Patent Application
20140211432
1. Technical Field
The described embodiments relate generally to a multipurpose fastener. More specifically, a fastener configured to both mechanically and electrically couple two circuit boards together is disclosed.
2. Related Art
As electronic devices become increasingly smaller, the electronic component density associated with those devices has commensurably increased due in part to reduced size of printed circuit boards. In an effort to increase available board space, some electronic device designs include at least two separate circuit boards. Coupling the two separate circuit boards together can involve time-consuming and/or costly attachment processes. To make matters worse, electrical attachments for inter-board communication and/or power transfer can take up valuable circuit board real estate that can be better used for circuit routing, additional electrical components, or ultimately making the product smaller. Unfortunately, small connectors of the type that can feasibly fit in constrained spaces tend to be somewhat unreliable, requiring a backup connector that can take up even more space on each of the printed circuit boards.
Therefore, what is desired is an efficient and reliable way to secure internal components within a constrained volume of space.
This paper describes various embodiments that relate to mechanically and electrically coupling printed circuit boards.
In a first embodiment, a multipurpose fastener is disclosed. The multipurpose fastener can be used to assemble an electronic device including a housing and at least a first printed circuit board (PCB). The first PCB includes electrically conductive traces and a number of electronic components electrically interconnected by way of the electrically conductive traces. The multipurpose fastener includes at least a body portion. The body portion includes at least the following: a mechanical securing feature configured to mechanically secure the first PCB, and an electrical connection feature configured to electrically connect to at least one of the electrically conductive traces of the first PCB.
In another embodiment, a multipurpose fastener is disclosed. The multipurpose fastener can be used to assemble an electronic device having a housing, a first printed circuit board (PCB), and a second PCB. The multipurpose fastener includes a sleeve portion. The sleeve portion includes at least the following: first region including a first conductive pathway, a second region including a second conductive pathway, and a third region electrically isolating the first conductive pathway from the second conductive pathway. When the sleeve portion is disposed between the first PCB and the second PCB, the sleeve portion provides a fixed distance between the first PCB and the second PCB.
In yet another embodiment, an electronic device is disclosed. The electronic device includes at least the following: an electronic device housing; a first printed circuit board (PCB), a second PCB oriented substantially parallel to the first PCB, and a multipurpose fastener. The multipurpose fastener includes at least the following: a body portion having a first end secured to the housing, and a sleeve portion configured to establish a pre-defined distance between the first PCB and the second PCB. The multipurpose fastener is configured to provide at least two discrete electrically conductive pathways between the first PCB and the second PCB.
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments.
The described embodiments may be better understood by reference to the following description and the accompanying drawings. Additionally, advantages of the described embodiments may be better understood by reference to the following description and accompanying drawings. These drawings do not limit any changes in form and detail that may be made to the described embodiments. Any such changes do not depart from the spirit and scope of the described embodiments.
Representative applications of methods and apparatus, according to the present application, are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting.
In the following detailed description, references are made to the accompanying drawings which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting, such that other embodiments may be used, and changes may be made, without departing from the spirit and scope of the described embodiments.
Conventional assembly techniques used in the manufacture of electronic devices generally rely upon a connector formed of a conductive material (such as solder, copper, etc.) to electrically couple internal electronic components. For example, various electronic components are mounted to a substrate and electrically connected to conductive trace connections to form what is referred to as a printed circuit board, or PCB. In order for the electronic device to operate in a prescribed manner, it may be necessary for one PCB to be electrically and mechanically connected to another PCB. For example, a first PCB in the form of a main logic board, or MLB, having a central processing unit, or CPU, can be electrically coupled to a second PCB in the form of a power supply board (PSB) using a single purpose electrical connector (referred to as a board-to-board connector). The board-to-board connector is used to provide an electrical connection between the PSB and MLB over which power (from the PSB to the MLB) and control signals (from the MLB to the PSB) can pass. Therefore, in the context of this discussion, the single purpose of the electrical connector refers to providing the electrical connection over which the various signals pass. A single purpose mechanical connector, such as a screw, can be used to mechanically secure the MLB and PSB to each other and/or to a support structure, such as a device housing. In this way, the device housing can provide structural support for the MLB and PSB.
However, when at least a portion of the device housing is electrically conductive, the device housing can be used as a chassis ground using yet another electrical connector to form a conductive path to the device housing. Therefore, assembly of the electronic device using an assembly process that relies upon single purpose connectors generally requires multiple instances of individual electrical and mechanical connectors. Accordingly, the overall part count and the complexity of the assembly process are increased resulting in a more costly and time consuming manufacturing experience. In addition to complicating the assembly process, the use of single purpose fasteners/connectors can take up valuable internal space that could otherwise be used for additional electronic components.
Therefore, an efficient fastener/connector system is described for use in assembly of an electronic device. The efficient fastener/connector system has the capability of both mechanically fastening and electrically connecting selected components disposed within a device housing. In one embodiment, the efficient fastener/connector system can take the form of a multipurpose fastener. The multipurpose fastener can include features that can be used for both electrically connecting and mechanically securing components of the electronic device. For example, a single multipurpose fastener can be used to mechanically and electrically couple a first PCB to a second PCB as well as to a device housing. Moreover, the same multipurpose fastener can also be used to provide a path to a conductive portion of the device housing to form a chassis ground. In this way, a single multipurpose fastener can be used to replace at least three conventional single purpose fasteners. Accordingly, the multipurpose fastener can greatly reduce part count, assembly complexity, and increase available space that can be used for additional electronic components.
The multipurpose fastener can take many forms. In one embodiment, the multipurpose fastener can include a body portion having features that cooperate to form electrical and mechanical connections. For example, the body portion can include a conductive element configured to form a conductive path between various components. The body portion can also include a mechanical element configured for fastening and securing selected ones of the components. The mechanical element can also provide structural aspects that can be used for placement of selected components within the device housing. For example, the body portion can include a mechanical fastening element in the form of a screw, or other such fastener, that can be used to mechanically secure a first PCB to a second PCB as well as to a support structure such the device housing. The mechanical fastening element can also include a structural element such as a sleeve. The sleeve can be secured to the first and second PCB and be used to position the first PCB with respect to the second PCB as well as with respect to other components or structural members. In some embodiments, the sleeve can include aspects that can be used to form electrically conductive paths. For example, the sleeve can include a first region having conductive material configured to provide a first conductive path. The sleeve can also include a second region having conductive material configured to provide a second conductive path. The first and second regions can be separated by a third region formed of electrically insulating material. In this way, the sleeve can provide structural support as well as any number of electrically conductive paths.
In one specific embodiment, a multipurpose fastener for securing at least the first and second PCBs to a housing of an electronic device can include: a housing insert, a body portion, a sleeve portion, and a fastening portion. The housing insert can be used to secure the body portion to the housing. As such, the housing insert can include a retention feature for coupling to the body portion. In some embodiments, the housing insert can be formed of electrically conductive material capable of providing a chassis ground in those situations where the chassis ground is not available (such as housing formed of non-conductive material such as plastic or ceramic). In this way, the housing insert can act as both retainer and a chassis ground.
An advantage of the multipurpose fastener is that the structure and the composition of the multipurpose fastener can take on many forms as may be required for a particular application. For example, in one embodiment, the multipurpose fastener can include a housing insert embedded in the housing during an injection molding process. In other cases, the insert can have a threaded portion such that the insert can engage with a corresponding threaded portion of the housing. Accordingly, the body portion can have a threaded first end coupled to the retention feature of the housing insert. In yet other cases, the housing insert can be press-fit, heat-staked, glued, or bonded to the housing. The body portion can have an electrical coupling feature operable to electrically couple electrical components secured to the body portion. For example, the electrical coupling feature can be used to electrically couple a first PCB to a second PCB. In this arrangement, the first PCB can be configured with an opening through which the body portion can pass. In some embodiments, the opening can take the form of a hole formed in the substrate of the first PCB. In other embodiments, the opening can take the form of a notch such that the first PCB only partially surrounds the body portion.
In another embodiment, the body portion can include a conductive sleeve portion that can be placed, in whole or in part, around the body portion. The conductive sleeve portion and body portion of the fastener can be separated by an insulation layer disposed between the conductive sleeve portion and the body portion. In some embodiments, the insulation layer can be disposed on an outer surface of the body portion. In other embodiments, the insulation layer can be disposed on an inside surface of the conductive sleeve portion. The conductive sleeve portion can be placed in such a way that the conductive sleeve portion can come in contact with selected conductive traces. In this way, conductive traces on the first and the second PCB can be electrically coupled together using the conductive sleeve portion.
In another embodiment, a multipurpose fastener can include at least a body portion and a sleeve portion. In this embodiment, the body portion can be coupled directly to the housing of an electronic device. In some embodiments, the fastening portion can be overmolded directly into the housing while, in other embodiments, a first end of the fastening portion can be threaded into the housing. In one specific embodiment, the first end of the fastening portion can be a self-tapping screw configured to engage an inner surface of the housing such that the first end of the body portion embeds itself into the housing. In other embodiments, the threaded portion of the body portion can engage threads associated with a pre-drilled hole to secure the fastening portion to the housing. In various other embodiments the body portion can be adhesively coupled, bonded, soldered, or press-fit into a portion of the housing.
Once the fastening portion is secured to the housing, a first PCB can be secured to the fastening portion. The first PCB can be secured to the fastening portion by an opening in the first PCB. The first PCB can be arranged on a flange feature of the fastening portion disposed proximate to the first end of the fastening portion. The flange feature can electrically couple the fastening portion to electrical traces disposed on a lower surface of the first PCB. A lower surface of the sleeve portion can be in direct contact with an upper surface of the first PCB and installed about the fastening portion of the fastener. In this embodiment, the sleeve portion has at least two separate conductive paths disposed therein. The conductive paths can be configured to electrically couple the first PCB to a second PCB in direct contact with an upper surface of the sleeve portion. The fastening portion of the fastener can also extend through an opening in the second PCB and a malleable head feature of the fastening portion can be reshaped after the second PCB is assembled below the head feature. In this way, the second PCB can be disposed between an upper surface of the sleeve portion and the reshaped malleable head feature of the fastening portion. In some embodiments, the reshaping of the head portion can electrically couple the fastening portion to an upper surface of the second PCB, thereby providing another electrically conductive pathway between the two PCBs.
These and other embodiments are discussed below with reference to
Fastener 108 can also be mechanically and electrically coupled to PSB 104. Second end 120 of body portion 110 can mechanically support a lower surface of PSB 104. Second end 120 can also be electrically coupled to electrically conductive trace 122 disposed on a lower surface of PSB 104. In this way, body portion 110 can be in electrical communication with any electrical components electrically coupled to electrically conductive trace 122. In this depiction, body portion 110 is shown mechanically coupled to fastening portion 124 of fastener 108 through opening 126 in PSB 104. The mechanical coupling between fastening portion 124 and body portion 110 can be at threaded interface 128. When threading on both body portion 110 and fastening portion 124 is conductive, the body portion and fastening portion 124 can be electrically coupled, thereby causing any components in electrical communication with body portion 110 to also be in electrical communication with fastening portion 124. Opening 126 can restrain PSB 104 in the X-Y plane, while second end 120 of body portion 110, in cooperation with bottom surface 130 of fastening portion 124, can secure PSB 104 in the Z-axis. In this way, fastening portion 124 cooperates with body portion 110 to mechanically constrain PSB 104 in each of axes X, Y and Z. Fastening portion 124 can also be in contact with electrically conductive trace 132. This particular configuration can then allow each of electrically conductive traces 116, 122, and 132 to each be in electrical contact across electrically conductive pathway 134. It should be noted that, in other embodiments, body portion and fastening portion 124 can be a single integrally formed piece.
Split sleeve portion 504 can have at least two distinct regions having conductive elements 514 and 516 disposed within a third region of insulation that is operable to both enclose conductive elements 514 and 516 and to electrically isolate them from each other. Conductive elements 514 and 516 can take the form of a curved I Beam, as depicted, such that they provide a substantial amount of structural support for split sleeve portion 504. Conductive elements 514 and 516 can show through the insulation region at least along a top and bottom surface of split sleeve portion 504 so that conductive elements 514 and 516 can be electrically coupled to conductive traces, such as trace 518, arranged on MLB 508. A split configuration of conductive elements in split sleeve portion 504 allows power to be passed through conductive element 514 and a grounding path to be established through conductive element 516. A number of distinct electrical traces can be coupled to each of conductive elements 514 and 516 allowing power delivery and grounding to a number of different components within an associated electronic device. In embodiments where body portion 502 is made of a conductive material, body portion 502 can act as an additional grounding path, power transfer conduit, or signal pathway in addition to the paths provided by conductive element 514 and 516.
Since split sleeve portion 602 is configured as described above to act as both a grounding and power conduit, power and grounding can still be accomplished with this embodiment of the multipurpose fastener. For example, power supply board 610 can include a grounding pathway allowing electrical component 612 to be grounded through electrical trace 614, which can then be routed through conductive elements 603 of split sleeve portion 602 and then to a ground plane associated with power supply board 610. Likewise, electrical component 612 can be electrically coupled to a second electrical trace 616, which can then be electrically coupled to a conductive element 603 of split sleeve portion 602. In this way, electrical component 612 can be both grounded and powered through a multipurpose fastener that includes only two parts. It should be noted that while body portion 604 is not shown in direct contact with sleeve portion 602, such a configuration can be desirable, as contact between body portion 604 and sleeve portion 602 can help to ensure proper radial alignment of sleeve portion 602 with respect to PCB 610 and PCB 618. It should be noted that while only one side of each of the boards is electrically coupled, the remaining sides can also benefit from the electrical coupling by way of more traditional vias disposed through each of the boards.
At step 810, a lower surface of a second PCB can be put in direct contact with the sleeve portion. The conductive nature of the sleeve portion allows the sleeve portion to electrically couple the first and second PCBs together. The sleeve portion can include multiple conductive elements providing separate electrically conductive paths through the sleeve portion. In one embodiment, power of varying voltages can be passed through the different conductive paths. An electrically conductive grounding path is also possible. At step 812, a fastening portion is inserted through an opening in the second PCB and into a retention feature of the body portion. Once the fastening portion is secured within the retention feature of the body portion, a head portion of the fastener is put in direct contact with a surface portion of the second PCB. In this way, that surface portion of the second PCB can be electrically coupled through the fastening portion and the body portion to the housing. The portion of the housing to which the body attaches can be coupled to a chassis ground, thereby efficiently coupling both the first and second PCB to the chassis ground.
The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.
