Abstract:
A self-aligning, signal isolating blindmate connector is presented. The blindmate connector may include a male blindmate connector adapted for receiving a female connector; a female connector and a shroud covering a junction between a mated male blindmate connector and a female connector.

Description:
BACKGROUND OF THE INVENTION 
   Programmable electronic circuit testers, such as the Agilent Technologies, Inc. 93000, are typically used during the manufacture of electronic devices and integrated circuit to test the performance of the device or integrated circuit being manufactured. Tests are conducted to assure that the device or integrated circuit satisfies associated design performance specifications. In order to test the device or integrated circuit, the tester is programmed to send an electrical signal or a suite of electrical signals to the device under test (DUT) and to measure the response(s) back from the DUT. The tester may test finished packaged devices or integrated circuits at various stages between initial wafer processing and final packaging. 
   A conventional tester  10 , is shown in  FIG. 1 . Tester  10  comprises a test head  12  electrically connected by cables routed through a conduit  14  to rack(s)  16  of electronic test and measurement instruments, such as AC and DC signal generators for applying electrical signals to a device or integrated circuit interfaced to the test head  12 , and signal analyzers, for example, a network analyzer, spectrum analyzer, oscilloscope, or other waveform digitizing or signal processing equipment, for measuring the response(s) to applied signals. Test head  12  may include circuitry that performs distribution of electrical signals, signal separation, frequency translation, amplification, attenuation, switching, or other conditioning or modification of electrical signals prior to being routed to the rack  16  or to a device or integrated circuit being tested. 
   Test head  12  interfaces to a device or integrated circuit through a load board  18  and a fixture board  20  mounted to the test head  12 . Alternatively, prior to installation of fixture board  20 , a calibration board (not shown), having a configuration similar to the fixture board may be connected to the test head  12  for calibrating the test head  12 . The configuration of the load board  18  depends on the type or family of device or integrated circuit being tested, such as an analog or digital electronic circuit, while the configuration of the fixture board  20  is generally specific to the family or particular device or integrated circuit under test (DUT). 
   Fixture board  20  interfaces to a device-under-test (DUT) board  22  that may comprise inductors, capacitors, and other electronic components or circuit mounted to or fabricated on the DUT board for decoupling, filtering attenuating or otherwise modifying electrical signals transmitted to or received from a device or integrated circuit under test. Finally, the DUT board  22  is connected to a socket  24  for effecting electrical connection(s) between tester  10  and the actual electronic circuit or device under test (DUT), such as a packaged device or integrated circuit  26 . Alternatively, socket  24  may be mounted directly to fixture board  20 . 
   Test head  12  is mounted to a dolly  28 . Test head  12  may be mounted by pivotal connections  30  to dolly  28 . Pivotal connections  30  enable test head  12  to be positioned in an approximately upward facing horizontal position so that the appropriate load board  18  and calibration or fixture board  20  and DUT board  22  with socket  24  can be mounted to test head  12  of tester  10  by an operator. Test head  12  may be pivoted to any angular position so that socket  24  may interface with an automated material handler  32 , for example, which rapidly feeds each DUT  26  to the tester  10  to be tested. 
   Alternatively, a wafer probe (not shown) may be substituted for the socket  24  mounted to the DUT board  22 . Pivotal connections  30  enable test head  12  to be pivoted to an inverted position to test devices or integrated circuits on a wafer (not shown) at a wafer probing station (not shown). 
   In order to interface socket  24  to the automated material handler  32 , or a wafer probe (not shown) at a wafer probing station (not shown), a frame  34  is mounted to test head  12 . A jig  36  that mates with frame  34  is mounted to the automated material handler  32  or wafer probing station (not shown) to align test head  12  with the handler or station so that packaged devices or integrated circuits or devices or integrated circuits on wafer can be tested. 
   The connectors (not shown) through which test head  12  is electrically connected to the calibration or fixture board  20  are subjected to many connections and disconnections during calibration and actual testing with tester  10 . However, the useful life of the tester  10  has heretofore greatly exceeded the useful life of the connectors in test head  12  and calibration or fixture board  20 . Also, the repeatability of the connections that are made decreases over time as the connectors degrade due to wear of the connectors. Moreover, high frequency coaxial connectors are relatively fragile, and the center conductor of such a connector can become damaged if the operator is not careful when coupling, decoupling and handling connectors. Furthermore, high frequency coaxial connectors are susceptible to RF energy leaking into or out of the connector, which can degrade the signal quality. 
   It would therefore be desirable to provide a connector structure to enable test head  12  to be repeatably connected and disconnected to the calibration or fixture board  20  over a longer period of the useful life of the tester  10 . Additionally, it would be desirable to provide a relatively rugged connector structure whereby the connector is less susceptible to wear and damage during coupling, decoupling and handling of the connectors. It would further be desirable to provide a connector that has improved signal isolation between connectors. Such a structure would facilitate the use of the tester  10  to perform setup and calibration, as well as the measurement process. 
   SUMMARY OF THE INVENTION 
   A blindmate connector with improved mating alignment and signal integrity is presented. In particular, the blindmate connector is an electrically conductive, approximately cylindrical male blindmate connector, adapted to receive a female connector; an electrically conductive, approximately cylindrical female connector; and an electrically conductive shroud having a first section surrounding a portion of the female connector and a second section adapted to receive the male blindmate connector as the male blindmate connector is mated with the female connector, the second section of the shroud surrounds and extends along an outer surface of the male blindmate connector when the male blindmate connector is mated with the female connector. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of this invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
       FIG. 1  illustrates an isometric view of a conventional electronic circuit tester; 
       FIG. 2  illustrates an exploded view of a test head, load board, and fixture board in the electronic circuit tester shown in  FIG. 1 , into which an improved blind mate connector in accordance with one embodiment of the invention is incorporated; 
       FIG. 3  illustrates a cross-sectional view of a male blindmate connector in accordance with one embodiment of the invention; 
       FIG. 4  illustrates a cross-sectional view of a compliant female connector incorporated into a test head of an electronic circuit tester for connection with the male blindmate connector in accordance with one embodiment of the invention; and 
       FIG. 5  illustrates a perspective view of a male blindmate mated with a compliant female connector and a perspective, exploded view of a male blindmate and compliant female connector in accordance with one embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2  shows a portion of an electronic circuit tester, namely, a test head  100 , a load board  112 , and a fixture board  114 . In accordance with one embodiment of the invention, a male blindmate connector  116 , as shown in  FIGS. 3–5 , may be incorporated into fixture board  114  for interconnecting test head  100  and fixture board  114 . Also, male blindmate connector  116  may be incorporated into a calibration board (not shown), which may be substituted for fixture head  114  during setup and calibration of the electronic circuit tester. 
   In operation, calibration or fixture board  114  may be installed on test head  100  so that one or more male blindmate connectors  116  mate with a corresponding number of female connectors  126  mounted in the test head  100 . For example, there can be twenty male blindmate connectors  116  and  20  corresponding female connectors  126 , as partially shown in  FIG. 2   
   Test head may comprise a pull down/eject ring  150  for installing the calibration or fixture board  114  on test head  100 . Pull down/eject ring  150  may have a plurality of slots  150 A. Calibration or fixture board  114  may have a plurality of pins  152 , which fit into slots  150 A, such that rotation of the board  114  causes axial movement of the male blindmate connectors  116  toward the female connectors  126  for effecting connection between the board  114  and test head  100 . 
   Male blindmate connector  116 , as shown in more detail in  FIG. 3  may comprise an electrically conductive, approximately cylindrical body portion  118 , having a central axis  120 . Body portion  118  may have a first, inner diameter D 1 . By way of example, body portion  118  may have an interior surface  118 A adapted to internally receive an outer conductor of a male connector (note shown) at a first end  118 B of body portion  118 . Additionally, body portion  118  may have a relieved region  118 C at a second end  118 D of the body portion. Body portion  118  may also have a second inner diameter D 2  at the relieved region  118 C. Interior surface  118 A at second end  118 D of body portion  118  may be tapered outwardly to provide a guide for a female connector (not shown in  FIG. 3 ) during insertion into the second end of body portion  118 . 
   Male blindmate connector  116  may further comprise an electrically conductive approximately cylindrical-solid center conductor  122  having an axis corresponding to central axis  120 . By way of example, center conductor  122  may have a female end  122 A juxtaposed with first end  118 B of body portion  118  and adapted to contact a center conductor (not shown) of a male connector (not shown) inserted into the first end of the body portion. The center conductor  122  may also have a male end  122 B juxtaposed with the second end  118 D of the body portion  118  and adapted to contact a center conductor  124  of a female connector  126  inserted into the second end of the body portion, as shown in  FIG. 4 . Male end  122 B of the center conductor  122  may comprise a male pin  122 C integral with the center conductor  122 . 
   As shown in  FIG. 3 , center conductor  122  has an exterior surface  122 E opposite the interior surface  118 A of body portion  118 . Center conductor  122  may have a diameter D 3  less than the first inner diameter D 1  of body portion  118  to provide an interstitial region  128  between body portion  118  and center conductor  122 . 
   First end  118 B of body portion  118  may comprise a second relieved region  118 E for insertion of the outer conductor (not shown) of a male conductor (not shown). Additionally, female end  122 A of center conductor  122  may be slotted, as shown in  FIG. 3 , to receive a male pin (not shown) integral with center conductor (not shown) of the male connector (not shown) when the male connector is inserted. Also, body portion  118  may have an exterior surface  118 F comprising threads  118 G at first end  118 B of body portion to mate with a coupling nut (not shown) of the male connector (not shown) after the male connector is inserted into the first end  118 B of body portion  118 . 
   Male blindmate connector  116  may also comprise an electrically conductive approximately cylindrical sleeve  130  having an axis corresponding to the central axis  120  and an internal surface  130 A and an external surface  130 B. The sleeve  130  is disposed in the relieved region  118 C at the second end  118 D of body portion  118  in electrical contact with body portion  118 . An increased diameter portion  130 C of sleeve  130  is adapted to contact an outer conductor  132  of female connector  126  inserted into the second end  118 D of body portion  118 , as shown in  FIG. 4 . The sleeve  130  may comprise a solid cylindrical portion  130 D having an outer diameter approximately corresponding to the inner diameter D 2  of the relieved region  118 C at the second end  118 D of body portion  118  and a slotted portion  130 E having an outer diameter D 4  smaller than the outer diameter of the solid cylindrical portion  130 D of the sleeve. 
   Male blindmate connecter  116  may also comprise dielectric material  134  disposed in the interstitial region  128  for supporting the center conductor  122  within body portion  118 . As shown in  FIG. 3 , each of the interior surface  118 A of body portion  118 , interior surface  130 A of sleeve  130 , and exterior surface  122 C of center conductor  122  may comprise stepped sections  118 H,  130 F and  122 D, respectively. Additionally, the dielectric material  134  may be a cylinder of dielectric material interposed in the interstitial region  128  between the respective stepped sections  118 H and  130 F of body portion  118 , on the one hand, and the stepped section  122 D of the exterior surface  122 C of center conductor  122  on the other hand, to retain the dielectric material. Also, the cylinder of dielectric material  134  has first and second ends  134 A and  134 B which may be relieved, as shown in  FIG. 3 , to provide inductive compensation for capacitance introduced by the stepped sections  118 H and  130 F of interior surfaces  118 A and  130 A of body portion  118  and sleeve  130  and the stepped section  122 D of exterior surface  122 C of the center conductor  122 . 
   Finally, male blindmate connector  116  may comprise means  136  for retaining sleeve  130  in body portion  118  when the sleeve is mounted within the body portion. Means  136  for retaining sleeve  130  may comprise a retaining ring having an outer diameter corresponding substantially to the inner diameter D 2  of the relieved region  118 C of body portion  118  and disposed within the second end  118 D of body portion  118  at approximately the intersection of the solid cylindrical portion  130 D and the slotted portion  130 E of the sleeve  130 . 
   As shown in  FIGS. 3 and 4 , the male blindmate connector  116  may comprise means  138  for mounting the male blindmate connector  116  to a calibration or fixture board  114 . Means  138  for mounting the male blindmate connector  116  may comprise an annular flange  1181  integral with the exterior surface  118 F of body portion  118  intermediate the first and second ends  118 B and  118 D of body portion  118 . Means  138  for mounting male blindmate connector  116  may also comprise a threaded section  118 J of the exterior surface  118 F of body portion  118  disposed between flange  1181  and one of the first and second ends  118 B and  118 D of body portion  118 . As shown in  FIG. 4 , threaded section  118 J may be adapted to be inserted through a hole  140  in the calibration or fixture board  114  until flange  1181  abuts the board and to receive a nut  142  to mount male blindmate connector  116  to the board by sandwiching the board between flange  1181  and nut  140 . 
   As shown in  FIGS. 4 and 5 , male blindmate connector  116  may be mounted to calibration or fixture board  114  and mated to female connector  126 . Female connector  126  may be a standard subminiature series A (SMA) or 3.5 millimeter connector. Female connector  126  may also be a compliantly mounted connector, as shown in  FIG. 4 . Accordingly, the outer conductor  132  of female connector  126  may comprise a skirt  132 A that resides in a first portion  144 A of a cylinder  144  provided in test head  100 . A spring  146  may be disposed in a second portion  144 B of the cylinder  144 . First and second portions  144 A and  144 B of cylinder  144  may be separated by an iris  144 C. 
   Finally, a shroud  200  is mounted to the outer conductor  132  of female connector  126  between outer conductor  132  of female connector  126  and spring  146 , so that spring  146  is captured between the iris  144 C and a ledge  148 A of shroud  200 . Shroud  200  may have a collar  240  that surrounds the outer conductor  132  of female connector  126 . Shroud  200  may have a cuff  210  that extends from the collar  240  and surrounds the exterior surface  118 F at the second end  118 D of the male blindmate connector  118 . 
   The inner diameter of collar  240  of shroud  200  is slightly greater than the outer diameter of the outer conductor  132 , but less than the skirt  132 A. The inner diameter of the cuff  210  of shroud  200  is slightly greater than the outer diameter of the male blindmate connector  118  at the second end  118 D. The tolerances between cuff  210  of shroud  200  and the exterior surface  118 F of male blindmate  118  may be as close as possible without interfering with alignment when the male blindmate connector  118  is being mated with the female connector  126 . The small gap between the cuff  210  of shroud  200  and the male blindmate connector  118  combined with the length of the cuff  210  extending over the male blindmate connector  118  create a waveguide like bandpass structure that will decrease signal leakage and cross-talk between different mated connector pairs  118  and  126  over certain frequency ranges. 
   Consequently, in operation, the spring  146  biases the shroud  200  and, hence, the female connector  126  away from iris  144 C of cylinder  144  of test head  100  toward male blindmate connector  116 . Extension of female connector  126  toward male blindmate connector  116  is limited by skirt  132 A encountering iris  144 C. Female connector  126  moves axially in first and second cylinder portions  144 A and  144 B of cylinder  144  of test head  100 , so that contact is effected between outer conductor  132  of the female connector and the increased diameter portion  130 C of the male blindmate connector  116 . 
   When female connector  126  and male blindmate connector  118  are mated, collar  240  of shroud  200  surrounds a portion of the female connector  126  between skirt  132 A and the second end  118 D of male blindmate connector  118 , while cuff  210  surrounds and extends up the second end  118 D of the male blindmate connector  118 . Thus, shroud  200  effectively covers and extends in either direction over the area mating junction between the male blindmate connector  118  and female connector  126 , providing improved RF and signal isolation into or out of the mated connectors  118  and  126  for improved signal integrity. 
   Shroud  200  provides pre-alignment as the male blindmate connector  118  and female connector  126  are beginning to engage during mating, which allows the amount of movement in the female connector  126  to be increased and also permits full tolerance stack up. Shroud  200  may include a tapered inner edge  230  at the open end of the cuff  210  for further alignment improvement as the male blindmate connector  118  is being mated with the female connector  126 . 
   In operation, the male blindmate connector  118  may be attached with many other male blindmate connectors  118  to a calibration or fixture board  114 . The male blindmate connectors  118  on the calibration or fixture board  114  will be brought into contact and interface with corresponding female connectors  126  mounted to a test head  100 . The female connectors may be mounted to permit some movement side to side, up and down as well as gimble. This movement may permit improved self-alignment with corresponding male blindmate connectors  118  during mating. Alignment problems may prevent mating, causing damage to connectors  118  and  126  or cause variations in microwave performance and signal integrity of mated connectors. 
   Shroud  200  may be made of nickel-plated aluminum, stainless steel, brass, beryllium copper or any other known metallic material. Shroud  200  may be made by machining or other similar known method. 
   As shown in  FIGS. 4 and 5 , a washer  300  may be used in shroud  200  to further improve signal integrity. Washer  300  may be substantially cylindrical with an inner diameter similar to the inner diameter of collar  240  and larger than the outer diameter of female connector  126 . Washer  300  may have an exterior diameter that is slightly less than the inner diameter of cuff  210 , such that when washer  300  is disposed within shroud  200 , washer  300  surrounds outer contact  132  of female connector  126  and rests between shelf  250  of shroud  200  and the second end  118 D of male blindmate connector  118 . 
   In one embodiment, washer  300  may comprise a microwave absorbing material, such as polyiron. In this embodiment, washer  300  may or may not contact the second end  118 D of male blindmate connector  118  when engaged within connectors  118  and  126 . In this embodiment, washer  300  absorbs RF energy from leaking into or out of mated connectors  118  and  126 , thus further improving signal integrity within the mated connectors. 
   In an alternative embodiment, washer  300  may comprise a thicker, compressible, conductive material, such as a conductive elastomer, or any similar material. In this embodiment, washer  300  would be in contact with the second end  118 D of male blindmate connector  118  to function more like a gasket and seal the junction between female connector  126  and male blindmate connector  118  against RF leakage into or out of the mated connectors, thus further improving signal integrity within the mated connectors. 
   Shroud  200  acts as a spring retainer, RF/signal isolation means, provides pre-alignment and improves self-alignment during mating of male blindmate  118  and female connector  126 . Washer  300  improves signal isolation between mated blindmate connector pairs  118  and  126 . 
   It will be appreciated from the above detailed description that the blindmate connector of the present invention provides improved alignment and signal integrity for blindmate connectors. Other embodiments are anticipated without deviating from the present invention, for example blindmate connectors may be used for other connections, such as high frequency connections from modules to other subsystems, connections to benchtop instruments in a production environment etc. Although this preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention, resulting in equivalent embodiments that remain within the scope of the appended claims.