Enclosure for a sheet-shaped ultracapacitor

Abstract

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 comprising an internal positive contact and an internal negative contact each disposed within the body and each in electrical communication with an external positive contact and an external negative contact respectively, 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 mold cavity in the body comprising a stack of alternating electrode layers and electrically insulating separator layers; an electrolyte disposed within the mold cavity and wetting the electrode layers; a positive lead electrically connecting a first group of one or more of the electrode layers to the internal positive contact.

Description

[0001] Cross Reference to Related Applications

[0002] This application is filed in accordance with 37 CFR § 1.53(b) and additionally claims the benefit of earlier filed provisional application entitled “Housing For Chip Form Ultracapacitor” US 63 / 033,371, filed October 3, 2017, US 62 / 567,752, entitled “Chip Ultracapacitor” filed October 3, 2017, and International Patent Application PCT / US2018 / 054231, entitled “Chip Form Ultracapacitor” filed October 3, 2018, the disclosures of which are incorporated by reference herein in their entireties for all purposes. TECHNICAL FIELD

[0003] The invention disclosed herein relates to energy storage devices, and in particular, to ultracapacitors configured for mounting to a circuit board. BACKGROUND

[0004] Numerous devices use electronic devices having components disposed on a circuit board. As with all electronic devices, an efficient power source is a necessity to power the components. One technique to provide a local power source on a circuit board involves the use of energy storage devices, such as batteries and capacitors.

[0005] Generally, conventional capacitors provide less than about 360 Joules / Kilogram specific energy, while conventional alkaline batteries have a density of about 590 kJ / kg. Ultracapacitors, also known as “super capacitors,” accept and deliver electrical charge much faster than batteries, and withstand many more charge and discharge cycles than rechargeable batteries. This makes super capacitor implementations an attractive solution for electrical engineers.

[0006] A first design obstacle is that typical ultracapacitors are much larger than conventional batteries for a given charge. Even with advances in power density, there is another issue facing the process. That is, assembly of the circuit requires components to be soldered to the circuit board. This “reflow process” generates heat that is significantly enough to degrade or destroy conventional ultracapacitors. Thus, while the use of ultracapacitors can be an attractive solution to power electronic devices mounted on a circuit board, such a solution is not yet available for compact designs requiring high power output. In addition to this, yet another problem with existing ultracapacitor technology is that such components have a limited life.

[0007] What is needed is an ultracapacitor suitable for powering electrical components mounted on a circuit board. Preferably, the ultracapacitor provides a compact design suitable for ever-shrinking components, is able to withstand reflow processing, and provides an effective operational life. SUMMARY

[0008] Additional aspects and embodiments of a sheet-shaped ultracapacitor are described herein.

[0009] 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 comprising an internal positive contact and an internal negative contact each mounted within the body and each in electrical communication with an external positive contact and an external negative contact, respectively, each of the external contacts providing electrical communication to an exterior of the body; an electric double layer capacitor (EDLC) energy storage cell mounted within a mold cavity in the body comprising a stack of alternating electrode layers and electrically insulating separator layers; an electrolyte mounted within the mold cavity and wetting the electrode layers; a positive lead electrically connecting a first group of one or more of the electrode layers to the internal positive contact; and a negative lead electrically connecting a second group of one or more of the electrode layers to the internal negative contact; wherein at least one of the external positive contact and the external negative contact is configured with an elongated external terminal configured to dissipate thermal shock to the energy storage device.

[0010] Various embodiments can include any one or combination of the features and elements described herein, alone or in any suitable combination. BRIEF DESCRIPTION OF DRAWINGS

[0011] The features and advantages of the present invention will be apparent from the following description made in conjunction with the accompanying drawings, in which:

[0012] Figure 1 is a top view of a comparative embodiment of an ultracapacitor disclosed herein;

[0013] Figure 2 is an isometric view depicting a comparative embodiment of a sheet-shaped capacitor according to the teachings herein;

[0014] Figure 3 is a top view of a package, body, or housing of a sheet-shaped capacitor. In this embodiment, the package is for a low profile design as shown in Figure 2 ;

[0015] Figure 4 is a bottom view of the package shown in Figure 3 ;

[0016] Figure 5 is a bottom view of the package shown in Figure 3 and 4a cross-sectional side view of the package shown in

[0017] Figure 6 is Figure 5 an exploded view of a portion of the depiction in

[0018] Figure 7 is a depiction of the internal electrical plumbing of the package Figures 1 to 6

[0019] Figures 8 to 11 is a graphical depiction of the thermal stress for reflow processing within the package. DETAILED DESCRIPTION

[0020] Disclosed herein are energy storage devices suitable for providing energy to a circuit board. Generally, the energy storage devices, referred to as "chip capacitors," are specialized ultracapacitors configured to fit the footprint of the surface of a circuit board. Advantageously, the chip capacitors are able to withstand the demands associated with the manufacture and assembly of board mounted circuits and subsequently provide performance superior to prior art energy storage devices.

[0021] This application is related to and continues the technology disclosed in the following applications: earlier application provisional application 62 / 567,752, filed October 3, 2017, entitled "Chip Ultracapacitor," and international patent application PCT / US2018 / 054231, filed October 3, 2018, entitled "Chip Form Ultracapacitor," the disclosures of which are incorporated herein by reference in their entirety for all purposes.

[0022] In this application, aspects are exhibited that demonstrate additional embodiments. Further, additional aspects create superior thermal stress dissipation during installation of the chip capacitor. Generally, by employing aspects such as a thinner ceramic package, the reflowable ultracapacitor will be compatible with high performance SSD cards and other electronic devices with strict design requirements.

[0023] There are several advantages to the footprint disclosed herein. For example, as the electronic market moves to increasingly thinner circuit boards, the chip capacitor has a component design that is suitable for such implementations, compatible with new design and manufacturing techniques. Additionally, the external pad design provided increases the solderable area, thus improving performance while accounting for large temperature changes without damaging the package, solder, or substrate. Further, the internal via design using internal bus bars and staggered vias makes the overall equivalent resistance of the package low. Finally, the internal pads are located at half the height of the raised shelf mold cavity, which is advantageous for manufacturing, helping to protect the pads from corrosion.

[0024] Figure 1 ​This depicts a "low profile" embodiment of the chip capacitor described in PCT / US2018 / 054231. In the PCT reference, the external dimensions of the chip capacitor are approximately 8 mm (width) × 11 mm (length). Figure 1 The image also shows a "low-profile" embodiment of the chip capacitor device. In this example, the external dimensions of the low-profile chip capacitor are approximately 9 mm (width) × 22 mm (length).

[0025] Since the capacitance of an energy storage unit is proportional to the surface area of ​​its electrodes, the capacitance of a larger low-profile unit is approximately twice that of a smaller unit (for convenience, the initial embodiment is referred to as a "standard unit"). Although the low-profile unit is thinner, it is wider, resulting in better volume utilization compared to the standard unit. Figure 2 An additional embodiment, namely the "high-power" version, is depicted. For example... Figure 2 As can be seen, high-power capacitors can be significantly higher than low-profile or low-power embodiments.

[0026] Figures 3 to 7 It is a description of aspects of the outer casing (also known as "body", "shell", "encapsulation" and other similar terms). Figure 3 Describe a top view of the casing and show a design that is generally similar to PCT / US2018 / 054231. Figure 7 The device of the main body 101 shown in the figure. In fact, the device in this article Figures 3 to 7 The shell is generally similar to the body of reference 101, with additional aspects described herein.

[0027] In this article Figure 4 An example of another embodiment of the main body 101 is described below. In this example, an example is shown. Figure 3 The bottom side of the housing is depicted in the figure. In this illustration, the housing includes three contacts (or "terminals") extending along the length of the housing. The contacts include a positive contact (i.e., a pad) separated from the negative contact (i.e., a pad) by a dummy contact (i.e., a pad). Figure 4 As shown, one of the contacts may include features that can be used to provide a visual indicator of polarity, such as a marking (see positive pad). The pad is designed to provide excellent thermal stress dissipation and management during the reflow process and also during high-temperature operation.

[0028] Turning Figure 5, a cross-sectional side view of the housing is shown. In this illustration, the housing contains a shelf. The shelf provides elevated internal contacts. Thus, the electrical leads of the storage cell (not shown here, but described in PCT / US2018 / 054231) are mounted to the elevated portion of the housing, which is raised from the internal floor of the housing. This design facilitates the manufacture of the sheet capacitor by simplifying the soldering progression, reducing internal corrosion by reducing exposure to electrolyte, and providing additional space for the electrical network within the housing (see Figure 7 ). An exploded view of the cross-sectional view is provided in Figure 6 . In some embodiments, the shelf contains a lip or collar (not shown) around each internal contact. The collar can be designed into the ceramic material used to form the body. Generally, the collar can be included to ensure electrical separation of the two internal contacts (i.e., to contain the solder material during the soldering process) and can also limit exposure of the internal contacts to electrolyte once the sheet capacitor is in use.

[0029] In Figure 7 , aspects of the electrical network are shown. Generally, the electrical network contains internal contacts that are exposed within the housing. The internal contacts can be disposed on a shelf as shown in Figure 5 and 6 . As described in Figure 4 (and 8), external pads (i.e., electrical contacts) are offset from the internal contacts and electrically connected to the internal contacts by intermediate circuit elements. As discussed herein, “offset” refers to a lateral offset of the internal contacts from the position of the external terminals. While some overlap can occur (if viewed from the top down), at least a portion of the internal contacts and / or external terminals are not aligned on top and thus, are offset from one another.

[0030] The intermediate elements contain a plurality of vias connected to an intermediate bus, which in turn is connected to another plurality of vias. The offset arrangement of the intermediate circuit elements causes heat (e.g., from the reflow process) to be distributed approximately evenly throughout the housing.

[0031] In addition to providing sufficient contact surface, the external pads are configured to dissipate heat during the reflow process, thereby limiting the impact on the storage cell and electrolyte within the housing.

[0032] In the depicted design, the configuration of the external pads permits the package to withstand temperature fluctuations above 100°C without cracking or otherwise damaging the solder. Figures 8 to 11 Modeling results of the thermal treatment are depicted.

[0033] Having introduced embodiments of an energy storage device for powering an electrical circuit, some additional aspects are now presented.

[0034] Various form factors can be implemented for surface mountable, reflowable, chip-shaped ultracapacitors (or simply "chip caps"). Chip caps can be configured in size to improve capacitance or other performance aspects, such as heat transfer during a reflow process. Elongated electrical contacts can be configured for thermal stress management. At least one electrical contact can be configured with a marking. The marking can be adapted to indicate, for example, polarity of the chip cap.

[0035] The adaptable design of the chip cap makes the device particularly suitable for use in solid state devices, as the chip cap is well adapted to a reflow process. At least in part due to the form factor of the chip cap, Internet of Things (IoT) technology can benefit from use of the chip cap. The electrical properties of the chip cap make the device well suited as a device for tracking charge (or "coulomb counting") in battery packs or similar devices. Use of the chip cap is advantageous in the automotive industry, as the chip cap has significant operational availability at high temperatures and in extreme environments. For example, the chip cap can be used to augment / support control bus operation. The high temperature tolerance of the chip cap makes the device well suited for use in medical devices that undergo high temperature sterilization processes.

[0036] In some embodiments, the chip cap includes a housing having a shelf. The shelf can include a lip or collar. The collar can be adapted to serve as a barrier and / or baffle during soldering to limit exposure to electrolyte. Manufactured chip caps can have elongated external contact pads that are adapted in length and width for thermal stress management. In some embodiments, an elongated pad runs along the length of the housing. In some embodiments, dummy pads (or terminals) are included. Dummy terminals can also be adapted for thermal stress management. Configuration of terminals for thermal stress management can include thermal stress modeling and can model performance during device assembly and subsequent operation. The chip cap can include an electrical network that exhibits internal contacts that are at least partially laterally offset from locations of the external terminals. The electrical network can include a bus bar. The bus bar can be configured for thermal stress management. A plurality of conductors in a via can extend from the internal contacts to the bus bar, and another plurality of conductors in the via can extend from the bus bar to the external terminals.

[0037] Various other components can be included and required to implement aspects of the teachings herein. For example, additional materials, combinations of materials, and / or omissions of materials can be used within the scope of the teachings herein to implement embodiments.

[0038] Various variations of the teachings herein can be implemented. Generally, variations can be designed according to needs of a user, designer, manufacturer or other similar interested party. Variations can be intended to meet certain performance standards deemed important by the parties described above.

[0039] CLAIM ELEMENTS UNLESS THE TERM "MEANS" OR "STEP-WEB" IS SPECIFICALLY USED IN A PARTICULAR CLAIM.

[0040] When introducing elements of the present application or the embodiments thereof, the articles "a," "an," and "the" are intended to mean one or more than one of the elements. Similarly, the term "another" is intended to mean one or more than one of the elements, when used in this description. The terms "including" and "having" are intended to be inclusive such that there can be additional elements other than the listed elements. As used herein the term "and / or" means and or. The term "exemplary" is used herein to mean an example, not a best example. In other words, the term "exemplary" is used herein to mean one example, among many examples, of an embodiment of the present application.

[0041] While the present application has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from the central scope thereof. Therefore, it is intended that the present application not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this application, but that the application will include all embodiments falling within the scope of the appended claims.

Claims

1. An energy storage device suitable for mounting on a printed circuit board using a solder reflow process, the device comprising: A sealed housing body includes an internal positive contact and an internal negative contact, each disposed within the body and each electrically connected to an external positive contact and an external negative contact, respectively, each of the external contacts providing electrical communication to the outside of the body; An electric double-layer capacitor (EDLC) energy storage unit, which is disposed within a cavity in the main body, comprises an alternating stack of electrode layers and electrically insulating partition layers; An electrolyte, which is disposed within the mold cavity and wets the electrode layer; Positive lead, which electrically connects a first group of one or more electrode layers in the electrode layers to the internal positive contact; as well as A negative lead that electrically connects a second group of one or more electrode layers in the electrode layers to the internal negative contact; At least one of the external positive contact and the external negative contact is configured with an elongated external terminal, which is configured to dissipate thermal shock to the energy storage device, wherein the elongated external terminal is a pad extending along the length of the body.

2. The device according to claim 1, further comprising a shelf disposed within the housing body, the shelf lifting the internal positive contact and the internal negative contact from the internal bottom plate of the housing body.

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

4. The device of claim 1, comprising at least one of the following: a busbar for connecting the internal positive contact to the external positive contact; and another busbar for connecting the internal negative contact to the external negative contact.

5. The device according to claim 1, wherein, The external positive contact and the external negative contact are each configured with a separate elongated pad extending along the length of the body, and wherein the external negative contact and the external positive contact are separated by an external elongated dummy contact pad extending along the length of the body parallel to the elongated pads of the external positive contact and the external negative contact.

6. The device according to claim 5, wherein, At least one of the elongated pads of the external dummy contact pad, the external negative contact, and the external positive contact extends along the entire length of the body that serves as the housing.

7. The device according to claim 5, wherein, At least one of the external positive contact and the external negative contact includes a mark configured to provide a visual indicator of polarity.

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