Patent Application
20150092360
Batteries are commonly used as sources of stored electrical energy for a variety of portable electronic devices ranging from laptop computers, mobile telephones, portable music players, wristwatches, navigational devices, and athletic performance monitoring devices, among many others. Furthermore, positioning of one or more batteries within an electronic device may be an important consideration from the perspective of a product designer/engineer, wherein the positioning of one or more batteries may be based upon issues related to the functionality, the aesthetics of the product, and size constraints, which can be particularly important in designing compact electronic devices.
In some instances, it may be desirable to use one or more overmolding processes during manufacture of a product, wherein overmolding refers to one or more processes to mold one or more substances at high temperatures and/or high pressures onto an existing material, component, etc. Accordingly, an overmolding process may be selected for manufacture of a portable electronic device based on a finished appearance of an overmolded product, the functionality and mechanical characteristics of an overmolded product, space and size constraints, or the economics of using an overmolding process, instead of one or more alternative manufacturing processes, among others. However, the temperature and/or pressure used during an overmolding process may exceed one or more temperature and pressure tolerance limits associated with a battery to be used in a given portable electronic device. As such, overmolding may damage the battery, or render the battery completely inoperable. Accordingly, a need exists for systems and methods that provide enhanced options for overmolding of batteries in such devices, particularly devices having a small form factor, or otherwise constrained internal space.
The present systems and methods described herein are provided to address the problems discussed above, and other problems, and to provide advantages and aspects not provided by prior battery solutions. A full discussion of the features and advantages of the present systems and methods is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.
The following presents a simplified summary of the present disclosure in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate or limit the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to the more detailed description provided below.
Aspects of the systems and methods described herein relate to a battery assembly. The battery assembly has a battery and an epoxy coating that at least partially covers the battery in order to resist the temperatures and pressures associated with an overmolding fabrication process that produces an overmolded structure to at least partially encapsulate the battery.
In the following description, reference is made to the accompanying drawings, which form a portion hereof, and in which are shown by way of illustration various example devices, systems, and environments in which aspects of the invention may be practiced. When the same reference number appears in more than one drawing, that reference number is used consistently in this specification and the drawings refer to the same or similar part or object throughout. It is to be understood that other specific arrangements of parts, example devices, systems, environments or other objects may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Also, while the terms “top,” “bottom,” “front,” “back,” “side,” “rear,” and the like may be used in this specification to describe various example features and elements of the invention, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures or the orientation during typical use. Additionally, the term “plurality,” as used herein, indicates any number greater than one, either disjunctively or conjunctively, as necessary, up to an infinite number. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of this invention. It is also understood that, as used herein, “providing” refers broadly to making an article available or accessible, including, e.g., for present and/or future actions to be performed on, by or in connection with, the article; for further clarity, such term as used herein, does not denote, connote or otherwise imply that any party is providing such article or that, in providing the article, any party will or has manufactured, produced, or supplied the article, or that the party providing the article has ownership or control of the article, unless and except if any such diction is explicitly set forth. Also, the reader is advised that the attached drawings are not necessarily drawn to scale.
In general, the present disclosure describes overmolding of a battery for use in a portable electronic device. In one implementation, the systems and methods described herein may be used to overmold a rechargeable lithium polymer (otherwise referred to as lithium-ion polymer, or polymer lithium ion) pillow-packed battery. However, one of ordinary skill will understand that the structures, configurations, systems and methods described herein may be employed using a variety of alternative battery types and configurations, including, but not limited to, alkaline, nickel cadmium, and nickel metal hydride batteries, among others. It is further understood that the structures, configurations, systems and methods described herein may be utilized or adapted for use in protecting a different type of electronic component during overmolding. In one implementation, such an electronic component may be a “circuit,” wherein a circuit may comprise one or more standard integrated circuits, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), memory chips (such as ROM, RAM, and the like), or any electronic component that may be susceptible to malfunction and/or failure if exposed to the temperatures and pressures of an overmolding process.
The systems and methods described herein allow a battery to remain operational after an overmolding process has been performed to encapsulate the battery within one or more overmolded materials during manufacture or fabrication. Accordingly, the systems and methods described herein allow a battery to withstand high temperatures and pressures associated with an overmolding process, wherein an overmolding process may involve a temperature of 220° C. or greater, and pressures ranging from 20 MPa to 35 MPa (3000 psi to 5000 psi). Conventionally, a combination of one or more of such temperature or pressure levels may damage, or render inoperable, a battery. As a more specific example of such withstanding capability, the systems and methods described herein are configured to resist, or substantially resist, the pressure and temperature employed in an overmold process to mold a flowable substance over one or more components that include a battery. In this way, the systems and methods described herein may resist, or substantially resist, among others: ingress of a flowable substance associated with an overmold process into a battery housing structure, mechanical stress above a predetermined acceptable mechanical stress threshold for a battery, mechanical strain or deformation above a predetermined acceptable mechanical strain or deformation threshold for a battery, and/or an ambient, or a peak temperature above one or more temperature limits associated with operation or storage of a battery.
In general, the systems and methods described herein allow a flowable material/substance to be overmolded around a battery using, among others, polymer injection molding systems and methods, wherein a flowable substance that may be overmolded around a battery may include one or more of: thermoplastic polyurethane (TPU), thermoplastic elastomers (TPE), silicone materials, and other moldable elastomers, as well as other polymer resins such as nylon, acetal, polycarbonate, and the like. Other examples of such flowable substances for overmolding include other types of polymeric and/or composite materials. It is understood that such flowable substances may be selected for properties such as viscosity (e.g., at process temperature and pressure), strength, resilience, flexibility (e.g., following molding), bonding capability, compatibility with other materials, visual appearance, texture, or other aesthetic qualities, and/or other properties. To illustrate, in example overmolding processes, a flowable substance may be selected due to having a viscosity of about 10 Pa·s, or more; in other example overmolding processes, a flowable substance may be selected due to having a viscosity of about 1 Pa·s, or more; and in yet another example overmolding processes, a flowable substance may be selected even if having a viscosity of up to 200 Pa·s.
In the descriptions that follow, it will be understood that the example overmolding processes are described in a simplified manner, and that additional steps and parameters may be involved in any implemented overmolding process. Further, in the following exemplary embodiments in this disclosure, one or more overmolding processes may be described for overmolding a battery with a thermoplastic elastomer (TPE) flowable substance, however one of ordinary skill will recognize that the exemplary embodiments of this disclosure may be practiced using one or more of the alternative flowable overmolding substances previously described, or any material suitable for use in an overmolding process, or combinations thereof.
In the descriptions that follow, references will be made to systems and methods for overmolding battery 140 of device 100, however one of ordinary skill will recognize that the systems and methods described herein may be generally practiced for overmolding a battery 140 for use in any electronic device, such as mobile telephones, portable music players, navigational devices, laptop computers, tablet computers, among others.
Flexible printed circuit 212 may be configured with circuitry, including one or more discrete or integrated electronic components, for controlling the operation of battery 140. In this way, flexible printed circuit 212 may control the rate of discharge and/or recharge of electrical energy from/to battery 140, respectively. In another embodiment, the circuitry for controlling the rate of recharge and discharge of electrical energy to and from battery 140 may be integrated into a single battery structure 140. Accordingly, flexible printed circuit 212 may consume electrical energy from battery 140 to execute one or more processes associated with the operation of an electronic device, such as electronic device 100 in which battery 140 is embodied. The flexible printed circuit 212 may also be configured to control the operation of one or more additional components of the device 100, such as the components 110a-c, the display 120, and/or other components. As depicted in
As depicted in
It is further noted that while battery 140 is depicted with a schematic structure that is substantially rectangular (cuboidal) in shape, the systems and methods described herein may be practiced with batteries embodied with alternative shapes, including, but not limited to, curved battery shapes that substantially conform to the curved structure of the outer casing structure 130 from
The systems and methods described herein allow for overmolding of, among others, battery 140 by using an epoxy (epoxy resin) to cover the battery 140 prior to one or more overmolding processes being carried out.
In one implementation, covering 310 protects battery 140 from high levels of heat and pressure that may be associated with an overmolding process. Specifically, covering 310 provides thermal and pressure resistance such that the outer surface (330a-330c) of battery 140 does not experience temperature and/or pressure above one or more predetermined thresholds associated with battery 140. In fact, the temperatures and/or pressures experienced by the battery 140 may be significantly different than the temperatures and/or pressures involved experienced by the cover, such as at least a 40% reduction or at least a 50% reduction in some embodiments. For example, injection techniques may involve pressures up to 76 MPa (11,000 psi) and temperatures of around 200° C., and the battery 140 with the covering 310 as described above may only be subjected to temperatures of around 110° C. and 20 MPa-35 MPa (3000 psi to 5000 psi) in such a process. Further, the greatest temperature and/or pressure may be experienced by the thin side edges of the battery 140 in one embodiment, which are the areas of the battery 140 that generally can withstand the greatest temperature and pressure. It is understood that the configuration of the covering 310 and/or the mold cavity may affect the temperature and/or pressure experienced by the battery 140 and the portions of the battery 140 that experience the greatest temperature and/or pressure. Additionally, or alternatively, covering 310 functions to resist, or distribute, a pressure associated with an overmolding process such that the mechanical stress experienced by an outer surface (330a-330c) of battery 140 remains below one or more predetermined mechanical stress thresholds associated with battery 140.
As schematically depicted in
It is known that a lithium polymer pillow pack battery 140, among other battery types and configurations, may expand, or “swell,” during operation. Advantageously, the epoxy covering 310 results in battery 140 being fully functional within structure 400, and without being adversely affected by battery expansion, or swell during charging and discharging.
Further advantageously, structure 400 may allow for space savings, and improved tolerance specification in, among others, the device 100. In this way, because covering 310 conforms exactly, or substantially exactly, to the shape of battery 140, a tolerance range associated with the dimensions of an inner cavity within the covering 310 to accommodate battery 140 is not required. In contrast, if a pre-formed structure is used to encapsulate battery 140, this pre-formed structure will have a tolerance range associated with an inner cavity that is to accommodate/encapsulate battery 140, and/or battery 140 will have a tolerance range for fitting within the inner cavity. The elimination of one or more tolerance ranges reduces the total aggregate tolerance of the entire assembly in which the battery 140 is utilized (e.g. device 100). This reduction in aggregate tolerance permits closer fitting in devices with tight space constraints.
For example, battery 140 may comprise a first width measuring 5.0 mm+/−0.5 mm. In one implementation, a pre-formed structure may be used to encapsulate the battery 140. Accordingly, the pre-formed structure may comprise an inner width corresponding to the first width of battery 140, and measuring 6.0 mm±0.5 mm. These tolerance ranges ensure that at their extreme values, e.g. when the first width measures 5.5 mm, and the inner width measures 5.5 mm, battery 140 will still fit within the pre-solidified structure. Continuing this example, the pre-formed structure may be designed to have a thickness of at least 2 mm. This thickness corresponds to an outer width measuring 11.0 mm±0.5 mm. In this way, at their extreme values of 6.5 mm and 10.5 mm, the pre-solidified structure thickness is at least 2 mm (2 mm on either side of battery 140 giving 4 mm total thickness). In contrast, using coating 310 as described above may achieve desired protection of battery 140 using less space within device 100, by eliminating at least the tolerance range associated with the inner width of the pre-formed structure. Specifically, for the exemplary same battery 140 with a first width measuring 5.0 mm±0.5 mm, it may be desirable to have coating 310 with a thickness of at least 2 mm. Due to the fact that the epoxy 310, before solidification, conforms exactly, or substantially exactly, to the shape of battery 140, no tolerance range associated with an inner width of the cavity that is to accommodate battery 140 needs to be specified. Accordingly, an outer width of epoxy coating 310, corresponding to the first width of battery 140, may measure 10.0 mm±0.5 mm. In this way, at their extreme values of 5.5 mm and 9.5 mm, the thickness of epoxy coating 310 will measure at least 2 mm on either side of battery 140. In this example, the epoxy coating 310 reduces the overall width requirement by 1.0 mm (11 mm outer width of pre-solidified structure versus 10 mm outer width of epoxy coating 310). This technique, when used on battery 140 alone, or in combination with other components, may represent significant space savings within a portable electronic device, such as device 100 from
In one implementation, components 140, 212, 214, and 310 may be held within the second mold 520 by one or more spacer, or standoff elements (not shown). Various implementations of spacer, or standoff elements will be readily understood to those of skill in the art, and in one embodiment, a portion of a frame of the device 100 may be used as such a spacer or standoff element. In this way, the second cavity 522 may extend around all of the components 140, 212, 214, and 310, and such that the inner walls of the second mold 520 are spaced apart from the components by distances 540a-540d. In one implementation, distances 540a-540d may each measure at least 0.25 mm (0.25 mm at a minimum). In another implementation, distances 540a-540d may each measure 0.25 mm on average. In yet another implementation, distances 540a-540d may each measure at least 0.5 mm, or 0.5 mm on average, or at least 1.0 mm, or 1.0 mm on average. In yet another implementation, distances 540a-540d may be equal to one another, or one or more of distances 540a-540d may differ from one another. Furthermore, and while not depicted in
In one implementation, the dimensions of the covering 310 may be such that a thickness (620a-620d) of the covering 310 between battery 140 and a surface (630a-630d) of overmolding material 410 is at least 0.25 mm. In another implementation, however, thicknesses 620a-620d are at least 0.5 mm, or at least 1.0 mm. In one exemplary implementation, thicknesses 620a-620d may each measure at least 0.25 mm. In another exemplary implementation, thicknesses 620a-620d may each measure at least 0.5 mm, or at least 1.0 mm. In another implementation, thicknesses 620a-620d may be equal to one another, or one or more of thicknesses 620a-620d may differ from one another.
In one implementation, battery 812 may be overmolded using a pre-formed protective casing 810. Protective casing 810 may be configured to withstand the high temperatures and high pressures associated with an overmolding process. Accordingly, protective casing 810 may be constructed from any suitable material with mechanical properties capable of withstanding overmolding conditions, including temperatures of 220° C. or greater, and pressures ranging from 20 MPa to 35 MPa or greater. In one implementation, protective casing 810 may be constructed from a stainless steel material, however one of ordinary skill will recognize that protective casing 810 may be constructed using other materials, such as, among others, other metals, alloys, polymeric materials, ceramics, or fiber-reinforced materials, or combinations thereof. In one implementation, battery 812 is inserted into protective casing 810 through a first opening 820, prior to an overmolding process. Casing 810 may also include a cap (not shown) to cover the opening and resist ingress of flowable materials during overmolding. Further, the casing 810 may include a passage that accommodates wired connections 814 (e.g., through the cap), which may be sealed with a potting compound or other sealant.
It will be readily apparent to those of skill in the art that alternative embodiments of the first section 1120, and second section 1122 may be used to protect battery 1110, without departing from the scope of the disclose described herein. Accordingly, the first section 1120 and second section 1122 may alternatively form a protective cover that is substantially cylindrical in shape, or substantially a cube shape, and the like.
While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and methods. Thus, the spirit and scope of the invention should be construed broadly as set forth in the appended claims.
