Patent Publication Number: US-2003224662-A1

Title: Short span compression connector for a disc drive

Description:
RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 60/384,940 filed May 30, 2002 entitled Short-Span Compression Connector. 
    
    
     
       FIELD OF THE INVENTION  
       [0001] The claimed invention relates generally to the field of digital data storage systems, and more particularly but not by way of limitation, to an apparatus and method for a short span compression connector for a data storage device.  
       BACKGROUND  
       [0002] Disc drives are used for data storage in modern electronic products ranging from digital cameras to computers and network systems. Ordinarily, a disc drive includes a mechanical portion, or head disc assembly, and electronics in the form of a printed circuit board assembly mounted to an outer surface of the head disc assembly. The printed circuit board assembly controls functions of the head disc assembly and provides a communication interface between the disc drive and a host being serviced by the disc drive.  
       [0003] Typically, the head-disc assembly has a disc with a recording surface rotated at a constant speed by a spindle motor assembly and an actuator assembly positionably controlled by a closed loop servo system. The actuator assembly supports a read/write head that writes data to and reads data from the recording surface.  
       [0004] The disc drive market continues to place pressure on the industry for disc drives with increased capacity at a lower cost per megabyte, higher rates of data throughput between the disc drive and the host and improved reliability.  
       [0005] Compression-type electrical connectors have an important role to play in modern disc drive assemblies. Due to manufacturability and efficient design, compression-type connectors are often the connector of choice for head-disc assembly applications, including flex circuitry, and service between the head-disc assembly and the printed circuit board assembly of the disc drive.  
       [0006] As the thickness of printed circuit boards continues to decrease, the amount of flex or warpage undergone by the printed circuit board increases. This is particularly true in the region of the compression-type connector, since connector contacts put a significant load on the printed circuit board, by necessity in a direction that decreases the contact force and thus the quality of the contact.  
       [0007] The severity of deflection of the printed circuit board can result in acceptable performance for contacts near the clamping means of the connector and unacceptable performance for contacts further from the clamping means. A typical technique to combat such effects is to fit more clamping means, which introduces yet another series of problems.  
       [0008] As such, challenges remain and a need persists for improvements in compression-type electrical connectors for use in disc drive type applications  
       SUMMARY OF THE INVENTION  
       [0009] In accordance with preferred embodiments, an apparatus for facilitating an electronic transfer of data is provided, which includes a compression connector housing with a clamping aperture, a plurality of compression contacts mounted to the compression connector housing, and a printed circuit board assembly with a contact pad corresponding with each of the plurality of compression contacts.  
       [0010] Each compression contact is maintained under a compressive load against corresponding contact pad by a compressive force imparted on the compressive connector housing by a fastener. The fastener includes an engagement portion and a head portion; the engagement portion passes through a fastener access aperture (sized to restrict passage of the head portion) and engages the clamping aperture. Upon full engagement with the clamping aperture a substantially uniform contact force between each of the plurality of compression contacts and each of the corresponding contact pads is attained.  
       [0011] Each compression contact conforms to a right triangle dimensional relationship defined by the following criteria: a connector housing with a clamping aperture, the connector housing having a length and a width; and a plurality of contacts communicating with the connector housing, wherein a line congruent with and substantially equal to the width of the connector housing forms a first leg of a right triangle, a line congruent with the length of the connector housing forms a second leg of the right triangle, a hypotenuse of the right triangle is formed by a line connecting the first leg to the second leg while bisecting the clamping aperture into two substantially equal portions to form a right triangular dimensional relationship between the width of the connector housing, the length of the connector housing and the clamping aperture of the connector housing, and further wherein a maximum length of a second leg substantially 1.5 times the length of the first leg.  
       [0012] These and various other features and advantages that characterize the claimed invention will be apparent upon reading the following detailed description and upon review of the associated drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013]FIG. 1 is a plan view of a disc drive constructed and operated in accordance with preferred embodiments of the present invention.  
     [0014]FIG. 2 is a perspective view of a functionally generic short-span compression connector of the disc drive of FIG. 1.  
     [0015]FIG. 3 is a plan view of a short-span compression connector with a single retention feature of the disc drive of FIG. 1.  
     [0016]FIG. 4 is a plan view of a short-span compression connector with a plurality of retention features of the disc drive of FIG. 1.  
     [0017]FIG. 5 is a partial cutaway elevational view of the short-span compression connector of FIG. 3 communicating with a flex circuit and held in compressive load with a printed circuit board assembly of the disc drive of FIG. 1 by a fastener.  
     [0018]FIG. 6 is a partial cutaway plan view of the of the printed circuit board assembly of FIG. 5.  
     [0019]FIG. 7 is an elevational view of the fastener of FIG. 5.  
     [0020]FIG. 8 is a flow chart of a method for facilitating electronic data exchange.  
    
    
     DETAILED DESCRIPTION  
     [0021] Referring now to the drawings, FIG. 1 provides a top plan view of a disc drive  100 . The disc drive  100  includes a rigid base deck  102 , which cooperates with a top cover  104  (shown in partial cutaway) to form a sealed housing for a mechanical portion of the disc drive  100 . Typically, the mechanical portion of the disc drive  100  is referred to as a head disc assembly  106 . A spindle motor  108  rotates a number of magnetic data storage discs  110  at a constant high speed. A rotary actuator  112  supports a number of data transducing heads  114  adjacent the discs  110 . The actuator  112  is rotated through application of current to a coil  116  of a voice coil motor (VCM)  118 .  
     [0022] During data transfer operations with a host device (not shown), the actuator  112  moves the heads  114  to concentric data tracks (one represented at  120 ) on the surfaces of the discs  110  to write data to and read data from the discs  110 . When the disc drive  100  is deactivated, the actuator  112  moves the heads  114  to texturized landing zones  122 ; the actuator  112  is then confined by latching a toggle latch  124 . Command and control electronics for the disc drive  100  are provided on a printed circuit board assembly  126  mounted to the underside of the base deck  102 .  
     [0023] It will now be understood that the present invention (as embodied herein and as claimed below) is generally directed to a short-span compression connector for data transfer applications. In a preferred embodiment, one such application is a short-span compression connector  128  attached to a flex-circuit  130  for use in conducting signals between the heads  114  and the printed circuit board assembly  126  mounted to the underside of the head disc assembly  124 .  
     [0024] Turning to FIG. 2, shown therein is a generic short-span compression connector  132  with a plurality of compression contacts  134  supported by a connector housing  136  that includes an attachment means  138  (also referred to as clamping means  138 ). It is noted that the clamping means provides a reasonably symmetric clamping force to each of the plurality of compression contacts  132  absent a need for external mechanical support such as stiffeners.  
     [0025] In a preferred embodiment, the warpage characteristics of a mating member (such as a printed circuit board assembly  126 ) with the short span compression connector  132  determines a direction for mounting the short span compression connector  132  to the mating member. For example, if a maximum warpage curvature of a printed circuit board occurs in one direction, the shortest side of the compression connector  132  is aligned in that direction. The connector housing  136  is preferably of a circular configuration (or any regular polygon of more than three sides).  
     [0026] The preferred embodiment is not specific as to the type of compression contacts  134  used. In general, any compression connector system must have mechanical compliance somewhere in the connector system, and that is generally and most easily provided in the contact structure. Beam type contacts, knitted wire contacts, or virtually any other type of contact, which includes mechanical compliance are anticipated for use by the present invention.  
     [0027] The substantially symmetric housing  136  provides the clamping means  138  substantially centrally located relative to the compression contacts  134 . The compression contacts  134  are configured to communicate directly with contact pads of a printed circuit board assembly. A fastener inserted through the printed circuit board assembly and communicating with the clamping means  138  provides the contact clamping force sufficient for reliable cooperation between the contact pads of the printed circuit board assembly and the compression contacts  134  of the generic short-span compression connector  132 .  
     [0028] The configuration of the generic short-span compression connector  132  is a preferred configuration for printed circuit board assemblies that demonstrate symmetry in warpage or for mounting surfaces less susceptible to warpage, such as the actuator  112  (of FIG. 1). Note that the clamping force provided to each of the compression contacts  134  must be essentially the same, because each contact  134  is dimensionally the same distance from the axis of the clamping means  138 .  
     [0029] Typically, a printed circuit board of a printed circuit board assembly is fabricated using a woven fiberglass base material, which has definite warp and woof directions; the board deflection in the two directions may not be equivalent. Lack of directional warpage symmetry of the printed circuit board assembly is accommodated by the present invention. As shown by FIG. 3, an alternate configuration of the preferred embodiment of the present invention is short-span compression connector  140 , which contemplates asymmetric warpage of a printed circuit board assembly by presenting a compression connector housing  142  of greater length than width. The direction of the more severe warpage per unit force shown by force vector  144 , is the direction selected for parallel alignment of the compression connector housing  142  along the width of the compression connector housing  142 . While the direction for the less severe warpage per unit force applied, shown by force vector  146 , is the direction selected for parallel alignment of the compression connector housing  142  along the length of the compression connector housing  142 .  
     [0030] By taking into consideration be warpage characteristics of a printed circuit board assembly, a substantially constant contact force between each of a plurality of compression contacts  148  and corresponding contact pads of a mating printed circuit board assembly may be maintained while increasing the overall pin count of compression connector  140 . In a preferred embodiment, each of the plurality of compression contacts  148  communicating with the connector housing  142 , maintains a dimensional relationship relative to a clamping aperture  150  that assures a substantially constant contact force between each of the plurality of compression contacts  148  and corresponding contact pads of the mating printed circuit wiring board.  
     [0031] Because of the asymmetrical characteristics at the printed circuit board, the connector housing  142  maintains an aspect ratio (length to width) of not more than 1.5. By maintaining an aspect ratio of not more than 1.5 for the connector housing  142  and by aligning the length of the connector housing  142  parallel to force vector  146 , a compressive load imparted on the clamping aperture  150  is distributed across each of the compression contacts  148  to assure proper electrical connection. Because the contact force eminates from the clamping aperture  150 , the aspect ratio of 1.5 is maintained relative to the clamping aperture  150 .  
     [0032] By adhering to the following triangular relationship, the aspect ratio of 1.5 for the compression connector housing  142  is maintained. The triangular relationship of interest occurs when the following conditions are true.  
     [0033] A line congruent with, and substantially equal to, the width of the compression connector housing  142  forms a first leg  152  of a right triangle  154 . A line congruent with a length of the compression connector housing  142  forms a second leg  156  of the right triangle  154 . A hypotenuse  158  of the right triangle  154  is formed by a line connecting the first leg  152  of the right triangle  154  to the second leg  156  of the right triangle  154  in which the line forming the hypotenuse  158  bisects the clamping aperture  150  into two substantially equal portions.  
     [0034] This right triangle, dimensional relationship between the width and a length of compression connector housing  142  and the clamping aperture  150  allows for short-span compression connectors of varying length. FIG. 4 shows a short-span compression connector  160  with a length substantially twice the length of the short-span connector  140  (of FIG. 3). Incorporation of a plurality of clamping apertures  162  into a connector housing  164  of the short-span compression connector  160  assures the right triangle dimensional relationship between the width and a length of the compression connector  160  and at least one of the plurality of clamping apertures  162  is maintained.  
     [0035]FIG. 5 shows the short-span compression connector  140  (of FIG. 3) attached to a flex circuit  130  of the disc drive  100  (of FIG. 1) and communicating with the printed circuit board assembly  126  of the disc drive  100 . A predetermined substantially uniform contact force is maintained between each of the plurality of compression contacts  148  and the printed circuit board assembly  126  by an engagement of a fastener  168  with the clamping aperture  150  of FIG. 3.  
     [0036] A convenient technique found for securing the fastener  168  to the clamping aperture  150  is to thread the interior wall of the clamping aperture  150  and select a corresponding screw such as the fastener  168  for engagement with the interior threaded wall. However, neither use of a screw for the fastener  168  or threaded walls for the clamping aperture  150 , whether used alone or in combination, constitute a limitation of the present invention. A multitude of alternative fastening techniques is well known in the art, any of which may be selected while remaining within the scope of the present invention.  
     [0037]FIG. 6 shows a plurality of contact pads  170  provided by the printed circuit board assembly  126 . Also shown in FIG. 6 is a fastener access aperture  172  of the printed circuit board assembly  126 . The fastener access aperture  172  promotes passage of the fastener  168  (of FIG. 5) for engagement with the clamping aperture  150 . Each of a plurality of contact pads  170  corresponds to a specific one of the compression contacts  148  of the compression connector  140  (of FIG. 3.)  
     [0038] Turning to FIG. 7, shown therein is the fastener  168  (of FIG. 5) having an engagement portion  174  and a head portion  176 . It is noted that the fastener access aperture  172  is sized to restrict passage of the head portion  176 , of the fastener  168 , while allowing passage of the engagement portion  174  of the fastener  168 . While FIG. 8 shows a flow chart  180  of a method for facilitating electronic data exchange, through the use of the compression connector  140  (of FIG. 3), starting at start step  182  and continuing at process step  184 . At process step  184 , each of the plurality of compression contacts  148  (of FIG. 3) are aligned with a corresponding contact pad of the plurality of contact pads  170  of the printed circuit board assembly  126  (of FIG. 6.)  
     [0039] At process step  186 , a substantially uniform contact force between each of the plurality of compression contacts  148  and one each of the corresponding plurality of contact pads  170  is attained by means for clamping each of the plurality of compression contacts  148  adjacent each of the corresponding plurality of contact pads  170 . The process concludes at end step  188 .  
     [0040] The means for maintaining the substantially uniform contact force includes a short-span compression connector housing  142  with a clamping aperture  150 , the connector housing  142  supporting the plurality of compression contacts  148  (of FIG. 3). Wherein a line congruent with, and substantially equal to, the width of the compression connector housing  142  forms a first leg  152  of a right triangle  154 . A line congruent with a length of the compression connector housing  142  forms a second leg  156  of the right triangle  154 . A hypotenuse  158  of the right triangle  154  is formed by a line connecting the first leg  152  of the right triangle  154  to the second leg  156  of the right triangle  154  in which the line forming the hypotenuse  158  bisects the clamping aperture  150  into two substantially equal portions, wherein a maximum length of a second leg  156  of the right triangle  154  is substantially 1.5 times the length of the first leg  152  of the right triangle  154 .  
     [0041] The compressive load developed to assure a proper connection is attained by passing the engagement portion  174  of the fastener  168  (of FIG. 7) through the fastener access aperture  172  of the printed circuit board assembly  126  (of FIG. 6) and engaging a threaded surface of the clamping aperture  150  of the compression connector housing  142  (of FIG. 3) with the engagement portion  174  of the fastener  168 . By torquing the fastener  168  to full engagement with the clamping aperture  150 , a substantially uniform contact force between each of the plurality of compression contacts  148  and each of the corresponding contact pads  170  is attained and maintained.  
     [0042] In accordance with preferred embodiments, a short-span compression connector (such as  140 ), with an attached flex circuit (such as  130 ), is positioned adjacent a printed circuit board assembly (such as  126 ). The printed circuit board assembly provides a contact pad (such as  170 ) corresponding to each of a plurality of corresponding compression contacts (such as  148 ) of the short-span compression connector.  
     [0043] Upon alignment of each of the plurality of compression contacts with each of the corresponding contact pads, a fastener (such as  168 ) is passed through a fastener access aperture (such as  172 ) of the printed circuit board assembly, and into mating contact with a clamping aperture (such as  150 ) of the short-span compression connector. Engagement of the fastener with the clamping aperture imparts and maintains a substantially constant contact force between each of the plurality of compression contacts of the short-span connector and the corresponding contact pads of the mating printed circuit board assembly.  
     [0044] Further in accordance with preferred embodiments, a data storage device (such as disc drive  100 ) includes a head disc assembly (such as  106 ) with a printed circuit board assembly (such as  126 ) attached to the head disc assembly, and a short-span compression connector (such as  140 ) attached to a flex circuit (such as  130 ) communicating with the printed circuit board assembly. The short-span compression connector includes a connector housing (such as  142 ) with a clamping aperture (such as  150 ), and a plurality of contacts (such as  148 ) communicating with the connector housing, wherein a line congruent with, and substantially equal to, the width of the compression connector housing (such as  142 ) forms a first leg (such as  152 ) of a right triangle (such as  154 ). A line congruent with a length of the compression connector housing forms a second leg (such as  156 ) of the right triangle. A hypotenuse (such as  158 ) of the right triangle is formed by a line connecting the first leg of the right triangle to the second leg of the right triangle in which the line forming the hypotenuse  158  bisects the clamping aperture into two substantially equal portions, wherein a maximum length of a second leg of the right triangle is substantially 1.5 times the length of the first leg of the right triangle.  
     [0045] It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed without departing from the spirit and scope of the present invention.  
     [0046] In addition, although the embodiments described herein are directed to an application of a short-span compression connector apparatus in a disc drive environment to facilitate data transfer, it will be appreciated by those skilled in the art that the apparatus can be applied in other types of data transfer environments without departing from the spirit and scope of the claimed invention.