Abstract:
A land grid array connector is provided having a carrier formed with a plurality of contact receiving passageways passing between major surfaces thereof. Each contact receiving passageway is plated over substantially the entire passageway between the two major surfaces. A resilient contact is inserted and frictionally held within each plated contact receiving passageway such that ends of each resilient contact protrude beyond each major surface of the carrier.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is related to electrical connectors and more particularly to a land grid array connector for connecting two parallel components having an array of contact locations on each.  
         BACKGROUND OF THE INVENTION  
         [0002]    Land grid array connectors are well known in the electrical connector art and are utilized for interconnecting parallel printed circuit boards or other parallel components. Typically, the parallel components or substrates have a plurality of contact locations known as lands which take the form of a conductive or plated section on the surface of the substrate. The lands are interconnected to traces of a circuit on or within the substrate which are thereafter connected to a plurality of components forming a circuit or system. Land grid array connectors typically feature a plurality of resilient contacts positioned within a substrate wherein the resilient contacts each have terminal ends projecting from opposite sides of the carrier. The land grid array connector is interposed between the two substrates to form an interconnection therebetween. The two substrates are sometimes clamped or otherwise held into position to compress the land grid array connector and associated contacts therebetween.  
           [0003]    An example, such a connector is shown in related U.S. Pat. Nos. 5,388,997 and 5,388,998. These patents teach a connection system for interconnecting a pair of rigid circuits to each other. The interconnection system taught by these patents features a plurality of compressive conductive members positioned within a carrier member. The compressive conductive members consist of coil springs having a pair of ends which electrically contact and are compressed between circuits of the pair of rigid circuit members.  
           [0004]    A problem exists with connectors in certain medical applications. More specifically, when a connector is utilized within certain medical imaging equipment such as a CT scanner, relatively high voltages may be applied to these connectors during the scanning process. As a result, an electrical potential is generated between each resilient contact and its associated substrate. This electrical potential consists of an electron charge build up between the contact and the or substrate. A physical impact or localized vibration may cause electron mobility at the build up and resultant current across the electron build up region between the contact and the substrate. Such electron mobility results in an electrical spike know as a ping which propagates through the system of a medical imaging apparatus. The ping may cause undesirable image output from the imaging device. Such undesirable output gives false readings in the form of dark spots on the resultant image which could be mistakenly diagnosed as a mass within the body of a patient under the imaging apparatus. It is therefore desirable to eliminate or at least reduce the build up of electrons in these applications in the area of the contact to substrate engagement.  
         SUMMARY OF THE INVENTION  
         [0005]    It is therefore an object of the present invention to provide an improved land grid array connector wherein electron build up at the location where contacts are held within a carrier is reduced.  
           [0006]    This and other objectives are achieved by providing a land grid array connector having a carrier. The carrier is formed with a plurality of contact receiving passageways passing between major surfaces thereof. Each contact receiving passageway is plated over substantially the entire passageway between the two major surfaces. A resilient contact is inserted and makes electrical contact and is held frictionally or may be soldered within each plated contact receiving passageway such that ends of each resilient contact protrude beyond each major surface of the carrier. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The invention will now be described by way of example with reference to the accompanying figures of which:  
         [0008]    [0008]FIG. 1 is a cross sectional view of a carrier for use in the land grid array connector of the present invention.  
         [0009]    [0009]FIG. 2 is a perspective cut away view of the land grid array connector according to the present invention.  
         [0010]    [0010]FIG. 3 is a cross sectional view of a land grid array connector having an alternate contact. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]    The invention will first be described generally with reference to FIG. 1. The land grid array connector  10  features two major components. First, a carrier  20  is formed of a suitable insulative or semiconductive material having a plurality of contact receiving passageways  26  formed therein. A resilient contact  30  is located within each contact receiving passageway  26 .  
         [0012]    Each of the major components will now be described in greater detail again with reference to FIG. 1. The carrier  20  features a plurality of contact receiving passageways  26  extending between first and second major surfaces  22 ,  24 . Each contact receiving passageway  26  may be formed as a cylindrical passageway which extends between the first and second major surfaces  22 ,  24 . Optionally, a raised or narrowed engagement section  27  may be formed within the contact receiving passageway  26 . At least the engagement section  27  and optionally the entire surface of the contact receiving passageway  26  is plated with a conductive material or series of conductive layers. The plating  28  may extend either over the engagement section  27 , along the entire inner surface of the contact receiving passageway  26  and also may extend over portions of the first and second major surfaces  22 ,  24  in the vicinity of each contact receiving passageway  26 . It should be understood, that while an array of four contact receiving passageways  26  are shown here in FIG. 1, this array is extendable in both dimensions to form suitable sized arrays having a plurality of contact receiving passageways  26  in order to accomplish the number of electrical interconnections necessary for a particular application.  
         [0013]    Next, the resilient contact  30  will be described in greater detail. The resilient contact  30  features a main body  36  which is located approximately in a central region of the contact  30 . Extending outward from the main body  36  are a pair of resilient sections extending to contact sections  32 ,  34 . In this exemplary embodiment, the main body  36  is a wound helical structure and the resilient sections are tapered helical structures continuously wound out from the main body  36 . The contact section  32 , extends beyond the first major surface  22  while the second contact section  34  extends beyond the second major surface  24 . The contact  30  is secured within its respective contact receiving passageway  26  by solder or an interference or frictional fit between the main body  36  and the plated engagement section  27  of the carrier  20 .  
         [0014]    An alternate embodiment of the carrier  120  and an alternate contact  130  will be described now with reference to FIGS. 2 and 3. The carrier  120  is similar to the carrier  20  in that it has first and second major surfaces  122 ,  124  and a plurality of contact receiving passageways  126  that extend therebetween. Each contact receiving passageway  126  contains plating  128  applied to the surfaces of the contact receiving passageway  126  and portions of the first and second major surfaces  122 ,  124 . The plating  128  is applied using well known techniques in the art for forming plated through holes in printed circuit boards. Each resilient contact  130  is similar to the resilient contact  30  in that it contains opposing contact sections  132 ,  134  which are located at free ends of resilient sections  138 . A main body  136  is fixed within each contact receiving passageway  126  and is in electrical contact with plating  128 . The resilient sections  138  that extend from the main body  136  are in the form of a serpentine spring. The main body  136 , the resilient sections  138  and the contact portions  132 ,  134  are each formed of a simply stamped conductive sheet. The contact section  132  extends beyond the major surface  122  and the contact section  134  extends beyond the major surface  124  each for contacting lands or pads on respective circuits to be interconnected.  
         [0015]    In operation, the land grid array connection  20 ,  120  allows current to pass between respective contact sections  32 ,  34 ,  132 ,  134  while the main body  36 ,  136  is in electrical contact with plating  28 ,  128  on the contact receiving passageways  26 ,  126 . When circuits are energized, there is therefore no electrical potential difference between the resilient contact  30 ,  130  and its respective carrier  20 ,  120 . Any electrical potential difference that may exist occurs between the plating  28 ,  128  and the carrier  20 ,  120 . Accordingly, any relative motion caused by vibration or impact between the contact  30 ,  130  and the contact receiving passageway  26 ,  126  of the carrier  20 ,  120  will not cause any electron flow since no electrical potential or electron build up exist between the contact  30 ,  130  and the plating  28 ,  128 . The undesirable effects of electron flow causing undesirable image patterns in medical imaging equipment is therefore minimized or eliminated.  
         [0016]    The plating  28 ,  128  within the contact receiving passageways  26 ,  126  also serve as a conductive path for any signal passing through a respective contact  30 , 130 . This has the advantageous effect of reducing the inductance of the interconnection across the contact  30 ,  130  and reduces the signal path length.  
         [0017]    The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.