368a and sliding first ring 338a over assembly frame <NUM> until it engages first step 362a.

In one embodiment, central pin <NUM> is inserted through seventh opening <NUM> so that it extends out of assembly frame <NUM> at both its ends. Once fully assembled, the ring-pin assembly is placed in a mold cavity and overmolded into a lead connector as previously described.

<FIG> illustrate assembly frame <NUM> in accordance with one embodiment. In one embodiment, assembly frame <NUM> is configured with first-fourth openings 468a, 468b, 468c, and 468d and with first-fourth steps 462a, 462b, 462c and 462d. First-fourth steps 462a, 462b, 462c and 462d are spaced along the longitudinal dimension of assembly frame <NUM> such that when a respective ring is placed adjacent the step, the ring will be situated in a desired longitudinal location relative to the final lead connector <NUM>. The longitudinal spaces between steps can be adjusted and tailored to any particular application or standard to ensure proper spacing between rings. First-fourth openings 468a, 468b, 468c, and 468d are configured to ensure that respective conductive pins are located properly to ensure conductive contact with appropriate rings and avoid inadvertent contact with the other rings and other conductors. Assembly frame <NUM> also include fifth opening 468e though its center, which can in one embodiment accommodate a central pin.

In the illustrated assembly frame <NUM>, first-fourth openings 468a, 468b, 468c, and 468d are configure as slots, with a longitudinally extending narrow slot-opening along the length of each opening. Configuring first-fourth openings 468a, 468b, 468c, and 468d as slots can be useful in assembling the pins and may have advantages in tooling in some embodiments. Once assembly frame <NUM> has respective conductive pins assembled into openings 468a, 468b, 468c, and 468d and rings assembled adjacent first-fourth steps 462a, 462b, 462c and 462d, it can be overmolded as described above for the other ring-pin assemblies, such that molded material will flow over and into the slots, completely surrounding the conductive pins.

Claim 1:
A method of manufacturing a lead connector (<NUM>) for an implantable medical device, the method comprising:
connecting proximal ends (46a, 46b, and 46c) of a plurality of conductive pins (46a, 46b, 46c) to a corresponding one of a plurality of ring contacts (38a, 38b, 38c) to form a plurality of ring-pin subassemblies (38a/48a, 38b/48b, 38c/48c);
assembling each of the plurality of ring-pin subassemblies (38a/48a, 38b/48b, 38c/48c) on an assembly frame (<NUM>) to form a ring-pin assembly (<NUM>), including inserting the plurality of conductive pins (46a, 46b, 46c) in a corresponding plurality of openings (68a, 68b, 68c, 68d) within the assembly frame (<NUM>) such that the corresponding plurality of ring contacts (38a, 38b, 38c) are spaced along a longitudinal dimension of the assembly frame (<NUM>),
wherein the plurality of openings (68a, 68b, 68c, 68d) are configured as cylindrical lumens with a diameter that accommodates the plurality of conductive pins (46a, 46b, 46c),
wherein the assembly frame (<NUM>) comprises a plurality of steps (62a, 62b, 62c) and wherein assembling each of the plurality of ring-pin subassemblies (38a/48a, 38b/48b, 38c/48c) on the assembly frame (<NUM>) further comprises placing one of the plurality of ring contacts (38a, 38b, 38c) adjacent one of the plurality of steps (62a, 62b, 62c), and
wherein the plurality of openings (68a, 68b, 68c, 68d) within the assembly frame (<NUM>) are configured to ensure no conductive pin of the plurality of conductive pins (46a, 46b, 46c) contacts any other conductive pin of the plurality of conductive pins (46a, 46b, 46c);
arranging the ring-pin assembly (<NUM>) within a mold cavity (<NUM>);
filling the mold cavity (<NUM>) with a mold material that at least partially surrounds the ring-pin assembly (<NUM>); and
removing a resulting lead connector (<NUM>) from the mold cavity (<NUM>).