Housing for chip-type ultracapacitor

Abstract

To provide an energy storage device that provides a compact design suitable for increasingly smaller components and survives reflow processing.SOLUTION: An ultracapacitor, which is an energy storage device suitable for mounting on a printed circuit board using a solder reflow process, comprises a sealed housing body comprising a positive internal contact and a negative internal contact, each disposed within the body and each in electrical communication with positive and negative external contacts, each of the external contacts providing electrical communication external to the body, an electric double layer capacitor (EDLC) energy storage cell disposed in a cavity within the body and comprising a stack of alternating electrode layers and electrically isolated separator layers, an electrolyte disposed in the cavity and wetting the electrode layers, and a positive lead electrically connecting a first group of one or more of the electrode layers to the positive internal contact.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of previously filed provisional application U.S. 63 / 033,371, filed under 37 CFR § 1.53(b), and also filed under 35 U.S.C. § 1.119(e), entitled "Housing For Chip Form Ultracapacitor," U.S. 62 / 567,752, filed October 3, 2017, entitled "Chip Ultracapacitor," and International Patent Application No. PCT / US2018 / 054231, filed October 3, 2018, entitled "Chip Form Ultracapacitor," the disclosures of which are incorporated herein by reference in their entireties for any purpose. [Background technology]

[0002] 1. Field of the Invention The invention disclosed herein relates to energy storage devices, and more particularly to ultracapacitors configured for mounting on electrical circuit boards.

[0003] 2. Description of Prior Art Countless devices use electronic devices with components located on circuit boards. As with all electronic devices, an effective power supply is a requirement to power the components. One technique for providing localized power on a circuit board involves the use of energy storage devices such as batteries and capacitors.

[0004] Typically, conventional capacitors provide a specific energy of less than about 360 joules per kilogram, while conventional alkaline batteries have a density of about 590 kJ / kg. Ultracapacitors (also called "supercapacitors") can receive and transfer charge much faster than batteries and can withstand many more charge-discharge cycles than rechargeable batteries. This makes ultracapacitor implementations an attractive solution for electrical engineers.

[0005] A first design obstacle is that typical ultracapacitors can be substantially larger than conventional batteries for a given charge. Despite advances in power density, another problem lies in the process: assembly of electrical circuits requires soldering components to a circuit board. This "reflow process" generates enough heat to degrade or destroy conventional ultracapacitors. Therefore, while the use of ultracapacitors can be an attractive solution for powering electronic devices mounted on circuit boards, this solution has not been utilized in compact designs requiring high power output. Another problem with existing ultracapacitor technology is the limited lifespan of such components.

[0006] What is needed is an ultracapacitor useful for powering electrical components located on circuit boards, preferably one that provides a compact design suitable for increasingly smaller components, can survive reflow processes, and provides a useful operating life. Summary of the Invention

[0007] Additional aspects and embodiments of chip form ultracapacitors are described herein.

[0008] Disclosed herein is an energy storage device suitable for mounting on a printed circuit board using a solder reflow process, the device comprising: a sealed housing body having a positive internal contact and a negative internal contact, each disposed within the body and in electrical communication with a positive external contact and a negative external contact, each of the external contacts providing electrical communication to an exterior of the body; an electric double layer capacitor (EDLC) energy storage cell disposed within a cavity within the body and comprising a stack of alternating electrode layers and electrically insulated separator layers; an electrolyte disposed within the cavity and wetting the electrode layers; a positive lead electrically connecting a first group of one or more of the electrode layers to the positive internal contact; and a negative lead electrically connecting a second group of one or more of the electrode layers to the negative internal contact, wherein at least one of the positive external contact and the negative external contact comprises an elongated external terminal configured to dissipate thermal shock to the energy storage device.

[0009] Various embodiments may include any of the features and elements described herein either alone or in any suitable combination. [Brief explanation of the drawings]

[0010] The features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

[0011] [Figure 1] FIG. 2 is a top-down view of a comparative embodiment of an ultracapacitor disclosed herein. [Figure 2] 10 is an isometric view of a comparative embodiment of a tip cap in accordance with the teachings herein. FIG. [Figure 3] 2 is a top-down view of the package, body, or case of a chip capacitor, in this embodiment the package is for a low profile design as shown in FIG. [Figure 4] FIG. 4 is a top view of the package shown in FIG. 3. [Figure 5] FIG. 5 is a cross-sectional side view of the package shown in FIGS. 3 and 4. [Figure 6] FIG. 6 is an exploded view of a portion of the depiction of FIG. 5. [Figure 7] FIG. 7 shows the internal electrical conduits of the package of FIGS. 1 to 6. [Figure 8-11] 1 is a pictorial illustration of thermal stresses within a package due to a reflow process. DETAILED DESCRIPTION OF THE INVENTION

[0012] Disclosed herein are energy storage devices useful for providing energy to circuit boards. The energy storage devices, commonly referred to as "chip caps," are specialized ultracapacitors configured in a form factor suitable for surface mounting on a circuit board. Advantageously, chip caps can withstand the demands associated with manufacturing and assembling board-mounted circuits and subsequently perform better than prior art energy storage devices.

[0013] This application is related to and continues the technology disclosed in prior provisional application No. 62 / 567,752, entitled "Chip Ultracapacitor," filed October 3, 2017, and International Patent Application No. PCT / US2018 / 054231, entitled "Chip Form Ultracapacitor," filed October 3, 2018, the disclosures of which are incorporated herein by reference in their entireties for all purposes.

[0014] Additional embodiment aspects are presented in this application. Among other things, the additional aspects provide excellent dissipation of thermal stress during chip cap installation. In general, by adopting aspects such as thinner ceramic packages, reflowable ultracapacitors will be compatible with high performance SSD cards and other electronic devices with stringent design requirements.

[0015] There are several advantages to the form factor disclosed herein. For example, as the electronics market moves to increasingly thinner circuit boards, with component designs suited to such implementations, the chip cap accommodates new design and manufacturing techniques. Additionally, the external pad design provided increases the solderable area, thereby improving performance in terms of large temperature changes without damaging the package, solder, or substrate. Furthermore, the internal via design using internal bus bars and staggered vias gives the package a low total equivalent series resistance. Finally, the internal pads are located on a raised ledge half the height of the cavity, facilitating manufacturing and helping to protect the pads from corrosion.

[0016] FIG. 1 shows a "low profile" embodiment of the tip cap described in PCT / US2018 / 054231. In the PCT reference, the outer dimensions of the tip cap are approximately 8 millimeters (width) by 11 millimeters (length). Also shown in FIG. 1 is a "low profile" embodiment of the tip cap device. In this example, the outer dimensions of the low profile tip cap are approximately 9 millimeters (width) by 22 millimeters (length).

[0017] Because the capacity of an energy storage cell is directly proportional to the surface area of ​​the electrodes, a larger, low-profile cell will have approximately twice the capacity of a smaller cell (for convenience, the first embodiment will be referred to as the "standard cell"). Although the low-profile cell is thinner, it is wider, resulting in a higher volume utilization than the standard cell. An additional embodiment, a "high-power" version, is shown in Figure 2. As can be seen in Figure 2, the high-power capacitor may be substantially higher or taller than the low-profile or low-power embodiments.

[0018] 3-7 illustrate aspects of a housing (also referred to as a "body," "case," "package," and other similar terms). FIG. 3 shows a top-down view of the case, revealing a device that is substantially similar to the body 101 shown in FIG. 7 of PCT / US2018 / 054231. Indeed, the case of FIGS. 3-7 herein is substantially similar to the body 101 of the reference, with additional aspects described herein.

[0019] Another example embodiment of the body 101 is shown in FIG. 4 herein. This example shows the bottom of the case shown in FIG. 3. In this view, the case includes three contacts (or "terminals") that extend along the length of the case. The contacts include a positive contact (i.e., pad) separated from a negative contact (i.e., pad) by a dummy contact (i.e., pad). As shown in FIG. 4, one of the contacts may include a feature such as a symbol (see positive pad) that can be used to provide a visual indicator of polarity. This pad design provides excellent dissipation and management of thermal stresses during the reflow process and high temperature operation.

[0020] Referring to FIG. 5, a cross-sectional side view of the case is shown. In this view, the case includes a ledge. The ledge provides elevated internal contacts. Thus, the storage cell's electrical leads (not shown here, but shown in PCT / US2018 / 054231) are attached to a raised portion of the case that is elevated from the interior floor of the case. This design facilitates tip cap manufacturing by simplifying weld deployment, reduces internal corrosion by reducing contact with the electrolyte, and provides additional room within the case for the electrical circuitry (see FIG. 7). An exploded view of the cross-section is provided in FIG. 6. In some embodiments, the ledge includes a rim or ring (not shown) surrounding each internal contact. The ring may be designed into the ceramic material used to form the body. In general, the ring may be included to ensure electrical isolation of the two internal contacts (i.e., containment of the weld material during the welding process) and, if a tip cap is used, may limit contact of the internal contacts with the electrolyte.

[0021] In Figure 7, aspects of the electrical circuitry are shown. Generally, the electrical circuitry includes internal contacts exposed within the case. The internal contacts may be located on ledges, as shown in Figures 5 and 6. As shown in Figure 4 (and Figure 8), external pads (i.e., electrical contacts) are offset from the internal contacts and are electrically connected to the internal contacts by intermediate circuit elements. As described herein, "offset" refers to the lateral offset of the internal contacts from the location of the external terminals. While some overlap may occur (when viewed from top to bottom), at least some of the internal contacts and / or external terminals are not aligned upwardly and are therefore offset from one another.

[0022] The intermediate elements include a plurality of vias that are connected to an intermediate bus, which in turn is connected to another plurality of vias. The offset arrangement of the intermediate circuit elements is such that heat (such as from a reflow process) is distributed substantially evenly throughout the case.

[0023] In addition to providing a sufficiently large contact surface, the external pads are configured to dissipate heat during the reflow process, thereby limiting the impact on the storage cells and electrolyte within the case.

[0024] In the illustrated design, the external pad configuration allows the package to withstand temperature fluctuations of over 100°C without the solder cracking or damage. Figures 8-11 show the results of modeling the thermal process.

[0025] Thus, having introduced embodiments of an energy storage device for powering an electrical circuit, some additional aspects are now presented.

[0026] Various form factors may be implemented for surface mount, reflowable chip form ultracapacitors (or simply "chip caps"). The chip caps may be sized to improve capacitance or other performance aspects such as heat transfer during the reflow process. Elongated electrical contacts may be configured for thermal stress management. At least one electrical contact may be configured with indicia. The indicia may be useful, for example, to indicate the polarity of the chip cap.

[0027] The adaptable design of the tip cap makes the device particularly useful in solid-state devices because the tip cap withstands reflow processes well. Internet of Things (IoT) technologies can benefit from the use of tip caps, at least in part due to the form factor of the tip cap. The electrical properties of the tip cap make the device suitable as a device for verifying charge (or "coulomb counting") in battery packs or similar devices. In the automotive industry, the use of tip caps is advantageous because they have significant operating life in high temperatures and extreme environments. For example, tip caps may be used to augment / assist control bus operation. The high-temperature durability of the tip cap makes the device very well suited for use in medical equipment that undergoes high-temperature sterilization processes.

[0028] In some embodiments, the tip cap includes a case having a ledge. The ledge may include a lip or a ring. The ring may be adapted for use as a barrier during welding and / or a dam to limit contact with the electrolyte. The tip cap may be manufactured with elongated external contact pads having a length and width adapted for thermal stress management. In some embodiments, the elongated pads run the length of the case. In some embodiments, dummy pads (or terminals) are included. The dummy terminals may also be adapted for thermal stress management. Configuring the terminals for thermal stress management may include thermal stress modeling to model performance during assembly and subsequent operation of the device. The tip cap may include an electrical network showing internal contacts that are at least partially laterally offset from the locations of the external terminals. The electrical network may include a bus bar. The bus bar may be configured for thermal stress management. Multiple conductors in vias may extend from the internal contacts to the bus bar, and another multiple conductors in vias may extend from the bus bar to the external terminals.

[0029] Various other components may be included or required to provide aspects of the teachings herein. For example, additional materials, combinations of materials, and / or omissions of materials may be used to provide additional embodiments within the scope of the teachings herein.

[0030] Various variations of the teachings herein may be implemented. In general, variations may be designed according to the needs of a user, designer, manufacturer, or other similar stakeholder. Variations may be intended to meet particular criteria of performance deemed important by that party.

[0031] No appended claim or claim element should be construed as invoking 35 U.S.C. §112(f) unless the words "means for" or "step for" are expressly used in a particular claim.

[0032] When introducing elements of the invention or embodiments thereof, the articles "a," "an," and "the" are intended to mean that there is one or more elements. Similarly, when used to introduce an element, the adjective "another" is intended to mean one or more elements. The terms "including" and "having" are intended to be inclusive so that additional elements may be present other than the listed elements. As used herein, the term "exemplary" is not intended to connote a superlative example. Rather, "exemplary" refers to an embodiment that is one of many possible embodiments.

[0033] While the present invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be apparent to those skilled in the art to adapt a particular equipment, situation, or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but the invention is intended to include all embodiments falling within the scope of the appended claims.

Claims

1. 1. An energy storage device suitable for mounting on a printed circuit board using a solder reflow process, said device comprising: a sealed housing body including a positive internal contact and a negative internal contact, each disposed within the body and each in electrical communication with a positive external contact and a negative external contact, each of the external contacts providing electrical communication to an exterior of the body; an electric double layer capacitor (EDLC) energy storage cell disposed within a cavity in the body and comprising a stack of alternating electrode layers and electrically insulating separator layers; an electrolyte disposed within the cavity and wetting the electrode layer; a positive lead electrically connecting a first group of one or more of the electrode layers to the positive internal contact; a negative lead electrically connecting a second group of one or more of the electrode layers to the negative internal contact; An energy storage device, wherein at least one of the positive external contact and the negative external contact comprises an elongated external terminal configured to dissipate thermal shock to the energy storage device.

2. The device of claim 1 , further comprising a shelf disposed within the housing body, the shelf elevating the positive and negative internal contacts from an interior floor of the housing body.

3. 2. The device of claim 1, wherein at least one of the positive and negative internal contacts is offset from the corresponding positive and negative external contacts.

4. 10. The device of claim 1, comprising at least one of a bus bar for connecting the positive inner contact with the negative outer contact and another bus bar for connecting the negative inner contact with the negative outer contact.

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