Patent Publication Number: US-10333212-B2

Title: Radiator, solderless interconnect thereof and grounding element thereof

Description:
DOMESTIC BENEFIT/NATIONAL STAGE INFORMATION 
     This application is a divisional of U.S. patent application Ser. No. 14/579,568, entitled “RADIATOR, SOLDERLESS INTERCONNECT THEREOF AND GROUNDING ELEMENT THEREOF,” which was filed on Dec. 22, 2014. The entire contents are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates to a radiator, a solderless interconnect of a radiator and grounding element of a radiator. 
     Interconnections of a dual-polarized radiator that function at the K u -band (i.e., the 12-18 GHz portion of the electromagnetic spectrum in the microwave range of frequencies) require small feature sizes and a tight connector pitch. Many coaxial interconnections will not fit under these conditional requirements or will require individual cables to be assembled as well. In either case, the coaxial interconnections often require epoxy bonds or solder at each element site. With a large array of element sites, this need for epoxy bonds or solder can leads to high labor and piece part costs while the epoxy or solder joints are themselves potential sources of failure for assemblies subjected to environmental requirements. Moreover, with a large array of radiators, insertion forces required to mate a transmit/receive (T/R) module will be very high. 
     Previously, interconnections of a dual-polarized radiator have used cables to interconnect to a T/R module, however this method does not allow the module to be replaced without requiring a time consuming disassembly of the antenna. Another method has involved miniaturized soldered interconnects. However, this process has added costs, potential for conductive joint failures, requires relatively large insertion forces and does not enable certain module styles. In still other cases, solderless interconnects into printed circuit boards (PCBs) are made but use a vertical transition (i.e., where the transition is normal to the plane of the PCB) where the contacts hit a pad on the top or bottom of the PCBs. 
     Meanwhile, current methods of assembling the PCBs to form an array of dual polarized radiators with a common RF ground have drawbacks as well. Generally, silver epoxy is dispensed along all the internal corners of the eggcrate structures formed by the crisscrossing PCBs and cured to hold the assembly together. This process has a high labor cost because automated dispensing of four internal corners for each crisscrossing location is not feasible for dual-polarized unit cell sizes as frequencies approach K u -band and beyond. Also, the length of the corner is often more than 1 inch depending on the design of the radiator, which is beyond some auto dispense capabilities. 
     SUMMARY 
     According to one embodiment of the present invention, a radiator is provided and includes an aperture plate defining multiple slots in first and second transverse directions, spring probes disposed within each of the multiple slots, printed circuit boards (PCBs) each having major and minor surfaces and being recessed on either side of multiple portions of one of the minor surfaces to define multiple pads plated with conductive pad material electrically interconnected with a PCB circuit and a grounding element. Each of the PCBs is disposed with the corresponding one of the minor surfaces inserted into a slot such that the PCBs form a crisscrossing pattern and the pads form horizontal blind-mate contacts with the spring probes that are in-plane with corresponding PCB planes. The grounding element is interposed between crisscrossing PCB pairs at complementary notches thereof. 
     According to another embodiment, a solderless interconnect is provided and includes an aperture plate defining a slot, a spring probe disposed within the slot and a printed circuit board (PCB) having major and minor surfaces. The PCB is recessed on either side of a portion of one of the minor surfaces to define a pad, which is plated with conductive pad material electrically interconnected with a PCB circuit, and the PCB is disposed with the one of the minor surfaces inserted into the slot such that the pad forms a horizontal blind-mate contact with the spring probe that is in-plane with a PCB plane. 
     According to yet another embodiment, a grounding element for a radiator is provided and includes a hairpin element and first and second legs extending substantially in parallel with each other from opposite ends of the hairpin element. Each of the first and second legs includes an exterior facing elastic grip element and an interior facing elastic grip element. 
     Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of a radiator assembly in accordance with embodiments; 
         FIG. 2  is a top down view of the radiator assembly of  FIG. 1 ; 
         FIG. 3  is a cutaway perspective view of the radiator assembly of  FIGS. 1 and 2 ; 
         FIG. 4  is a side view of the radiator and interconnects to spring probe of  FIGS. 1 and 2 ; 
         FIG. 5  is a perspective view of a radiator printed circuit board (PCB) in accordance with embodiments; 
         FIG. 6  is a perspective view of a grounding element for use with the radiator of  FIGS. 1-4  in accordance with embodiments; 
         FIG. 7  is an enlarged view of a portion of the grounding element of  FIG. 6 ; 
         FIG. 8  is an enlarged view of a portion of the grounding element of  FIG. 6  in accordance with alternative embodiments; 
         FIG. 9  is a perspective view of an aperture plate at an initial assembly stage in accordance with embodiments; 
         FIG. 10  is a side view of spring probes inserted into the aperture plate of  FIG. 9 ; 
         FIG. 11  is a perspective view of PCBs with grounding elements being inserted into first direction slots of the aperture plate of  FIG. 9 ; 
         FIG. 12  is a perspective view of PCBs with grounding elements being inserted into second direction slots of the aperture plate of  FIG. 9 ; and 
         FIG. 13  is a perspective view of grounding elements being installed into a crisscrossing radiator PCB assembly. 
     
    
    
     DETAILED DESCRIPTION 
     As will be described below, interconnections for a dual-polarized radiator use plated edges on the radiator PCBs and a mounting of the PCBs into a slot on a structural metalized plate. In this manner, the plated edge is allowed to mate with a spring probe to form a horizontal (i.e., parallel to and in-plane with the PCB plane) RF interconnect. Because the spring probe engages to a fully RF matched pad on the edge of PCB, there is no need to solder an additional block or pin to the PCB, thereby removing the cost and potential failure associated with that part and operation. Ground contact is achieved by affixing the PCBs to the metalized plate either mechanically with fasteners that engage blocks on the PCB or by bonding the boards to the plates. 
     In addition, ground contact between crisscrossing PCBs can be achieved without any manual dispensing and curing in order to reduce manufacturing costs and lead times by the installation of ground clips. Such installation requires no specialized tools and be done on all boards in parallel, improving factory throughput. Ground finger spacing and overhang beyond the board slots can be easily modeled and features can provide additional tuning for the radiator design. 
     With reference to  FIGS. 1-4 , a dual-polarized, offset notch radiator assembly  10  is provided. The radiator assembly  10  includes an aperture plate  20 , spring probes  30  (see  FIG. 3 ), printed circuit boards (PCBs)  40  and grounding elements  50 . The aperture plate  20  is made of metal or a metallic alloy and is provided as a volumetric body  21  with a planarized surface  22 . As shown in  FIG. 2 , the planarized surface  22  is marked by a series of multiple slots including first slots  23  that extend in parallel with one another in a first direction and second slots  24  that extend in parallel with one another in a second direction, which is transversely oriented relative to the first direction. 
     The first slots  23  may extend partially into the body  21  from the planarized surface  22  and include opposing sidewalls  231  and a basewall  232  (as particularly shown in  FIG. 3 ). The basewall  232  extends between the sidewalls  231  at a lowest end of the first slot  23 . The second slots  24  may extend partially into the body  21  from the planarized surface  22  and include opposing sidewalls  241  and a basewall  242 . The basewall  242  extends between the sidewalls  241  at a lowest end of the second slot  24 . The first slots  23  and the second slots  24  intersect with one another to form multiple crisscrossing locations  25  arrayed along the planarized surface  22 . 
     Although the first slots  23  and the second slots  24  are illustrated in  FIGS. 1-3  as being perpendicular to one another, it is to be understood that this is not required and that other embodiments exist in which the first slots  23  form non-right angles with the second slots  24  at the crisscrossing locations  25 . For the purposes of clarity and brevity, however, the following description will relate to only the perpendicular embodiment. 
     As shown in  FIG. 3 , the spring probes  30  may be disposed within the first slots  23  and within the second slots  24 . To that end, the spring probes  30  may be provided as a plurality of spring probes  30  with multiple spring probes  30  disposed within at least one of the first slots  23  and at least one of the second slots  24 . That is, where multiple spring probes  30  are disposed within a first slot  23 , the multiple spring probes  30  may be disposed at regular intervals from one another and, in particular embodiments, the multiple spring probes  30  may be disposed at regular intervals between corresponding crisscrossing locations  25 . Similarly, where multiple spring probes  30  are disposed within a second slot  24 , the multiple spring probes  30  may be disposed at regular intervals from one another and, in particular embodiments, the multiple spring probes  30  may be disposed at regular intervals between corresponding crisscrossing locations  25 . 
     In any case, with reference to  FIGS. 3 and 4 , each spring probe  30  may be provided as a radio frequency (RF) spring probe that includes an elongate body  31 , which is sized to fit within the corresponding first/second slot  23 / 24 , a spring-loaded probe tip  32  and a probe end tip  33 . The spring-loaded probe tip  32  is provided at a first longitudinal end of the spring probe  30  and the probe end tip  33  is provided at a second longitudinal end of the spring probe  30 , which is opposite the first longitudinal end. The spring-loaded probe tip  32  is elastically movable along a longitudinal axis of the spring probe  30  and extends partially into the corresponding first/second slot  23 / 24  with the probe end tip  33  protruding beyond a surface of the aperture plate  20  opposing the planarized surface  22 . 
     Each PCB  40  includes an internal layer of integrated circuitry  41  and an antenna structure  42  coupled to the integrated circuitry  41 . More generally, each PCB  40  has first and second opposite major surfaces  43 , first and second minor end surfaces  44 , a radiative minor surface  45  and a base minor surface  46  (see  FIGS. 3 and 4 ). The antenna structure  42  is disposed on at least one or both of the first and second major surfaces  43 . The first and second minor end surfaces  44  oppose one another and are disposed at locations corresponding to opposite ends of the first/second slots  23 / 24 . The radiative minor surface  45  opposes the base minor surface  46  and is disposable to face away from the planarized surface  22 . The base minor surface  46  is disposable within a corresponding one of the first/second slots  23 / 24  as will be described below. 
     In accordance with embodiments, the radiative minor surface  45  for each PCB  40  may include a series of protrusions  47 . The protrusions  47  may be directed to extend away from the planarized surface  22  and may be disposed at regular intervals from one another or, in particular cases, at locations corresponding to the crisscrossing locations  25 . 
     As shown in  FIGS. 1 and 3 , each of the PCBs  40  is insertable into a corresponding one of the first slots  23  or the second slots  24 . With multiple PCBs  40  thus inserted into a corresponding number of first slots  23  and second slots  24 , the PCBs  40  form a crisscrossing (or egg carton) pattern  400  that includes multiple PCB crisscrossing locations  401 . Each PCB crisscrossing location  401  corresponds to a crisscrossing location  25  and to a corresponding pair of protrusions  47 . In addition, each PCB  40  is formed to define multiple notches  402  at locations corresponding to the PCB crisscrossing locations  401  such that the PCBs  40  inserted into the first slots  23  can fit with the PCBs  40  inserted into the second slots  24  (see  FIG. 1 ). 
     The notches  402  for each PCB  40  may be substantially similar in length or may have differing lengths. For example, the notches  402  for the PCBs  40  inserted into the first slots  23  may be longer than the notches  402  for the PCBs  40  inserted into the second slots  24 . In any case, the notches  402  may have lengths that permit flat insertions of each of the PCBs into the first and second slots  23  and  24 . In accordance with further embodiments, the notches  402  may be sufficiently wide so as to receive the complementary PCB  40  therein along with the corresponding one of the grounding elements  50  (to be described below). 
     With reference to  FIGS. 3-5 , each of the PCBs  40  is disposable with the base minor surface  46  inserted into either one of the first slots  23  or one of the second slots  24 . With each of the first slots  23  and the second slots  24  being wider than the PCBs  40 , the insertion permits the base minor surface  46  to sit at or near the basewalls  232  and  242 . Thus, for a PCB  40  inserted into a first slot  23 , the base minor surface  46  sits at or near the basewall  232  and the portions of its first and second major surfaces  43  proximate to the base minor surface  46  complementarily face the sidewalls  231 . Similarly, for a PCB  40  inserted into a second slot  24 , the base minor surface  46  sits at or near the basewall  242  and the portions of its first and second major surfaces  43  proximate to the base minor surface  46  complementarily face the sidewalls  241 . 
     As shown in  FIGS. 4 and 5 , the base minor surface  46  of each of the PCBs  40  includes a portion  410  with the PCB  40  being formed to define a recess  411  on either sides of the portion  410  to define the portion  410  as a pad  420 . Each recess  411  has an annular shape with a curvature into the body of the PCB  40 . The pad  420  may be provided as a planarized surface that is plated with conductive pad material  421 , which is coplanar with the base minor surface  46 . The conductive pad material  421  may be electrically interconnected with the integrated circuitry  41 . In addition, at least the first and second major surfaces  43  and the portions of the base minor surface  46  remote from the pad  420  may be plated with conductive surface material  422  to form, for example, the antenna structures  42 . In such cases, the conductive pad material  421  is electrically insulated from the conductive surface material  422  by way of the recesses  411  and by way of a material groove  423  defined on either side of the pad  420 . 
     In accordance with embodiments, the base minor surface  46  of each PCB  40  may include multiple pads  420 . The multiple pads  420  may be disposed at regular intervals and, in particular cases, at regular intervals that correspond to the locations of the multiple spring probes  30  disposed in each of the first/second slots  23 / 24 . 
     With the insertion of each of the PCBs  40  into the first and second slots  23  and  24 , the pads  420  each form horizontal blind-mate contacts  100  with spring-loaded probe tips  32  of the spring probes  30  that are in-plane with corresponding PCB planes. That is, for a given pad  420  of a given PCB  40 , the pad  420  contacts with a spring-loaded probe tip  32  of a spring probe  30  in one of the first/second slots  23 / 24  in the plane of the PCB  40 . Thus, for a given set of multiple pads  420  of a given PCB  40 , the multiple pads  420  each contact with spring-loaded probe tips  32  of corresponding spring probes  30  in one of the first/second slots  23 / 24  with all of the contacts being horizontal blind-mate contacts  100  in the plane of the PCB  40 . Each pad  420  may be RF matched with a corresponding spring probe  30 . 
     Since the pad(s)  420  contacts with the spring-loaded probe tip(s)  32 , the spring-loaded probe tip  32  retracts upon such contact and thereby results in secure contact being made between the pad(s)  420  and the spring-loaded probe tip(s)  32  despite the contact being blind. As such, while soldered connections are generally used in conventional devices, the need for solder to be applied between the pad(s)  420  and the spring-loaded probe tip(s)  32  is eliminated. 
     With reference back to  FIGS. 1 and 2 , the PCBs  40  may be grounded to the aperture plate  20  and to each other by at least one of fasteners and epoxy bond  60 . When cured, as shown in  FIG. 2 , the epoxy bond  60  may take the form of a shape defined by the crisscrossing PCBs  40 . Thus, if the crisscrossing PCBs  40  are perpendicular to one another and provided at regular intervals, the epoxy bond  60  will be square. In addition, edges of the epoxy bond  60  may be turned upwardly along the corresponding PCBs  40  (see  FIG. 13 .) 
     With reference to  FIGS. 1 and 6-8 , the grounding element  50  is interposed between crisscrossing pairs of PCBs  40  at complementary notches  402  thereof. As shown in  FIG. 6 , the grounding element  50  includes a hairpin element  51 , a first leg  52  and a second leg  53 . The hairpin element  51  has a U-shaped cross-section with a cross beam and a pair of leg beams extending substantially in parallel from opposite ends of the cross beam. The first leg  52  extends from a distal end of one of the leg beams along a longitudinal axis of the leg beam. The second leg  53  extends from a distal end of the other of the leg beams along a longitudinal axis of the leg beam. The first and second legs  52  and  53  may be substantially parallel with one another and may have substantially similar lengths or, in some cases, different lengths that can accommodate other features of the PCBs  40 . 
     In accordance with embodiments, the grounding element  50  (i.e., the hairpin element  51 , the first leg  52  and/or the second leg  53 ) may be formed of beryllium copper (BeCu) or another similar material. In any case, at least the hairpin element  51  may be formed to be elastically responsive to compression of the first and second legs  52  and  53  together or to stretching of the first and second legs  52  and  53  apart. In accordance with further embodiments, the hairpin element  51 , the first leg  52  and the second leg  53  are all elastically responsive to compression of the first and second legs  52  and  53  together or to stretching of the first and second legs  52  and  53  apart. 
     As shown in  FIGS. 7 and 8 , the first leg  52  may include a series of discrete leg portions  520  that are respectively attachable to the distal end of the leg beam of the hairpin element  51  and to adjacent discrete leg portions  520 . Similarly, the second leg  53  may include a series of discrete leg portions  530  that are respectively attachable to the distal end of the leg beam of the hairpin element  51  and to adjacent discrete leg portions  530 . The first and second legs  52  and  53  may include a same number of the discrete leg portions  520  and  530  or different numbers thereof. Moreover, the discrete leg portions  520  may have the same or different lengths or sizes than the discrete leg portions  530 . 
     With particular reference to  FIG. 7 , the first leg  52  includes a spine element  54 , one or more exterior facing elastic grip elements  55  and one or more interior facing elastic grip elements  56 . The exterior facing elastic grip elements  55  face outwardly from the spine element  54  and are configured to grip a first one of the crisscrossing pairs of PCBs  40 . Each exterior facing elastic grip element  55  includes first and second opposed exterior facing flanges  550  and first and second opposed elastic members  551  by which the first and second opposed exterior facing flanges  550  are elastically coupled to the spine element  54 . The first and second opposed exterior facing flanges  550  cooperatively form a groove through which the corresponding PCB  40  can be slid during an assembly or disassembly operation. The interior facing elastic grip elements  56  face inwardly and are configured to grip a second one of the crisscrossing pairs of PCBs  40 . Each of the interior facing elastic grip elements  56  includes an interior facing flange  560  and an elastic member  561  by which the interior facing flange  560  is elastically coupled to the spine element  54 . 
     The second leg  53  includes a spine element  57 , one or more exterior facing elastic grip elements  58  and one or more interior facing elastic grip elements  59 . The exterior facing elastic grip elements  58  face outwardly from the spine element  58  and are configured to grip the first one of the crisscrossing pairs of PCBs  40 . Each exterior facing elastic grip element  58  includes first and second opposed exterior facing flanges  580  and first and second opposed elastic members  581  by which the first and second opposed exterior facing flanges  580  are elastically coupled to the spine element  57 . The first and second opposed exterior facing flanges  580  cooperatively form a groove through which the corresponding PCB  40  can be slid during an assembly or disassembly operation. The interior facing elastic grip elements  59  face inwardly and are configured to grip the second one of the crisscrossing pairs of PCBs  40 . Each of the interior facing elastic grip elements  59  is constructed similarly as the interior facing elastic grip elements  56  and includes an interior facing flange and an elastic member by which the interior facing flange is elastically coupled to the spine element  57 . 
     The interior facing flange  560  of the first leg  52  and the interior facing flange of the second leg  53  oppose one another and cooperatively form a groove through which the corresponding PCB  40  can be slid during an assembly or disassembly operation. 
     With particular reference to  FIG. 8  and, in accordance with alternative embodiments, each of the interior facing elastic grip elements  56 / 59  may include first and second dimple arrays  70  that are respectively disposed along the respective spine elements  54  and  57  of the first and second legs  52  and  53 . The first and second dimple arrays  70  are provided as protrusions from the spine elements  54  and  57  and may be arranged in respective columns or in respective staggered formations. Each dimple in the first and second dimple arrays  70  may have a unique or standardized size and shape. 
     With reference to  FIGS. 9-13 , a method of assembly of the radiator assembly  10  will now be described. As shown in  FIG. 9 , at an initial stage the method of assembly includes the provision of the first and second slots  23  and  24  in the planarized surface  22  of the aperture plate  20  as well as a machining of tubular recesses  80  along the first and second slots  23  and  24  in a matrix-like arrangement. The tubular recesses  80  are sized to tightly fit around the spring probes  30  such that the spring probes  30  may be supportively inserted into the tubular recesses  80  with the spring-loaded probe tips  32  substantially aligned with the first and second slots  23  and  24  (see  FIG. 10 ). In accordance with embodiments, the tubular recesses  80  may include shoulder surfaces  802  that are supportive of corresponding flanges  301  of the spring probes  30  (see  FIG. 10 ). 
     At a next assembly stage and, with reference to  FIGS. 11 and 12 , the grounding elements  50  are fit into grooves  501  that are formed in each of the PCBs  40  at the notches  402 . In accordance with embodiments, the PCBs  40  to be inserted into the first slots  23  have grooves  501  that face upwardly (see  FIG. 11 ) whereas the PCBs  40  to be inserted into the second slots  24  have grooves  501  that face downwardly (see  FIG. 12 ). Thus, with the PCBs  40  inserted into the first slots  23  as shown in  FIG. 11 , the grounding elements  50  for those PCBs  40  face upwardly to slidably receive the PCBs inserted into the second slots  24  as shown in  FIG. 12 . As noted above, the insertions of the PCBs  40  into the first and second slots  23  and  24  result in the spring-loaded probe tips  32  forming the horizontal blind-mate contacts in the respective planes of the PCBs  40 . 
     At a final assembly stage and, with reference to  FIG. 13 , once the PCBs  40  are inserted into the first and second slots  23  and  24 , the epoxy bonds  60  can be curably fit into the spaces defined between the PCBs  40 . 
     Although  FIGS. 1-3  illustrate that the radiator assembly  10  includes the embodiments of  FIGS. 4 and 5  along with the embodiments of  FIGS. 6-8  (i.e., the horizontal contacts are presented in combination with the grounding elements  50 ), it is to be understood that this combination of features is not required. That is, in accordance with embodiments, the radiator assembly  10  can include the horizontal contacts of  FIGS. 4 and 5  along with another PCB-PCB grounding feature such as manual or automatic dispensation of epoxy. By contrast, in accordance with alternative embodiments, the radiator assembly  10  can include the grounding elements  50  of  FIGS. 6-8  with another interconnection configuration. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one more other features, integers, steps, operations, element components, and/or groups thereof. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The described embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 
     While the preferred embodiment to the invention had been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.