Abstract:
A connector frame including a first component and a second component. The frame components substantially surround first and second connector halves, each half including an insulative housing and a plurality of contacts secured to the insulative housing. The frame components engage in order to progressively mate the contacts of the connector. A method of mating a connector including the steps of engaging the first and second components of the connector frame; and progressively connecting the contacts of the first and second connector halves.

Description:
RELATED APPLICATION 
     This invention is related to commonly assigned U.S. patent application Ser. No. 09/209,132, filed on Dec. 10, 1998, U.S. Pat. No. 6,093,042, herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector and more particularly to a connector frame for use with such a connector for achieving a low insertion force in an electrical connector with a high density and/or a large number of contacts. 
     2. Brief Description of Earlier Developments 
     Contemporary improvements in computer systems and communications equipment generally involve miniaturization and increased operating speeds. Designers must adapt the electrical connectors used in these systems to cope with such changes. Various attempts to reduce the size of electronic equipment, e.g. personal portable devices and integrated circuits, and to add additional functions to such equipment has resulted in an ongoing drive for miniaturization of all components, especially the electrical connectors. Efforts to miniaturize electrical connectors have included reductions in the pitch between terminals in single or double row linear connectors, so that a relatively high number of I/O or other lines can be interconnected. 
     Several types of electrical connectors exist that have adapted to miniaturization and to the increased operating speeds. One type is a zero insertion force (ZIF) connector. ZIF connectors use a force reduction mechanism either to spread a contact apart before receiving its mating contact or to provide mechanical advantage to a contact so that it may spread apart and engage its mating contact. 
     While beneficial in larger applications, current ZIF designs may not be preferred in high contact density, miniaturized environments. Due to the addition of a force reduction mechanism, ZIF connectors can be complex and costly, particularly when miniaturization is required. In addition, the use of smaller actuators may not have sufficient strength to spread a contact apart or to mate the contacts. The actuators also may not fit within footprint limitations. ZIF connectors may not provide sufficient contact wipe to ensure a stable electrical contact. Furthermore, even with a mechanical advantage, ZIF connectors may still have a peak insertion force that is undesirably high when each contact mates simultaneously. 
     Another type of electrical connector proposed for use in the high density, miniaturized environment, incorporates plug and receptacle halves, wherein one of the halves includes contacts with differential heights. Some of the contacts reside at one elevation, while the others reside at a different elevation. As the connector halves are pressed together, the taller contacts mate first, followed by the shorter contacts. The connector exhibits a lower peak insertion force because not all of the connectors mate in parallel (i.e. at the same time). 
     Connectors with differential height contacts, however, may not be preferred in high contact density miniaturized connectors. Producing differential height contacts are viewed as impractical due to the strict manufacturing tolerances required. 
     Consequently, a need exists for a connector that exhibits acceptable insertion force characteristics in a high density, miniaturized environment. 
     SUMMARY OF THE INVENTION 
     The shortcomings of the prior art are overcome in the present invention by a frame including a first component and a second component. The frame components substantially surround first and second connector halves, each half including an insulative housing and a plurality of contacts secured to the insulative housing. The frame components engage in order to progressively mate the contacts of the connector. Each frame is preferably stamped and formed from a sheet of suitable conductive material. 
     These and other objects of the present invention are achieved in another aspect of the present invention by a frame having a first component and a second component rotatably engageable along an axis of rotation. Each frame component substantially surrounds a connector half having an insulative housing and a plurality of contacts secured to the insulative housing. The contacts are arranged generally perpendicular to the axis of rotation. 
     These and other objects of the present invention are achieved in another aspect of the present invention by a method for mating a connector substantially surrounded by a connector frame, having a first component and a second component. The connector includes a first half and a second half, each including an insulative housing and a plurality of contacts secured to the housing. The method includes the steps of engaging the first and second components; and progressively connecting the contacts of the first and second connector halves. 
     These and other objects of the present invention are achieved in another aspect of the present invention by a board-to-board array conenctor which includes first and second halves, both attachable to respective substrates. The halves each include an insulative housing and a plurality of contacts secured to the housing and arranged in a series of columns. A board-to-board frame is also provided having first and second frame components, each substantially surrounding respective connector halves and secured to the surface of respective substrates. An end of the first frame component has a hinge assembly, for mating with a hinge mating portion of an end of the second frame component. The frame components are rotated to progressively mate columns of the connector halves in a direction away from the hinge assemblies. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other uses and advantages of the present invention will become apparent to those skilled in the art upon reference to the specification and the drawings, in which: 
     FIG. 1 is a plan view of a first connector frame component constructed in accordance with the present invention. 
     FIG. 2 is a side view of the portion of FIG. 1 denoted by  2 — 2 . 
     FIG. 3 is a plan view of a first embodiment of a second connector frame component in accordance with the present invention. 
     FIG. 4 is a side view of the portion of FIG. 3 denoted by  4 — 4 . 
     FIG. 5A is a side view of the first and second connector frame components of the first embodiment of the present invention before mating of a connector. 
     FIG. 5B is a side view of the first and second connector frame components of the first embodiment of the present invention during mating of a connector. 
     FIGS. 6A and 6B are illustrations of mated first and second connector frame components of the first embodiment of the present invention without modules surrounded thereby and/or attached thereto. 
     FIG. 7A is a perspective view of a second embodiment of a first connector frame component in accordance with the present invention. 
     FIG. 7B illustrates the hinge assembly of a second embodiment in accordance with the present invention. 
     FIG. 8 is a perspective view of a third embodiment of first and second connector frame components in accordance with the present invention. 
     FIG. 9 is a cut-out side view of a mating portion of the third embodiment of first and second connector frame components in accordance with the present invention. 
     FIG. 10 is a perspective view of a connector frame component of a fourth embodiment of the present invention. 
     FIG. 11 is a plan view of a first half of an exemplary high density connector to be mated by the various frame connector embodiments of the present invention. 
     FIG. 12 is a plan view of a second half of an exemplary high density connector to be mated by the various frame connector embodiments of the present invention. 
     FIG. 13 is a graph comparing estimated insertion forces with and without the connector frame of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In general, the present invention is a board-to-board electrical connector frame that surrounds electrical connector plug and receptacle halves to be mated, yielding a high density, low peak insertion force connector. In accordance with the present invention, rather than mating the contacts of the connector halves in parallel (i.e. all of the contacts at the same time), the connector frame sequentially mates the contacts. Sequential mating of the contacts is achieved by preferably rotating a first connector frame component holding one connector half relative to a second connector frame component holding the other connector half. Hinge assemblies on the first and second connector frame components interface to allow rotation and alignment of the contacts of the respective connector halves precisely. The sequential mating of the connector contacts by the connector frame of the present invention causes the connector to exhibit a lower peak mating force when compared to electrical connectors that mate contacts in parallel. 
     FIGS. 1-6 display a first embodiment of the present invention. As shown by FIG. 1, a first connector frame component  100 , for surrounding and holding one connector half, e.g., a receptacle half, to be positioned in rectangular region  120 , may have throughholes  105  for securing the connector frame to a printed circuit board, substrate or the like with suitable fasteners (e.g., screws, bolts or rivets). Extended portions  115  interlock with corresponding depressed connector half housing portions (not shown FIGS. 11 and 12) for precise alignment. It is noted that any structure or technique for securely mounting the connector half to frame component  100  can be utilized without departure from the present invention. Connector frame walls  110  and  111  extend vertically out of the plane of FIG. 1 so as to define a substantially U or J-shaped cross section. Holes  125  are formed on opposing sides of the frame  100 . Support rod  130 , which is the basis for one half of a hinge assembly of the first embodiment, has its ends inserted into holes  125 . In this embodiment, frame  100  is preferably stamped and formed from a suitable sheet of conductive material, such as stainless steel. 
     Rather than using holes  105  to mount frame  100  to PCB  50  with suitable fasteners, frame  100  could be mounted, for example, to pads (not shown) on PCB  50  with solder. As with holes  105 , preferably the corners of frame  100  mount to PCB  50 . In one embodiment, frame  100  could have bosses (not shown) stamped therein to extend below the remainder of frame  100 . The bosses would rest on the pads of PCB  50 , with the remainder of frame  100  preferably remaining spaced from PCB  50 . Frame  100  can mount to PCB  50  before, simultaneous with, or subsequent to mounting of connector half  300  to PCB  50 . To surface mount frame  100  to PCB  50 , frame  100  is preferably made from a suitable material, such as phosphor bronze, or the material could have a suitable plating thereon. 
     As shown in FIG. 3, a second connector frame component  200 , for surrounding and holding another connector half, e.g. a plug half, to be positioned in rectangular region  220  may have throughholes  205  for securing the connector frame to a printed circuit board, substrate or the like. Extended portions  215  interlock with corresponding depressed portions of the connector housing (not shown FIGS.  11  and  12 ?) for precise alignment. Again, it is noted that any structure or technique for securely mounting the connector half to frame component  100  can be utilized without departure from the present invention. Connector frame walls  210  and  211  extend vertically out of the plane of FIG. 3 so as to define a substantially U or J-shaped cross section. 
     When connector frame components  100  and  200  are mated, walls  110  and  210  preferably align in a generally co-planar manner. Whereas walls  211  are formed to align in a side by side manner with walls  111 . This positioning is assisted by bent corner  230 . In operation, as connector frame component  200  rotates towards connector frame component  100  any misalignment is corrected by the sliding action of wall  111  over bent corner  230 . The bent corners  230  act as a lead-in surface which provides, initially, rough alignment between the frames  100 ,  200 , then progressively finer alignment with further rotation of the frames  100 ,  200 . As seen in FIG. 5B, the frames  100 ,  200  achieve sufficient alignment before any mating of contacts  300   a ,  400   a  occurs. If necessary, however, the contacts  300   a ,  400   a  can provide additional minor alignment to the connector during mating. 
     FIGS. 5 and 6 demonstrate workings of the hinge assembly and correspondingly, the mating action for plug and receptacle connector modules  300  and  400  positioned within and attached to frame components  100  and  200 . Although shown as a single module, frames  100 ,  200  could accept a plurality of modules  300 ,  400 . Each module  300 ,  400 , preferably, would fit in a correspondingly sized opening  120 ,  220 . Connector half  400  is surrounded by connector frame component  100 , which in turn is secured to a substrate  50 , such as a printed circuit board. Similarly, connector half  300  is positioned within and attached to frame component  200 , which is secured to a substrate  60 . Curved portions  225  are formed so as to hook between rod  130  and the bottom of frame  100 . Rod  130  defines an axis  135  about which connector frame components  100  and  200  are rotatable with respect to each other. FIG. 5B shows the connector halves  300  and  400  in an unmated or open position. FIG. 5B shows the connector halves  300  and  400  in a near mated position i.e., at the point of rotation of connector frame components  100  and  200  right before the contacts of the connector halves touch. It will be appreciated from this view that subsequently, a sequential mating of contacts will occur. First, row of contacts  300   a  will mate with row of contacts  400   a , then row of contacts  300   b  will mate with row of contacts  400   b , then row of contacts  300   c  will mate with row of contacts  400   c , and so on. Due to the sequential mating of rows, the peak insertion force for the connector will be minimized since the insertion forces associated with the individual rows of contacts do not occur simultaneously. 
     The difference in the coefficient of thermal expansion (CTE) of the substrates and the connector, and coplanarity of the connector frames are two important considerations with large scale array connectors. CTE differential can introduce stress into the solder joints that couple the connector and the substrate. Solder joint stress potentially reduces the thermal reliability of the connector. CTE differential can also warp the connector. Connector warp potentially misaligns the mating connectors, increasing the required peak insertion force. Connector warp may also affect the coplanarity of the fusible components that couple the connector to the substrate. It can thus be appreciated that the provision of separate components which make each connector frame allows for some small amount of movement between connectors, to reduce the effects of CTE mismatch, while still providing precise alignment of the connector halves. FIGS. 6A and 6B are illustrations of mated first and second connector frame components of the first embodiment of the present invention without modules  300 ,  400 . 
     FIG. 7A depicts an alternative embodiment of a connector frame construction in accordance with the present invention. A portion of a first connector frame half  500  having a part of a hinge assembly formed thereon is shown. Portions  515  of sheet metal base frame  520  have been scaled back and bent upwards to form a substantially circular arch  505  defining throughputs  510 . Connector frame half  500 , similar to connector frame  100 , is designed to surround and attach to a connector half as with the first embodiment. Frame  500  is preferably soldered around arch  505  to prevent frame  500  from lifting off of a printed circuit board (PCB). 
     The structure of frame half  500  can be used with a connector frame component  200 , as described with respect to the first embodiment. In such a combination, the rod  130  of the first embodiment is replaced by arch  505 , throughputs  510  and the area underneath arch  505 . With a corresponding arch portion  505  located on the other side of such a connector frame component  500 , the mating action will be substantially the same as shown and described with respect to FIGS. 5 and 6. The arch portions  505 , correspond to and cooperate with curved portions  225  of a connector frame component  200 , providing an axis of rotation to achieve sequential contact mating of a connector. 
     FIG. 7B illustrates the hinge assembly of FIG. 7A in more detail. A curved portion  225 , when directed towards and underneath arch  505  via throughputs  510 , forms the hinge assembly of the present embodiment. Arch  505  is elevated to allow curved portion/extension  225  to slide underneath more easily. 
     FIGS. 8-9 illustrate a third embodiment of a connector frame constructed in accordance with the present invention. A portion of a first connector frame component  600  and a portion of a second connector frame component  650  constitute a part of a hinge assembly. Frame component  600  has an extending tang  610  adapted to fit inside hinge hole  660  in frame component  650 . Tang  610  preferably has a width less than the diameter of hinge hole  660  to allow rotation of the frames  100 ,  200  without interference. Connector frame components  600  and  650 , similar to frame halves  100  and  200 , are designed to surround and attach to connector halves as with the first and second embodiments. Consequently, when connector frame component  650  rotates about an axis y substantially defined by the center of hinge hole  660 , sequential mating of the contacts of connector halves surrounded by the frame components is achieved. FIG. 9 is a section view of the tang  610 /hole  660  hinge assembly when connector frame components  600  and  650  have positioned a connector in the un-mated condition. 
     In this embodiment, frame  650  deflects tab  610  during insertion into frame  600 . Once hole  660  aligns with tab  610 , tab  610  will resile to a position within hole  660 . Other methods of securing frames  600 ,  650  are possible, however. For instance, tab  610  could be bent into hole  660  after frame  650  is aligned with frame  600 . In addition, side wall  601  of frames  600  could have a dimple (not shown) rather than tab  610 . Similar to the other embodiments, the dimple would reside within hole  660  of frame  650  to allow rotation of frames  600 ,  650 . 
     As seen in FIG. 8, side walls  601  of frame  600  include outwardly flared sections  603 . As with bent corners  230  of frame  200 , outwardly flared sections  603  act as lead-in surfaces. Outwardly flared sections  603  provide, initially, rough alignment between frames  600 ,  650 . The outwardly flared sections  603  then provide progressively finer alignment with further rotation of the frames  600 ,  650 . The frames  600 ,  650  achieve sufficient alignment before any mating of contacts occurs. If necessary, however, the contacts can provide additional minor alignment to the connector during mating. 
     FIG. 10 is a perspective view of a further embodiment of a connector frame constructed in accordance with the present invention. Connector frame component  700  can be employed in conjunction with connector frame half  100  of the first embodiment, the connector frame component  500  of the second embodiment, and like embodiments. If used in conjunction with frame half  100 , rectangular or U-shaped indentations  710  guide connector frame component  700  onto rod  130 . Connector frame component  700  can then rotate about rod  130 , to achieve the sequential mating as taught and described with respect to FIGS. 5 and 6. 
     Each of the embodiments of a connector frame in accordance with the present invention are designed so that a connector frame component surrounds, positions, mounts to or holds a connector half stationary relative to the connector frame component. FIGS. 11 and 12 illustrate exemplary plug and receptacle connector modules. Connector halves  300  and  400  generally have a planar insulative housing  315  and  415 , respectively, and are preferably manufactured from a plastic, such as liquid crystal polymer (LCP). Connector halves  300  and  400  have a mounting side (not shown) that faces a substrate, e.g., and is suitable for the arrangement and attachment of various types of high density grid array solder technology such as ball grid array, ceramic grid array, column grid array and the like, and as disclosed in International Publication number WO 98/15989 (hereby incorporated by reference). 
     Arrays of contacts  310  and  410   a-b  reside within arrays of apertures  305  and  420  in housings  315  and  415 , respectively. Apertures  305  and  420  preferably retain contacts  310  and  410   a-b  within housings  315  and  415  using, for example, a projection extending into the apertures from a side wall. Contacts  315  and  415  remain within apertures  305  and  420 , e.g., by an interference fit with the projection. Since connector half  300  generally mates with connector half  400  along an axis that is generally defined by the various hinge assemblies of connector frame embodiments of the present invention, contacts  310  and  410   a-b  are also generally perpendicular to the mating axis of connector halves  300  and  400 . Housings  315  and  415  extend around the perimeter to protect contacts  310  and  410   a-b  from damage and act as a board stiffener. As seen in FIGS. 1 and 3, and as could be the case for any of the embodiments of the present invention, walls  110  and  210  can extend around the entire perimeter of housings  315  and  415 , and portions  115 ,  215  frictionally retain modules  300 ,  400  by engaging depressed portions  325 ,  425 . Other methods of retaining modules are possible. For instance, modules  300 ,  400  could have a stop (not shown) or latch structure (not shown) to retain the portions  115 ,  215  to modules  300 ,  400  in a more positive manner than a friction fit. 
     Although the figures display blade-type contacts on the plugs, other types of contacts, such as round pins, could be used with the present invention. In addition, the connector halves  300  and  400  could employ several different types of contacts at one time. Also, some contacts could carry a signal or ground, while others carry power. This, for example, allows the connectors of the present invention to be hot matable. 
     FIG. 13 compares the estimated insertion forces for a typical connector and estimated insertion forces for a connector mated with a connector frame of the present invention. As used herein, a typical connector refers to a connector in which all of the contacts mate in parallel. In other words, a typical connection without a connector frame in accordance with the present invention mates all of the contacts at the same time. A typical connector produces the insertion force-versus-time path designated  901  in FIG. 13. A typical connector exhibits a peak at the point designated  903  along path  901 . The peak is located approximately midstream along the time period. 
     A connector frame of the present invention mating a connector (using the same number of contacts, but sequentially mated) produces the insertion force-versus-time path designated  905  in FIG.  13 . The connector frame technique of the present invention exhibits a peak at the point designated  907  along path  905 . The peak is located approximately at the end of the time period. Hence, the peak insertion force  907  due to a connector frame of the present invention is well below the peak insertion force  903  of a parallel mating of a typical connector. 
     While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modification and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. For example, while an exemplary connector has been depicted in FIGS. 11 and 12, it can be appreciated by one of ordinary skill in the art of connector design, that numerous variations of high density connectors exist, and that it would be obvious to include variant connector designs with the rotatable mating as provided in the present invention. Furthermore, while a connector frame in accordance with the present invention is preferably made of sheet metal, for durability and low cost of manufacture, there are numerous materials, such as plastics, ceramics, and the like which would also provide low cost, high durability solutions. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.