Abstract:
An array and method of forming an array of solder-holding clips is provided, suitable for fabrication by automatic progressive stamping techniques, and for ganged application to a corresponding array of terminal pins of an electrical device, for soldering such pins directly to the conductive pads or internally plated holes of a substrate, or to provide a lead connecting such pins to a substrate.

Description:
[0001]    The present application claims the benefit of prior provisional application Serial No. 60/006,205 filed Nov. 3, 1995, in the names of Joseph Cachina, Jack Seidler, and James R. Zanolli, entitled “SOLDER-HOLDING CLIPS FOR APPLYING SOLDER To CONNECTORS OR THE LIKE. ” 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention concerns apparatus and methods for joining connectors or other electrical components, having solder-less pin-type or other terminals, to substrates, such as printed circuit boards, or to other components.  
           [0003]    When joining a multi-terminal component, such as a connector, to a substrate by soldering, particularly a substrate with internally plated holes, special provisions have often been required, such as shown in U.S. Pat. Nos. 4,597,625; 4,802,862; 4,883,435; 5,139,448; and 5,334,059. Such components have terminals which do not carry solder, so that these situations have generally required special means for providing solder to the component terminals and to contact pads on the substrate, and/or to the electro-plated lining of holes in the substrate. One approach to providing solder to the component terminals and contact pads is to provide solder paste in and around the particular area, such as a hole. However, this approach generally does not provide a sufficient volume of solder to properly join the component terminals and contact pads.  
           [0004]    Such connectors commonly have their pins gold-plated, which must then interface gold-to-gold with gold plating on the substrate. Accordingly, the connectors cannot be wave soldered, and are commonly either hand-soldered or have solder doughnuts placed on each terminal pin and then reflowed with hot air. For connectors with a large number of terminals, this assembly method is costly.  
           [0005]    The present invention provides a simple and inexpensive way of applying solder in such situations, which may readily be automated, without requiring separately applying solder paste to the component terminals or to the plated holes or contact pads of the substrate.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the present invention, an array of solder-holding clips is provided, which is readily applied manually or by automation to a corresponding array of connector or other component terminals, facilitating joining such terminals to the contact pad and in-hole plating of a substrate or like device. 
       
    
    
       [0007]    The present invention will become more apparent from the following Brief Description of the Drawings and Description of Preferred Embodiments.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 shows a plan view of a fragmentary length of a blank for producing an embodiment of the present invention;  
         [0009]    [0009]FIG. 2 shows a plan view of a fragmentary length of a finished product according to the present invention, using the blank of FIG. 1;  
         [0010]    [0010]FIG. 3 shows a cross-sectional view of FIG. 2 taken along line  3 - 3  thereof;  
         [0011]    [0011]FIG. 4 shows a plan view of a fragmentary length of an embodiment of the present invention joining a connector having pin terminals to a substrate;  
         [0012]    [0012]FIG. 5 shows an enlarged cross-sectional view of an embodiment of FIG. 4 taken along line  5 - 5  thereof;  
         [0013]    [0013]FIG. 6 shows a cross-sectional view of an embodiment of the present invention similar to FIG. 5, after reflow of the solder and breaking away of the carrier strip;  
         [0014]    [0014]FIG. 7 shows a cross-sectional view similar to FIG. 5, of another embodiment of the present invention, with the solder-holding clip in a different position;  
         [0015]    [0015]FIG. 8 shows a plan view of a fragmentary length of a blank for producing a modified form of the present invention;  
         [0016]    [0016]FIG. 9 shows a plan view of a fragmentary length of a solder-holding clip array using the blank of FIG. 8;  
         [0017]    [0017]FIG. 10 shows a cross-sectional view of FIG. 9 viewed along line  10 - 10  thereof;  
         [0018]    [0018]FIG. 11 shows a plan view of a fragmentary length of the clip holder arrangement of FIG. 9 joining a connector to a substrate;  
         [0019]    [0019]FIG. 12 shows an enlarged cross-sectional view of FIG. 11 viewed along line  12 - 12  thereof;  
         [0020]    [0020]FIG. 13 shows a fragmentary plan view of a modification of the device of FIG. 12, adapting it to connect to a second substrate;  
         [0021]    [0021]FIG. 14 shows a side view of the device of FIG. 13;  
         [0022]    [0022]FIG. 15 shows a plan view of another embodiment of the present invention;  
         [0023]    [0023]FIG. 16 shows a cross section of the embodiment of FIG. 15 viewed along line  16 - 16  thereof;  
         [0024]    [0024]FIG. 17 shows a fragmentary top view of FIG. 16 viewed along the line  17 - 17  thereof;  
         [0025]    [0025]FIG. 18 shows the device of FIG. 15 assembled on a pair of connectors;  
         [0026]    [0026]FIG. 19 shows an alternative embodiment for surface mounting a connector on a substrate;  
         [0027]    [0027]FIG. 20 shows a plan view of another embodiment of the present invention;  
         [0028]    [0028]FIG. 21 shows a perspective view of a portion of the device of FIG. 20;  
         [0029]    [0029]FIG. 22 shows the device of FIG. 20 positioned between a connector and a circuit board, prior to solder reflow;  
         [0030]    [0030]FIG. 23 shows the device of FIG. 22, after solder reflow; and  
         [0031]    [0031]FIG. 24 shows an elevational view of another embodiment of the present invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0032]    FIGS.  1 - 6  shows one embodiment of the present invention. As seen in FIG. 1, a long flat strip  11  of electrically conductive material such as copper or beryllium copper is stamped into the shape of the intermediate blank shown. This is preferably done by progressive stamping to produce an array of a large number of repeated blanks  17  for one form of clip-holder according to the present invention. Alternatively, the strip  11  need not be formed from electrically conductive material, since the solder portions attached to the clips provide the necessary conductivity to electrically connect a terminal to a substrate or other component. The strip  11  is formed with a longitudinally extending carrier section  15  having customary indexing or sprocket holes  13  spaced along its length, to aid in moving the strip in successive steps through a progressive stamping machine. The carrier strip  15  is integral with individual clips  17  extending laterally therefrom at regular intervals therealong, spaced correspondingly to the spacing of terminals or pins on the electrical connectors with which the clips  17  are to be used in the manner described below. By way of example, the clips  17  may be spaced with a pitch of 0.05 or 0.100 inch.  
         [0033]    Integrally formed with the carrier strip  15  are a pair of spaced fingers  19  on each clip, joined to the carrier strip  15  by a connecting piece  21 , which has a notch  23  formed therein to permit the carrier strip  15  to be readily broken away or otherwise separated from the sequence of clips  17 . The fingers  19  are spaced apart a distance d coordinated with the width of the pins or terminals of the circuit element  31  (see FIGS.  4  to  6 ) with which the clip  17  is used.  
         [0034]    As seen in FIGS. 2 and 3, a solder mass  25 , preferably in the form of a section of solder wire, is placed across the pairs of fingers  19 , which are then rolled partially around the solder mass  25 , sufficiently to hold the solder in place. This is readily fabricated in the course of the progressive stamping, by laying a solder wire  25  (which preferably includes a solder flux) across a number of the clips  17 , curling the fingers  19  around the solder wire  25  as shown in FIGS. 2 and 3, and cutting away the solder in the area between the clips  17 , leaving a solder mass  25  held by each pair of fingers  19 , and of a volume appropriate for the required soldering action.  
         [0035]    In use, as shown in FIGS. 4 and 5, a connector or other circuit component  31  having a plurality of aligned terminals or pins  33  is passed through correspondingly spaced internally electroplated holes  35  of a substrate  37 . While the substrate  37  is illustrated as oriented vertically in FIG. 5, it will be understood that it may be horizontal or with other orientations, as may be appropriate. A ganged strip of clips  17  of which a portion is shown in FIG. 2, with a number of clips corresponding to the number of component terminals to be soldered to the substrate  37 , is then placed over the array of connector terminals  33  as illustrated in FIG. 4. For example, if the component  31  has  21  terminals in alignment, a section of the clip array of FIG. 4 having  21  clips will be applied over the component terminals  33  as shown, and severed from the remainder. The separation of the fingers  19  of each clip is selected so that there will be a frictional engagement between each clip  17  and its corresponding connector terminal  33 , so that the strip of clips will be retained in the position shown in FIGS. 4 and 5 during subsequent operations. It will be understood that where the component  31  has two or more rows of terminals, each row of terminals of the component  31  may be provided with a strip of the clips of FIG. 4, although only one row is shown in FIGS. 4 and 5.  
         [0036]    Then, heat is applied to the solder, as by heated air or other conventional means, which causes the solder to reflow and to be drawn by capillary action into the space between the terminal  33  and the sides of the plated substrate hole  35 . The hole  35  has a metallic surface, as by being electroplated on its interior, as indicated at  39 . The plating may extend around onto the flat surface of the substrate  37  to form contact pads, as illustrated at  41 . Normally, a slight space  43  is left between the terminal  33  and the plating  39  of the substrate hole  35 , into which the molten solder will be drawn. In normal practice this space may not be deliberately provided, since the customary slight irregularities in formation of the component terminal or the electro-plating  39  in the hole  35  will permit the molten solder to flow therebetween to bond the terminal  33  to the electro-plated layer  39 , as indicated in FIG. 6. After the soldering is completed, the carrier strip  15  is broken away from the individual clips  17  at the breakaway notches  23 , leaving the clips  17  in place but soldered to the component terminal, the plating of the hole, and to the contact pad  41 . If desired, the carrier strip may be broken away before the soldering is accomplished, although this is not preferred.  
         [0037]    [0037]FIG. 7 shows an alternate way of using the clips of FIGS. 2 and 3. In this instance, a connector or other component  31   a  is shown having two rows of terminal pins  33  instead of one row as shown in FIG. 5. In this instance the clips  17  are positioned on the component pins  33  before the component pins  33  are inserted into the substrate  37 , and are positioned between the component  31   a  and the substrate  37 . Heat is supplied as in the case of FIGS. 5 and 6 to join the pins  33  to the plated hole  39  of the substrate by soldering.  
         [0038]    [0038]FIGS. 8 through 12 show a modified form of the present invention. As seen in FIG. 8, the blank has a carrier strip  115  with indexing holes  113  similar to FIG. 1. Extending laterally from the carrier strip  115  are the individual solder-holding clips  117 . As seen in FIG. 8, each clip blank  117  is joined to the carrier strip  115  by a connecting piece  121  having a breakaway notch  123 . The individual clip blank  117  includes a body portion  147  having slits  149  extending adjacent the edges of the body portion  147  to form fingers  119  integral at one end with the body portion  147 . As indicated in FIG. 9, a solder wire  151  (preferably including a solder flux) is laid over the successive body portions  147  of a portion of the array of clips  117  as the array moves along the progressive stamping apparatus. As seen in FIGS.  9  to  11 , the fingers  119  are then curled around the solder wire  151  to hold it on the body portions  147 . After the solder wire  151  is applied and held by the fingers  119 , holes  145  are formed as seen in FIG. 9, as by punching through the clip bodies  147 . At the same time, the solder wire  151  is separated into two segments straddling each hole  145  and a gap  153  is made in the solder wire  151  between adjoining clip bodies  147  as seen in FIGS. 9 and 11. In this way, each body portion  147  carries two solder masses  125 , straddling its hole  145 . The holes  145  are dimensioned to engage the component terminals  133  frictionally, to position a solder mass on either side of the respective terminal  133  as shown in FIG. 11. In this way the array of clip bodies is retained on the component terminals  133 . The solder masses  125  remaining held by each clip body  147  are dimensioned to provide adequate solder for joining each clip  117  to its respective component terminal  133 .  
         [0039]    As seen in FIGS. 11 and 12, this form of solder-holding clip may be used in the same manner as shown in FIGS.  6  or  7  or  12 .  
         [0040]    Further, the clip  117  may be used to join a component  31  or  131  with any desired further substrate or another component, whether or not substrate  137  is present. As shown in FIGS. 13 and 14, the clips  117  may be formed with extensions  161  which may be used as terminals or leads to other apparatus. For example the end of each extension  161  may be formed into an edge clip shape  163  for a substrate as shown in FIG. 13 and  14 , to permit coupling of the component  131  pins to a further substrate (not shown) parallel to the component  131  or in alignment thereto. By bending extension  161  at right angles, the further substrate may be perpendicular to substrate  137 . In place of edge clip  163 , the end of each extension  161  may be formed for surface mounting to a substrate contact pad, or may have any other desired configuration.  
         [0041]    FIGS.  15 - 18  show a further modification of the present invention. In this instance, each solder-holding clip  219  is formed with a pair of sides  201  joined by a back  203 . Each side  201  has a pair of fingers or tabs  205  extending partially around a solder mass  225 , leaving a space  207  between the solder mass  225  and the back  203 , for receiving a terminal pin  209  of a connector  211 . Alternatively, preferably the spacing between the arms  201  is dimensioned to frictionally engage the pins  209 . As shown in FIG. 18, the pin  209  passes through a substrate  213 , having an internally plated hole and/or a conductive pad to which the pin  209  is to be soldered.  
         [0042]    This form of invention also is adapted for multi-stage progressive stamping. In fabrication, an elongated strip of conductive material is stamped as shown in FIG. 15 to have a carrier strip  215  with a series of the clips  219  extending laterally therefrom. The body is bent into the U-shape shown in FIG. 17 to form clip sides  201  each with a pair of tabs or fingers  205 . A solder wire  225  of a diameter conforming to the separation between the pairs of fingers  205  is laid between the pairs of fingers  205 , and the fingers are then bent partially around and staked into the solder wire  225 . The solder wire  225  is then cut between the clips  219 , leaving an amount of solder appropriate for the specific use for the clips. A connecting portion  221  serves to join the clip  219  to the carrier strip  215 , and is bent with an offset as shown in FIGS. 17 and 18, so that when assembled to a row of terminals  209 , interference is avoided between the terminal pins  209   a  and  209   b  and the carrier strip  215 .  
         [0043]    The spacing between the clips  209  is correlated to the spacing between the pins  209   a  or  209   b  of the connector  211 , so that in use a section of the strip of FIG. 15 having a number of clips  219  equal to the number of pins  209  in a row of the connector  211 , may be inserted over the pins  209  as shown in dashed lines  209  in FIG. 15 and also in FIG. 18. FIG. 18 shows connectors  211  illustratively of the dual row type, having terminal pins  209   a  and  209   b  equally spaced in the direction perpendicular to the plane of the paper. It will be understood that the present invention may be used with any number of rows of terminal pins, from one row up. By way of illustration, the connectors  211  may be of the J1 or J2 type, and the substrate  213  may be a PC 104  board. Illustratively the terminals  209  may be spaced at 0.100 inch intervals, and the pins may be 0.480 inches long with a 0.025 inch square cross section.  
         [0044]    Upon reflowing, the solder will flow around the pins  209  and by capillary action into the internally plated holes of the substrate  213 . After the soldering is completed, each clip has its joining section  221  broken or cut off, as by a notch  223  formed therein.  
         [0045]    The solder-holding clips of the present invention are usable not only to solder a connector or other component having non-solder-bearing terminals to through-plated holes of a substrate, but may also be used to solder a lead having any desired terminal configuration to a pin or other terminal of an electrical component. FIG. 19 shows the lead clip  219  with its lead  221  bent out at a right angle to terminal pin  209 , and terminated in a solder-holding arrangement  250  to permit surface mounting of connector  211  on a substrate (not shown). The solder-holding arrangement may have any appropriate construction, such as shown in U.S. Pat. No. 4,679,889.  
         [0046]    Referring now to FIG. 20, therein is shown an alternative embodiment of the present invention, which is similar to that shown in FIGS.  1 - 6 . However, as seen in FIG. 20, clip  317  is provided with two pairs of fingers  319 , with one pair of fingers being located on the side of clip  317  adjacent carrier strip  15 , and the other pair of fingers being located on the opposite side of clip  317 . Clip  317  has a generall double I-shape, which may be formed by a progressive stamping operation. Two solder portions  321  are positioned laterally across the two pairs of fingers  319 . The solder portions  321  may be formed in much the same manner as solder wire  25  (FIG. 2).  
         [0047]    Each pair of fingers  319  is then curled around the corresponding solder portion  321  to thereby securely retain the solder portion  321  (FIG. 21). As shown in FIG. 20, the solder sections  321  extend partially into the central aperture in clip  317 . Referring now to FIG. 22, therein is shown a connector or other circuit component  31  having a plurality of pins  33 , with each of the pins  33  passing through the central aperture of a corresponding clip  317 . Because the solder portions  321  extend partially into the central aperture, they act to frictionally engage the inserted pin  33 . After the clips  317  are positioned on the connector  31 , the pins  33  are subsequently inserted into corresponding holes  35  of a substrate  37 . Heat is then applied, which causes the solder sections  321  to reflow and be drawn into the space between the terminals  33  and the sides of the holes  35  (FIG. 23). Although the clip  317  shown in FIGS.  20 - 23 , is shown as being positioned between the connector  31  and substrate  37 , the clip  317  may also be used where it is positioned after the substrate  37  is mated with the clip  317 , similar to FIG. 5.  
         [0048]    Referring now to FIG. 24, therein is shown the use of a pair of clips  219  (after the removal of connecting portion  221 ) for soldering a pair of pins  33  on a connector  31  to a pair of contact pads  350  positioned on opposite sides of a substrate  37 . Effectively, the pair of clips  219  provide a “straddle mount”between the connector pins  33  and the substate  37 . As shown in FIG. 24, the clips  219  are positioned with their solder portions  225  facing each other. The connector pins  33  are then inserted into the opposed clips  219 , and the substrate is positioned in between clips  219  so as to be frictionally engaged by the opposed solder portions  225 . Heat is applied, as described above, to cause the solder to reflow. The clips  219  may be provided as a pair of arrays to thereby solder an edge connector to two rows of contact pads, wherein each row is positioned on opposite sides of the substrate  37 .  
         [0049]    It will be understood that the solder elements  25 ,  125 ,  151  and  321  may incorporate customary solder flux to facilitate the proper soldering operation.  
         [0050]    While the solder-holding clips of the present invention are illustratively described as used with the terminals of a connector, it will be understood that these clips may be used in joining terminals of integrated circuit chips, chip holders, resistors, capacitors and other non-solder bearing electrical components to contact pads or plated holes of printed circuit boards or other substrates.  
         [0051]    The foregoing embodiments should be understood as exemplary only, the present invention being defined by the following claims.