Patent Publication Number: US-8981245-B2

Title: Modular molded interconnect devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/657,658, filed Jun. 8, 2012 and entitled “Modular Molded Interconnect Devices” by Dinh et al., which is incorporated by reference in their entirety for all purposes. 
    
    
     FIELD OF THE DESCRIBED EMBODIMENTS 
     The described embodiments relate generally to interconnect devices, and more particularly, embodiments of the present invention relate to modular molded interconnect devices. 
     BACKGROUND 
     An interconnect device is an apparatus configured to allow connectivity between electrical devices or portions of a circuit. A molded interconnect device (MID) is an injection-molded thermoplastic part with integrated electronic circuit traces to allow for this connectivity. Generally, thermoplastics may be used to cast and mold a plurality of MIDs for use in the manufacture of a plurality of different end-user devices. 
     As is generally appreciated, electronic circuit traces may become worn, separable from underlying substrates (i.e., the MID itself), or may malfunction entirely during regular use. Depending upon any end-user device&#39;s structural configuration, it may become exceedingly difficult to service the end-user device absent damage to other portions of the device or removal and replacement of entire integrated portions of the device. 
     Therefore, what is needed are modular molded interconnect devices which overcome these and other drawbacks. 
     SUMMARY OF THE DESCRIBED EMBODIMENTS 
     This paper describes various embodiments that relate to molded interconnect devices. These devices may include a main body molded from a moldable material with at least one conductive path disposed on a surface thereof. 
     According to an embodiment of the present invention, a switching subassembly includes a modular molded interconnect bracket and a switching device arranged on the modular molded interconnect bracket. The modular molded interconnect includes at least one electronic circuit trace arranged thereon configured to interconnect a portion of a flexible printed circuit board and to support a portion of the flexible printed circuit board. The switching device is configured to contact portions of the at least one electronic circuit trace. 
     According to another embodiment of the present invention, a switching assembly includes a flexible printed circuit board, a modular molded interconnect bracket arranged to support at least a portion of the flexible printed circuit board, and a switching device arranged on the modular molded interconnect bracket. The flexible printed circuit board has at least one printed electronic circuit trace. The modular molded interconnect bracket has at least one electronic circuit trace arranged thereon configured to interconnect a portion of the printed electronic circuit trace. The switching device is configured to contact portions of the at least one electronic circuit trace. 
     According to another embodiment of the invention, a switching assembly includes a modular molded interconnect bracket having at least one electronic circuit trace arranged thereon configured to interconnect a portion of a flexible printed circuit board and to support a portion of the flexible printed circuit board, the modular molded interconnect bracket being defined by a molding process and a laser-direct structuring process for forming the at least one electronic circuit trace. The switching assembly further includes a switching device arranged on the modular molded interconnect bracket configured to contact portions of the at least one electronic circuit trace. The switching assembly further includes a cosmetic button cover engaged with the compliance switching device. The switching assembly further includes a housing engaged with the cosmetic button cover. The switching assembly further includes at least one fastener arranged to support the modular molded interconnect bracket against the flexible printed circuit board and the flexible printed circuit board against the housing. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  shows an exploded view of a switch assembly comprising a modular molded interconnect device, according to an embodiment of the present invention. 
         FIG. 2  illustrates a top-planar view of a modular molded interconnect device, according to an embodiment of the present invention. 
         FIG. 3  illustrates a side planar view of a modular molded interconnect device, according to an embodiment of the present invention. 
         FIG. 4  illustrates a two-dimensional planar slice of the assembled switch assembly of  FIG. 1 . 
         FIG. 5  illustrates a two-dimensional planar slice of an alternate assembled switch assembly comprising a modular molded interconnect device, according to an embodiment of the present invention. 
         FIG. 6  illustrates a flow chart of a method of forming a modular molded interconnect device, according to an embodiment of the invention. 
         FIG. 7  illustrates a flow chart of a method of assembling a switch assembly, according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF SELECTED 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. 
     An interconnect device is an apparatus configured to allow connectivity between electrical devices or portions of a circuit. A molded interconnect device (MID) is an injection-molded thermoplastic part with integrated electronic circuit traces to allow for this connectivity. Generally, thermoplastics may be used to cast and mold a plurality of MIDs for use in the manufacture of a plurality of different end-user devices. 
     According to some exemplary embodiments of the present invention, a MID may include a Laser Direct Structuring (LDS) MID. A LDS MID may include a thermoplastic material doped with a metal-plastic additive activated by means of laser or coherent light. A LDS MID may be injection molded such that a plurality of similar devices may be produced with repeatable quality and function. Upon molding, or at any desired subsequent time, a laser writes or traces a desired course for an electronic circuit traces on a surface of the LDS MID. The desired circuit traces may be any suitable circuit traces traceable upon a surface of the LDS MID. 
     The surface of the LDS MID reacts to the incident laser light such that the metal-plastic additive described above forms a surface texture or “roughness” which exposes or activates metallic portions of the additive. These metallic portions form nuclei for subsequent metallization of the traced circuit path. 
     For example, in subsequent device processing, the LDS MID may be exposed to a copper bath. This exposure allows for a first layer of conductor to adhere to the formed nuclei on the surface of the LDS MID. Successively layers of copper, nickel, gold, or other suitable conductors may subsequently be adhered to the first layer such that a durable electronic surface trace is formed. 
     The LDS process may be characterized by other, suitable processing steps either omitted or added to those process steps described above. For example, although generally molded, any modular molded interconnect structure described herein may also include embedded fibers, metal structures, or any other supportive features to adjust or increase rigidity. Therefore, exemplary embodiments should not be limited to any particular form of laser tracing or conductive plating, but rather should be construed to encompass all equivalent acts, structures, and/or materials according to any desired implementation of the present invention. 
     Hereinafter, embodiments of the invention are described in detail with reference to the Figures, which present various embodiments of switch assemblies incorporating and comprising modular molded interconnect devices and methods of forming the same. 
       FIG. 1  shows an exploded view of a switch assembly comprising a modular molded interconnect device, according to an embodiment of the present invention. As illustrated, the switch assembly  10  may include a housing or portion of a housing  11 . The housing  11  may, according to one embodiment, be a housing for a portable electronic device. The housing  11  may be formed of any suitable material, including aluminum, aluminum alloy, stainless steel, titanium, plastic, thermoplastic, glass, or any other material. According to one embodiment of the invention, the housing  11  is formed from a single block of material defined by a milling process. Although depicted as a corner, it should be understood that the housing  11  may include one or more panels, bosses, through holes, attachment holes, ridges, edges, or any other suitable component not illustrated here for the sake of clarity. Furthermore, the housing  11  may define at least one inner cavity for arranging and supporting a plurality of electronic components, for example, for assembling a personal electronic device. 
     The housing  11  may include an opening or through-hole  19  arranged therethrough. The opening  19  may be a substantially rectangular opening with chamfered, rounded, or graded corners configured to receive and engage a cosmetic button or button cover. The opening  19  may be a milled opening in a direction generally orthogonal to a major plane X′-Z′ defined by the housing  11  (noted in  FIG. 3 ). As such, the opening  19  generally restricts movement of cosmetic buttons engaged therewith along a single major axis, for example, Z′. 
     The assembly  10  further includes a cosmetic button cover  12  arranged to be received and engaged with the housing  11  at opening  19 . The cosmetic button cover  12  may be formed of any suitable material, including the same or similar material as the housing  11 . Alternatively, or in combination, the cosmetic button cover  12  may be formed of a different material than that of the housing but include a surface treatment or have a treated surface which renders a surface of the cosmetic button cover  12  to appear the same or similar to the housing  11 . 
     The assembly  10  further includes a shim or spacer  13  arranged to be received and engaged with an inner or bottom portion of the cosmetic button cover  12 . The shim  13  may be a simple metal shim, plastic shim, adhesive strip, or any combination thereof. For example, the shim  13  may be a relatively slim piece of rigid material with adhesive applied on at least one outer surface to allow adhesion or attachment to the cosmetic button cover  12 . According to other embodiments, the shim  13  may be a piece of adhesive tape or compliant material. 
     The assembly  10  further includes flexible printed circuit board (PCB)  14 . The flexible PCB  14  may be termed a “flex PCB” or any other suitable alternative herein. The flex PCB  14  may be formed of a relatively flexible material allowing for integration of printed/embedded conductive electronic circuit paths thereon and/or therein. The flex PCB  14  may include at least two through holes  20  arranged therethrough. The at least two through holes  20  may be dimensioned to be aligned with complementary fastener receiving holes arranged on or in the housing  11 . The flex PCB  14  may include one or more circuit paths or interconnects arranged therein somewhat similar to conventional rigid circuit boards. 
     The assembly  10  may further include a pushbutton or switching device  15  arranged to engage with shim  13  and cosmetic button cover  12 . The pushbutton  15  may be a momentary button biased to be separated from a base substrate  17  (described below). The pushbutton  15  may be formed of a pliable or elastomeric material allowing for depression of the pushbutton  15  against the base substrate  17 . The pushbutton  15  may include a conductive segment or segments arranged therein, that, when depressed against the base substrate  17 , allows for electrical conduction across at least a portion of the base substrate  17 . Alternatively, the pushbutton  15  may include two or more fixed or relatively fixed contact pads arranged to be adhered to the base substrate  17 , for example, through application of solder or conductive adhesive. The pushbutton  15  may be configured to selectively switch a conductive path between the two or more contact pads in response to depressing the pushbutton  15 . 
     The assembly  10  further includes modular molded interconnect bracket  16 . The modular molded interconnect bracket  16  may be a modular molded interconnect device as described above, and therefore may also be referred to as a LDS MID, LDS bracket, or any similar term. The modular molded interconnect bracket  16  may include the base substrate  17  arranged thereon. The base substrate  17  may include at least one electronic circuit trace created thereon such that depression of the button  15  against said surface causes an electric current to flow, a voltage to equalize, and/or a signal to transfer through the flex PCB  14  which is useable by a portable electronic device or any other suitable device comprising the assembly  10  or a portion thereof. Alternatively, the base substrate  17  may include at least one electronic circuit trace created thereon in communication with two or more contact pads of the button  15  such that operation of the pushbutton  15  causes an electric current to flow, a voltage to equalize, and/or a signal to transfer through the flex PCB  14  which is useable by a portable electronic device or any other suitable device comprising the assembly  10  or a portion thereof. 
     The assembly  10  further includes fasteners  18  configured to fasten the entire assembly  10  to the housing  11  such that the cosmetic button cover  12  is received and engaged by the housing, the shim  13  is engaged with the cosmetic button cover  12 , the flex PCB  14  is arranged against the housing  11 , the pushbutton  15  is engaged with the shim  13 , and the modular molded interconnect bracket  16  is engaged with the pushbutton  15  and the flex PCB  14 . In this manner, the elastomeric biasing force provided by the pushbutton  15  biases the cosmetic button cover  12  such that at least a portion of the cosmetic button cover  12  is accessible through the housing  11 , and such access causes the flex PCB  14  to engage the base substrate  17  and cause a signal, current, or voltage readable or accessible through the flex PCB  14  responsive to operation of the pushbutton  15 . 
     Turning now to  FIGS. 2-3 , a more detailed discussion of the base substrate  17  and bracket  16  is provided. 
       FIGS. 2-3  illustrate a top-planar view and a side planar view of the modular molded interconnect bracket  16 , according to an embodiment of the present invention. As shown, the bracket  16  includes the base substrate  17  arranged on outer surface  101 . The substrate  17  includes circuit traces  102 ,  103 ,  104 ,  105 ,  106 , and  107 . Circuit traces  102 ,  103 ,  104 ,  105 ,  106 , and  107  may be formed through a Laser Direct Structuring process as described herein, and may be formed of any suitable conductor, including copper or aluminum. Circuit traces  102  and  103  are arranged as annular traces about through holes  110 ,  111  which penetrate the bracket  16  to allow fastening with fasteners  18 . Circuit traces  102  and  103  are configured to couple with complementary annular or at least partially annular circuit traces or conductive paths exposed on the flex PCB  14 . Circuit traces  104  and  105  (e.g., contact pads) are arranged to contact a complementary circuit trace or external pad arranged on a surface of pushbutton  15 . Circuit traces  106  and  107  are coupled between traces  103 ,  104  and  102 ,  105 , respectively, and therefore allow communication between portions of the flex PCB  14  upon appropriate applied force of the pushbutton  15  when arranged as illustrated in  FIGS. 4-5 . 
     The entire bracket  16  may be formed of plastic, thermoplastic, or any other suitable material. The bracket  16  may also be a laminated molded bracket formed with a plurality of material layers. The bracket  16  may also be impregnated with fibers, metal structures, or other enforcements to increase strength of the bracket  16 . 
       FIG. 4  illustrates a two-dimensional planar slice of the assembled switch assembly of  FIG. 1 . As shown, the assembly  10  may be assembled and fastened using fasteners  18  engaged with holes  401  which are complementary and aligned with associated through holes of the flex PCB  14  and the bracket  16 . Furthermore, appropriate peripheral portions of the pushbutton  15  may be soldered to the conductive traces  105  of the bracket  16  with solder or conductive adhesive  201  to form a switching subassembly. Alternatively, the structural support provided by the fasteners  18  may keep the pushbutton  15  in appropriate alignment. As further shown, elastomeric members  202  may elastically couple the cosmetic button cover  12  to the housing  11 . The elastomeric members  202  may be a single elastomeric member arranged about a periphery of the cosmetic button cover  12 , or may include two or more elastomeric segments. 
     It should be understood that as the pushbutton  15  and bracket  16  are easily separable from the assembly  10  as illustrated in  FIG. 1  and  FIG. 4 , both components are easily replaceable either during initial product assembly processes or during a repair/rework cycle. Therefore, it is appreciated that there is a reduced risk of damaging other components in the switch assembly  10  and also other components of any end-user device when utilizing the module bracketing techniques described and illustrated herein. As such, cost for repairing or replacing a defective or malfunctioning button  15  or bracket  16  are reduced as compared to conventional techniques. 
     Although described and illustrated with basic functionality, it should be understood that the embodiments above may be varied in many ways. For example,  FIG. 5  illustrates a two-dimensional planar slice of an alternate assembled switch assembly  300  comprising a modular molded interconnect device, according to another embodiment of the present invention. 
     As shown, the assembly  300  is functionally similar to the assembly  10 , but includes varied componentry to adjust the look and feel of the basic switch assembly  10 . For example, the housing  302  may be beveled and machined to enhance durability, look, and feel. Furthermore, the cosmetic button cover  301  is also shaped, machined, and beveled. Furthermore, elastomeric members  303  are enhanced and coupled beneath the button cover  301  to alter touch and physical feedback characteristics of the shim  304  and button  305 . Furthermore, the bracket  307  includes an altered side profile which may enhance the usage of space in a portable electronic device. Similarly, the profiles of conductive trances  311 ,  313 , and  312  are altered to match the new profile of the bracket  307 . Solder  306  may also be used to couple the button  305  to bracket  307 , or may be omitted. Fasteners  308  and  309  are of differing profiles to match the change in profile of the bracket  307 . Finally, flex PCB  310  is also altered to match the profile of bracket  307 . 
     As described above, switch assemblies implementing modular molded interconnect devices may be used in a plurality of devices, and may include a modular molded interconnect bracket having at least one electronic circuit trace arranged thereon configured to interconnect a portion of a flexible printed circuit board, and a switch arranged to contact portions of the at least one electronic circuit trace coupled to the modular molded interconnect bracket. 
     Hereinafter, methods of forming modular molded interconnect devices, switching subassemblies, and switching assemblies for use in electronic devices are described in detail with reference to  FIGS. 6-7 . 
     Turning to  FIG. 6 , a flowchart of the method  600  of forming a modular molded interconnect device is illustrated, according to an embodiment of the invention. The method  600  may include preparing a mold configured to form an interconnect device at block  601 . Preparing the mold may include any suitable cleaning, alignment, preheating, or testing process necessary to prepare the mold to receive material for forming the device. 
     The method  600  further includes injecting the prepared mold with material to form the interconnect device at block  603 . The material may include plastic, thermoplastic, or any other suitable material with at least a fraction thereof comprising a dopant material reactive to forming conductive metal traces or receiving, adhering, and supporting conductive metal traces. The dopant may be a metal-plastic additive. The metal-plastic additive may include any suitable additive including minerals, metal alloys, or other materials for laser direct structuring processes. 
     The method  600  further includes cooling and/or removing the molded interconnect device from the mold at block  605 . 
     The method  600  further includes activating the dopant material for a subsequent metallization process at block  607 . The activating may include exposing portions of surfaces of the molded interconnect device to laser light. 
     The method  600  further includes forming circuit paths and/or pads on the activated dopant material  609 . For example, suitable circuit paths may be somewhat similar to those illustrated in  FIG. 2 . 
     The method  600  further includes forming a switching subassembly at blocks  611 ,  613 , and  615 , and device testing of the subassembly at block  617 . 
     For example, forming the subassembly may include applying solder or conductive adhesive to the formed contact paths or circuit paths at block  611 , aligning and engaging a switching device (e.g., pushbutton  15 ) to the pads at block  613 , and reflowing the solder or curing the adhesive to form the subassembly at block  615 . 
     The formed subassembly may be used in a switching assembly, such as assembly  10 . 
       FIG. 7  illustrates a flow chart of a method  700  of assembling a switch assembly, according to an embodiment of the invention. The method  700  includes aligning and engaging a cosmetic button or button cover in a recess of a housing panel at block  701 . For example cosmetic button  12  may be aligned an engaged with hole  19  of housing  11 . 
     The method  700  further includes attaching a shim or compliance member to the engaged cosmetic button at block  703 . For example, shim  13  may be engaged with or attached to the cosmetic button  12 . 
     The method  700  further includes aligning a flex PCB or interconnects about the shim and cosmetic button at block  705 . For example, holes  20  of flex PCB  14  may be aligned with complementary holes  401  of the housing  11 . 
     The method  700  further includes engaging a switching subassembly with the cosmetic button, shim, and interconnect at block  707 . For example, through holes of the modular molded interconnect device may be aligned with complementary through holes of the flex PCB  14  and holes  401 . 
     Thereafter, the method  700  includes fastening the entire assembly with fasteners at block  709 . The fastening may include aligning, inserting, engaging, and retaining fasteners  18  with holes  401 . 
     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.