Patent Description:
Implantable medical devices (IMDs), for example, neurostimulators, pacemakers and defibrillators, may include one or more leads and electrodes disposed on the leads for delivering electrical stimulation to muscles or nerves or for sensing response of tissue to the stimulation. IMDs may include a hermetically sealed housing containing a power source, for example, a battery, and control electronics for controlling the stimulation that may be coupled to a lead connector block.

The lead connector block may couple a lead to the control electronics, either directly or through a lead extension. The lead connector block may include electrical contacts for electrically coupling the electrodes via the lead to the control electronics. While the lead connector block provides electrical coupling between the control electronics and the lead, the lead connector block also maintains a seal between the lead and the IMD housing to prevent body fluids from entering the housing, to prevent contamination and short-circuiting. Documents <CIT>, <CIT> and <CIT> disclose known mold assemblies and corresponding methods of use according to the prior art.

In some examples, an example mold assembly includes a first core, a second core, and a retaining cap. The first core defines an insert seat configured to receive a mold insert. The second core defines a pin portion configured to contact at least a first insert surface defined by the mold insert. The second core defines a curved end portion opposing the pin portion. The first core and the second core are configured to define a mold volume adjacent the mold insert. The retaining cap is disposed about the curved end portion defined by the second core. The retaining cap defines a curved cap surface in contact with the curved end portion. The retaining cap secures the second core at a predetermined orientation relative to the first core within predetermined tolerances.

In some examples, an example technique includes positioning a mold insert on an insert seat defined by a first core of a mold assembly. The example technique includes disposing a retaining cap about a curved end portion defined by a second core of the mold assembly. The example technique includes securing the second core at a predetermined orientation relative to the first core within predetermined tolerances such that a pin portion defined by the second core contacts at least a first insert surface defined by the mold insert and such that the first core and the second core define a mold volume adjacent the mold insert. The example technique includes depositing mold material within the mold volume adjacent the mold insert.

Example mold assemblies and techniques according to the disclosure may be used to provide a seal on an internal hermetic connector (IHC) segment portion to form an IHC segment. IHC segments may be assembled to form an IHC assembly. A lead connector block of a medical device may include an IHC assembly to provide a hermetically sealed conductive path between a medical device and an external component. For example, an implantable medical device may include an IHC assembly to provide a hermetically sealed conductive pathway between circuitry within a sealed housing of the medical device and a lead outside the sealed housing.

<FIG> is a schematic and conceptual side view of an example medical device <NUM> including an example internal hermetic connector (IHC) assembly <NUM>. IHC assembly <NUM> provides a conductive path extending between circuitry (not shown) within a hermetically sealed housing of medical device <NUM> and a lead (not shown) outside the hermetically sealed housing. The conductive path may include a conductor pin or terminal that is electrically insulated from the hermetically sealed housing. IHC assembly <NUM>, while providing a conductive path, also maintains the seal between medical device <NUM> and its environment. In examples in which medical device <NUM> is implanted in a patient, such sealing may avoid problems arising from contamination and short-circuiting by body fluids adjacent implanted medical device <NUM>.

In some examples, IHC assembly <NUM> may substantially reduce lead interconnect volume of medical device <NUM> connected to a lead by combining the functionality of a lead connector block and an electrical feedthrough into a relatively compact modular component. IHC assembly <NUM> may be formed by stacking and joining a number of IHC segments.

<FIG> is a schematic and conceptual side view of internal hermetic connector assembly <NUM> of <FIG>. IHC assembly <NUM> may assume the form of a hermetic cylinder including a series of modular IHC segments <NUM>, for example, 13a to 13i, as shown in <FIG>. IHC assembly <NUM> may include a fewer or greater number of IHC segments than shown in <FIG>. Each IHC segment <NUM> may define an internal void, and the internal voids combine to define a channel or bore defined by IHC assembly <NUM>. An end of a lead may be introduced into the channel, and electrical contacts at the end of the lead may be coupled with respective interior electrical contacts within an interior of IHC assembly <NUM>. An exterior of IHC assembly <NUM> may have respective outer electrical contacts coupled with the interior electrical contacts. For example, each respective IHC segment <NUM> may include one or more metal or alloy ferrules <NUM> and <NUM> and an electrical spring contact <NUM> that provides a conductive path between the interior of IHC assembly <NUM> electrically coupled to the lead and the exterior of IHC assembly <NUM> electrically coupled to circuitry within medical device <NUM>. Thus, IHC assembly <NUM> may allow an external component such as a lead to be electrically coupled to circuitry within medical device <NUM> while maintaining a hermetic seal between the interior of medical device <NUM> and an environment external to medical device <NUM>.

IHC assembly <NUM> may include additional components, for example, an end pin <NUM> disposed at one end of IHC assembly <NUM>, a collar <NUM>, and a lead connector <NUM> defining an opening for introducing a lead into IHC assembly <NUM>.

<FIG> is a schematic and conceptual side view of an internal hermetic connector segment <NUM>, for example, internal hermetic connector segment 13a of IHC assembly <NUM> of <FIG>. IHC segment <NUM> includes a first ferrule <NUM>, a second ferrule <NUM>, and an insulator <NUM> between the first ferrule and the second ferrule <NUM>. One or both of the first and second ferrules <NUM> and <NUM> may be annular, or include annular segments, or have any suitable shape for surrounding a lead. One or both of the first and second ferrules <NUM> and <NUM> may include the same or different conductive material. The conductive material may include a metal or an alloy. In some examples, the metal or the alloy may include titanium, steel (for example, stainless steel), nitinol, niobium, platinum iridium, MP35N alloy, platinum-iridium alloy, or any other metal or alloy suitable for medical or surgical applications or combinations thereof. In some examples, the metal or alloy consists of titanium. The titanium may be a medical grade titanium, for example, Grade <NUM> titanium.

Insulator <NUM> may include any suitable rigid or semi-rigid insulating material, for example, glass or ceramic. The glass may include LaBor-<NUM> glass material, which is a glass about <NUM>% B<NUM>O<NUM>, about <NUM>% CaO, about <NUM>% MgO, about <NUM>% La<NUM>O<NUM>, about <NUM>% SiO<NUM> and about <NUM>% Al<NUM>O<NUM>, wherein percentages are mole percentages, and the CaO and/or MgO may be replaced with corresponding amounts of SrO. In some examples, the glass may include Ta-<NUM> glass (nominally, <NUM> weight % SiO<NUM>, <NUM> weight % Al<NUM>O<NUM>, <NUM> weight % B<NUM>O<NUM>, <NUM> weight % CaO, <NUM> weight % MgO and <NUM> weight % La<NUM>O<NUM>), Cabal-<NUM> glass (aluminum oxide [Al<NUM>O<NUM>]:boron oxide [B<NUM>O<NUM>]:calcium oxide [CaO]:magnesium oxide [MgO], for example, with relative approximate concentrations of <NUM>:<NUM>:<NUM>:<NUM> (mol %), and sodium oxide (Na<NUM>O), potassium oxide (K<NUM>O), silicon oxide (SiO<NUM>) and arsenic oxide (As<NUM>O<NUM>) at maximum concentrations of thousands parts per million), or lead-free phosphate glasses.

In some examples, insulator <NUM> consists of glass. The insulating material of insulator <NUM> may electrically insulate first ferrule <NUM> from second ferrule <NUM>. Insulator <NUM> may be annular, or include annular segments, or may have any suitable shape or geometry, for example, a shape or geometry complementary to one or more surfaces defined by first or second ferrules <NUM> or <NUM>. In the example shown in <FIG>, first ferrule <NUM>, second ferrule <NUM>, and insulator <NUM> are annular and co-concentric. However, in other examples, different configurations may be used for one or more of first ferrule <NUM>, second ferrule <NUM>, and insulator <NUM>. Insulator <NUM> may secure first ferrule <NUM> to second ferrule <NUM>. For example, surfaces defined by insulator <NUM> may be joined, welded, adhered, or otherwise bonded to respective surfaces defined by first and second ferrules <NUM> and <NUM>, such that insulator <NUM> secures first and second ferrules <NUM> and <NUM> at a fixed relative orientation.

IHC segment <NUM> also includes seal <NUM>. Seal <NUM> may include a semi-soft or soft sealing material for providing a hermetic seal at at least one surface defined by IHC segment <NUM> to ultimately provide a hermetic seal to IHC assembly <NUM>. The sealing material may include silicone, silicone rubber, fluorocarbons, fluorosilicone rubber, an elastomer, a thermoplastic elastomer, or any suitable moldable material. The silicone material may include a two-part, platinum-catalyzed, translucent silicone material with a predetermined durometer hardness. In some examples, the durometer hardness may be between <NUM> Shore A and <NUM> Shore A. For example, the durometer hardness may be <NUM> Shore A. In some examples, seal <NUM> consists of silicone rubber. The sealing material may be formed by allowing a mold material to set or cure. The mold material may include a mold composition that may be fluid to flow into and occupy a mold volume under first predetermined conditions, and that may solidify, cure, or set, under second predetermined conditions. For example, the mold material may include liquid silicone rubber that may be flowable to occupy a mold volume until it cures to form a seal substantially defined by the mold volume. The solidification, setting, or curing may be initiated by one or more of heat treatment, cooling, UV (ultraviolet) light exposure, pressure changes, formation of chemical bonds, or polymer cross-linking and network propagation, or by other suitable setting, curing, or solidification techniques. In some examples, seal <NUM> may be secured to IHC segment <NUM> by a primer or bonding agent. For example, at least a part of a surface defined by IHC segment <NUM> may be coated with a primer that secures seal <NUM> to the surface. The primer may include any suitable agent capable of bonding or securing seal <NUM> to IHC segment <NUM>. In some examples, the primer may include a silicone-based primer.

Seal <NUM> may define a surface that substantially confirms to a predetermined surface defined by IHC segment <NUM>, for example, an inner surface of IHC segment <NUM>, as shown in <FIG>. In some examples, seal <NUM> may define a relative flat surface and a relatively uniform thickness. In other examples, seal <NUM> may define a portion with a varying thickness, or a portion that defines a protrusion from seal <NUM>. For example, as shown in <FIG>, seal <NUM> may define a seal flange <NUM>. In some examples, seal flange <NUM> may assist in securing a lead portion inserted in IHC assembly <NUM>. Alternatively, or in addition, seal flange <NUM> may provide a seal to prevent shorting between contacts on a lead connected to IHC assembly <NUM> and contacts on defined by IHC assembly <NUM>, and may aid in securing the lead while maintaining minimal insertion and withdrawal forces. In some examples, seal flange <NUM> may be provided with any suitable configuration. For example, seal flange <NUM> may include more than one protrusion.

IHC segment <NUM> may thus include IHC segment portion 13a, which includes first and second ferrules <NUM> and <NUM>, and insulator <NUM>. Seal <NUM> may be provided or formed on IHC segment portion 13a including first and second ferrules <NUM> and <NUM> and insulator <NUM>, by molding a silicone portion onto IHC segment portion 13a to form IHC segment <NUM> shown in <FIG> and <FIG>. For example, IHC segment portion 13a may be disposed and secured within a mold assembly, and a seal formulation, for example, a liquid silicone rubber formulation, may be injected into the mold assembly to occupy and solidify within a predetermined mold volume to define seal <NUM>.

However, mold assemblies and techniques used for molding seal <NUM> onto IHC segment portion 13a to form IHC segment <NUM> may present problems. For example, improperly controlled molding may lead to dimensional variability in IHC segment <NUM>, for example, in overall height and axial alignment of the components of IHC segment <NUM>. Insulator <NUM> bonding or securing the first and second ferrules <NUM> and <NUM> may be fragile, or susceptible to cracking, chipping, or shattering on exposure to high molding pressures or stresses. The first or second ferrules <NUM> or <NUM> may get damaged. Air may be introduced during the molding process, resulting in bubbles or pockets of trapped air in seal <NUM>. Applied or injected sealing material may escape from a mold volume, resulting in "flash," or excess mold material attached to or protruding from a seal molded on the IHC segment portion. For example, flash can occur even with gaps as small as <NUM> inches at mold volume surfaces during injection molding. Such flash may prevent proper assembly of IHC segments <NUM>, or may compromise the hermetic seal provided by IHC assembly <NUM>. Removing flash from a molded IHC segment may entail secondary operations steps that may increase manufacturing times and costs. Additionally, removing flash may be difficult because of the relatively small size of the IHC segments.

Providing an interference fit between the mold components, for example, between mold cores of a mold and a mold insert (for example, IHC segment portion 13a onto which seal <NUM> is molded) may reduce or eliminate flash and other problems. For example, a slight interference may provide a good shutoff to escaping mold material and prevent flash. However, an interference fit, while mitigating flash, may result in or exacerbate other problems. In particular, an interference fit may impart additional stresses on insulator <NUM> in IHC segment <NUM>, and even a relatively slight interference fit, as small as <NUM> inch, between IHC segment portion 13a including insulator <NUM> and the mold may cause insulator <NUM> to fracture.

Example mold assemblies and techniques according to the disclosure may be used to provide a seal on an internal hermetic connector (IHC) segment portion to form an IHC segment, while reducing or avoiding one or more problems associated with molding.

<FIG> is a schematic and conceptual exploded partial view of an example mold assembly <NUM> including a first core <NUM> and a second core <NUM> for molding seal <NUM> on a mold insert including internal hermetic connector segment portion 13a. <FIG> is a schematic and conceptual exploded cross-sectional partial view of example mold assembly <NUM> of <FIG>.

One or both of first or second cores <NUM> or <NUM> may include metal, alloy, ceramic, glass, polymer, compacted material, or any other suitable material or combinations thereof.

First core <NUM> defines an insert seat <NUM> configured to receive a mold insert. As shown in <FIG>, the mold insert may include IHC segment portion 13a. Insert seat <NUM> may be defined by one or more regions or portions of a surface of first core <NUM>. Insert seat <NUM> may include a flat surface region, a curved surface region, a polygonal surface region, or any surface region complementary to at least a portion of a surface of the mold insert. Insert seat <NUM> may thus retain the mold insert, for example, IHC segment portion 13a, in a fixed orientation relative to first core <NUM> or second core <NUM>. In some examples, first core <NUM> defines a first core pin <NUM>. First core pin <NUM> may be a protruding portion of first core <NUM>, as shown in <FIG>. A portion or a surface of first core pin <NUM> may contact one or both of a portion of a surface of second core <NUM> or the mold insert. In some examples, a surface of first core pin <NUM> may by surrounded by a complementary surface of the mold insert, for example, a surface <NUM> defined by IHC segment portion 13a, to define at least a portion of a mold volume which may be occupied by a mold material, as described elsewhere in the disclosure. In some examples, first core <NUM> may include a first core sleeve <NUM> surrounding at least a portion of first core pin <NUM>. One or both of first core pin <NUM> and first core sleeve <NUM> may define insert seat <NUM>, for example, at least a portion of insert seat <NUM>. In some examples, the mold insert may contact surfaces of one or both of first core pin <NUM> or first core sleeve <NUM> when secured on insert seat <NUM>. First core sleeve <NUM> may be configured to restrict motion of first core <NUM> to motion along or about a longitudinal axis defined by first core sleeve <NUM>. For example, first core sleeve <NUM> may be secured to first core pin <NUM> by an interference fit between an outer first core pin surface defined by first core pin <NUM> and an inner core sleeve surface defined by first core sleeve <NUM>.

Second core <NUM> may define a pin portion <NUM> configured to contact at least a first insert surface defined by the mold insert. For example, the first insert surface may include a surface of IHC segment portion 13a adjacent pin portion <NUM>, as shown in <FIG>. Thus, first core <NUM> and second core <NUM> may secure the mold insert, for example, IHC segment portion 13a, on seat insert <NUM> between one or more of first core pin <NUM>, first core sleeve <NUM>, or pin portion <NUM>, when mold assembly <NUM> is assembled.

<FIG> is a schematic and conceptual partial cross-sectional view of example mold assembly <NUM> of <FIG> assembled with the mold insert secured between first and second cores <NUM> and <NUM>. For example, first core pin <NUM> of first core <NUM> abuts pin portion <NUM> defined by second core <NUM>. When mold assembly <NUM> is assembled, one or more surfaces of surfaces defined by first core <NUM>, second core <NUM>, and the mold insert may define a mold volume <NUM>. For example, surface <NUM> defined by IHC segment portion 13a, a surface <NUM> of pin portion <NUM>, a surface of first core pin <NUM>, and insert seat <NUM> may define mold volume <NUM>, as shown in <FIG>. One or both of first core <NUM> and second core <NUM> may define a runner <NUM> fluidically connected to opening <NUM> of fan gate <NUM> to admit or inject mold material into mold volume <NUM>. One or both of first core <NUM> and second core <NUM> may define fan gate <NUM> fluidically connected to one or both of mold volume <NUM> or runner <NUM> to admit mold material from runner <NUM> into mold volume <NUM>. Thus, in some examples, mold assembly <NUM> may include the mold material occupying mold volume <NUM>.

When mold assembly <NUM> is assembled, the relative orientation and alignment of first core <NUM> and second core <NUM> may determine stresses or forces applied to the mold insert, the orientation of the mold insert, and gaps or openings in mold volume <NUM> that may allow mold material to escape, resulting in flash formation. For example, if first core <NUM> and second core <NUM> are spaced or distanced apart beyond a predetermined threshold spacing, the mold insert may not be properly secured between first core <NUM> and second core <NUM>, and may move when mold material is injected into or allowed to flow into mold volume <NUM>. An increased spacing may also lead to gaps or openings between respective surfaces of first core <NUM>, second core <NUM>, and the mold insert. In contrast, reducing the spacing or distance between first core <NUM> and second core <NUM> may reduce gaps or openings, and may substantially mechanically or physically secure the mold insert within the assembly. However, reducing the spacing may increase in the stresses or forces exerted on the mold insert, for example, on IHC segment portion 13a, which may damage one or more components of IHC segment portion 13a, or may bend, fracture, shatter, or otherwise affect the integrity of one or more of first or second ferrules <NUM> or <NUM> or insulator <NUM>. Further, relative misalignment of first core <NUM> and second core <NUM>, for example, from relative tilting beyond a predetermined tolerance, may add to the stresses on the mold insert. For example, too much deflection may result in insulator <NUM> cracking or breaking the bond between insulator <NUM> and first or second ferrules <NUM> or <NUM>.

Thus, maintaining predetermined geometric and stress tolerances within the mold assembly may help in reducing or avoiding one or more problems discussed in the disclosure. For example, securing second core <NUM> relative to first core <NUM> in a predetermined orientation subject to predetermined tolerances, for example, geometric tolerances such as relative spacing and alignment, may help maintain the mold insert in a secured position or orientation, reduce or avoid development of stresses beyond predetermined tolerances, or reduce or avoid gaps or openings that may lead to flash. The predetermined tolerances may include one or both of insert height of the mold insert, for example, of IHC segment portion 13a, and relative tilt between the first and second ferrules <NUM> and <NUM>. For example, application of compressive forces or tilting forces by first or second core <NUM> or <NUM> that may push, pull, or tilt ferrules <NUM> or <NUM> beyond a range of acceptable tolerances may cause one or more of insulator <NUM> or ferrules <NUM> or <NUM> to break or deform. Mold assembly <NUM> may help to promote securing or maintaining one or more of first core <NUM>, second core <NUM>, and the mold insert within predetermined tolerances. Further, manufacturing variations in preparing different batches or samples of the mold insert may lead to variations in the relative spacing and tilting between components of the mold insert, for example, between first and second ferrules <NUM> and <NUM>. These manufacturing variations may also change the forces and stresses ultimately applied to components of the mold insert when seated on insert seat <NUM>. For example, mold assembly <NUM> in a first configuration for accommodating a first mold insert that substantially conforms to manufacturing tolerances may not sufficiently conform to a second mold insert that may deviate from manufacturing tolerances. Thus, if components of mold assembly <NUM> can accommodate manufacturing variations within predetermined manufacturing tolerances for the mold insert, for example, by slightly changing relative spacing and orientation between components of mold assembly <NUM>, that may help with relieving stresses on the mold insert and in avoiding gaps and openings that may lead to flash formation.

<FIG> is a schematic and conceptual partial cross-sectional view of example mold assembly <NUM> including first core <NUM>, second core <NUM>, the mold insert (for example, IHC segment portion 13a), a retaining cap <NUM>, and a retaining sleeve <NUM>. In some examples, as shown in <FIG>, second core <NUM> defines a curved end portion <NUM> opposing pin portion <NUM>. Retaining cap <NUM> may be disposed about curved end portion <NUM> defined by second core <NUM>. Retaining cap <NUM> may define a curved cap surface <NUM> in contact with curved end portion <NUM>. In some examples, curved cap surface <NUM> of the retaining cap is substantially concave, and curved end portion <NUM> of second core <NUM> is substantially convex and conforms to curved cap surface <NUM>. For example, curved cap surface <NUM> and curved end portion <NUM> may define a ball and socket-type joint. In some examples, curved cap surface <NUM> of retaining cap <NUM> and curved end portion <NUM> of second core <NUM> define a ball joint configured to allow second core <NUM> to pivot relative to retaining cap <NUM> while securing second core <NUM> at the predetermined orientation within the predetermined tolerances. In other examples, curved cap surface <NUM> and curved end portion may define other suitable complementary surfaces, for example, spheroidal, hyperbolic, or ellipsoidal surfaces.

Thus, in some examples, retaining cap <NUM> secures second core <NUM> at a predetermined orientation relative to first core <NUM> within predetermined tolerances. Further, the complementary curved end portion <NUM> and curved cap surface <NUM> may allow slight relative motion or realignment of second core <NUM> relative to first core <NUM> or the mold insert, which may assist with relieving, mitigating, or redistributing stresses or pressures so that stresses experienced by the mold insert are within predetermined tolerances. Providing retaining cap <NUM> in mold assembly <NUM> may help to avoid or reduce one or more problems described in the disclosure. Retaining cap <NUM> may include materials similar to those described with reference to first and second cores <NUM> and <NUM>. Retaining cap <NUM> may define a second runner channel <NUM>, such that second core <NUM> and retaining cap <NUM> together define runner <NUM> fluidically connected to mold volume <NUM> to admit mold material into mold volume <NUM>.

In some examples, mold assembly <NUM> may include retaining sleeve <NUM> disposed between a surface defined by retaining cap <NUM> and one or both of first core <NUM> and second core <NUM>. Retaining sleeve <NUM> may define a first inner sleeve surface <NUM> disposed about at least insert seat <NUM> of first core <NUM>. In some examples, first inner sleeve surface <NUM> contacts an outer surface of first core <NUM>, for example, an exterior surface of first core sleeve <NUM>, as shown in <FIG>. Retaining sleeve <NUM> may define a second inner sleeve surface <NUM> disposed about at least pin portion <NUM> of second core <NUM>. Retaining sleeve may define an outer sleeve surface <NUM>, wherein retaining cap <NUM> defines a retaining surface <NUM> contacting outer sleeve surface <NUM> of retaining sleeve <NUM>. Retaining cap <NUM> may be secured to retaining sleeve <NUM> by an interference fit between retaining surface <NUM> and outer sleeve surface <NUM>. In some examples, retaining cap <NUM> is secured to retaining sleeve <NUM> by a threaded fit between a first thread defined by retaining surface <NUM> and a second thread defined by outer sleeve surface <NUM>.

In some examples, retaining sleeve <NUM> secures first core <NUM> to maintain the predetermined orientation of second core <NUM> relative to first core <NUM> within the predetermined tolerances. For example, retaining sleeve may secure one or more of first core <NUM>, second core <NUM>, and retaining cap <NUM> in predetermined orientations by one or both of an interference fit or a threaded fit at respective contacting surfaces, for example, at first inner sleeve surface <NUM>, second inner sleeve surface <NUM>, or outer sleeve surface <NUM>. Retaining sleeve <NUM> may define additional features to provide a secure fit. For example, retaining sleeve <NUM> may define an annular landing <NUM>, and first core <NUM> may define an annular lip <NUM>, where annular landing <NUM> secures annular lip <NUM>. In some examples, first core sleeve <NUM> of first core <NUM> defines annular lip <NUM>, as shown in <FIG>. Annular landing <NUM> may limit the relative longitudinal spacing between first core <NUM> and second core <NUM>, for example, between first core pin <NUM> and pin portion <NUM>. Annular landing <NUM> may be defined by sleeve <NUM> between first inner sleeve surface <NUM> and second inner sleeve surface <NUM>.

Thus, one or both of retaining cap <NUM> and retaining sleeve <NUM> may help in holding one or more of the mold insert, first core <NUM>, and second core, within predetermined relative orientations, while still allowing the mold insert, first core <NUM>, and second core to slightly move within the range of tolerances to account for manufacturing variations which may cause slight geometric variations in the mold insert. For example, mold assembly <NUM> may accommodate for variations in mold insert height and tilt while allowing for adjustability in the shut off force being applied to the mold insert to avoid flashing. Thus, mold assembly <NUM> including one or both of retaining cap <NUM> and retaining sleeve <NUM> may reduce or avoid one or more problems associating with molding described in the disclosure. In some examples, one or both of retaining cap <NUM> or retaining sleeve <NUM> may be repositioned after placing the mold insert on insert seat <NUM> between first and second cores <NUM> and <NUM>, for example, by releasing and re-securing the interference fit to adjust to variations in height of the mold insert, and the ball and socket joint-type configuration of retaining cap <NUM> and second core <NUM> may be adjusted or self-adjust to account for variations in tilt of the mold insert. At the same time, one or both of retaining cap <NUM> or retaining sleeve <NUM> may be repositioned to apply appropriate shut off forces at contacting surfaces of the mold insert, first core <NUM>, and second core <NUM>, to prevent formation of gaps or openings that may release mold material to avoid flash formation.

Thus, mold assembly <NUM> may maintain the clamping forces from the molding assembly independent of the forces applied to the mold insert within the mold assembly. Further, the amount of forces or stressed applied to the mold insert may be reduced even while providing sufficient shut off forces by securing mold components by interference or threaded fits. For example, mold clamping forces may be applied to retaining cap <NUM>, while forces applied to the mold insert may be controlled by the threaded fit or interference fit between retaining cap <NUM> and retaining sleeve <NUM>.

In some examples, air or another gas may be introduced into mold volume <NUM> with the mold material. Such air or gas may get trapped within mold volume <NUM>, and ultimately into the mold material, resulting in voids, pockets, or bubbles in seal <NUM>. To avoid accumulation of air or gas, in some examples, first core <NUM> may define at least one overflow vent <NUM> configured to remove or vent air from the mold volume. In some examples, one or both of first core sleeve <NUM> or first core pin <NUM> defines at least one overflow vent <NUM>. At least one overflow vent <NUM> may include a plurality of fluidically connected vents, pores, channels to vent air or gas from mold volume <NUM> outside mold assembly <NUM>. Fan gate <NUM> may have a ring gate design to feed the mold volume with a uniform packing pressure to the mold insert as the mold material solidifies to form seal <NUM>, offering a more uniform shrink as seal <NUM> cools about and adjacent to IHC segment portion 13a in mold assembly <NUM>, and during post cure processes. Ring gates, however, may tend to trap air due to the flow pattern as mold volume <NUM> fills with the mold material, especially in the case of molding small components such as IHC segment portion 13a. While a vacuum system may be used to remove air or gas, the vacuum system may be sufficient. Thus, in some examples, vent <NUM> may provide an overflow to removed substantially all air or gas from mold volume <NUM> and avoid formation of air pockets or bubbles in seal <NUM>.

Thus, mold assembly <NUM> may be used to mold seal <NUM> on IHC segment portion 13a to form IHC segment <NUM>, while reducing or avoiding problems such as flash formation, air bubbles, and breakage or damage to IHC segment <NUM>. While mold assembly <NUM> is described with reference to a single mold insert, mold assembly may be used to provides seals on more than one mold insert, for example, by serially molding seals on a series of mold inserts. In some examples, an example assembly may include a plurality of mold assemblies, and respective seals may be provided on each of a plurality of mold inserts respectively disposed within respective mold assemblies of the plurality of mold assemblies.

Example techniques described with reference to <FIG> may be used to operate mold assembly <NUM>. However, any other suitable techniques may also be used to operate mold assembly <NUM>. Further, while mold assembly <NUM> was described with reference to an example mold insert including IHC segment, mold assembly can be used to provide a seal on, adjacent, or about any suitable mold insert.

<FIG> is a flowchart illustrating an example technique for molding seal <NUM> on a mold insert, for example, internal hermetic connector segment portion 13a. The example technique of <FIG> is described with reference to the mold assemblies shown in <FIG>, <FIG>, and <FIG> only as an example. The example technique may be performed using other suitable mold assemblies. While the example technique is described with reference to an operator, an industrial robot or an automated or semi-automated assembly tool may be used to perform example techniques according to the disclosure, for example, by inspecting, manipulating, orienting, fitting, or securing, one or more components. The example technique of <FIG> may include positioning a mold insert on insert seat <NUM> defined by first core <NUM> of mold assembly <NUM> (<NUM>). In some examples, the example technique may include positioning the mold insert, for example, IHC segment portion 13a, on a surface or within a volume or chamber at least partly defined by first core <NUM>. The positioning (<NUM>) may be performed by an operator, for example, manually, or semi-automatically or automatically, by an industrial robot. For example, the operator or industrial robot may inspect and orient first core <NUM> and the mold insert, and place the mold insert on first core <NUM> (<NUM>).

The example technique may include disposing retaining cap <NUM> about curved end portion <NUM> defined by second core <NUM> of mold assembly <NUM> (<NUM>). For example, an operator may substantially align retaining cap <NUM> about a center of second core <NUM>, and secure retaining cap <NUM> about second core by threaded or interference fit. In some examples, the example technique includes disposing retaining sleeve <NUM> about one or both of first or second cores <NUM> or <NUM> (<NUM>). For example, an operator may orient retaining sleeve <NUM> about first or second core <NUM> or <NUM>, and secure retaining sleeve <NUM> in contact with and about first or second core <NUM> or <NUM> by threaded or interference fit. The operator may dispose retaining cap <NUM> such that it is secured to one or both of second core <NUM> or retaining sleeve <NUM>, or to first core <NUM>, for example, via retaining sleeve <NUM>, or by direct contact with first core <NUM>. The example technique may include orienting one or both of first core <NUM> or second core <NUM> such that first core pin <NUM> defined by first core <NUM> abuts pin portion <NUM> defined by second core <NUM>, and such that one or both of first core pin <NUM> and first core sleeve <NUM> surrounding at least a portion of first core pin <NUM> define the insert seat, as described with reference to <FIG>.

The example technique may include securing second core <NUM> at a predetermined orientation relative to first core <NUM> within predetermined tolerances such that pin portion <NUM> defined by second core <NUM> contacts at least a first insert surface defined by the mold insert and such that first core <NUM> and second core <NUM> define mold volume <NUM> adjacent the mold insert (<NUM>). For example, the operator may use one or both of retaining cap <NUM> or retaining sleeve <NUM> to secure first core <NUM> to second core <NUM>.

In some examples, the example technique further includes securing first core sleeve <NUM> to first core pin <NUM> by an interference fit or a threaded fit between an outer first core pin surface defined by first core pin <NUM> and an inner core sleeve surface defined by first core sleeve <NUM>. In some examples, securing second core <NUM> at the predetermined orientation within predetermined tolerances relative to first core <NUM> includes disposing first inner sleeve surface <NUM> defined by retaining sleeve <NUM> about at least insert seat <NUM> of first core <NUM>, disposing second inner sleeve surface <NUM> defined by retaining sleeve <NUM> about at least pin portion <NUM> of second core <NUM>, and securing retaining surface <NUM> defined by retaining cap <NUM> about outer sleeve surface <NUM> of retaining sleeve <NUM> such that curved cap surface <NUM> defined by retaining cap <NUM> contacts curved end portion <NUM> defined by second core <NUM>. Securing retaining surface <NUM> defined by retaining cap <NUM> about outer sleeve surface <NUM> defined by retaining sleeve <NUM> may include providing an interference fit or threading retaining surface <NUM> over outer sleeve surface <NUM>. In some examples, the example technique further includes securing annular lip <NUM> defined by first core sleeve <NUM> or by first core <NUM> to annular landing <NUM> defined by retaining sleeve <NUM>. In some examples, the operator may use one or more vises, clamps, grips, platforms, or other securement devices to secure one or both of first core <NUM> or second core <NUM>.

The example technique may include depositing mold material within mold volume <NUM> adjacent the mold insert (<NUM>). For example, the operator may allow mold material to flow through runner <NUM> and fan gate <NUM> across opening or openings <NUM> into mold volume <NUM>. In some examples, the example technique may include injection molding, and the operator may cause the mold material to be injected into mold volume <NUM> via runner <NUM> and fan gate <NUM>, for example, at predetermined temperatures or pressures. The mold material may include a settable or curable mold composition that may cure or set under predetermined conditions (<NUM>) when occupying mold volume <NUM> to form seal <NUM> defined by mold volume <NUM> as described elsewhere in the disclosure. In some examples, the example technique may include one or both of maintaining a temperature or a pressure within mold volume <NUM> within a respective predetermined temperature range or a respective predetermined pressure range. For example, a first predetermined temperature or first predetermined pressure may maintain mold material occupying mold volume <NUM> in a fluid state until mold volume <NUM> is completely occupied, while a second predetermined temperature or second predetermined pressure may initiate setting, solidification, or curing of the mold material to eventually form seal <NUM> defined by mold volume <NUM>.

After the setting, the example technique may include separating first core <NUM> and second core <NUM>, or other components of mold assembly <NUM>, and removing the mold insert including molded seal <NUM> from mold assembly <NUM> (<NUM>). For example, seal <NUM> may be molded on IHC segment portion 13a using example mold assemblies and techniques according to the disclosure to prepare IHC segment <NUM>. IHC segments <NUM> may further be assembled to form IHC assembly <NUM> as described elsewhere in the disclosure.

Thus, example mold assemblies and techniques according to the disclosure may be used to mold seals on, about, or adjacent to medical device components, while mitigating, reducing, or avoiding problems associated with molding or overmolding such as flash formation and stress-induced cracking or breakage.

Claim 1:
A mold assembly for manufacturing internal hermetic lead connectors for implantable medical devices, comprising:
a first mold (<NUM>) defining an insert seat (<NUM>) configured to receive a mold insert;
a second mold (<NUM>) defining a pin portion (<NUM>) configured to contact at least a first insert surface defined by the mold insert, wherein the second mold (<NUM>) defines a curved end portion opposing the pin portion (<NUM>), and wherein the first mold (<NUM>) and the second mold (<NUM>) are configured to define a mold volume (<NUM>) adjacent the mold insert; and
a retaining cap (<NUM>) disposed about the curved end portion defined by the second mold (<NUM>), wherein the retaining cap (<NUM>) defines a curved cap surface in contact with the curved end portion, and wherein the retaining cap (<NUM>) is configured to secure the second mold (<NUM>) at a predetermined orientation relative to the first mold (<NUM>) within predetermined tolerances.