U.S. patent application number 15/347471 was filed with the patent office on 2017-03-02 for filtered feedthrough assembly for implantable medical electronic devices.
The applicant listed for this patent is Cardiac Pacemakers, Inc.. Invention is credited to Patrick J. Barry, James E. Blood, Troy Anthony Giese, Michael J. Lyden, Robert M. Mohn, Randy White.
Application Number | 20170064816 15/347471 |
Document ID | / |
Family ID | 52597317 |
Filed Date | 2017-03-02 |
United States Patent
Application |
20170064816 |
Kind Code |
A1 |
Barry; Patrick J. ; et
al. |
March 2, 2017 |
FILTERED FEEDTHROUGH ASSEMBLY FOR IMPLANTABLE MEDICAL ELECTRONIC
DEVICES
Abstract
A filtered feedthrough assembly for an implantable medical
device comprises a ferrule, an electrical insulator coupled to the
ferrule by a connection element, a plurality of feedthrough
conductors extending through the electrical insulator, a printed
circuit board (PCB), and plurality of capacitors. The PCB is
coupled to the ferrule or the electrical insulator, and includes
one or more ground layers and a plurality of vias. The connection
element is electrically coupled to the ground layer through the
vias. The capacitor has a ground terminal electrically coupled to
the ground layer through at least one of the vias, and a conductor
terminal electrically coupled to the feedthrough conductor.
Inventors: |
Barry; Patrick J.; (North
St. Paul, MN) ; White; Randy; (Blaine, MN) ;
Giese; Troy Anthony; (Blaine, MN) ; Blood; James
E.; (Shoreview, MN) ; Lyden; Michael J.;
(Shoreview, MN) ; Mohn; Robert M.; (Maple Grove,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cardiac Pacemakers, Inc. |
St. Paul |
MN |
US |
|
|
Family ID: |
52597317 |
Appl. No.: |
15/347471 |
Filed: |
November 9, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14628119 |
Feb 20, 2015 |
9521744 |
|
|
15347471 |
|
|
|
|
61943130 |
Feb 21, 2014 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 3/4038 20130101;
H05K 5/0247 20130101; H05K 1/0231 20130101; H05K 5/04 20130101;
Y10T 29/49139 20150115; H05K 3/10 20130101; A61N 1/086 20170801;
H05K 3/32 20130101; A61N 1/3754 20130101; H05K 1/115 20130101; H05K
1/181 20130101; H05K 2201/10015 20130101 |
International
Class: |
H05K 1/02 20060101
H05K001/02; H05K 1/18 20060101 H05K001/18; H05K 3/40 20060101
H05K003/40; A61N 1/08 20060101 A61N001/08; H05K 5/04 20060101
H05K005/04; H05K 5/02 20060101 H05K005/02; A61N 1/375 20060101
A61N001/375; H05K 1/11 20060101 H05K001/11; H05K 3/32 20060101
H05K003/32 |
Claims
1. A filtered feedthrough assembly for an implantable medical
device, comprising: a ferrule configured to be connected to a metal
case of the implantable medical device; a feedthrough conductor
extending from outside the metal case to inside the metal case; a
printed circuit board (PCB) coupled to the ferrule, wherein the PCB
includes a plurality of ground layers and a plurality of vias in
electrical contact with the plurality of ground layers; a
connection element electrically coupled to the ferrule and the
ground layer of the PCB through the vias; and a filter circuit
electrically coupled to the feedthrough conductor and electrically
coupled to the ground layer of the PCB through at least one of the
vias.
2. The filtered feedthrough assembly of claim 1, further comprising
a conductive epoxy disposed within at least one of the vias to
electrically couple the connection element to the ground layer.
3. The filtered feedthrough assembly of claim 1, wherein the PCB
includes a plurality of ground layers and wherein the vias traverse
the plurality of ground layers.
4. The filtered feedthrough assembly of claim 3, further comprising
a plurality of feedthrough conductors extending through the
electrical insulator, and a plurality of capacitors each associated
with one of the plurality of feedthrough conductors.
5. The filtered feedthrough assembly of claim 4, wherein each
capacitor of the plurality of capacitors includes a ground terminal
electrically coupled to the plurality of ground layers by at least
one of the vias, and a conductor terminal electrically coupled to a
respective one of the feedthrough conductors.
6. The filtered feedthrough assembly of claim 3, further comprising
at least one ground pin electrically coupled to the ground
layers.
7. The filtered feedthrough assembly of claim 6, wherein the number
of ground pins equals the number of ground layers of the PCB.
8. The filtered feedthrough assembly of claim 1, wherein the
connection element is a gold braze material.
9. The filtered feedthrough assembly of claim 1, wherein a
conductive epoxy is disposed within at least one of the plurality
of vias to contact the connection element so as to provide a
continuous electrical path between the connection element and the
ground layer.
10. The filtered feedthrough assembly of claim 1, including an
electrical insulator arranged around the feedthrough conductor, and
wherein the connection element is a gold braze material disposed so
as to attach the electrical insulator to the ferrule.
11. An implantable medical device comprising: a metallic housing; a
ferrule connected to the metallic housing; a feedthrough conductor
extending from outside the metallic housing case to inside the
metallic housing; a printed circuit board (PCB) coupled to the
ferrule, wherein the PCB includes a plurality of ground layers, and
a plurality of vias traversing the ground layers; a connection
element electrically coupled to the ferrule and the ground layer of
the PCB through the vias; and a filter circuit electrically coupled
to the feedthrough conductor and electrically coupled to the ground
layer of the PCB through at least one of the vias.
12. The implantable medical device of claim 11, wherein a
conductive epoxy is disposed within the plurality of vias so as to
electrically couple the electrically conductive connection element
to the plurality of ground layers.
13. The implantable medical device of claim 11, wherein the
electrically conductive connection element is a gold braze
material, and wherein the conductive epoxy is disposed within at
least one of the plurality of vias to contact the gold braze
material so as to provide a plurality of electrical paths
electrically coupling the gold braze material to the plurality of
ground layers.
14. The implantable medical device of claim 11, further comprising
at least one ground pin electrically coupled to the plurality of
ground layers.
15. The implantable medical device of claim 14, wherein the at
least one ground pin is coupled to the plurality of ground layers
by a conductive epoxy injected into at least one of the plurality
of vias.
16. The implantable medical device of claim 11, wherein the
plurality of ground layers comprises one of four ground layers,
three ground layers, and two ground layers.
17. The implantable medical device of claim 11, including an
insulator arranged around the feedthrough conductor.
18. The method of making a filtered feedthrough assembly for an
implantable medical device, the method comprising: providing a PCB
having a plurality of ground layers and a plurality of vias
extending through the ground layers; disposing a plurality of
filter circuits on the PCB, wherein a filter circuit is
electrically coupled to the plurality of ground layers through at
least one of the vias; arranging a plurality of feedthrough
conductors to each pass through a plurality of ferrules, wherein
each ferrule includes an electrically conductive connection
element; electrically coupling each of the feedthrough conductors
to a filter circuit; and electrically coupling the connection
element of each of the ferrules to the plurality of ground layers
through the vias.
19. The method of claim 18, including coupling an electrical
insulator to each of the ferrules using the connection element of
each of the ferrules.
20. The method of claim 18, including disposing a conductive
material in the plurality of vias so as to contact the connection
element of each of the ferrules and provide a plurality of parallel
electrical paths from the connection element of each of the
ferrules to the plurality of ground layers.
Description
CLAIM OF PRIORITY
[0001] This application is a continuation of U.S. application Ser.
No. 14/628,119, tiled Feb. 20, 2015, which claims priority to
Provisional Application No. 61/943,130, filed Feb. 21, 2014, each
of which is herein incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to hermetic seal feedthroughs
and electromagnetic interference filters integrated into one or
more feedthrough assemblies. The present disclosure particularly
relates to hermetic seal feedthroughs containing a printed circuit
board (PCB) with multiple ground layers and multiple ground
pins.
BACKGROUND
[0003] Medical devices may be surgically implanted within a patient
and may include devices such as cardiac pacemakers, defibrillators,
neurostimulators, and cardiac monitors. These implantable medical
devices typically include a hermetically-sealed metal case
including circuitry for generating electrical signals that are
delivered to the patient's heart through one or more conductors
that pass from the interior of the can to the exterior of the can
through a feedthrough assembly that includes the hermetic seal.
This hermetic seal serves to isolate the circuitry within the metal
case from tissue, blood, and other patient fluid.
[0004] In addition to the electrical signals generated by the
circuitry of the implantable medical device, externally generated
electromagnetic signals can also pass through the hermetic seal via
the feedthrough assembly and interfere with proper operation of the
implantable medical device. Thus, electromagnetic interference
filters are often integrated into implantable medical devices to
filter these externally generated electromagnetic signals to
maintain the intended voltage levels along the conductors. The
electromagnetic filters typically include complex multilayer
laminated capacitors that are configured to filter external signals
of hundreds of volts and are therefore often quite expensive, which
may increase the cost of the implantable medical device as a whole.
Thus, there is a need for improved filtered feedthrough assemblies
for implantable medical devices.
SUMMARY
[0005] In Example 1, a filtered feedthrough assembly for an
implantable medical device, the filtered feedthrough assembly
comprising a ferrule, an electrical insulator, a feedthrough
conductor, a printed circuit board (PCB) and a capacitor. The
ferrule is configured for attaching the feedthrough assembly to the
implantable medical device. The electrical insulator is coupled to
the ferrule by a connection element. The feedthrough conductor
extends through the electrical insulator. The PCB is coupled to the
ferrule or the electrical insulator, the PCB including aground
layer and a plurality of vias, the connection element being
electrically coupled to the ground layer through the vias. The
capacitor has a ground terminal electrically coupled to the ground
layer through at least one of the vias, and a conductor terminal
electrically coupled to the feedthrough conductor.
[0006] In Example 2, the filtered feedthrough assembly of Example
1, further comprising a conductive epoxy disposed within at least
one of the vias to electrically couple the connection element to
the ground layer.
[0007] In Example 3, the filtered feedthrough assembly of either of
Examples 1 or 2, wherein the PCB includes a plurality of ground
layers and wherein the vias traverse the plurality of ground
layers.
[0008] In Example 4, the filtered feedthrough assembly of any of
Examples 1-3, further comprising a plurality of feedthrough
conductors extending through the electrical insulator, and a
plurality of capacitors each associated with one of the plurality
of feedthrough conductors.
[0009] In Example 5, the filtered feedthrough assembly of any of
Examples 1-4, wherein each capacitor includes a ground terminal
electrically coupled to the plurality of ground layers by at least
one of the vias, and a conductor terminal electrically coupled to a
respective one of the feedthrough conductors.
[0010] In Example 6, the filtered feedthrough assembly of any of
Examples 1-5, further comprising at least one ground pin
electrically coupled to the ground layers.
[0011] In Example 7, the filtered feedthrough assembly of any of
Examples 1-6, wherein the number of ground pins equals the number
of ground layers of the PCB.
[0012] In Example 8, the filtered feedthrough assembly of any of
Examples 1-7, wherein the connection element is a gold braze
material disposed so as to attach the electrical insulator to the
ferrule.
[0013] In Example 9, the filtered feedthrough assembly of any of
Examples 2-8, wherein the conductive epoxy is disposed within the
at least one of the plurality of vias adjacent to the connection
element material on as to provide a continuous electrical path
between the connection element and the plurality of ground
layers.
[0014] In Example 10, the filtered feedthrough assembly of Example
9, wherein the conductive epoxy is disposed within multiple vias
adjacent to the connection element so as to provide a plurality of
continuous electrical paths between the connection element and the
plurality of ground layers.
[0015] In Example 11, the filtered feedthrough assembly of any of
Examples 2-9, wherein the conductive epoxy is a silver conductive
epoxy.
[0016] In Example 12, an implantable medical device comprising an
implantable pulse generator including a metal case defining a
hermetically-sealed inner region and an outer region, and the
filtered feedthrough assembly of any of Examples 1-11. The ferrule
is hermetically attached to the metal case of the implantable pulse
generator such that the feedthrough conductors extend from the
outer region to the inner region.
[0017] In Example 13, the implantable medical device of Example 12,
further comprising an implantable lead coupled to the pulse
generator and including a plurality of electrodes, each electrode
electrically coupled to at least one of the feedthrough
conductors.
[0018] In Example 14, a method of making a filtered feedthrough
assembly for an implantable medical device, the method comprising
providing a PCB having a ground layer, a plurality of vias, and at
least one capacitor having a ground terminal electrically coupled
to the ground layer through at least one of the vias, and a
conductor terminal, and coupling an electrical insulator to a
ferrule using a connection element. The method further comprises
disposing a feedthrough conductor through the electrical insulator,
and coupling the PCB to one or more of the ferrule, the electrical
insulator and the feedthrough conductor. The method further
comprises electrically coupling the feedthrough conductor and the
conductor terminal of the capacitor, and electrically coupling the
connection element to the ground layer through the vias.
[0019] In Example 15, the method of Example 14, wherein
electrically coupling the connection element to the ground layer(s)
includes injecting conductive epoxy into the vias to form a
plurality of conductive paths between the connection element and
the ground layer(s).
[0020] In Example 16, the method of either of Examples 14 or 15,
wherein forming the PCB includes forming a PCB having a plurality
of ground layers, and wherein the plurality of vias traverse the
plurality of ground layers.
[0021] In Example 17, a filtered feedthrough assembly for an
implantable medical device, comprising a metallic ferrule, an
electrical insulator, a plurality of feedthrough conductors, a
printed circuit board (PCB), and a plurality of capacitors. The
metallic ferrule is configured to be hermetically attached to a
metal case of the implantable medical device, and the electrical
insulator is coupled to the metallic ferrule by an electrically
conductive connection element. The plurality of feedthrough
conductors extend through the insulator from a first side to a
second side thereof. The PCB is disposed adjacent to the second
side of the insulator, the PCB including a plurality of ground
layers, and a plurality of vias traversing the ground layers, the
vias configured to provide a plurality of electrically conductive
paths through the ground layers. The plurality of capacitors each
have a ground terminal and a conductor terminal, wherein the ground
terminal is electrically coupled to the plurality of ground layers
through at least one of the plurality of vias, and the conductor
terminal is electrically coupled to at least one of the plurality
of feedthrough conductors.
[0022] In Example 18, the filtered feedthrough assembly of Example
17, wherein the electrically conductive connection element is
electrically coupled to the plurality of ground layers through the
plurality of vias.
[0023] In Example 19, the filtered feedthrough assembly of either
of Examples 17 or 18, wherein a conductive epoxy is disposed within
the plurality of vias so as to electrically couple the electrically
conductive connection element to the plurality of ground
layers.
[0024] In Example 20, the filtered feedthrough assembly of any of
Examples 17-19, wherein the electrically conductive connection
element is a gold braze material disposed so as to attach the
electrical insulator to the metallic ferrule, and wherein the
conductive epoxy is disposed within at least one of the plurality
of vias adjacent to the gold braze material so as to provide a
plurality of electrical paths electrically coupling the gold braze
material to the plurality of ground layers.
[0025] In Example 21, the filtered feedthrough assembly of any of
Examples 17-20, further comprising at least one ground pin
electrically coupled to the plurality of ground layers.
[0026] In Example 22, the filtered feedthrough assembly of Example
21, wherein the at least one ground pin is coupled to the plurality
of ground layers by a conductive epoxy injected into at least one
of the plurality of vias,
[0027] In Example 23, the filtered feedthrough assembly of any of
Examples 17-22, wherein the plurality of ground layers comprises
one of four ground layers, three ground layers, and two ground
layers.
[0028] In Example 24, an implantable medical device comprising a
metal case defining a hermetically-sealed inner region and an outer
region, pulse generator circuitry disposed within the inner region,
and a filtered feedthrough assembly. The filtered feedthrough
assembly includes a metallic ferrule, an electrical insulator, a
plurality of feedthrough conductors, a printed circuit board (PCB),
and a plurality of capacitors. The ferrule is hermetically attached
to the metal case of the implantable medical device. The electrical
insulator is coupled to the metallic ferrule by an electrically
conductive connection element. The plurality of feedthrough
conductors extend through the insulator from the outer region to
the inner region, at least some of the feedthrough conductors being
operatively coupled to the pulse generator circuitry within the
inner region and further being configured to be operatively coupled
and to an electrode on an implantable lead. The PCB is disposed
adjacent to the electrical insulator within the inner region, the
PCB including a plurality of ground layers, and a plurality of vias
traversing the ground layers, the vias configured to provide a
plurality of electrically conductive paths through the ground
layers. The plurality of capacitors each have a ground terminal and
a conductor terminal, wherein the ground terminal is electrically
coupled to the plurality of ground layers through at least one of
the plurality of vias, and the conductor terminal is electrically
coupled to at least one of the plurality of feedthrough
conductors.
[0029] In Example 25, the implantable medical device of Example 24,
wherein the electrically conductive connection element is
electrically coupled to e plurality of ground layers through the
plurality of vias.
[0030] In Example 26, the implantable medical device of either of
Examples 24 or 25, wherein a conductive epoxy is disposed within at
least one of the plurality of vias so as to electrically couple the
electrically conductive connection element to the plurality of
ground layers.
[0031] In Example 27, the implantable medical device of any of
Examples 24-26, wherein the conductive epoxy is disposed within
each of the plurality of vias to contact the electrically
conductive connection element so as to provide a plurality of
electrical paths electrically coupling the electrically conductive
connection element to the plurality of ground layers.
[0032] In Example 28, the implantable medical device of any of
Examples 24-27, wherein the electrically conductive connection
element is a gold braze material disposed no as to attach the
electrical insulator to the metallic ferrule, and wherein the
conductive epoxy is disposed within each of the plurality of vias
to contact the gold braze material so as to provide a plurality of
electrical paths electrically coupling the gold braze material to
the plurality of ground layers.
[0033] In Example 29, the implantable medical device of any of
Examples 24-28, further comprising at least one ground pin
electrically coupled to the plurality of ground layers.
[0034] In Example 30, the implantable medical device of Example 29,
wherein the at least one ground pin is coupled to the plurality of
ground layers by a conductive epoxy injected into at least one of
the plurality of vias.
[0035] In Example 31, the implantable medical device of any of
Examples 24-30, wherein the plurality of ground layers comprises
one of four ground layers, three ground layers, and two ground
layers.
[0036] In Example 32, a method of making a filtered feedthrough
assembly for an implantable medical device, the method comprising
providing a PCB having a plurality of ground layers, a plurality of
vim extending through the ground layer, and a plurality of
capacitors, each of the capacitors having a conductor terminal and
aground terminal electrically coupled to the plurality of ground
layers through at least one of the vias. The method further
comprises coupling an electrical insulator to a ferrule using an
electrically conductive connection element, and disposing a
plurality of feedthrough conductors through the electrical
insulator and attaching the feedthrough conductors to the
electrical insulator. In addition, the method comprises coupling
the PCB to one or more of the ferrule, the electrical insulator and
the feedthrough conductors, electrically coupling each of the
feedthrough conductors to the conductor terminal of a respective
one of the capacitors, and electrically coupling the connection
element to the plurality of ground layers through the vias.
[0037] In Example 33, the method of Example 32, further comprising
electrically coupling a plurality of ground pins to the ferrule of
the feedthrough assembly.
[0038] In Example 34, the method of either of Examples 32 or 33,
wherein electrically coupling the connection element to the
plurality of ground layers includes disposing a conductive material
in the plurality of vias so as to contact the connection element
and provide a plurality of parallel electrical paths from the
connection element to the plurality of ground layers.
[0039] In Example 35, the method of Example 34, wherein disposing
the conductive material in the plurality of vi as includes
disposing a conductive epoxy in the plurality of vias.
[0040] While multiple embodiments are disclosed, still other
embodiments of the present disclosure will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the disclosure.
Accordingly, the drawings and detailed description are to be
regarded as illustrative in nature and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is an example of an implantable medical device
including a feedthrough assembly according to the present
disclosure;
[0042] FIG. 2A is a top perspective view of an exemplary
feedthrough assembly according to embodiments of the present
disclosure;
[0043] FIG. 2B is a bottom perspective view of an exemplary
feedthrough assembly according to embodiments of the present
disclosure;
[0044] FIG. 3 is a cross-sectional elevation view through the
feedthrough assembly of FIGS. 2A-2B; and
[0045] FIG, 4 is an example method of forming a feedthrough
assembly according to example embodiments of the present
disclosure.
[0046] While the disclosure is amenable to various modifications
and alternative forms, specific embodiments have been shown by way
of example in the drawings and are described in detail below. The
intention, however, is not to limit the disclosure to the
particular embodiments described. On the contrary, the disclosure
is intended to cover all modifications, equivalents, and
alternatives failing within the scope of the disclosure as defined
by the appended claims.
DETAILED DESCRIPTION
[0047] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and specific
embodiments in which the disclosure may be practiced are shown by
way of illustration. It is to be understood that other embodiments
may be used and structural changes may be made without departing
from the scope of the present disclosure.
[0048] The present disclosure presents a feedthrough assembly for
implantable medical devices that includes a multilayer printed
circuit board with multiple ground layers that serve as a
parallel-path ground return mechanism of an electromagnetic filter
system of the feedthrough assembly. In addition, the feedthrough
assembly may include a plurality of ground pin connections, which,
along with the multiple ground layers, decrease inductive effects
of the ground path, improve signal attenuation properties of the
feedback assembly, and bolster the overall band filtering
performance of the electromagnetic filter system.
[0049] FIG. 1 is a generalized schematic diagram of one embodiment
of a system 100. The system shown is a portion of a cardiac rhythm
management system. Various embodiments of system 100 include
external or implantable pulse generators, pacer/defibrillators,
cardioverters, defibrillators, cardiac resynchronization therapy
(CRT) systems, any combination of the foregoing, or any other
system using or maintaining cardiac rhythms. Further system
embodiments include any implantable medical device that requires a
hermetic seal, such as neuro-stimulators, insulin pumps,
implantable sensors, and the like.
[0050] In the embodiment of FIG. 1, cardiac rhythm management
system 100 includes an implantable pulse generator 105 coupled to
heart 110 via one or more endocardial or epicardial leads, such as
a lead 115. In the illustrated embodiment, the lead 115 includes
one or more defibrillation electrodes, such as for delivering
defibrillation therapy via first defibrillation electrode 120A
and/or second defibrillation electrode 120B. As shown, the lead 115
may also include additional electrodes, such as for delivering
pacing therapy via a pacing/sensing electrode 125 (which in the
illustrated embodiment is configured as a ring electrode). In
various embodiments, the lead 115 may also include an additional
tip electrode at the distal end thereof, which in conjunction with
the ring electrode 12.5 can provide for bi-polar pacing and sensing
capabilities.
[0051] In the illustrated embodiment, the lead 115 is shown
extending into the right ventricle of the heart 110. In other
embodiments, additional leads can be coupled to the implantable
pulse gene or 105 for implantation within, for example, the right
atrium and/or the coronary venous system (i.e., for pacing/sensing
of the left ventricle in a bi-ventricular pacing scheme such as a
CRT system).
[0052] Because the pulse generator 105 is implantable, it includes
a hermetic seal for isolating the electronic components within the
pulse generator from the external environment. Electrical signals
sensed on the lead or leads need to pass through the hermetic seal
to communicate with the electronics of the pulse generator 105 that
are internal to the metal case 130. Electrical signals originating
from the internal electronics for delivery to the heart 110 by the
lead 115 also need to pass through the hermetic seal. The system
100 shown is a generalized system. Typically several electrical
signals pass through the hermetic seal.
[0053] FIGS. 2A and 2B are top and bottom perspective views,
respectively, of an embodiment of a feedthrough assembly 200 for
use in the implantable pulse generator 105 of FIG. 1, As shown, the
feedthrough assembly 200 includes a plurality of feedthrough
conductors 215 and a ferrule 220, which in the illustrated
embodiment has a first end 222 and a second end 224 and a middle
portion 226 between the first end 222 and the second end 224. In
some embodiments, the ferrule 220 may be formed of titanium or any
other metallic material. Furthermore, the ferrule 220 is configured
to be coupled to the metal case 130 (see FIG. 1) of an implantable
medical device by placing the ferrule 220 in an opening in the
metal case 130 and welding the ferrule 220 to the metal case 130 at
an outer perimeter of the ferrule 220.
[0054] As further shown, the feedthrough assembly 200 includes an
electrical insulator 230, which may be mounted within or coupled to
the ferrule 220, for example, using gold brazing techniques. The
electrical insulator 230 may include a plurality of holes 231
through which the feedthrough conductors 215 may pass. The
feedthrough conductors 215 may be mounted within and extend through
the plurality of holes 231 and may extend through the respective
feedthrough holes 231 so as to extend from an outer portion 242 to
an inner portion 240 of the feedthrough assembly 200. The
feedthrough conductors 215 may be hermetically connected to the
electrical insulator 230 at the holes 231, for example, using a
gold-brazed joint, soldered joint, welded joint, or other coupling
method providing a hermetic connection between the feedthrough
conductors 215 and the electrical insulator 230. In the various
embodiments, the feedthrough conductors 215 operate to electrically
couple the lead electrodes (see FIG. 1) to pulse generator
circuitry within the inner region defined by the metal case 130 of
the pulse generator 105. In various examples, the feedthrough
conductors 215 are pins, wires (e.g., gold-plated wires, palladium
alloy wires, and platinum alloy wires), or a combination
thereof.
[0055] As further shown, the feedthrough assembly 200 may include a
ground wire 204, which may be electrically coupled to a ground pin
244 attached to the ferrule 220. In an aspect, the ground pin 244
may be attached and electrically coupled to the ferrule 220 by
welding or brazing. In some examples, the ground wire 204 and/or
ground pin 244 may comprise a circuit trace, weld, brazing joint,
via, electrically conductive epoxy, or any other conductive
material configured to provide an electrical ground to the
feedthrough assembly 200. Furthermore, though a single ground wire
204 and ground pin 244 are shown, a plurality of ground pins 244
and/or ground wires 204 may be provided in feedthrough assembly 200
to provide parallel ground paths for electromagnetic signals to be
filtered. In various embodiments, the ground wire 204 and/or ground
pin 244 are omitted.
[0056] As further shown in FIG. 2B, the feedthrough assembly 200
includes a plurality of capacitors 252 and a printed circuit board
(PCB) 254 having a plurality of holes 256 extending therethrough.
As shown, the feedthrough conductors 215 are positioned through the
holes 256 of the PCB 254. The PCB 254 provides the electrical
coupling between the capacitors 252 and the feedthrough conductors
215 via electrical traces (not illustrated) on the PCB that are
electrically coupled to a conductor terminal (not illustrated) on
each capacitor 252. As will be appreciated, the use of electrical
traces to connect components on a PCB will be readily understood by
the skilled artisan, and need not be discussed in greater detail
herein.
[0057] In the various embodiments, except as specifically described
herein, the PCB 254 can have a conventional PCB configuration,
including a non-conductive substrate and conductive traces and/or
pads formed thereon, including a ground layer 255 that can be
electrically coupled to the metal case 130 of the implantable pulse
generator 105 of FIG. 1 (through, for example, the ground wire 204
and ground pin 244, if present, or by directly attaching the ground
layer 255 to the metal ferrule 220 using a conductive attachment
means such as metal brazing and also attaching the ferrule 220 to
the metal case 130 using a similar conductive attachment means,
such as metal brazing or a weld) so as to serve as an electrical
ground for the feedthrough assembly 200.
[0058] Additionally, PCB 254 includes a plurality of vias 258
extending through the PCB 254 and, consequently, the ground layer
255. In various embodiments, the surfaces of the vias 258 are
plated with a conductive metal (e.g., copper, aluminum, and the
like) to provide conductive paths to the ground layer 255 of the
PCB 254. Additionally, the vias 258 are operable to provide an
electrical ground path for the capacitors 252 by an electrical
trace (not shown) electrically coupling the conductive plating of a
respective via 258 to a ground terminal (not shown) on each
capacitor 252.
[0059] As explained in additional detail elsewhere herein, a
plurality of the vias 258 may be filled with conductive material
(e.g. conductive epoxy, silver conductive epoxy, aluminum, copper,
etc.) to further enable effective EMI filtering by providing
multiple ground paths for elements of the feedthrough assembly 200.
In particular, the vias 258 can provide multiple electrical paths
to ground to the conductive connection element (e.g., gold braze
material) used to attach the electrical insulator 230 to the
ferrule 220.
[0060] In one embodiment, the capacitors 252 have a breakdown
voltage that is configured to withstand defibrillation or
electrocautery voltages that may be introduced to the feedthrough
assembly 200 from the exterior through feedthrough holes 231. In
some examples, the capacitors 252 have a breakdown voltage in the
range of 400 volts to 2000 volts or may have a breakdown voltage of
about 1500 volts. Furthermore, capacitors 252 may be ceramic
capacitors and may be configured to be surface-mounted to PCB 254
and/or wire-mounted or soldered thereto. Additionally, capacitors
252 may have a capacitance value configured to filter signals
having a particular frequency and/or voltage value, For example, in
some embodiments, capacitors 252 may have capacitance values
configured to tune the capacitors to filter signals having
frequencies in a band utilized in magnetic resonance imaging
processes.
[0061] FIG. 3 is a cross-sectional elevation view of the
feedthrough assembly 200 according to one embodiment. As can be
seen in FIG. 3, the electrical insulator 230 is attached to an
inner surface of the ferrule 220 by an attachment or connection
element 300. In various embodiments, the connection element 300 is
made of an electrically conductive material. various embodiments,
the connection element 300 may be formed by a brazing operation
using a conductive metal such as gold, silver and the like, which
forms a hermetic bond between the electrical insulator 230 and the
inner surface of the ferrule 220. Similarly, the feedthrough
conductor 215 may also be attached to an inner surface of the
electrical insulator 230 and to the PCB 254 (and consequently, the
one or more ground layers 255 thereof) by the same or a similar
conductive attachment technique.
[0062] FIG. 3 further illustrates one of the vias 258 disposed
adjacent o an inner side of the ferrule 220 and the electrical
insulator 230 (i.e., the side corresponding to the
hermetically-sealed inner region of the implantable pulse generator
105 enclosed by the metal case 130, see FIG. 1). As further shown,
a conductive material 305 is disposed within the via 258 so as to
contact the connection element 300 to provide an electrical path
through the PCB 254. Furthermore, because the via 258 extends
through the ground layer 255 of the PCB 254, the conductive
material 305 also provides an electrically conductive path to
electrically couple the connection element 300 to the ground layer
255. In various embodiments, a plurality of the vias 258 are also
disposed in the same manner as the via 258 illustrated in FIG. 3
(i.e., adjacent to the inner surface of the electrical insulator
230), and are also filled with the conductive material 305 in the
same or a similar manner so as to form multiple conductive paths
between the connection element 300 and the ground layer 255.
[0063] In various embodiments, the conductive material 305 may be
any conductive material capable of being disposed into the one or
more vias 258, In one embodiment, the conductive material 305 is a
conductive epoxy, e.g., a silver conductive epoxy, a conductive
polymer, or a metallic material such as copper.
[0064] In various embodiments, the PCB 254 may be a multi-layer PCB
including a plurality of ground layers separated by suitable
insulating layers (not shown). In such embodiments, the vias 258
can extend through the entire thickness of the multi-layer PCB,
thus providing an electrical connection to the multiple ground
layers. In various embodiments, the multi-layer PCB 254 can have
three ground layers and four insulating layers, though any number
of ground layers 302 or insulating layers 304 are contemplated by
the present disclosure. Additionally, in some embodiments utilizing
one or more ground pins 244 (see FIGS. 2A-2B), the PCB 254 may
include the same number of ground pins as the number of ground
layers in the PCB 254.
[0065] In some embodiments, multilayer PCB 254 may comprise a
multilayer FR4 PCB. Insulating layers may comprise any electrical
insulating material or dielectric, such as, but not limited to FR4,
glass epoxy, silicates, or the like. Additionally, the ground
layers of multilayer PCB 254 may comprise layers of conductive
material, which may include any conductive material, such as, but
not limited to copper, aluminum, or any other conductive metal or
semiconductor. In some embodiments, one or more layers of copper or
aluminum foil may be laminated to one or both sides of an
insulating material (e.g., FR4 material) to form alternating ground
and insulating layers.
[0066] FIG. 4 is a flow diagram of an example method 400 of
providing a feedthrough assembly for filtering electromagnetic
interference in an implantable medical device. Method 400 is
provided as a set of steps represented by blocks. Though the
various steps are presented in a particular order in example method
400 as illustrated in FIG. 4, it is to be understood that one or
more of these steps may be performed in a different order than
illustrated and/or may be excluded from the example method without
departing from the methods contemplated herein.
[0067] For example, at block 402, method 400 may include providing
a PCB having one or more ground layers, a plurality of vias
extending through the ground layers, and one or more capacitors. In
one embodiment, providing the PCB can include forming a plurality
of ground layers and at least one insulating layer in a multilayer
PCB. In some examples, this may include forming the ground layers
and insulating layers by deposition, etching, photolithography, FR4
circuit layer bonding, or any other method of forming layers of
conductors and insulators in a multilayer PCB.
[0068] Furthermore, at block 406, the method 400 may include
coupling an electrical insulator to a feedthrough ferrule using a
conductive connection element. In one embodiment, the electrical
insulator may be soldered or brazed to the ferrule using a
conductive metal such as gold or silver as the soldering or brazing
metal.
[0069] In an additional aspect, method 400 may include, at block
410, coupling the PCB to the ferrule, the electrical insulator,
and/or one or more feedthrough conductors disposed through the
electrical insulator. In one embodiment, the feedthrough conductors
are also attached to the electrical insulator and/or the PCB using
an electrically conductive material such as a metal braze material
(e.g., gold). In addition, the method 400 further includes, at
block 414, electrically coupling each feedthrough conductor to a
conductor terminal on a respective one of the capacitors. In
various embodiments, aground terminal on each capacitor is
electrically connected, e.g., via solder to a trace on the PCB, to
one of the vias (which is plated with a conductive material) so as
to electrically couple the respective ground terminal to the ground
layers of the PCB.
[0070] At block 418, the method 400 further includes electrically
coupling the connection element to the ground laver(s) of the PCB
through the vias. In one embodiment, a conductive material is
disposed in the plurality of vias, and this conductive material
contacts the connection element to provide a plurality of
electrical paths from the connection element to the ground layers.
In various embodiments, the conductive material may be a conductive
epoxy, conductive polymer, metal, and the like.
[0071] In addition, in some examples, method 400 may include
electrically coupling the plurality of ground layers to one or more
ground pins, which can be electrically coupled to the ferrule of
the feedthrough assembly. Furthermore, the method 400 may include
securing the feedthrough assembly to a metal can of the implantable
medical device.
[0072] Various modifications and additions can be made to the
exemplary embodiments discussed without departing from the scope of
the present disclosure. For example, while the embodiments
described herein refer to particular features, the scope of this
disclosure also includes embodiments having different combinations
of features and embodiments that do not include all of the
described features. Accordingly, the scope of the present
disclosure is intended to embrace all such alternatives,
modifications, and variations as fall within the scope of the
claims, together with all equivalents thereof.
* * * * *