Systems and methods for thermal management in wireless power transfer systems

Abstract

According to the present disclosure, there is provided an implantable battery pack. The implantable battery pack of the present disclosure includes a housing, a plurality of battery cells disposed within the housing, and an electronics layout disposed within the housing, the electronics layout electrically connected to the plurality of battery cells. The electronics layout includes at least one printed circuit board carrying electronics, and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 128,513, filed December 21, 2020, the entire disclosure of which is incorporated herein by reference.

[0002] (Technical field) The present disclosure relates generally to wireless power transfer systems, and more particularly to thermal management in wireless power transfer systems. [Background technology]

[0003] Ventricular assist devices (VADs), also known as ventricular assist devices (VADs), are implantable blood pumps used for both short-term (i.e., days or months) and long-term (i.e., years or lifelong) purposes in patients suffering from a condition in which the heart cannot provide adequate circulation, commonly referred to as heart failure or congestive heart failure. Patients suffering from heart failure can use VADs while awaiting a heart transplant or as long-term destination therapy. In another example, patients can use VADs during recovery after cardiac surgery. In this way, VADs can assist (i.e., partially assist) a failing heart, effectively replacing the function of the natural heart.

[0004] A VAD can be powered using a wireless power transmission system, which typically includes an external transmitting resonator and an implantable receiving resonator configured to be implanted within the patient's body. Such a wireless power transmission system is also known as a transcutaneous energy transmission system (TETS).

[0005] In such wireless power transfer systems, an implantable battery pack is used to facilitate power supply and control of the VAD. The implantable battery pack includes, for example, lithium-ion battery cells that can be charged relatively quickly at a relatively high current. However, the lithium-ion battery cells and the electronics required to charge and discharge them generate a significant amount of heat. Therefore, in implantable battery packs that include lithium-ion battery cells, it is important to effectively manage the heat generated by the implantable battery pack. Summary of the Invention [Means for solving the problem]

[0006] The present disclosure relates to an implantable battery pack comprising: a housing; a plurality of battery cells disposed within the housing; and an electronics layout disposed within the housing and electrically connected to the plurality of battery cells, the electronics layout including at least one printed circuit board carrying electronics; and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack.

[0007] The present disclosure also relates to an electronics layout for use in an implantable battery pack having a housing and a plurality of battery cells, the electronics layout including at least one printed circuit board carrying electronics, and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack.

[0008] The present disclosure also relates to a method of assembling an implantable battery pack, the method including the steps of disposing a plurality of batteries within a housing, and disposing an electronics layout within the housing and electrically connecting the electronics layout to the plurality of batteries, the electronics layout including at least one printed circuit board carrying electronics, and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a simplified electrical diagram of one embodiment of a wireless power transfer system of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating the wireless power transmission system of FIG. 1 used to supply power to a ventricular assist device (VAD). [Figure 3A] FIG. 3A is a top view of one embodiment of an electronics layout for use with the implantable device shown in FIG. [Figure 3B] FIG. 3B is a bottom view of the electronic device layout shown in FIG. 3A. [Figure 4] FIG. 4 is a perspective view showing the electronic device layout shown in FIGS. 3A and 3B in a folded state. [Figure 5] FIG. 5 is a schematic diagram illustrating heat flow through an implantable battery pack including the electronics layout shown in FIGS. 3A, 3B, and 4B. [Figure 6] FIG. 6 is a diagram showing a thermal simulation of the implantable battery pack shown in FIG. [Figure 7] FIG. 7 is a plan view of another electronic device layout 700. [Figure 8] FIG. 8 is an exploded view of an implantable battery pack including the electronics layout shown in FIG. [Figure 9] FIG. 9 is a schematic diagram illustrating heat flow through the implantable battery pack shown in FIG. [Figure 10] FIG. 10 shows a thermal simulation of an implantable battery pack. [Figure 11] FIG. 11 shows a thermal simulation of an implantable battery pack. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure relates to a system and method for managing heat in a wireless power transfer system, including an implantable battery pack including a housing, a plurality of battery cells disposed within the housing, and an electronics layout disposed within the housing, the electronics layout electrically connected to the plurality of battery cells, the electronics layout including at least one printed circuit board carrying electronics, and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack.

[0011] Referring now to the drawings, Figure 1 shows a simplified electrical circuit of an exemplary wireless power transfer system 100. The system 100 includes an external transmitter resonator 102 and an implanted receiver resonator 104. In the system shown in Figure 1, a power source Vs is electrically connected to the transmitter resonator 102, and the power source Vs provides power to the transmitter resonator 102. The receiver resonator 104 is connected to a load 106 (e.g., an implantable medical device). The receiver resonator 104 and the load 106 may be electrically connected to a switching or rectifying device (not shown).

[0012] In this exemplary embodiment, the transmitting resonator 102 includes a coil Lx connected to a power supply Vs by a capacitor Cx. Additionally, the receiving resonator 104 includes a coil Ly connected to a load 106 by a capacitor Cy. The coil Lx (inductor Lx) and the coil Ly (inductor Ly) are connected with a coupling coefficient k. Mxy is the mutual inductance between the two coils. The mutual inductance Mxy is related to the coupling coefficient k as shown in the following equation (1).

[0013]

number

[0014] In operation, the transmitting resonator 102 wirelessly transmits power supplied from the power source Vs. The receiving resonator 104 receives the wirelessly transmitted power from the transmitting resonator 102 and supplies the received power to the load 106.

[0015] FIG. 2 illustrates an embodiment in which an external coil 202 (e.g., the transmit resonator 102 shown in FIG. 1 ) is used to wirelessly transmit power to an implantable coil 204 (e.g., the receive resonator 104 shown in FIG. 1 ) implanted within a patient 200. The implantable coil 204 uses the received power to power an implantable device 206. For example, the implantable device 206 may include a pacemaker or a heart pump (e.g., a left ventricular assist device (LVAD)). In some embodiments, the implantable coil 204 and / or the implantable device 206 may include a battery or may be connected to a battery 207. For example, as shown in FIG. 2 , the battery 207 is connected between the implantable coil 204 and the implantable device 206.

[0016] In one embodiment, the external coil 202 is communicatively coupled to the computing device 210, for example, via a wired or wireless connection, so as to send and receive signals to and from the computing device 210. In some embodiments, the computing device 210 also serves as a power source for the external coil 202. In other embodiments, the external coil 202 is connected to a separate power source (not shown). The computing device 210 comprises a memory device 214 and a processor 212 communicatively coupled to the memory device 214. In some embodiments, computer-executable instructions are stored on the memory device 214.

[0017] The computing device 210 further includes a user interface (UI) 216. The user interface (UI) 216 presents information to a user (e.g., the patient 200). The user interface (UI) 216 may include a display adapter (not shown) connected to a display device such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, and / or an “electronic ink” display. In some embodiments, the user interface (UI) 216 includes one or more display devices. Additionally, in some embodiments, the presentation interface does not generate visual content but generates audible and / or computer-generated sound content. In an exemplary embodiment, the user interface (UI) 216 displays one or more representations or images designed to assist the patient 200 in positioning the external coil 202 to optimize the connection between the external coil 202 and the implanted coil 204. In some embodiments, the computing device 210 may be a wearable device. For example, in one embodiment, the computing device 210 is a wristwatch and the user interface (UI) 216 is displayed on the wristwatch.

[0018] The implantable device 206 may be powered using an implantable battery pack that includes battery cells that are recharged by power transfer between the external coil 202 and the implantable coil 204. Because the implantable battery pack is an implantable device, it is important to manage the thermal energy generated by the implantable battery pack. For example, to ensure proper operation, at least some regulations require that the exterior surface of an implantable device not exceed the temperature of the surrounding tissue (i.e., 37°C).

[0019] Implantable battery packs containing lithium-ion battery cells generate more heat energy (compared to implantable battery packs containing other types of battery cells). Therefore, effective thermal management solutions are needed to facilitate maintaining the exterior surfaces of such implantable battery packs at an acceptable temperature. The more effective the thermal management, the faster the lithium-ion batteries can be charged.

[0020] The systems and methods of the present disclosure facilitate spreading heat generated within an implantable battery pack substantially uniformly over the exterior surface (e.g., titanium housing) of the implantable battery pack, i.e., the systems and methods of the present disclosure facilitate reducing hot spots on the exterior surface of the implantable battery pack.

[0021] As described herein, electronic components (e.g., power conversion devices) that generate more heat within the implantable battery pack are mounted on a printed circuit board (PCB) located approximately in the center of the implantable battery pack. The printed circuit board (PCB) is further connected to one or more thermally conductive wings to facilitate heat diffusion throughout the battery pack. A graphite foil (graphite sheet) may also be placed within the implantable battery pack to facilitate heat diffusion.

[0022] With regard to heat dissipation, a sphere of homogeneous material with a heat source at the center of the sphere will have a uniform heat flux across the sphere's exterior. However, an implantable battery pack obviously has a different shape and a different combination of materials than a sphere. Therefore, as described herein, the disclosed technology facilitates relatively uniform heat dissipation in an implantable battery pack by conducting heat to specific locations on the exterior of the battery pack through a combination of thermally insulating and conductive materials. Furthermore, the disclosed technology places electronic components that contribute to heat generation and heat dissipation in specific locations within the battery pack. For example, in embodiments of the present disclosure, the power conversion circuitry is generally located in the center of the battery pack.

[0023] Figure 3A is a top view of one embodiment of an electronics layout 300 for use with implantable device 206 (shown in Figure 2). Figure 3B is a bottom view of electronics layout 300. Electronics layout 300 is included in an implantable battery pack that facilitates powering implantable device 206. The implantable battery pack may be integrated into implantable device 206 or may be connected to implantable device 206.

[0024] 3A and 3B, electronics layout 300 is shown in a flat or unfolded configuration. As described herein, electronics layout 300 is placed in a folded state (shown in FIG. 4) when placed within an implantable battery pack. Electronics layout 300, as described herein, facilitates even dissipation of heat generated by battery cells within the implantable battery pack.

[0025] 3A, 3B, and 4, electronic device layout 300 includes a first printed circuit board (PCB) 302, a second PCB 304, a third PCB 306, and a fourth PCB 308. In this embodiment, a microcontroller and digital signal processor are mounted on first PCB 302, a power conversion device and battery charging device are mounted on second PCB 304, a filtering device (e.g., electrostatic discharge device) is mounted on third PCB 306, and a boost device (e.g., DC-DC step-up converter device) is mounted on fourth PCB 308. Alternatively, other suitable electronic devices may be mounted on PCBs 302, 304, 306, and 308.

[0026] Additionally, a first flexible thermally conductive connector 310 extends between the first PCB 302 and the second PCB 304, a second flexible thermally conductive connector 312 extends between the second PCB 304 and the third PCB 306, and a third flexible thermally conductive connector 314 extends between the third PCB 306 and the fourth PCB 308. The thermally conductive connectors 310, 312, and 314 may be, for example, flexible PCBs extending between the relatively rigid PCBs 302, 304, 306, and 308.

[0027] To facilitate heat dissipation, the electronics layout 300 includes one or more thermally conductive wings connected (coupled) to the relatively rigid PCBs 302, 304, 306, and 308. In the embodiment shown in Figures 3A, 3B, and 4, a first thermally conductive wing 320 is connected to a first edge 322 of the first PCB 302, and a second thermally conductive wing 324 is connected to a second edge 326 opposite the first edge 322 of the first PCB 302. Similarly, a third thermally conductive wing 330 is connected to a first edge 332 of the second PCB 304, and a fourth thermally conductive wing 334 is connected to a second edge 336 opposite the first edge 332 of the second PCB 304. Furthermore, a fifth thermally conductive wing 340 is connected to a first edge 342 of the third PCB 306, and a sixth thermally conductive wing 344 is connected to a second edge 346 of the third PCB 306 that is opposite the first edge 342. The fifth thermally conductive wing 340 and the sixth thermally conductive wing 344 may enable connection to, for example, a hermetic feedthrough. Additionally, a seventh thermally conductive wing 350 is connected to a first edge 352 of the fourth PCB 308, and an eighth thermally conductive wing 354 is connected to a second edge 356 of the fourth PCB 308 that is opposite the first edge 352. The thermally conductive wings 320, 324, 330, 334, 340, 344, 350, 354 may be made of, for example, copper and may be somewhat flexible. Alternatively, the thermally conductive wings 320, 324, 330, 334, 340, 344, 350, 354 may be made from any suitable material that has a relatively high coefficient of heat transfer.

[0028] In some embodiments, the thermal conduction wings are connected to only some of the PCBs 302, 304, 306, and 308. For example, in one embodiment, the electronic device layout 300 includes only the third thermal conduction wing 330 and the fourth thermal conduction wing 334 (both connected to the second PCB 304).

[0029] It is important to note that heat flux (q) flows along the path of least thermal resistance. Specifically, heat flux is expressed as q = (ΔT*A*λ) / L, where ΔT is the temperature change, A is the cross-sectional area through which heat flows, L is the distance the heat flows, and λ is the heat transfer coefficient.

[0030] When the electronics layout 300 is placed inside an implantable battery pack, it is placed in a folded state, as shown in FIG. 4 . As shown in FIG. 4 , in the folded state, the first PCB 302, the second PCB 304, and the fourth PCB 308 are stacked vertically, with the second PCB 304 being placed between the first PCB 302 and the fourth PCB 308. Generally, the second PCB 304 (which includes the power conversion device and the battery charging device) generates the most heat. Therefore, the second PCB 304 is placed in the center of the folded electronics layout 300 (and the implantable battery pack). The third PCB 306 is placed on a side of the folded electronics layout 300 and is oriented substantially perpendicular (orthogonal) to the first PCB 302, the second PCB 304, and the fourth PCB 308.

[0031] Without the thermal conduction wings, heat would flow toward the center of the top and bottom of the implantable battery pack (i.e., above the center of the first PCB 302 and below the center of the fourth PCB 308) because of the small distance (L) and large cross-sectional area (A), despite the relatively small heat transfer coefficient of air (λ).

[0032] Therefore, to effectively manage heat, thermally conductive materials (e.g., thermally conductive wings) are used to increase the heat flux toward the sides of the electronics layout 300 (and the implantable battery pack). Furthermore, the thermally conductive wings are connected to the electronic components that generate relatively large amounts of heat by thermal vias (not shown). The thermal vias may be filled with copper to further improve heat dissipation.

[0033] 3A, 3B, and 4, the third thermally conductive wing 330 and the fourth thermally conductive wing 334 include solder connections 360 for connecting battery cells (e.g., lithium ion battery cells) to the third thermally conductive wing 330 and the fourth thermally conductive wing 334. The battery cells are positioned between the thermally conductive wings as shown in FIGS. 5 and 6 (described below).

[0034] To dissipate heat, the thermally conductive wings conduct heat to the battery and the housing of the implantable battery pack. Graphite foil (graphite sheet) may be laminated to the inside of the housing to enhance heat dissipation. Graphite foil has anisotropic thermal conductivity, conducting approximately 800 times more heat in its plane than out of its plane.

[0035] Figure 5 is a schematic diagram illustrating heat flow through an implantable battery pack 500 that includes an electronics layout 300. As shown in Figure 5, the implantable battery pack includes an electronics assembly 300 (electronics layout 300) disposed within an outer housing 502. The arrows in Figure 5 represent heat flow through the implantable battery pack 500.

[0036] As described above, in the implantable battery pack 500, the battery cell 504 is disposed between the thermally conductive wings 320, 324, 330, 334, 350, and 354. Furthermore, a plastic fastener 508 is disposed between the battery cell 504 and the outer housing 502. As shown in FIG. 5 , heat generated in the circuit 510 on the second PCB 304 flows from the second PCB 304 through the thermally conductive wings 330 and 334 to the battery cell 504 and the plastic fastener 508 outside the PCB, and then to the outer housing 502. To further improve heat dissipation, the plastic fastener 508 may be made of a material with desirable thermal conductivity. Similarly, heat generated in the first PCB 302 and the fourth PCB 308 flows through the thermally conductive wings 320, 324, 350, and 354 to the outside of the PCB. Such heat flow results in the heat being spread much more evenly over the outer housing 502 rather than being concentrated in only a few spots on the outer housing 502 .

[0037] FIG. 6 shows the heat flow density [W / mm 2 6 shows a thermal simulation 600 of the circuit 510. As shown in the thermal simulation 600, the heat generated by the circuit 510 is distributed relatively evenly throughout the implantable battery pack. Also shown in FIG. 6 is a graphite foil 602 disposed on the inner surface of the outer housing 502. As discussed above, the graphite foil 602 further improves heat dissipation throughout the implantable battery pack 500.

[0038] 7 is a plan view of another electronics layout 700 in an unfolded state. The electronics layout 700 includes a first PCB 702, a second PCB 704, a third PCB 706, and a fourth PCB 708. In this embodiment, a microcontroller and digital signal processor are mounted on the first PCB 702, a power conversion device and battery charging device are mounted on the second PCB 704, and a boost device (e.g., a DC-DC step-up converter device) is mounted on the fourth PCB 708. Alternatively, other suitable electronics may be mounted on the PCBs 702, 704, 706, and 708.

[0039] Additionally, a first thermally conductive connector 710 extends between the first PCB 702 and the second PCB 704, a second thermally conductive connector 712 extends between the second PCB 704 and the fourth PCB 708, and a third thermally conductive connector 714 extends between the first PCB 702 and the third PCB 706. The thermally conductive connectors 710, 712, and 714 may be, for example, flexible PCBs extending between the relatively rigid PCBs 702, 704, 706, and 708.

[0040] To facilitate heat dissipation, in this embodiment, the electronics layout 700 includes two thermally conductive wings 730 connected to the second PCB 704. In contrast to the electronics layout 300 (shown in FIGS. 3A, 3B, and 4), no thermally conductive wings are connected to the PCBs 702, 706, and 708 other than the second PCB 704. The thermally conductive wings 730 may be made of copper, for example, and may also be somewhat flexible. Alternatively, the thermally conductive wings 730 may be made of any suitable material with a relatively high coefficient of heat transfer.

[0041] 8 is an exploded view of another implantable battery pack 800 including the electronics layout 700. Similar to the electronics layout 300, the electronics layout 700 is placed in a folded state when placed within the implantable battery pack 800. As shown in FIG. 8, the implantable battery pack 800 includes the electronics layout 700, battery cells 802 (e.g., lithium-ion battery cells), plastic fasteners 804, and a titanium outer housing 806. The implantable battery pack 800 further includes graphite foils 810 (graphite sheets). Although two graphite foils 810 are shown, additional graphite foils may be included (e.g., placed on the top and bottom of the electronics layout 300).

[0042] Figure 9 is a schematic diagram illustrating the heat flow through the implantable battery pack 800 including the electronics layout 700. The arrows in Figure 9 represent the heat flow through the implantable battery pack 800. As shown in Figure 9, the thermally conductive wings 730 extend only from the second PCB 704, yet heat is still spread substantially evenly from the second PCB 704 through the battery cells 802 to the titanium outer housing 806.

[0043] As described above, the systems and methods of the present disclosure facilitate a much more uniform distribution of heat throughout the implantable battery pack. For example, FIG. 10 illustrates a thermal simulation 1000 of an implantable battery pack 1002 that does not implement the systems and methods of the present disclosure, and FIG. 11 illustrates a thermal simulation 1100 of an implantable battery pack 1102 that implements the systems and methods of the present disclosure. As shown in FIG. 10 , in the thermal simulation 1000 of the implantable battery pack 1002, thermal energy is concentrated at one location on the outer surface of the implantable battery pack 1002. In contrast, as shown in FIG. 11 , in the thermal simulation 1100 of the implantable battery pack 1102, thermal energy is more uniformly distributed across the outer surface of the implantable battery pack 1102. Furthermore, the maximum temperature of the outer surface of the implantable battery pack 1102 in FIG. 11 is 0.5°C lower than the maximum temperature of the outer surface of the implantable battery pack 1002 in FIG. 10.

[0044] The present disclosure relates to a system and method for managing heat in a wireless power transfer system, including an implantable battery pack including a housing, a plurality of battery cells disposed within the housing, and an electronics layout disposed within the housing, the electronics layout electrically connected to the plurality of battery cells, the electronics layout including at least one printed circuit board carrying electronics, and at least one thermally conductive wing connected to and extending from the at least one printed circuit board, the at least one thermally conductive wing configured to dissipate heat generated by the electronics throughout the implantable battery pack.

[0045] While embodiments and examples of the present disclosure have been described with reference to particular embodiments, it is to be understood that these embodiments and examples are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that various modifications can be made to the exemplary embodiments and examples, and other arrangements can be devised, without departing from the spirit and scope of the present disclosure as defined by the appended claims. Accordingly, this application is intended to cover all such modifications and variations of the embodiments, and their equivalents.

[0046] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and practicing any methods incorporated therein. The patentable scope of the invention is defined by the claims, and may include alternative embodiments that occur to those skilled in the art. Such alternative embodiments are intended to be within the scope of the claims if they include elements that do not deviate from the literal language of the claims, or if they include equivalent elements that do not deviate substantially from the literal language of the claims.

Claims

1. An implantable battery pack, comprising: Housing and a plurality of battery cells disposed within the housing; an electronics layout disposed within the housing and electrically connected to the plurality of battery cells; The electronic device layout includes: at least one printed circuit board carrying electronics; at least one thermally conductive wing connected to and extending from the at least one printed circuit board; the at least one thermal conduction wing is configured to dissipate heat generated by the electronic device throughout the implantable battery pack; the at least one printed circuit board includes a first printed circuit board carrying a power conversion device and a battery charging device; The at least one thermal conduction wing comprises: a first thermally conductive wing extending from a first edge of the first printed circuit board; a second thermally conductive wing extending from a second edge of the first printed circuit board opposite the first edge; the first printed circuit board is disposed closer to the center of the implantable battery pack than the first thermal conduction wing in a direction in which the first thermal conduction wing extends from the first printed circuit board, and the second thermal conduction wing is disposed closer to the center of the implantable battery pack than the second thermal conduction wing in a direction in which the second thermal conduction wing extends from the first printed circuit board; Implantable battery pack.

2. 2. The implantable battery pack according to claim 1, The battery pack, wherein the plurality of battery cells includes a plurality of lithium ion battery cells.

3. 2. The implantable battery pack according to claim 1, further comprising at least one graphite sheet disposed within the housing; The implantable battery pack, wherein the one graphite sheet is configured to further dissipate heat generated by the electronic device.

4. 2. The implantable battery pack according to claim 1, The implantable battery pack, wherein the at least one thermally conductive wing is made of copper.

5. 2. The implantable battery pack according to claim 1, The implantable battery pack, wherein the at least one thermally conductive wing includes at least one solder connection for electrically connecting the at least one printed circuit board to the plurality of battery cells.

6. 1. An electronics layout for use with an implantable battery pack comprising a housing and a plurality of battery cells, the electronics layout comprising: at least one printed circuit board carrying electronics; at least one thermally conductive wing connected to and extending from the at least one printed circuit board; the at least one thermal conduction wing is configured to dissipate heat generated by the electronic device throughout the implantable battery pack; the at least one printed circuit board includes a first printed circuit board carrying a power conversion device and a battery charging device; The at least one thermal conduction wing comprises: a first thermally conductive wing extending from a first edge of the first printed circuit board; a second thermally conductive wing extending from a second edge of the first printed circuit board opposite the first edge; an electronic device layout, wherein the first printed circuit board is positioned closer to the center of the implantable battery pack than the first thermal conduction wing in a direction in which the first thermal conduction wing extends from the first printed circuit board, and the second thermal conduction wing is positioned closer to the center of the implantable battery pack than the second thermal conduction wing in a direction in which the second thermal conduction wing extends from the first printed circuit board.

7. 7. The electronic device layout of claim 6, The at least one thermally conductive wing is made of copper.

8. 7. The electronic device layout of claim 6, the at least one thermally conductive wing includes at least one solder connection for electrically connecting the at least one printed circuit board to the plurality of battery cells.

9. 7. The electronic device layout of claim 6, The at least one printed circuit board comprises: a second printed circuit board connected to the first printed circuit board by a first flexible thermally conductive connector; a third printed circuit board connected to the second printed circuit board by a second flexible thermally conductive connector; a fourth printed circuit board connected to the third printed circuit board by a third flexible thermally conductive connector; The electronic device layout can be arranged in a folded state in which the second printed circuit board is stacked between the first printed circuit board and the fourth printed circuit board.

10. 1. A method of assembling an implantable battery pack, comprising: disposing a plurality of battery cells within a housing; disposing an electronics layout within the housing and electrically connecting the electronics layout to the plurality of battery cells; The electronic device layout includes: at least one printed circuit board carrying electronics; at least one thermally conductive wing connected to and extending from the at least one printed circuit board; the at least one thermal conduction wing is configured to dissipate heat generated by the electronic device throughout the implantable battery pack; the at least one printed circuit board includes a first printed circuit board carrying a power conversion device and a battery charging device; The at least one thermal conduction wing comprises: a first thermally conductive wing extending from a first edge of the first printed circuit board; a second thermally conductive wing extending from a second edge of the first printed circuit board opposite the first edge; the first printed circuit board is disposed closer to the center of the implantable battery pack than the first thermal conduction wing in a direction in which the first thermal conduction wing extends from the first printed circuit board, and the second thermal conduction wing is disposed closer to the center of the implantable battery pack than the second thermal conduction wing in a direction in which the second thermal conduction wing extends from the first printed circuit board; method.

11. 11. The method of claim 10, The method, wherein the plurality of battery cells includes a plurality of lithium ion battery cells.

12. 11. The method of claim 10, disposing at least one graphite sheet within the housing; The method, wherein the one graphite sheet is configured to further spread heat generated by the electronic device.

13. 11. The method of claim 10, The method, wherein the at least one thermally conductive wing is made of copper.

14. 11. The method of claim 10, The method, wherein the at least one thermally conductive wing includes at least one solder connection for electrically connecting the at least one printed circuit board to the plurality of battery cells.

Images