Patent Publication Number: US-6217373-B1

Title: Thin-film electrical termination and method for making

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to electrical conductor connections and terminations and deals more particularly with an improved thin-film electrical termination and a method for terminating a thin-film electrical conductor. 
     In the electronic industry the term thin-film technology relates to several categories of product including, flexprint, membrane switches, touch pads, high density flat cable, sculptured flex circuits and integrated circuit components. Two forms of conductive materials are generally employed in these products, namely etched copper and electrically conductive ink containing a relatively high percentage silver. The etched copper offerings are generally an extension of printed circuit board technology and employ fine line copper traces having a thickness in the range of 0.001-0.002 inches. The silver ink-type products feature circuit paths printed or silk-screened on a substrate and having a thickness generally within the range of 0.0003-0.0007 inches. 
     The electrical termination of thin-film conductive members offer a wide range of product and process alternatives. The etched copper variety, being the more stable of the two options, is suitable for termination by several standard termination techniques including edge connection for printed circuit boards employing a stiffener or paddle board approach, soldering or welding including laser techniques, contact piercing type crimped terminations, and pressure or spring termination designs. 
     Where the conductive ink concept is employed methods of termination to other conductive media has been quite limited. Multiple contact pressure schemes have been proposed and employed particularly for direct connection to conventional printed circuit boards to facilitate traditional means of interface activity. A low density (0.050 inch or more contact spacing) MYLAR pierce/crimp terminal has been utilized which enables a pluggable interface to standard cable type conductors (stranded or solid wires). However, direct termination to stranded or solid conductive wires has heretofore not been feasible. This limitation coupled with new high density termination requirements has created a need for an improved means for termination to thin-film conductors of both etched copper and conductive ink-types. The present invention is concerned with the aforesaid problem. 
     Accordingly, it is the general aim of the present invention to provide an improved thin-film termination and method for terminating thin-film traces, particularly conductive ink traces, directly to conventional solid wire conductors. It is a further aim of the present invention to provide an improved, economical termination and termination method to facilitate low cost, high density termination of electrically conductive thin-film traces. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a thin-film electrical termination is formed within a terminal assembly which includes a cradle member having a top surface and an energy director cap having a bottom surface disposed in opposing relation to the top surface of the cradle member. The cradle member has a conductor receiving slot which opens upwardly through its top surface. An axially elongated electrical connector received within the slot includes an upwardly exposed axially extending electrical conducting portion. An associated portion of a circuit membrane disposed between the cradle member and the energy director cap has an electrically conductive trace thereon which includes a downwardly facing contact portion engaged with the upwardly exposed axially extending electrical conducting portion of the conductor within the slot. Connecting means extend through apertures formed in the membrane at opposite sides of the trace and integrally join to the top surface of the cradle member to the bottom surface of the energy director cap for maintaining the energy director cap in assembly with the cradle member with a portion of the membrane clamped therebetween and the contact portion of the trace in resilient bearing engagement with the upwardly facing axially extending electrical conducting portion of the electrical conductor, whereby the electrical conductor is maintained in electrically terminating relation to the electrically conductive trace. Energy directors provided on the top surface of the cradle member and on the bottom surface of the energy director cap are welded together within the circuit membrane apertures by the simultaneous application of pressure and high frequency vibratory energy to the cradle member and the energy director cap to form the terminal assembly within which the thin-film termination is formed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary top plan view of a terminal assembly embodying the invention and terminating a cable to circuit traces on a keypad. 
     FIG. 2 is a fragmentary side elevational view of the terminal assembly and keypad shown in FIG.  1 . 
     FIG. 3 is a somewhat enlarged fragmentary sectional view taken along the line  3 — 3  of FIG.  1 . 
     FIG. 4 is a fragmentary plan view showing a portion of the circuit membrane termination tab and the stiffener support tab of the keypad shown in FIGS. 1 and 2. 
     FIG. 5 is a perspective view of the terminal assembly shown in FIG.  1 . 
     FIG. 6 is a perspective view of the cradle member. 
     FIG. 7 is a somewhat enlarged top plan view of the cradle member. 
     FIG. 8 is a rear end elevational view of the cradle member. 
     FIG. 9 is a sectional view taken generally along the line  9 — 9  of FIG.  7 . 
     FIG. 10 is a somewhat enlarged fragmentary sectional view taken along the line  10 — 10  of FIG.  7 . 
     FIG. 11 is a somewhat enlarged fragmentary end elevational view showing a secondary energy director. 
     FIG. 12 is a somewhat enlarged fragmentary elevational view showing a portion of the cradle wall including a typical conductor receiving slot. 
     FIG. 13 is a somewhat schematic view of a testing apparatus for determining the compressibility factor of an electrical conductor. 
     FIG. 14 is a perspective view of the energy director cap shown in an inverted position. 
     FIG. 15 is a somewhat enlarged bottom plan view of the energy director cap of FIG.  14 . 
     FIG. 16 is a rear elevational view of the energy director cap. 
     FIG. 17 is a sectional view taken along the line  17 — 17  of FIG.  16 . 
     FIG. 18 is a somewhat schematic fragmentary elevational view of the cradle member and illustrates the compression allowance. 
     FIG. 19 is an exploded fragmentary perspective view showing a typical thin-film termination in accordance with the present invention before final assembly. 
     FIG. 20 is a somewhat schematic fragmentary elevational view showing a termination in an initial stage of assembly. 
     FIG. 21 is similar to FIG. 20 but shows the termination after final assembly. 
     FIG. 22 is a fragmentary sectional view taken along the line  22 — 22  of FIG.  21 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT AND METHOD 
     The present invention may be embodied in a single thin-film electrical termination or in a plurality of such electrical terminations. In the drawings and in the description which follows, the invention is illustrated and described with reference to a typical product which has a high density array of electrical terminations. The product, illustrated in FIGS. 1-3, includes a terminal assembly embodying the invention and indicated generally at  10 , shown connected in terminating relation to a keypad of a type well known in the electronics art and designated generally by the numeral  12 . 
     The illustrated keypad  12 , which is specifically adapted to control an associated electronic device (not shown), essentially comprises a multi-layer membrane switch and includes a circuit membrane  14 , which, as oriented in FIG. 1, has a plurality of electrical conductive ink circuit traces  16 ,  16  imprinted on its upper surface. In accordance with the present invention, each circuit trace  16  is electrically terminated within the terminal assembly  10  by direct electrical connection to an associated one of the plurality of individually insulated resilient compressible electrical conductors  18 ,  18  which comprise a flexible shielded flat cable, indicated by the letter C. The illustrated cable C has an RJ45 telecommunications plug connector  20  electrically connected to its free end for plugging engagement with a mating telecommunications jack (not shown) such as a jack on a computer or other electronic device to be controlled by the keypad switch  12 . 
     Further referring to FIG. 1, the illustrated keypad  12  essentially comprises a generally rectangular multi-layer structure and includes a graphic layer or faceplate  11 , which has a plurality of touch pads  13 ,  13 , and a generally rectangular dome switch assembly, indicated generally at  15 , which includes a switch plate  17  sandwiched between apertured spacers  19  and  21  and located below the faceplate  11 , as shown in FIGS. 1 and 3. The dome switch assembly  15  has a plurality of switch domes aligned with apertures in the spacers  19  and  21  and with the touch pads  13 ,  13  and is operated by the touch pads  13 ,  13 . The circuit membrane  14  which carries the circuit traces  16 ,  16  is positioned immediately below the switch dome assembly  15  to cooperate with the switch domes, in a manner well known in the electrical switch art, and comprises a thin sheet of flexible dielectric material, preferably MYLAR, having a thickness of about 0.005 inches. The circuit membrane  14  has a generally rectangular main body portion which substantially complements the rectangular faceplate  11  and the rectangular dome switch assembly  15 . A termination tab, indicated by the letter T, which comprises a part of the circuit membrane  14  is integrally connected to the main body portion of the membrane  14  and extends outwardly from an associated edge of the main body portion of the membrane and beyond the rear edge of the faceplate  11 . Adhesive layers (not shown) maintain the various keypad components in assembly with each other. 
     The illustrated keypad  12  further includes a rectangular stiffener indicated by the numeral  25 . The presently preferred stiffener  25  is formed from a sheet of LEXAN complements the other rectangular layers which comprise the keyboard  12  and which also include the faceplate  11 , the dome switch assembly  15 , the circuit membrane  14  and the spacers  19  and  21 . The stiffener  25  preferably comprises an outer layer of the keypad  12  and has a support tab  27  integrally formed on it which projects outwardly from it in underlying relation to an associated portion of the termination tab T. The termination tab T extends outwardly for some distance beyond the outer edge of the support tab  27  as shown in FIG.  4  and for a purpose which will be hereinafter evident. 
     The traces on the circuit membrane  14  may, for example, be defined by etched copper or other electrically conductive material, however, the presently preferred thin-film circuit traces  16 ,  16  are formed by an electrically conductive ink compound containing approximately 80 percent silver and which is applied to the upper surface of the circuit membrane  14 , as it appears oriented in FIGS. 1 and 4. The conductive ink traces  16 ,  16  may be printed on the circuit membrane  14  or may be applied to it by a silk-screening process or any other appropriate application means. In the illustrated embodiment the traces define switching circuits on the main body portion of the circuit membrane  14  and extend from the main body portion outwardly across the termination tab T in closely spaced parallel relation to each other. Each trace  16  has a width of 0.002 inches. The parallel traces  16 ,  16  on the tab T are spaced on 0.004 inches centers, as shown in FIG.  4 . 
     Further referring to FIG. 4, an in-line series of rectangular apertures  23 ,  23  arranged in alternate series with the traces  16 ,  16  and in parallel relation to each other, die-cut or otherwise formed in the extending end portion of the termination tab T, that is the portion of the tab T which extends beyond the support tab  27 . The apertures  23 ,  23  extend through the tab T and open through the upper surface of the tab T between each pair of adjacent traces  16 ,  16  and immediately adjacent the outermost traces at the opposite ends of the series. The width of each rectangular aperture  23  is at least equal to the spacing between a pair of adjacent apertures, as shown in FIG.  4 . The traces  16 ,  16  substantially cover the spaces between adjacent apertures  23 ,  23 . Since the keypad  12  has eight circuit traces  16 ,  16  to be terminated, nine rectangular apertures  23 ,  23  are formed in the termination tab T. Thus, each trace  16  is disposed between and immediately bordered by an associated pair of parallel rectilinear apertures  23 ,  23  in a region of termination defined by the outwardly extending portion of the termination tab T. 
     Before further considering a thin-film electrical termination and the method by which such a termination is made, the terminal assembly  10 , which comprises a part of each termination and within which each termination is formed will be considered in some detail. Specifically, the terminal assembly  10  is made by ultrasonically joining or welding together two unitary terminal sections which include a cradle member, indicated generally at  22 , and an energy distribution cap, designated generally by the numeral  24 . 
     Referring now to FIGS. 5-9, and considering first the cradle member, the illustrated cradle member  22  is molded from an ultrasonically weldable dielectric thermoplastic material, preferably LEXAN, the same material from which the keypad stiffener  25  is made. The cradle member  22  has a generally rectangular bottom wall  26  and a pair of opposing side walls  28 ,  28 , which project upwardly from the bottom wall. A front wall  30  projects upwardly from the forward marginal edge portion of the bottom wall  26  and extends transversely of the bottom wall between the sidewalls  28 ,  28 . A cradle wall  32  projects upwardly from the bottom wall  26  and extends across a central portion of the cradle member  32  between the sidewalls  28 ,  28  in rearwardly spaced relation to the front wall  30 , substantially as shown. The sidewalls  28 ,  28  and the cradle wall  22  cooperate to define an upwardly facing top surface  34 . The front wall  30  and forward end portions of the sidewalls  28 ,  28  form an upwardly facing upper surface  36  generally parallel to but somewhat below the plane of the top surface  34 . A pair of generally cylindrical blind guide bores  35 ,  35  formed in the sidewalls  28 ,  28  open upwardly through the top surface  34  transversely at opposite ends of the cradle wall  32 , substantially as shown. Energy directors  37 ,  37  and  38 ,  38  project upwardly from the top surface  34  and extend along the sidewalls  28 ,  28 . Each of the energy directors  37 ,  37  and  38 ,  38  has an apex angle of approximately 90°, as best shown in FIG. 10, where the apex angle is indicated by the letter A. The cradle member  22  defines an upwardly open cavity  39  forward of the cradle wall  32  and an upwardly and rearwardly open recess  41 , rearward of the cradle wall, best shown in FIG. 6 for receiving a portion of the cable C. A cable retaining energy director  40  projects upwardly from the bottom wall  26  within the recess  41  and extends generally transversely of the recess near the rear end of the recess, substantially as shown. An integral conductor stabilizing pedestal  47  projects upwardly from the bottom wall  26  within the recess  41  and extends transversely of the recess in close proximity to and in parallel alignment with the cradle wall  32 , substantially as shown in FIGS. 6-9. 
     A transversely extending in-line array or series of parallel conductor receiving slots  42 ,  42  and  43  separated from each other by parallel barriers  44 ,  44  are formed in the cradle wall  32 , extend from front to rear across the cradle wall  32  and open upwardly through the top surface  34 , substantially as shown for receiving the individual conductors  18 ,  18  which comprise the cable C. A secondary energy director  45  projects upwardly from a portion of the top surface  34  of each barrier  44  and extends centrally along the barrier in a direction generally parallel to the direction of slot extent. Secondary energy directors  45 ,  45  are also located on the top surface  34  transversely outboard of the endmost slots  42  and  43  in the series. Each secondary energy director  45  has an apex angle of  60  degrees as shown in FIG. 11, where the apex angle is indicated by the letter B. The number of conductor receiving slots  42 ,  42  and  43  provided may vary and will be determined by the number of individual electrical connections or thin-film terminations to be formed within the terminal assembly  10 . The illustrated terminal assembly  10  is adapted to accommodate eight thin-film terminations, therefore eight conductor receiving slots are formed in the cradle wall  32  and nine secondary energy directors  45 ,  45  are provided, one more than the number of slots, so that each of the slots  42 ,  42  and  43  is generally bordered by or disposed between a pair of secondary energy directors  45 ,  45 . It should be noted that seven of the eight illustrated conductor receiving slots are substantially identical and are identified by the numerals  42 ,  42 , whereas, the eighth slot, identified by the numeral  43 , which occupies the number one pin position at one end of the in-line series, has a slot depth greater than the slot depth of the other seven slots, for a purpose which will be hereinafter discussed. 
     A typical conductor receiving slot  42 , shown in FIG. 12, has opposing parallel sidewalls  46 ,  46  and a bottom or inner end wall  48  shaped to substantially complement an associated portion of an electrical conductor  18  to be received therein. The width dimension of the slot  42 , indicated by the numeral  50  in FIG. 12, is substantially equal to the nominal width dimension of an associated electrical conductor  18  to be received therein. 
     The depth of each slot  42  is predetermined to satisfy the physical characteristics and dimensions of portion of a single conductor or a plurality of conductors to be received within the slot. Thus, for example, where a conductor  18  to be connected to an associated trace  16  comprises a resilient axially elongated stranded soft copper wire conductor, such as a 28AWG seven strand conductor, which will undergo significant physical and more specifically cross-section dimensional change when subjected to a radially directed compressive force of a predetermined magnitude, as contemplated by the assembly method of the present invention, this factor must be considered in determining required slot depth, as will be hereinafter further discussed. The change in cross-sectional dimension resulting from the application of a radially directed force of known magnitude to an axially elongated portion of a compressible conductor during assembly of the terminal assembly  10 , and hereinafter referred to as the compressibility factor, is determined for at least one of the conductors  18 ,  18  to be connected to the traces  16 ,  16  and is employed in determining the optimum depth dimension of the slots  42 ,  42  which receive the conductors  18 ,  18  therein, as will be hereinafter discussed. 
     The compressibility factor for a conductor may, for example, be determined by providing a sample testing device, indicated generally at  32 ′ in FIG. 13, made from the material from which the cradle member  22  is made, having a test slot  42 ′ corresponding generally to the slot  42  shown in FIG. 12, a width dimension  50 ′ substantially corresponding to the nominal cross-sectional dimension of a stranded wire conductor  18 , and a bottom or inner end wall  48 ′ which complements an associated lower portion of a conductor  18 , substantially as shown. A downwardly directed force of known magnitude to be applied by an ultrasonic welding machine in assembling the electrical terminal assembly  10  is applied to a bare axially extending portion of the conductor by a ram  52  slideably received within the slot  42 ′. The ram  52  has a downwardly facing bearing surface  54  at its lower end for engaging an upwardly exposed portion of the conductor  18  within the slot  42 ′. The resulting compressibility factor, which may be expressed as a percentage change in the nominal cross-sectional dimension of a stranded wire conductor  18 , measured in the direction of applied force and in response to the force of known magnitude, may then be utilized to determine the depth dimension of the slot  42  required in practicing the invention. A further discussion of the compressible factor and the manner in which it is determined and employed in an ultrasonic welding process for terminating electrical conductors to form electrical connections is found in my copending U.S. patent application Ser. No. 08/393,843d, entitled METHOD FOR MAKING ELECTRICAL CONNECTION, filed Feb. 24, 1995, assigned to the assignee of the present invention, and hereby adopted by reference as part of the present disclosure. 
     It should now be apparent that when the invention is practiced with compressible conductors of other kinds, as, for example, solid wire conductors or solid electrical terminals used to terminate thin-film conductors or traces, the compressibility factor will be a consideration in the design of a proper cradle member for use in practicing the invention and may be determined using a test sample conductor or terminal disposed within a test slot, generally as aforedescribed. 
     The energy director cap  24 , best shown in FIGS. 14-17 is adapted for mating engagement with the cradle member  22  and also comprises a generally rectangular member molded or otherwise formed preferably from the same ultrasonically weldable dielectric thermoplastic material from which the cradle member  22  is made. The energy director cap  24 , which is shown in an inverted position in FIGS. 14 and 15, has an upper wall  56  and a pair of opposing sidewalls  58 ,  58  having bottom surfaces  60 ,  60 . The forward end portion of the side walls  58 ,  58  are stepped downwardly for complementary mating engagement with the forward ends of the cradle member side walls  28 ,  28 . A pair of cylindrical dowel pins  62 ,  62  sized to be received within and complement the cylindrical guide bores  35 ,  35  in the cradle member project downwardly from the sidewall bottom surfaces  60 ,  60 . The dowel pins  62 ,  62  cooperate with the guide bores  35 ,  35  to assure proper alignment of the cradle member  22  and the energy director cap  24  during assembly. 
     A bearing wall  64  extends transversely between the sidewalls  58 ,  58  has a downwardly facing bottom surface  66  upwardly spaced from the lower surfaces  60 ,  60  a distance substantially equal to the thickness of the circuit membrane  14  as best seen in FIG. 14. A plurality of pairs of longitudinally and transversely spaced apart primary energy directors  68 ,  68 , equal in number to the number of rectangular apertures  23 ,  23  in the termination tab T, project downwardly from the bottom surface  66 . Each pair of primary energy directors  68 ,  68  is aligned with an associated aperture  23  when the energy director cap  24  is assembled with the cradle member  22 . The energy director cap  24  has a downwardly and rearwardly open recess  70 , substantially as shown, for cooperating with the recess  41  in the cradle member  22  to receive an end portion of the cable C. An energy director  72  projects downwardly from the upper wall  56  within the recess  70  and extends transversely along the upper wall  56 . Like the energy director  40  on the cradle member, the energy director  72  on the cap has an apex angle of approximately 90°. The energy director  72  is disposed immediately above and in parallel alignment with the energy director  40  when the energy director cap  24  is assembled with the cradle member  22 . 
     The energy director cap  24  also defines a forwardly and downwardly open recess  76  for receiving and containing the support tab  27  on the keypad  12  when the terminal assembly  10  is assembled with the keypad. Energy directors  78 ,  78  depend from the upper wall  56  within the recess  76  and extend transversely of the recess, substantially as shown in FIGS. 14 and 15, for engaging the support tab  27 . 
     Preparatory to forming the terminal assembly  10  and connecting it in terminating assembly to the keypad  12 , an end portion of the outer insulation jacket  18  is removed from the flat cable C to expose end portions of the eight (8) individually insulated stranded wire conductors  18 ,  18  which comprise the cable. Insulation is then stripped from each individual conductor  18 , preferably in spaced relation to the exposed free end of the conductor, to provide an exposed axially extending electrically conductive portion of the conductor axially spaced from the free end of the conductor and having an axial length substantially equal to the axial length of a slot  42  or  43  within which the stripped portion of the conductor is to be received. The cradle member  22  is then preferably positioned with the slots  42 ,  42  opening in an upward direction to receive the various conductors  18 ,  18 . Thereafter, an exposed axially extending bare wire portion of each conductor  18  is positioned within an associated one of the slots  42 ,  42  and  43 , the insulated free ends of the conductors  18  being disposed within the cavity  39 . 
     As previously noted, the slot  43  located at the number 1 pin position at one end of the array of slots has a depth somewhat greater than the depth of the other slots  42 ,  42  in the cradle member. The illustrated slot  43  is adapted to accommodate two vertically stacked stranded wire conductors. One of the two stacked conductors is an individually insulated stacked conductor  18  from which insulation has been stripped, as herein before described. The other of the conductors is a drain wire, that is a bare or uninsulated wire which is disposed within the outer insulation jacket of the cable C in contacting engagement with metal shielding within the cable insulation jacket. Thus, electrical grounding paths may be established between the cable shielding, the telecommunications plug  20  and one of the electrically conductive traces  16 ,  16  carried by the circuit membrane termination tab T and connected to a grounding plane (not shown) located within the keypad  12 . Where two such wires are to be disposed within a single cradle slot, such as the slot  43 , for example, for termination to an associated trace  16  on the termination tab T, a determination of the compressibility factor for the two wires is made to enable determination of the required depth of the slot  43  as herein before discussed. 
     When the various electrical conductors  18 ,  18  have been properly positioned within the slots  42 ,  42  and  43 , the lower portion of the cable C will be disposed within the cradle member recess  41  with insulated portions of the various conductors  18 ,  18  resting upon the conductor stabilizing pedestal  47 . It should now be noted that each of the conductors  18 ,  18  includes an upwardly exposed axially extending conducting portion  80  which extends in the direction of slot extent and which is disposed at a level above the level of the cradle member top surface  34  to provide compression allowance, as best shown in FIG. 18 where the compression allowance is indicated by the numeral  82 . 
     After the various electrical conductors  18 ,  18  have been properly positioned within the slots  42 ,  42 , and  43 , the termination tab T on the circuit membrane  14  is positioned on the cradle member  22  with the traces  16 ,  16  on the termination tab T facing in a downward direction, so that a contacting portion of each trace  16  is disposed in overlying engagement with an upwardly exposed axially extending conducting portion  80  of an associated electrical conductor  18 . When the termination tab T has been properly positioned as aforedescribed, each secondary energy director  45  projects upwardly into an associated one of the apertures  23 ,  23 . 
     The energy director cap  24  is next positioned on the cradle member  22  with the dowel pins  62 ,  62  engaged within the cylindrical guide bores  35 ,  35 . When the cap is properly positioned the primary energy directors  68 ,  68  which depend from the energy director cap bottom surface  66  are automatically aligned in registration with the rectangular apertures  23 ,  23  in the circuit membrane termination tab T. A pair of primary energy directors  68 ,  68  associated with each aperture  23  is positioned in transverse crossing relation to opposite end portions of a secondary energy director  45  disposed within that aperture. The support tab  27  is located within the recess  76  and engaged by the energy directors  78 ,  78  on the cap. The cradle member  22  and the energy director cap  24  are now ready for final assembly. 
     In accordance with the presently preferred method for practicing the invention, the pre-assembled sections of the terminal assembly  10 , which include the cradle member  22  and the energy director cap  24 , are supported within a suitable fixture mounted on an ultrasonic welding machine (not shown) while compressive force is applied to the supported sections by the horn of the welding machine. When the applied force reaches a predetermined first magnitude the horn of the welding machine applies ultrasonic vibratory energy to the pre-assembled sections  22  and  24  to weld the sections together at the interfaces defined by the coengaging primary and secondary energy directors while the applied force is simultaneously increased until a second predetermined force magnitude is attained. The assembly is then maintained under compression until the welds solidify. More specifically, after the pre-assembled terminal assembly  10  has been positioned in the ultrasonic welding machine, compressive force is applied to the terminal assembly to urge the top and bottom surfaces of the cradle member  22  and the cap  24  toward each other. Ultrasonic vibratory energy and compressive force are then simultaneously applied to the assembly to melt the various energy directors at points of contact therebetween. Thus, the primary energy directors  68 ,  68  are melted at the points of engagement with the secondary energy directors  45 ,  45  whereby connecting welds are produced within and near the opposite ends of each of the rectangular apertures  23 ,  23 . It should be noted that the central portion of each secondary energy directors  45 , that is, the portion of the secondary energy director  45  which extends between the primary energy directors  68 ,  68  in each slot  23 , does not undergo substantial melting. However, slight melting may occur where the apex of each secondary energy director central portion engages the bottom surface of the energy director cap. The application of high frequency vibratory energy to the assembly melts the energy directors  36  and  38  to further weld the energy director cap to the cradle member. Welding may also occur between the dowel pins  66 ,  66  and the bores  35 ,  35  in which these pins are received thereby providing additional integrity to the resulting assembled structure. 
     The energy directors  40  and  72  at the top and bottom surfaces of the cable receiving recess  70  burn into the outer insulation jacket of the cable C, thereby welding the insulation jacket to the terminal assembly providing strain relief for the cable relative to the terminal assembly  10 . The pedestal  47  is welded to the insulation on each of the individually insulated wire conductors  18 ,  18 , during the assembly process and serves to stabilize the latter conductors so that the conductor terminations resist movement in response to lateral movement of the cable C relative to the terminal assembly  10  formed by the cradle member  22  and the energy director cap  24 . The ultrasonic welding operation also serves to melt the energy directors  78 ,  78 , thereby welding the terminal assembly to the support tab  27  on the keypad  12 . 
     During the ultrasonic welding process some wiping action occurs between the coengaging surfaces of the contact portion of each trace  16  and the axially extending conduction portion of each associated electrical conductor  18 , that is the portion of each conductor which is disposed within each slot  42  and in engagement with an associated trace  16  within the slot. This wiping action assures production of a substantially gas-tight termination or connection between the coengaging portions of each electrical conductor  18  and its associated trace  16 . 
     The primary and secondary energy directors are strategically positioned to form welds or integral connecting portions of the cradle member and energy director cap which extend through the apertures  23 ,  23  the connection portions being indicated by the numerals  75 ,  75  and shown in FIGS. 21 and 22. Thus, a pair of connecting portions  75 ,  75  are formed which extend through each aperture  23  proximate the opposite ends of the aperture so that four points of connection are established between the cradle member  22  and the energy director cap  24  with respect to each terminated trace  16  (i.e. two connecting portions  75 ,  75  adjacent each side of each trace  16 ). Since the aforesaid connecting portions disposed within the slots  23 ,  23  are formed while the terminal assembly  10  is under compression and the various conductors  18 ,  18  are compression by the associated traces  16 ,  16  which bear upon the conductors the stored energy in each resilient conductor  18  continuously biases the conductor toward and into contacting engagement with its associated trace  16  after the assembly has been completed. Due to the strategic location of the points of contact between the primary and secondary energy directors which cooperate within the slots to define the integral connecting portions  75 ,  75 , heat dissipation is controlled during the welding process so that the delicate traces  16 ,  16  are not exposed to excessive heat while the terminal assembly sections  22  and  24  are being welded together. Substantially the only heat sink at each termination is provided by the connector  18  which comprises the termination. The various other energy directors which form the welds to maintain the energy director cap and cradle member in assembled relation to each other are remotely located relative to the regions of termination, which regions are generally defined by traces between the rectangular apertures  23 ,  23 . Thus, the two part terminal assembly  10  is effectively assembled without exposing the regions of electrical termination to excessive heat. The insulation on the stranded conductor free end portions located within the cavity  39  controls the wire strands at the free ends of the conductors  18 ,  18  to prevent electrical shorting between the strands at the free ends of adjacent conductors in the high density array. The bottom surface of the energy director cap  24  cooperates with the top surface of the cradle member to sandwich the membrane  14  in a flat condition therebetween and prevents molten plastic material from migrating between the coengaging surfaces of the terminal assembly  10  and the membrane  14  while the two sections of the terminal assembly are being welded together.