Abstract:
An electrical connector comprising an insulative body, a plurality of pins carried by the body and a ferromagnetic element that rides on one of the plurality of the pins. The ferromagnetic element provides a low pass filter capability for signals transmitted over the one pin.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is continuation of U.S. patent application Ser. No. 12/889,249, filed Sep. 23, 2010. The entire contents are incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to connectors such as board-to-board level connectors used in computers and other electronic devices. More particularly, embodiments of the invention pertain to connectors having one or more magnetic elements integrated into the connector to reduce signal interference and other noise. 
     Modern computer and other electronic systems typically include electronic components packaged on one or more printed circuit boards (PCBs). Board-to-board (B2B) connectors are used to connect electronic components formed on one PCB to those formed on another PCB. As such, B2B connectors come in a variety of different shapes and formats depending on the type of connection required for a particular application. 
       FIGS. 1A-1C  are simplified perspective views of three different B2B connectors  10 ,  20  and  30  designed to affect perpendicular, horizontal and mezzanine type connections, respectively. For convenience, and since from a functional standpoint the primary components of each of connectors  10 ,  20  and  30  are generally identical,  FIGS. 1A-1C  use the same reference numbers to refer to similar components among the connectors. In each of  FIGS. 1A-1C , a B2B connector is shown that includes a male connector portion  11  and a female connector portion  15  attached to PCBs  12  and  16 , respectively. Male connector  11  includes contacts  13  that extend from an insulative housing  14 . Female connector  15  includes contacts  17  that, while not shown in  FIG. 1A , extend within an insulative housing  18  in which contact locations  19 , adapted to mate with contacts  13 , are formed. Contacts  13  and  19  are soldered to their respective PCB. When male connector  11  is engaged with female connector  15 , electrical connections are made between circuits on PCB  12  and PCB  16 . 
     Ferrite materials have been previously used to combat signal noise in electronic circuits. As one example, ferrite beads, which as their name implies are small devices made of ferrite material having a hole in their center through which an electric signal wire can pass, have been incorporated onto printed circuit boards for noise reduction. Over time, the density of electronic components, electronic traces and other elements has increased on PCBs and the spacing or pitch of contacts  13  and  17  required in the connectors such as connectors  10 ,  20  and  30  discussed above has become smaller. The decreases in size make it difficult for components such as ferrite beads, the physics of which cannot be shrunk like electronic traces, to be incorporated onto the boards. These factors combine so that it is sometimes not possible to choose the most optimal signal layout to prevent cross-talk between pins so that signal transmission is not adversely effected. Thus, despite the use of ferrite beads and other ferrite elements on PCBs to improve signal characteristics, improved techniques for suppressing noise in electronic circuits are desirable. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a connector that has improved noise reduction capabilities as compared to standard connectors. Embodiments of the invention surround one or more of the connector pins with a ferromagnetic material that filters unwanted high frequency noise from the signal transmitted by the one or more pins. Some embodiments of connectors according to the present invention integrate ferromagnetic elements in the connector by coupling the ferromagnetic elements directly to one or more of the connector pins. Other embodiments incorporate a ferrite material within the connector body itself. While embodiments of the invention are particularly useful for board-to-board connectors, the invention is not so limited and can be applied to any type of connector where noise reduction is beneficial. 
     In one particular embodiment, an electrical connector is provided that comprises an insulative body, a plurality of pins carried by the body and a ferromagnetic element that rides on one of the plurality of the pins. The ferromagnetic element provides a low pass filter capability for signals transmitted over the one pin. In certain embodiments, ferromagnetic elements are provided on each of the plurality of pins and in some specific embodiments, the ferromagnetic elements are ferrite beads. 
     In another embodiment, an electrical connector is provided that comprises an insulative body and a plurality of pins carried by the body. A portion of the insulative body that surrounds a cross-sectional portion of one or more of the plurality of pins comprises ferrite particles that provide a low pass filter capability for signals transmitted over the pins. In certain embodiments, the insulative body is formed from a ferrite-thermoplastic material. In other embodiments, the insulative body includes a thermoplastic base portion and ferrite-thermoplastic inserts attached to the base portion that provide the low pass filter capability. 
     In still another embodiment, an electronic component is provided that comprises a printed circuit board and an electrical connector. The printed circuit board has a plurality of conductive traces formed on its surface. The electrical includes an insulative body that carries a plurality of pins and a ferromagnetic element coupled to one of the pins. The pins are electrically coupled to the conductive traces formed on the printed circuit board; and the ferromagnetic element provides a low pass filter capability for signals transmitted over the pin to which it is coupled. 
     To better understand the nature and advantages of these and other embodiments of the present invention, reference should be made to the following description and the accompanying figures. It is to be understood, however, that each of the figures is provided for the purpose of illustration only and is not intended as a definition of the limits of the scope of the present invention. It is to be further understood that, while numerous specific details are set forth in the description below in order to provide a thorough understanding of the invention, a person of skill in the art will recognize that the invention may be practiced without some or all of these specific details. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  are simplified perspective views of three different types of board-to-board connectors according to the prior art; 
         FIG. 2  is a simplified perspective view of a female connector  40  according to an embodiment of the present invention; 
         FIG. 3  is a simplified cross-sectional view of connector  40  shown in  FIG. 2  along lines  3 - 3 ; 
         FIG. 4  is a simplified perspective view of a female connector  50  according to another embodiment of the present invention; 
         FIG. 5  is a simplified perspective view of a female connector  60  according to yet another embodiment of the present invention; 
         FIG. 6  is a simplified perspective view of a female connector  70  according to still another embodiment of the present invention; 
         FIG. 7  is are a simplified cross-sectional view of a female connector  80  according to another embodiment of the invention taken along the same lines  3 - 3  shown in  FIG. 2 ; 
         FIG. 8  is a simplified cross-sectional view of a female connector  90  according to another embodiment of the invention; and 
         FIG. 9  is a simplified cross-sectional view of a male connector  100  according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to better appreciate and understand the present invention, reference is made to  FIGS. 2 and 3  where  FIG. 2  is a simplified perspective view of a female connector  40  according to one embodiment of the present invention and  FIG. 3  is a simplified cross-sectional view of connector  40  taken along lines A′A′. Connector  40  includes a plurality of pins  42  that extend from an insulative housing or body  44 . Pins  42  can be electrically coupled to circuitry formed on a printed circuit board  35  by aligning the ends of the pins with circuit traces (not shown) on PCB  35  and soldering the pins thereto with solder  49 . Each of the pins  42  is made from a conductive material and may be plated to improve conductivity and resistance to oxidation. In on particular embodiment, pins  42  are made from a copper alloy such as phosphor bronze. 
     Body  44  is made from an insulative material, such as liquid crystal polymer (LCP) or other similar thermoplastic materials with high mechanical strength, strong resistance to cracking and a low dielectric constant. Body  42  includes an interior cavity  46 . Pins  42  extend from each of the major opposing sides  44   a  and  44   b  of the body into a portion of cavity  46  where they are exposed and can be electrically coupled to a pin in a corresponding male connector (now shown) designed to mate with connector  40 . Cavity  46  is formed around a raised center section  47  that facilitates proper alignment of a corresponding male connector (not shown) when the connectors are mated together. 
     Connector  40  also includes a plurality of ferromagnetic elements  48  operatively coupled to pins  42 . Each ferromagnetic element  48  is a passive low pass filter component that reduces high frequency noise on its respective pin by attenuating signals above a cut-off frequency of the filter. Ferromagnetic elements  48  can be made from any appropriate ferrite material and, and in one particular embodiment are ferrite beads that can threaded over pins  42  such that a portion of the pin traverses the hole in the bead. 
     Different ferrite materials have different filter ranges. Thus, the low pass filtering properties of the ferromagnetic element are determined by the ferrite material the element is made from as well as the element&#39;s dimension. When a ferromagnetic element  48  is a ferrite bead, the beads dimensions, including its length and its outer diameter as compared to its inner diameter, affect its noise reduction properties. Once the desired cutoff frequency and attenuation level for a given connector is identified (e.g., based on the types of signals the connector is expected to be used for), a person of skill in the art can design a ferromagnetic element  48  or select a commercially available ferrite bead that has matching filtering characteristics. 
     As shown in  FIG. 3 , which is a simplified cross-sectional view of connector  40  taken along lines  3 - 3 , each ferromagnetic element  48  is integrated onto an end of its corresponding pin  42  where the pin extends out from housing  44 . In this manner the ferromagnetic element rides on its respective pin at a location between where the pin is soldered to PCB  35  (solder connection  49 ) and a location where the pin extends from housing  44 . 
     The size of the hole through ferromagnetic element  48  can be matched to the diameter of the pin  42  so that the ferromagnetic element fits tightly over the pin and can be secured in place by friction. In other embodiments, ferromagnetic element  48  can be bonded to pin  42  with an appropriate adhesive. In some embodiments ferromagnetic element  48  is a single piece of ferrite material that can be slid over the pin from its end towards the body while in other embodiments element  48  is a clamp-on type device that can be positioned at a desired location over the pin in the open position and then clamped shut to secure itself onto the pin. 
     Connectors used in applications that require high frequency signals, such as data signals received over an antenna from a WiFi or cellular network connection where the signal frequency is in or near the Gigahertz range, are particularly susceptible to noise problems. Some modern portable computing devices such as smart phones include two or more separate antennas adapted to receive signals at different frequencies. For example, a first antenna may be adapted to receive Bluetooth and 802.11 (e.g., WiFi) signals in the 2.4 GHz and 5 GHz range while a second antenna may be adapted to receive voice signals over a cellular network at 850 MHz or 1900 MHz. In one particular embodiment, a connector is provided that includes different ferromagnetic elements  48  matched to different filter ranges. Thus, a first ferromagnetic element that acts as a low pass filter suited for 2.4 GHz and 5 GHz signals can be operatively coupled to the pin associated with the Bluetooth and 802.11 antenna while a second ferromagnetic element that acts as a low pass filter suited for 850 MHz and 1900 MHz signals can be operatively coupled to the pin associated with the voice signals. In other embodiments, it is possible to have ferromagnetic elements  48  with different filtering characteristics associated with each pin on the connector. 
       FIG. 4  is a simplified cross-sectional view of a connector  50  according to another embodiment of the invention. Connector  50  includes ferromagnetic elements  48  that ride their respective pins  42  at a location within body  44  and thus are generally not visible on connector  50  unless the connector is taken apart. The embodiment of  FIG. 4  has the benefit of securing ferromagnetic elements  48  completely within the body so that that ferromagnetic elements cannot be accidentally separated from the connector unless the connector itself is taken apart. 
     Body  44  in connector  50  can be formed in an injection molding or similar process. Prior to the formation of body  44 , ferromagnetic elements  48  can be threaded, clamped or otherwise positioned over pins  42  in connector  50 . The pins with attached ferromagnetic elements can then be placed in an appropriate mold so that body  44  is formed around the pins and around the ferromagnetic elements coupled to the pins. 
     In the embodiments discussed above with respect to  FIGS. 2-4 , a ferromagnetic element  48  is coupled to each of the pins  42  in connector  40 . Other embodiments may include ferromagnetic elements coupled to only a subset of the pins  42 , such as only pins that carry signals which are the most susceptible to high frequency noise. Such embodiments may be particularly useful where the pitch of the connector leaves little space for ferromagnetic elements. As an example, reference is now made to  FIG. 5 , which is a simplified perspective view of a female connector  60  according to another one embodiment of the present invention. As shown, connector  60  includes fourteen pins, seven that extend from a first major side  44   a  and seven pins that extend from a second major side  44   b . Ferromagnetic elements  48  are positioned on every other pin such that pins without ferromagnetic elements are interleaved with pins having ferromagnetic elements coupled to them. This arrangement allows the pins to be placed closer together than they may otherwise be positioned in the embodiments discussed with respect to  FIGS. 2-4  and/or allows each ferromagnetic element  48  to be larger than it otherwise may be allowing additional design choices and frequency characteristics for each ferromagnetic element  48 . 
     In other embodiments where smaller connector pitches are required or otherwise used, ferromagnetic elements  48  can be staggered in order to enable pins  42  to be positioned closer together and/or to enable larger diameter ferromagnetic elements than is otherwise possible.  FIG. 6 , which is a simplified perspective view of a female connector  70  according to another embodiment of the present invention, is illustrative of such embodiments. As shown in  FIG. 6 , adjacent ferromagnetic elements  48   a  and  48   b  are arranged in a staggered relationship so that the placement of element  48   a  does not interfere with the placement of element  48   b , and vice-versa, allowing the pitch of pins  42  to be tighter than otherwise possible. Other types of staggering relationships are possible. 
     As another illustration of a staggered arrangement,  FIG. 7  shows a simplified cross-sectional view of a female connector  80  according to another embodiment of the invention. While not shown in  FIG. 7 , from a perspective view connector  80  is similar to connector  60  shown in  FIG. 6  except that connector  80  does not include ferromagnetic elements  48   a  and  48   b  coupled to its pins  42  at a position outside housing  44 . Instead, the ferromagnetic elements are included in connector  80  within housing  44 . Along a first set of pins, ferromagnetic elements  48  are positioned within connector  80  coupled to a vertical section of the connector pins as shown in  FIG. 4 . Along a second set of pins, interleaved with the first set of pins, connector  80  includes ferromagnetic elements  48   c  that are positioned along a flat portion of pin  42  near a top of the connector as shown in  FIG. 7 . Positioning the ferromagnetic elements on different, non-overlapping portions of the pins within connector body  44  results in the ferromagnetic elements  48  and  48   c  having a staggered relationship within the body. 
       FIG. 8  is a simplified cross-sectional view of a connector  90  according to yet another embodiment of the invention. Connector  90  incorporates a ferrite material directly in the insulative body  94  of the connector and thus each of pins  42  is surrounded by ferrite body  94  over the length of the pin embedded within the body. Ferrite particles or powder can incorporated into body  94  by first mixing the particles/powder with a thermoplastic resin such as LCP. Preferably the ferrite-thermoplastic mixture is sufficiently mixed so that the ferrite material is evenly distributed throughout the mixture. Once the ferrite-thermoplastic mixture is formed, it can be injected into a mold shaped in the form of body  94  using an injection molding or similar process. The signal filtering properties of ferrite body  94  will depend on the volume of ferrite particles in the body and the composition of the ferrite particles as well as the size and shape of body  94  itself. Each of these factors can be varied as needed so that body  94  can be designed to suppress unwanted high frequency noise from pins  42 . 
     In some embodiments, magnetized insulative bodies are used for both the male and female connectors to form a magnetic connector system in which the male and female connectors magnetically attract each other to form a secure connection. In order to break the connection, the magnetic force of the connector system must first be overcome. A pair of male and female magnetized connectors according to embodiments of the invention may be formed, for example, by the ferrite-thermoplastic injection molding process described above. The male and female connectors can then be magnetized to have opposite polarities so that they attract each other when they are placed in sufficient proximity with each other. 
       FIG. 9  is a simplified cross-sectional view of a connector  100  according to another embodiment of the invention. Connector  100  includes a insulative body  102  that includes a thermoplastic base portion  104  and ferrite-thermoplastic inserts  106 ,  108 . Base portion  104  can be similar in composition to body  44  discussed above with respect to connector  40  and thus can be made from a thermoplastic material such as LCP. Ferrite inserts  106  and  108  can each be made from a ferrite-thermoplastic mixture as described above with respect to body  94 . Each of base portion  104  and inserts  106 ,  108  can be formed in an injection molding process or other suitable process. Insert  106  is shaped so it can be secured to base portion  104  by, for example, a snap-on fit or with an adhesive. Insert  108  can then similarly be secured to insert  106 . Inserts  106 ,  108  combine to form an upper portion of body  102  through which pins  42  are inserted. The pins may be integrated into body  102  after insert  106  is attached to base portion  104  but before insert  108  is attached or may be inserted through body  102  after each of the separate pieces  104 ,  106   108  are assembled together. Alternatively, inserts  106 ,  108  can be fabricated as a single insert that is formed by an injection molding process around pins  42  and then the subassembly of pins  42 , insert  106 ,  108  can be secured to base portion  104  with an adhesive or snap-on fit to complete the assembly of connector  100 . 
     In some embodiments, where high frequency filtering is desirable for a subset of pins  42 , base portion  104  is formed to accept inserts  106 ,  108  only at pin locations where such filtering is desirable. Thus, in locations where inserts are not needed, body  102  is made up entirely of base portion  104  which is shaped so that the pins extend through the base portion in that portion of the connector rather than through the inserts. In locations where inserts  106 ,  108  are used, the cross-section of the connector would include inserts  106 ,  108  as shown on connector  100  in  FIG. 9 . It should be noted, however, that while inserts  106 ,  108  are shown in  FIG. 9  as generally having an L-shaped cross-section, the invention is not limited to any particular shape for the ferrite-thermoplastic inserts. Inserts having a variety of other shapes are possible. 
     As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. For example, while embodiments of the invention were discussed above with respect to B2B connectors, the inventions described herein can be used in conjunction with any connector where reduction of noise that may otherwise travel on the connector pins is desirable. As another example, while most of the illustrate examples of the invention discussed above were presented with respect to female connectors suitable for a mezzanine type connection, the invention is equally applicable to male connectors and connectors used parallel, horizontal and other arrangements. Additionally, embodiments of the invention can be used in both the female and mating male connectors in a connector system. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.