Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/852,813 filed Oct. 19, 2006. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the field of electrical connectors, and in particular to a miniaturized Universal Serial Bus (USB) connector socket, such as a Micro-B USB socket, and providing therein thermally-coupled over-current and over-voltage circuit protection elements. 
         [0004]    2. Introduction to the Invention 
         [0005]    Standardized plug and socket connectors are widely employed in the electrical and electronic arts. One example, the Universal Serial Bus (USB), is a widely recognized and followed connectivity specification that was first developed in 1995 by technology companies. The USB specification provides an interconnect mechanism which includes transfer of serial data as well as operating power via standard form electrical connectors. By the USB specification a USB-compliant power supply will provide a peripheral device with a fixed voltage in a range of 4.75 and 5.25 Volts with current of at least 0.5 Amperes. The USB specification has evolved with the general trend toward electronic circuit miniaturization, and has specified a Mini-B USB connector plug and socket to handle miniature peripheral devices such as digital cameras, PDAs, and hand-sets, for example; see USB 2.0 Specification ECN #1: Mini-B Connector, Oct. 20, 2000. More recently the even smaller Micro-B USB connector plug and socket have been proposed. 
         [0006]    While USB has provided ease of use, expandability, and speed for the end user and has resulted in widespread adoption and use in countless personal computing, consumer electronics, and mobile devices, the success of this standard has increased the likelihood of over-voltage/over-current electrical fault conditions. Electrical faults are known to occur, making unprotected downstream electronics devices susceptible to damage. Typical over-voltage/over-current faults include inductively induced voltage spikes, voltage spikes from intermittent connections (defective cords or dirty/corroded contacts) and/or over-voltage charger connections resulting from component failure or user error (plugging in the wrong charging unit, for example). Less typical but possible faults include reversal of voltage supply polarity. Because USB has become such a ubiquitous power-charging interface, some vendors have supplied AC to DC converters with a USB output connector. These converters may have unknown, inadequate, or non-existent voltage regulation and transient-suppression characteristics. Unprotected devices may be damaged by over-voltage/over-current conditions when connected to such unregulated converters having standardized connectors, such as a USB connector plug. While the USB standard strongly recommends inclusion of an over-current protection element, such as a fuse, as part of each peripheral appliance having a USB connector socket, separate over-current protection elements take up printed circuit board space and may not be conveniently accessed by the user for replacement or reset. Examples of USB connector sockets may be found in U.S. Pat. No. 6,217,378 (Wu) for “Universal Serial Bus Connector”, and U.S. Pat. No. 6,217,389 (Jatou) for “Universal Serial Bus Connector with Integral Over-current Protection Device and Indicator”. While the Jatou &#39;389 patent suggests including a resettable fuse within a USB connector socket, there is no teaching or suggestion as to how one might effectively combine thermally-coupled over-voltage and over-current protection elements within a USB connector socket, much less a much smaller Micro-B USB connector socket. 
         [0007]    Discrete over-voltage and over-current protection elements for electrical circuits are well known. Known over-voltage circuit protection elements include reverse avalanche breakdown diodes, zener diodes, transient voltage suppression diodes, thyristors, multilayer varistors, gas plasma ionization devices, and Schottky diodes, whether alone or combined with other circuit elements such as pass transistors and operational amplifiers, for example. Known over-current circuit protection elements include metallic fuses, thermally activated circuit breakers, and thermistors. As used herein, the term “thermistor” includes resistors which vary in resistance as a function of temperature. One known example of an over-current protection element is the polymeric positive temperature coefficient (PPTC) thermistor. 
         [0008]    Devices exhibiting a positive temperature coefficient of resistance effect are well known and may be based on certain ceramic materials, e.g., barium titanate, or conductive polymer compositions comprising a polymeric matrix component and a particulate conductive filler material dispersed within the polymer matrix. At relatively low, ambient temperatures the PPTC thermistor has a low electrical resistance, on the order of a few Ohms or less. However, when the PPTC thermistor is exposed to a high temperature resulting from ohmic heating, for example, the polymeric matrix expands and separates the conductive particulates, resulting in a very high electrical resistance, often by as much as five or more orders of magnitude greater than the low temperature resistance. The temperature at which the PPTC thermistor transitions from low resistance to high resistance is known as the switching or “trip” temperature, T s . When the PPTC thermistor cools to a temperature below the trip temperature, T s , the polymeric matrix solidifies and shrinks, thereby returning the device to its low-resistance state. When used as an in-series over-current protection device, the PPTC thermistor is referred to as being “resettable”, in that it trips to high resistivity when heated to the switching temperature, T s , thereby decreasing current flow through the protected circuit. When the over-current condition is removed, the PPTC thermistor automatically resets to low resistivity when it cools to below T s , thereby restoring a low ohmic path enabling full current flow through the protected circuit when electrical power is reapplied thereto. 
         [0009]    By “PPTC” is meant a composition including a polymeric matrix and having an R 14  value of at least 2.5 and/or an R 100  value of at least 10, and it is preferred that the composition should have an R 30  value of at least 6, where R 14  is a ratio of resistivities at the end and beginning of a 14° C. range, R 100  is a ratio of resistivities at the end and beginning of a 100° C. range, and R 30  is a ratio of resistivities at the end and beginning of a 30° C. range. Generally, the compositions used in PPTC thermistor elements of the present invention show increases in resistivity which are much greater than these minimum values. 
         [0010]    Suitable conductive polymer compositions and elements, and methods for producing the same, are disclosed for example in U.S. Pat. No. 4,237,441 (van Konynenburg et al.), U.S. Pat. No. 4,545,926 (Fouts et al.), U.S. Pat. No. 4,724,417 (Au et al.), U.S. Pat. No. 4,774,024 (Deep et al.), U.S. Pat. No. 4,935,156 (van Konynenburg et al.), U.S. Pat. No. 5,049,850 (Evans et al.), U.S. Pat. No. 5,250,228 (Baigrie et al.), U.S. Pat. No. 5,378,407 (Chandler et al.), U.S. Pat. No. 5,451,919 (Chu et al.), U.S. Pat. No. 5,747,147 (Wartenberg et al.) and U.S. Pat. No. 6,130,597 (Toth et al.), the disclosures thereof being expressly incorporated herein by reference thereto. 
         [0011]    It is known to provide planar PPTC thermistors in electrical connection and thermal contact with electronic components such as zener diodes, metal oxide semiconductor field effect transistors (MOSFETs), and more complex integrated circuits forming voltage/current regulators, as exemplified by the teachings and disclosures set forth in commonly assigned U.S. Pat. No. 6,518,731 (Thomas et al.) (particularly  FIGS. 45-47 ), the disclosure thereof being expressly incorporated herein by reference thereto. Also, see, for example, U.S. Pat. No. 3,708,720 (Whitney et al.), U.S. Pat. No. 6,700,766 (Sato) and U.S. Patent Publication 2004/0275046 (Morimoto et al.). While shunt protectors such as semiconductors and series protectors such as PPTC thermistors simultaneously respond to excessive electrical energy, one reason for combining semiconductor circuit protection devices with PPTC thermistors is that the semiconductor devices respond to over-voltage conditions at electronic speeds in microsecond ranges, whereas PPTC thermistors operate relatively much more slowly in reaching the switching temperature, T s , generally measured in milliseconds. By thermally coupling the semiconductor device to the PPTC thermistor, heat first generated in the semiconductor device is rapidly transferred to the PPTC thermistor in order to accelerate heat rise to the switching temperature, T s . While the foregoing patents show combinations of semiconductor devices and PPTC thermistor devices in thermal contact, those patents do not show or suggest inclusion of fully integrated over-voltage/over-current circuit protection elements inside standardized and highly miniaturized connector sockets, such as a Micro-B USB connector socket. 
         [0012]    Miniaturized electrical connectors including connector sockets that conform to a standardized specification are constrained by size requirements and pin configurations such that it becomes difficult to include any additional electrical components, elements or devices within the size requirements and still maintain conformance with the standard connector/socket specification. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    One object of the present invention is to provide a miniaturized electrical connector including thermally-coupled over-voltage and over-current protection elements in a manner overcoming limitations and drawbacks of the prior art. 
         [0014]    Another object of the present invention is to provide a miniaturized electrical connector socket that includes power supply and return lines wherein the socket includes circuitry connected between the power supply and return lines for protecting against over-voltage and over-current events. 
         [0015]    Another object of the present invention is to provide over-current and over-voltage circuit protection for electronic equipment without requiring any circuit board space beyond that required for a miniature connector socket. 
         [0016]    Another object of the present invention is to provide a readily manufacturable and simplified connector structure including thermally-coupled over-current and over-voltage circuit protection elements. 
         [0017]    A further object of the present invention is to provide a miniature connector socket that conforms to a standardized connector specification, such as the specification for a Micro-B USB connector socket, and includes within the specified package outline additional circuit elements including a rapidly acting over-voltage circuit protection zener diode that is thermally-coupled to a slower acting over-current circuit protection PPTC thermistor in order to accelerate operation of the thermistor, thereby providing a drop-in replacement or substitute fully in conformance with the specification. 
         [0018]    One more object of the present invention is to provide a connector socket with a premade and tested hybrid electronics circuit module comprising an over-current circuit protection element and an over-voltage circuit protection element connected thereto and in thermal contact therewith. 
         [0019]    In accordance with principles and aspects of the present invention, an electrical connector, such as a surface-mountable Micro-B USB connector socket, comprises a plurality of discrete conductor leads including at least a power supply lead and a power return lead and at least one data signal lead, and most preferably at least two differential data signal leads, each lead including a connector pin portion at one end and a circuit connector portion at an opposite end. The connector further includes a plastic body encapsulating unexposed portions of the plurality of discrete conductor leads of a pin array and enclosing an over-current circuit protection element and an over-voltage circuit protection element. The over-current circuit protection element, such as a PPTC thermistor, is connected in series with the power supply lead to form a supply side portion and a load side portion. The over-voltage circuit protection element, such as a zener diode, is connected in shunt across the load side portion of the power supply lead and the power return lead and is also thermally coupled to the over-current circuit protection element in order to accelerate heating thereof to a tripped state during a circuit protection event. A formed sheet metal shell surrounds at least a portion, and preferably substantially all, of the plastic body and registers the plastic body and exposed portions of the pin array in a predetermined alignment. In one preferred embodiment the plurality of discrete conductor leads includes a first transverse mounting plate and a second transverse mounting plate with the over-voltage circuit protection element being mounted between the first and second mounting plates and with the over-current circuit protection element being mounted on an opposite side of the first transverse mounting plate exposed within a well defined by the plastic body. Most preferably, the well includes a peripheral space or channel surrounding the over-current protection element to provide room for thermal expansion occurring during an over-current event. In another preferred embodiment a single transverse mounting plate is defined, and the over-current circuit protection element is combined with the over-voltage circuit protection element as a hybrid electronic module and mounted to the single plate and electrically connected to leads or contact lands of the pin array within the well. 
         [0020]    These and other objects, advantages, aspects and features of the present invention will be more fully understood and appreciated upon consideration of the detailed description of preferred embodiments presented in conjunction with the following drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The invention is illustrated by the drawings in which  FIG. 1  is an electrical schematic diagram of a miniature power/data connector plug, and a mating socket having integrated over-voltage and over-current protection elements in accordance with principles of the present invention. 
           [0022]      FIG. 2  is an orthogonal view in upward projection of one embodiment of a Micro-B USB connector socket incorporating principles of the present invention and showing the plug entry end, bottom side segments and right side of an outer shell. 
           [0023]      FIG. 3  is an orthogonal view in upward projection, showing a contact pin array molded into a plastic body of the  FIG. 2  socket structure. 
           [0024]      FIG. 4  is a downward orthogonal view showing one preferred form of a pin, connector and lead array of the  FIG. 2  socket structure. 
           [0025]      FIG. 5  is an upward orthogonal view of the  FIG. 4  pin, connector and lead array. 
           [0026]      FIG. 6  is a top plan view of the  FIGS. 4 and 5  pin, connector and lead array, showing an over-voltage protection element mounted on one side of a transverse heat spreading plate, and an over-current protection element mounted on an opposite side of the transverse heat spreading plate. 
           [0027]      FIG. 7  is a right side view in elevation of the  FIGS. 4 and 5  pin, connector and lead array showing relative placements of the over-voltage protection element, the transverse pin-array plate, and the over-current protection element. 
           [0028]      FIG. 8  is a side view in elevation and section of the  FIG. 2  assembled socket structure taken along a section line  7 - 7  in  FIG. 2 . 
           [0029]      FIG. 9  is an orthogonal view in upward projection, showing the bottom side segments, right side and rear side of the outer shell of the  FIG. 2  socket structure together with surface mount contact pin extensions. 
           [0030]      FIG. 10  is a cutaway side assembly view in elevation of an alternative preferred Micro-B USB connector socket structure in accordance with principles of the present invention, wherein the over-current protection element is sandwiched between the transverse heat spreading plate and the over-voltage protection element. 
           [0031]      FIG. 11  is an enlarged rear view in elevation of the molded plastic body of the  FIG. 10  alternative socket structure. 
           [0032]      FIG. 12  is an enlarged rear view in elevation of an alternative preferred Micro-B USB connector socket structure in accordance with principles of the present invention, wherein the over-current protection element is in a side-by-side arrangement with the over-voltage protection element, and wherein both protection elements are mounted to a common heat transfer plate and are electrically connect at edge connection pads to aligned pads of the socket structure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    With reference to  FIG. 1 , an exemplary electrical connector assembly including a socket  10  and a mating plug  12  is shown diagrammatically. In this preferred example the socket  10  and plug  12  are in accordance with the Micro-B USB connector specification and provide power supply and return lines, differential data signal lines and an extra line, provided for example to identify the peripheral device of which the socket  10  is a part. The exemplary plug  12  extends from a distal end of a shielded electrical multi-conductor cable  14  and includes a molded plug housing comprising an electrical shield  16  forming a cable shield connection  18  connected to the electrical shield of the cable, and five connector pins  20 ,  22 ,  24 ,  26  and  27 . In this particular arrangement, cable shield connection  18  interconnects the cable shield and the plug electrical shield  16 , connector pin  20  connects to an electrical power supply wire, connector pins  22  and  24  connect to a differential data signal twisted pair, connector pin  26  connects to a power and signal ground return reference wire, and connector pin  27  connects to an optional ID wire. A non-illustrated other end of the cable  14  typically connects to a power and signal source, either through another USB plug, or directly. 
         [0034]    The exemplary Micro-B USB socket  10  includes an electrical shield  30  and shield connection  32  for electrically connecting to the cable shield connection  18  of a compatible plug  12 . The socket  10  also includes a power supply pin  34  for connecting to pin  22 , two differential signal pins  36  and  38  for connecting to the data pin pair  22  and  24 , a data signal and power return pin  40  for connecting to plug pin  26 , and a peripheral ID pin  41  for connecting to the connector pin  27 . While  FIG. 1  diagrams the plug  12  as having pins and the socket as having receptacles, in practice both plug and socket contacts include aspects of pins and receptacles, as is well known and understood in the USB art. 
         [0035]    In accordance with aspects of the present invention, an over-current device  42  and an over-voltage device  44  are integrated into and included within the plug  10 . The over-current device  42  is connected in series between the power supply pin  34  and a socket connection lead  46 . The over-voltage device  44  is connected in shunt across the connection lead  46  and a ground return lead  52  which in turn extends from the data signal and power return pin  40 . Most preferably, the over-current device  42  is a PPTC thermistor, and the over-voltage device  44  is a high speed electronic device, most preferably a zener diode (as used herein “zener diode” includes a reverse breakdown avalanche diode). While a zener diode is presently preferred, other voltage-limiting electronic circuit elements are clearly within the contemplation of the present invention. Because the over-voltage device  44  responds to over-voltage conditions very rapidly, on the order of microseconds or faster, heat is quickly generated in the electronic device  44 . This heat is thermally coupled via a heat transfer medium  54 , denoted by the arrow labeled T in  FIG. 1 , to the PPTC thermistor  42  in order to raise its temperature and accelerate its trip to a high resistance state. The socket  10  also includes connection leads  48  and  50  respectively connecting to the two differential signal pins  36  and  38  and a connection lead  55  connecting to the peripheral ID pin  41 . When a zener diode implements the over-voltage device  44 , additional circuit protection is provided against reversed polarity of the power supply, since in the event of reversed polarity of the supply and return leads  34  and  40 , the zener diode  44  will rapidly conduct and generate heat to aid tripping of the PPTC thermistor  42  in accordance with the diode&#39;s forward conduction characteristic. 
         [0036]      FIG. 2  sets forth one presently preferred embodiment of the socket  10  in accordance with the present invention. In this embodiment the socket  10  includes a molded plastic body  28  ( FIG. 3 ) incorporating a pin, connector and lead array  90  ( FIGS. 4 and 5 ) held in place by the formed metal shield  30 . A metal structure forming the shield  30  is most preferably formed by stamping and bending from a sheet of suitably thin sheet metal. As formed, the shell  30  includes a top wall  56  a left side wall  58 , a right side wall  60 , a left bottom wall segment  62 , a right bottom wall segment  64  and a back wall  82 . As formed the left bottom wall segment  62  and the right bottom wall segment  64  define complementary interlocking features  66  in the nature of a dove tail or puzzle piece arrangement for locking the two complementary bottom wall segments  62  and  64  together to form a locked, continuous bottom wall. The top wall  56  includes an outer flanged lip  68 . The left side wall has an outer flanged lip  70  and surface mounting tab  72 . The right side wall  60  in similar fashion includes an outer flanged lip  74  and a surface mounting tab  76 . The bottom wall segments  62  and  64  respectively include outer flanged lip segments  78  and  80 . The outer flanged lips  68 ,  70 ,  74  and lip segments  78  and  80  act to guide insertion of a compatible connector plug into mechanical and electrical engagement within the socket  10 . Slot features  84  defined in side walls  58  and  60  function to receive protrusions or bosses  86  of the molded plastic body  28 , thereby aiding in aligning and securing the plastic body  28  and its contact array  90  inside the shell  30 . 
         [0037]    As shown in  FIG. 2 , the pins  34 ,  36 ,  38   40 , and  41 , and the corresponding connection leads  46 ,  48 ,  50 ,  52 , and  55 , are formed within, and are positioned in the formed metal shell  30  by the plastic body  28 . The leads  46 ,  48 ,  50 ,  52  and  55  are flattened and aligned to be parallel with a plug-insertion axis of the connector socket  10  to facilitate surface mounting and connection to aligned connection pads of a printed circuit substrate of electronic circuitry (not shown) to be protected against over-current and over-voltage conditions in accordance with the present invention. While a surface mounting arrangement with a plug-insertion axis parallel to the aligned circuit board connection leads  46 ,  48 ,  50 ,  52  and  55  is presently preferred, those skilled in the art will understand that the principles of the present invention are equally applicable to a miniaturized socket having thru-hole pins and mounting tabs, or other known mounting arrangements and orientations including ones normal to the facing surface of an underlying printed circuit board substrate. 
         [0038]      FIG. 3  illustrates one presently preferred form of the molded plastic body  28 . The body  28  includes an elongated neck portion  29  extending from a generally rectangular body portion  31 . Features such as recesses  33  and the bosses  86  enable the plastic body  28  to be securely and properly registered to and mounted within the metal shell  30  of the socket  10 . Exposed portions of the pin, connector and lead array  90  ( FIG. 4 ) define contact pins  34 ,  36 ,  38 ,  41  and  40 , and also define flattened mounting tab ends of leads  46 ,  48 ,  50 ,  55  and  52  as shown in  FIG. 3 . The plastic body  28  is most preferably formed by injection molding over the pin, connector and lead array  90  in suitable thermoplastic molding apparatus. The body  28  is most preferably formed from a dielectric thermoplastic material, such as a minimum UL 94-V0 rated, 30 percent glass-filled polybutylene terephthalate (PBT) or polyethylene terephthalate (PET), or better, material. 
         [0039]      FIGS. 4 ,  5 ,  6  and  7  illustrate an example of a pin, connector and lead array  90  as including segments defining pins  34 ,  36 ,  38 ,  41  and  40 , and also defining a transverse heat spreading and transfer plate  92  which connects directly to lead  46 , a ground return plate segment  94  extending from the pin  40  and lead  52 , and a connection segment  96  extending from the pin  34 . As shown in the  FIGS. 4 and 5  embodiment, the over-voltage protection element  44  is sandwiched between (and connected to) the ground plate segment  94  and a front side of the transverse heat spreading plate  92 , whereas the over-current protection element  42  is mounted and connected to a back side of the transverse heat spreading plate  92  and is also connected to the connection segment  96 . The plate segment  94  includes a portion aligned with ground return lead  52 , while the connection segment  96  is formed as part of, and is aligned with, pin  34  (as seen in  FIG. 5 ). Transverse plate  92  is formed with and is directly connected to the lead  46 , thus electrically connecting the PPTC thermistor current protection element  42  in series between pin  34  and lead  46  (as diagrammed in  FIG. 1 ). In the present example the transverse heat spreading and transfer plate  92  forms the heat transfer medium  54  directly between the over-voltage element  44  and the adjacent portion of the over-current element  42 . In this particular arrangement, the plate  92  also functions to spread the heat over a greater area of the over-current PPTC thermistor element  42 , thereby facilitating more rapid tripping to its high resistance, circuit protective state. 
         [0040]    A sacrificial bridging web (not shown in  FIGS. 4 and 5 ) most preferably connects the pins  34 - 41  along the front of the lead pin array  90 , and another sacrificial bridging web interconnects the leads  46 - 55  at the rear end of the array  90  in order to maintain alignment of the pin, connector and lead array  90  prior to overmolding of the plastic body  28 . These sacrificial bridging webs of a lead frame forming the contact pin array  90  are sheared off and discarded as part of the manufacturing process after injection molding of the plastic body is complete. The connector pin array  90  is most preferably die formed or stamped from a suitable metal substrate, such as 0.3 mm phosphor bronze, nickel silver, or other suitable metal sheet material, and then coated with a suitable coating material such as tin. 
         [0041]      FIG. 7  and the  FIG. 8  sectional view show a peripheral space  98  that is provided between the edges of the over-current element  42  and the adjacent molded plastic body  28 . This peripheral space  98  enables the over-current element  42 , particularly when implemented as a PPTC thermistor, to expand in the tripped state without being impeded by the plastic body  28 .  FIG. 9  shows the completed socket assembly  10  and illustrates the back wall  82  and other features of the shell  30  and plastic body  28 . 
         [0042]      FIGS. 10 and 11  illustrate an alternative form of Micro-B USB connector socket  10 A embodying principles of the present invention. Elements which are the same as described for socket  10  have the same reference numerals and description. In this alternative arrangement, the over-current and over-voltage protection elements  42 A and  44 A are formed as an integrated hybrid electronics circuit module which is premade and tested, and then attached to the back side of the lead pin array plate  92 .  FIG. 10  also illustrates the peripheral channel or space  98  separating the PPTC thermistor  42  from the adjacently facing inside walls of the molded plastic body  28 A. In this arrangement the over-voltage protection element  44 A is in direct thermal and electrical contact with the PPTC thermistor element  42 A, thereby providing thermal transfer to accelerate trip of the PPTC thermistor  42 A during an over-voltage/over-current event. Details concerning fabrication and assembly of a hybrid electronic circuit module comprising a zener diode in thermal and electrical contact with a PPTC thermistor are set forth in commonly assigned U.S. patent application Ser. No. 11/392,974 (Montoya et al.) filed on Mar. 27, 2006, and entitled “Surface Mount Multi-layer Electrical Circuit Protection Device With Active Element Between PPTC Layers” (Now U.S. Publication No. 2006/0215342A1 published on Sep. 28, 2006), the disclosure thereof being expressly incorporated herein by reference thereto. 
         [0043]    Following formation of the plastic body  28 A, the hybrid electronic circuit module comprising elements  42 A and  44 A is inserted into the recess space at the back and electrically connected thereto as by bonding a terminal electrode of the PPTC thermistor component  42 A to form the connection to pin  34  to the transverse plate  92 , and then bending connection segments  96  and  100  respectively over and into contact position with aligned connection regions of the PPTC thermistor component  42 A and the zener diode component  44 A, respectively, as shown in  FIG. 11 . The connection section  96  is then electrically connected to the PPTC thermistor component  42 A by a suitable bonding agent, such as low temperature solder, and forms the common node connection between the PPTC thermistor  42  and the cathode of the zener diode  44 A leading to the connection lead  46 . The connection section  100  is likewise electrically connected to e.g. an anode electrode connection of the zener diode  44  and internally connected to the ground return lead  52 . The completed plastic body assembly  28 A is then ready for insertion into and inclusion within the outer metal shell  30  of the socket  10 A. After the body assembly  28 A is inserted into the formed metal shell  30 , the back side  82  is folded down to lock the assembly  28  in place within the completed socket, as shown in  FIG. 8 , for example. 
         [0044]    Alternatively, as shown in the  FIG. 12  embodiment of a socket  10 B in accordance with principles of the present invention, the over-voltage protection element  44 A and the over-current protection element  42 B are arranged in a side-by-side configuration and mounted to a heat transfer and mounting plate  93  providing a lateral heat transfer medium  54  and providing a hybrid subassembly. In this embodiment of the present invention the molded plastic body  28 B is formed to provide conductor segments  96 A and  100 A extending inwardly from an inside face of a molded top wall region  105  of the plastic body  28 B defining the recess for receiving the over-current and over-voltage protection hybrid subassembly. A third conductor segment  102  extends inwardly from an inside face of a molded bottom wall region  107  of the plastic body  28 B. The conductor segment  96 A is aligned with, and connected to, pin  34 ; and the conductor segment  102  is aligned with, and connected to, lead  46 . The conductor segment  100 A is aligned and connected in common with ground return pin  40  and lead  52 . Edge connector pads  97  and  103  are formed at opposite edges of the over-current protection element  42 B, with pad  97  aligning with conductor segment  96 A, and with pad  103  aligning with conductor segment  102 . A pad  101  formed at an edge of the over-voltage protection element  44 A enables a ground return connection to be made, e.g. to an anode electrode of a zener diode. The arrangement shown in  FIG. 12  enables the assembled hybrid electronics circuit module to be inserted into the recess defined by molded plastic body  28 B and electrically connected by solder bridges between segment  96 A and pad  97 , between segment  100 A and pad  101 , and between segment  102  and pad  103 , without any need for bending pins as was used in the  FIGS. 10 and 11  example. In the example of  FIG. 12 , pad  103  is also connected to the heat transfer and mounting plate  93  which forms a common electrical connection between elements  42 B and  44 A. 
         [0045]    Advantageously, the alternative sockets  10 A and  10 B enable usage of a circuit protection module comprising e.g. a PPTC thermistor element and e.g. a zener diode. The module may be separately made, assembled and pretested as a hybrid electronics circuit module prior to inclusion within the structure of the socket  10 A or socket  10 B. 
         [0046]    In making the miniaturized socket of the present invention, the pin, connector and lead array  90  is formed out a sheet of suitable contact material by stamping or die forming. In the case of the first preferred embodiment, the over-voltage protection element, e.g. zener diode  44 , is then positioned between and respective surface electrode terminals secured to plates  92  and  94 , as shown in  FIGS. 4 and 5 . Then, the over-current protection element, e.g. PPTC thermistor  42  may be secured to an opposite face of the elongate transverse plate  92  forming the common node connection between the cathode of the zener diode  44  and the PPTC thermistor  42 . The connection segment  96  may then be secured to and bonded to the non-common electrode of the PPTC thermistor  42 . The plastic body  28  is then formed by injection-molding over the completed lead frame  90 , with mold features ensuring the provision of the peripheral channel  98  to accommodate dimensional expansion of the PPTC thermistor  42  when operating in its tripped and thermally expanded state. Any sacrificial alignment features of the lead frame connector pin array  90  remaining following the molding step are then cut off, e.g., by a shearing operation. Also, the completed plastic body assembly  28  may then receive a thin protective corrosion-resistant overcoat. After the sheet metal shell  30  is stamped out and partially folded into its final shape, the completed plastic body  28  assembly is inserted into the shell and locked in place by folding down the rear wall  82  thereof. 
         [0047]    The alternative embodiment connector socket  10 A is similarly made with the exception that the lead frame  90 A is formed with connection segments extending laterally to enable the over-current/over-voltage circuit module to be separately attached. The plastic body  28 A is injection-molded around the lead frame  90 A and any sacrificial alignment features are removed. Then, the electronic module is installed by connecting the non-common one of the PPTC thermistor&#39;s electrodes to the plate  92 A. Then connection segments  96  and  100  are bent around the hybrid electronics module and connected to the common electrode between the PPTC thermistor component  42 A and the cathode of the zener diode component  44 A, and the anode electrode of the zener diode component  44 A, respectively. The completed plastic body assembly  28 A may then receive a thin protective corrosion-resistant overcoat and is then ready for insertion into the partially completed metal shell  30 , and completion of the socket  10 A as described above. 
         [0048]    The alternative embodiment connector socket  10 B employs edge connection pads formed on the zener diode  44 A and the PPTC thermistor  42 A and connected directly to pins, as shown in the referenced U.S. Publication No. 2006/0215342A1, without the need for bending over the connection segments  96  and  100  as shown in  FIG. 10 . In this particular example, the pin, connector and lead array is formed without the transverse heat spreading plate  92 , since that function is provided by the heat transfer and mounting plate  93  of the hybrid electronics circuit module. 
         [0049]    Those skilled in the art will appreciate that connection segment  96  is aligned vertically with connection lead  46 , and connection segment  100  is aligned vertically with connection lead  52  as shown in the elevational view of  FIG. 11 . This geometric arrangement efficiently utilizes the space within the available footprint or envelope of the standard connector socket, so that the sockets  10 ,  1  OA and  10 B affording over-voltage and over-current protection element, may be directly substituted for compliant standard sockets without these circuit protection capabilities. 
         [0050]    While the present invention has been illustrated as embodied in an exemplary Micro-B, USB, connector socket, those skilled in the art will appreciate that over-current/over-voltage circuit protection elements and modules may be included in other forms of connectors, whether plugs, sockets, or both, and whether conforming to a standard or being a unique design. In particular, the present invention is directly applicable to the standardized Mini-B USB connector socket and enables a fully compatible, drop-in replacement or substitution for a Mini-B USB connector socket not including integrated over-voltage and over-current protection elements. Moreover, the present invention may employ a variety of over-voltage circuit protection elements beyond zener diodes, and may employ a variety of over-current circuit protection elements, including for example ceramic positive temperature coefficient thermistor devices, as well as polymeric positive temperature coefficient thermistor devices, for example. 
         [0051]    Having thus described preferred embodiments of the invention, it will now be appreciated that the objects of the invention have been fully achieved, and it will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. Therefore, the disclosures and descriptions herein are purely illustrative and are not intended to be in any sense limiting.

Technology Category: 5