Abstract:
Described is a single connector attachment (SCA) connector that improves blind mating between plug and receptacle SCA connectors. The SCA connector has an insulative shell with opposing end walls and opposing sidewalls. The end walls and sidewalls define a substantially rectangular recess within which a plurality of electrical contacts is disposed. One of the end walls of the shell has a chamfer. The slope of the chamfer enables plug and receptacle SCA connectors to continue coming together although their respective housings may come against each other before the alignment guiding features of the SCA connectors are able to achieve alignment.

Description:
FIELD OF THE INVENTION 
   The invention relates generally to electrical connectors. More particularly, the invention relates to improved mating for single connector attachment (SCA) disk connectors. 
   BACKGROUND 
   Fibre Channel is an electrical interface standard used to interconnect devices physically. Various types of electrical connectors can be used in support of Fibre Channel. One type is a single connector attachment (SCA) connector. One SCA connector connects a Fibre Channel disk drive directly to a midplane or backplane of a storage enclosure and carries the command signaling, power input signals, and outputs required by the disk drive. Typically, the disk drive has a plug (male) SCA connector that mates with a receptacle (female) SCA connector on the midplane. The current version of SCA is SCA-2, and the SFF (Small Form Factor) Committee standard SFF-8451 governs the SCA-2 connector interface. 
     FIG. 1  shows a prior art receptacle SCA connector  10  about to mate with a plug SCA connector  12 . At opposite ends of the receptacle SCA connector  10  are alignment guides  14 - 1 ,  14 - 2  (generally,  14 ). Each alignment guide  14  receives a respective alignment post  16 - 1 ,  16 - 2  when the plug and receptacle SCA connectors join. The alignment guides  12  facilitate blind mating, that is, a user can connect a disk drive to the midplane without needing to see either the plug or receptacle SCA connector. 
   The plug and receptacle SCA connectors each have a respective D-shaped housing  18 ,  20  with one or more rows of contacts (or pins) disposed therein (not shown). Normally, the housing  18  of the plug SCA connector closely receives the housing  20  of the receptacle SCA connector. Under certain conditions, however, the plug and receptacle SCA connectors will not mate, although all physical features of the plug and receptacle SCA connectors, and the delivery system (e.g., drive bay) that joins them, conform to the SCA-2 industry standard for SCA connectors. For example, when the angle of plugging a disk drive into a midplane slightly diverges from perpendicular relative to the midplane, the plug and receptacle SCA connectors can bind before their contacts regions are able to mate. More specifically, the housings  18 ,  20  of the plug and receptacle connectors may collide (at point  22 ) before the alignment guides  12  are able to align the plug SCA connector properly with respect to the receptacle SCA connector. 
   SUMMARY 
   In one aspect, the invention features a single connector attachment (SCA) connector comprising an insulative shell having opposing end walls and opposing sidewalls. The end walls and sidewalls define a substantially rectangular recess within which a plurality of electrical contacts is disposed. One of the end walls of the shell has a chamfer. 
   In another aspect, the invention features a storage system comprising a midplane and one or more single connector attachment (SCA) connectors connected to the midplane. Each SCA connector includes an insulative shell with opposing end walls and opposing sidewalls. The end walls and sidewalls define a substantially rectangular recess within which a plurality of electrical contacts is disposed. One of the end walls of the shell has a chamfer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and further advantages of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
       FIG. 1  is a side view of a prior art receptacle SCA connector about to mate with a prior art plug SCA connector. 
       FIG. 2  is a side view of an embodiment of a receptacle SCA connector constructed in accordance with the invention, with a chamfer at one end of a D-shaped shell or housing. 
       FIG. 3  is a side view of the chamfer in closer detail. 
       FIG. 4  is a top view of the receptacle SCA connector of  FIG. 2 . 
       FIG. 5  is a perspective view of the receptacle SCA connector of  FIG. 2 . 
       FIG. 6  is a side view of another embodiment of a receptacle SCA connector constructed in accordance with the invention. 
       FIG. 7  is a perspective view of a disk drive with a plug SCA connector about to connect to one of a plurality of receptacle SCA connectors on a midplane. 
   

   DETAILED DESCRIPTION 
   Receptacle SCA connectors constructed in accordance with the present invention include a chamfer at one or both ends of the insulative shell that houses the electrical contacts and mates with the contact housing of a plug SCA connector. In general, the chamfer is a beveled edge at an end of the shell. In one embodiment, the chamfer alters the radius of the D-shape of a standard receptacle SCA connector. This change of the D-shape facilitates mating, particular blind mating, between the plug and receptacle SCA connectors. 
   In general, SCA-2 standards, e.g., SFF-8451 for 40- and 80-pin SCA connectors and draft standard SFF-8053i for 20-pin SCA connectors, specify the size, length, width, height, board mounting, pin location, and specific mating features. Such standards provide some latitude that allows suppliers to distinguish their SCA connector from other connectors: not all features of SCA connectors are covered. For example, the radius of the D-shaped shell (one at each end) is a feature that the SCA-2 standards do not specify (and, thus, typically varies from supplier to supplier). Accordingly, the receptacle SCA connectors of the invention conform to the relevant SCA-2 standard since the chamfers modify a non-standardized feature. Further, receptacle SCA connectors of the invention can be used with standard SCA-2 compliant plug SCA connectors. 
     FIG. 2  shows a side view of an embodiment of a receptacle SCA connector  40  constructed in accordance with the invention. The receptacle SCA connector  40  includes a connector body  42  and an insulative shell or housing  44 . The connector body  42  has an alignment guide  46  at each end of the connector  40 . The insulative shell  44  has a recess (shown in phantom) that houses a plurality of contacts, here seen extending through the connector body  42  and emerging as pins  48 . In this embodiment, there are 20 pins. Other embodiments can have fewer or more (e.g., 40, 80) than 20 pins, without departing from the principles of the invention. 
   At one end of the insulative shell  44  is a chamfer  50 . The slope of the chamfer  50  prevents the insulative shell  44  of the receptacle SCA connector  40  from binding if the shell  44  comes against the housing of the plug SCA connector during mating. As a result, the insulative shell  44  can enter the housing of the plug SCA connector sufficiently far to allow the alignment posts of a plug SCA connector to engage the alignment guides  46  of the receptacle SCA connector and thus align the SCA connectors for proper mating. 
     FIG. 3  shows a side view of the chamfer  50  in closer detail. The chamfer  50  is disposed at a corner region (shown within a circle  60  in  FIG. 2 ) of the insulative shell  44 , at a juncture of an end wall  62  and a top edge  64  of the insulative shell  44 . The chamfer  50  is at an angle θ with respect to a plane  65  defined by an outer side surface  67  of the end wall  62 . The plane  65  is illustrated as a dashed line with double-headed arrows extending tangential to the outer side surface  67  of the end wall  62 . In one embodiment, the angle θ is approximately 30 degrees. Angles other than 30 degrees can be used in the practice of the invention, provided the chamfer  50  has sufficient slope to prevent the insulative shell  44  from binding, as described above. In one embodiment, the chamfer  50  is 1 mm×2 mm in dimension. More specifically, the chamfer  50  “cuts away” approximately 1 mm (denoted by reference numeral  66 ) of the top edge  64  and 2 mm (denoted by reference numeral  68 ) of the end wall  62 . 
   Referring now to  FIG. 4  and  FIG. 5 ,  FIG. 4  shows a top view of the receptacle SCA connector  40  of  FIG. 2 , with the D-shaped insulative shell  44  and alignment guides  46 , and  FIG. 5  shows a perspective view of the receptacle SCA connector  40 . The insulative shell  44  has opposing end walls  62 - 1 ,  62 - 2  (generally,  62 ) and opposing sidewalls  80 - 1 ,  80 - 2  (generally,  80 ). The end walls  62  and sidewalls  80  define a generally rectangular recess  82  within which are disposed the contacts  88 . Each end wall  62  has a curved edge (corresponding to the curved ends of the D-shaped shell  44 ). Here, the end wall  62 - 1  has the chamfer  50 , which cuts into curved edge of that end wall. Each alignment guide  46  has a recess  84  for receiving an alignment post of a plug SCA connector. 
     FIG. 6  is a side view of another embodiment of a receptacle SCA connector  40 ′ constructed in accordance with the invention. The receptacle SCA connector  40 ′ is similar in construction to the receptacle SCA connector  40  of  FIG. 2 . One difference: the receptacle SCA connector  40 ′ has a plurality of chamfers  50 - 1 ,  50 - 2 , whereas the receptacle SCA connector  40  has only one. For the receptacle SCA connector  40 ′, each end wall  62 ′- 1 ,  62 ′- 2  has a respective chamfer  50 - 1 ,  50 - 2 . By having a chamfer at each end of the shell  44 ′, the receptacle SCA connector  40 ′ is symmetric and, thus, can accommodate misalignment of the plug SCA connector at either end. 
     FIG. 7  shows a data storage environment  100  in which receptacle SCA connectors constructed in accordance with the invention may be used. The data storage environment  100  includes an enclosure (not shown), at least one disk drive  102  with a plug SCA connector  104 , here, about to connect to one of a plurality of receptacle SCA connectors  40  mounted to a midplane  106  by way of a delivery system (not shown), e.g., a drive storage bay. As another exemplary environment, the plug SCA connector  104  can be incorporated in a hard drive for use in a personal computer, and the receptacle SCA connector  40  mounted to a motherboard. 
   While the invention has been shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims. For example, as described herein, receptacle SCA connectors are mounted on a backplane or midplane and plug SCA connectors are incorporated into hard drives or disk drives, however, such roles can be reversed without departing from the principles of the invention.