Abstract:
A system and method of joining together first and second electric terminals includes providing the second terminal with an aperture extending therethrough and a notch therein. The first and second terminals are positioned in overlapping relationship with one another so the aperture overlaps the first terminal to provide access to the first terminal through the second terminal, and so the notch overlaps the first terminal. Heat is applied to the first terminal through the aperture in the second terminal to heat the first and second terminals. The end of a solder wire is positioned in engagement with the notch of the heated second terminal to locate the solder wire with respect to the terminals and to melt the solder wire to form a solder pool that contacts the first and second terminals.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates generally to a method of soldering, and more particularly to a method of soldering together metallic terminals, such as those found in a fuel injector.  
         BACKGROUND OF THE INVENTION  
         [0002]    Soldering has long been used for joining together metallic components. In its basic practice, at least two metallic components to be joined are heated to an elevated temperature. The components must be heated to the required temperature such that the solder wire melts upon contact with the heated components. As the solder wire melts, it begins to flow and exhibits a “wetting” behavior as the flow moves along the surfaces of the joined components. Often, the quality of the soldered joint is dependent upon the wetting behavior of the solder flow. More specifically, the mechanical and electrical properties of the soldered joint are dependent upon achieving the proper wetting behavior of the solder flow.  
         SUMMARY OF THE INVENTION  
         [0003]    For optimum solder flow, the components to be joined should be simultaneously and as evenly heated as possible. As a result, temperature gradients within and between the components are decreased and the temperature distribution within and between the components is substantially homogeneous.  
           [0004]    Contact-type soldering techniques often do not yield a substantially homogeneous temperature distribution within and between the components to be joined. Such contact-type soldering techniques can include using a soldering iron or a similar tool to apply heat via a direct point contact to the components to be joined. Typically, the portion of the component in direct contact with the tip of the soldering iron has the highest temperature, while the portion of the component farthest from the point of contact with the soldering iron has the lowest temperature. The difference in temperature within and between the components to be joined yields a temperature gradient that can have a negative effect on the solder flow and the quality of the soldered joint.  
           [0005]    Another soldering technique, non-contact laser soldering, provides some advantages over contact soldering techniques. With non-contact laser soldering, the laser beam can strike a larger area of the components to be joined, therefore decreasing the temperature gradient within and between those components. However, in applications where the laser beam is prevented from directly striking one of the components, a temperature gradient still results between the components.  
           [0006]    Additional problems in the general practice of soldering can include positioning and guiding the solder wire to the desired location relative to the components to be joined. This is especially a problem in applications requiring automation, rather than manpower. While humans can manually adjust the location of the solder wire to attain the desired solder flow, achieving this control within an automated system is complicated and very expensive.  
           [0007]    The invention provides for significant improvement to a method of soldering metallic terminals. The invention provides a method of soldering using a non-contacting heat source, such as a laser, to heat the components to be joined. The components are configured to aid in their heating and to guide the solder wire to an optimum location with respect to the components.  
           [0008]    More specifically, the invention provides a method of joining together first and second electrical terminals. The method includes providing the second terminal with an aperture extending therethrough, positioning the first and second terminals in overlapping relationship with one another to provide access to the first terminal through the aperture in the second terminal, applying heat to the first terminal through the aperture in the second terminal to heat the first and second terminals, and positioning a solder wire in engagement with at least one of the heated first and second terminals to melt the solder wire and to form a solder pool that contacts the first and second terminals. This method substantially improves the heat transfer through the terminals and decreases the temperature gradient throughout and between the terminals, thereby improving the quality of the soldered joint.  
           [0009]    In one aspect of the invention, applying heat includes directing a beam through the aperture to strike the first terminal and having at least a portion of the beam reflect off the first terminal to strike the second terminal adjacent the aperture to heat the second terminal. The beam can be generated by suitable lasers, including a solid-state laser, a gas laser, an excimer laser, a dye laser, or a semiconductor laser.  
           [0010]    In another aspect of the invention, the first terminal is coupled to a fuel injector and the method further includes placing the fuel injector in a fixture to secure the fuel injector before applying heat to the first and second terminals. The second terminal is coupled to a retainer clip and the method further includes placing the retainer clip on the fuel injector to position the second terminal in overlapping relationship with the first terminal.  
           [0011]    The invention also provides another method of joining together first and second electrical terminals. The method includes providing the second terminal with a notch therein, positioning the first and second terminals in overlapping relationship with one another so the notch overlaps the first terminal, providing a solder wire having an end, positioning the end of the solder wire in engagement with the notch of the second terminal to locate the solder wire with respect to the terminals, and melting the solder wire to form a solder pool that contacts the first and second terminals. This method provides a guide for the solder wire so that the solder flow is consistently developed in the desired location.  
           [0012]    In one aspect of the invention, positioning the end of the solder wire in the notch includes feeding the solder wire from a solder feeding machine. The notch is sized to receive the end of the solder wire.  
           [0013]    The invention further provides a method of joining together first and second electrical terminals using a combination of the methods described above. The method includes providing the second terminal with an aperture extending therethrough and a notch therein, positioning the first and second terminals in overlapping relationship with one another so the aperture overlaps the first terminal to provide access to the first terminal through the second terminal and so the notch overlaps the first terminal, applying heat to the first terminal through the aperture in the second terminal to heat the first and second terminals, providing a solder wire having an end, positioning the end of the solder wire in engagement with the notch of the heated second terminal to locate the solder wire with respect to the terminals, and to melt the solder wire to form a solder pool that contacts the first and second terminals.  
           [0014]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a partially-exploded perspective view of a fuel injector and a connector terminal assembly embodying the present invention.  
         [0016]    [0016]FIG. 2 is a perspective view of the fuel injector and connector terminal assembly of FIG. 1, illustrating a terminal portion of a connector terminal being soldered to an injector terminal.  
         [0017]    [0017]FIG. 3 is an enlarged perspective view of the injector terminals and connector terminals shown in FIGS.  1 - 2 , illustrating a soldered,pair of terminals and a pair of terminals in the process of being soldered.  
     
    
       [0018]    Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    The invention is embodied in a method and system of soldering together metallic terminals. While the method and system are shown and described as being applied to the manufacture of fuel injectors, those skilled in the art will recognize that the soldering method and system of the invention can be applied to the manufacture of other articles or devices having electrical terminals or other components that require soldering. In the embodiment described below, the soldering method and system of the invention is fully automated, however, those skilled in the art will recognize that some or all of the method could also be carried out manually without deviating from the invention.  
         [0020]    The soldering system and method of the invention can stand alone, or can be one of a plurality of stages in a manufacturing and/or assembly line. For the purposes of this description, only the soldering stage will be described with the understanding that additional manufacturing and/or assembly processes can be carried out both upstream and downstream of the soldering stage.  
         [0021]    Referring now to FIG. 1, at the beginning of the soldering stage a workpiece is supported by a fixture, or workpiece carrier  10 . In an automated system, multiple workpiece carriers  10  are disposed on a conveyor belt (not shown). The conveyor belt transports each workpiece carrier  10  and its accompanying workpiece through a soldering station (not shown). In the illustrated embodiment, the workpiece is a Bosch model number “EV14” fuel injector  14  available from the Robert Bosch Corporation. Those skilled in the art, however, will recognize that the soldering method and system can also be practiced with other fuel injector models, or with other devices that require soldering of components.  
         [0022]    The illustrated fuel injector  14  includes an inlet end  18 , an outlet end  22 , and a pair of injector terminals  26   a,    26   b  that are intermediate the inlet end  18  and outlet end  22 , and that are electrically connected to the electromagnetic coil (not shown) of the fuel injector  14 , as is understood in the art. The illustrated injector terminals  26   a,    26   b  are each about 2 mm wide and about 3.5 mm long. The inlet end  18  of the illustrated injector  14  is defined in part by an extension tube  30  having an outer cylindrical surface  34 . As seen in FIGS. 1 and 2, the workpiece carrier  10  supports the fuel injector  14  in an inclined orientation relative to horizontal so that the inlet end  18  is oriented generally vertically below the outlet end  22 . While the angle of incline from horizontal can vary, angles of between about 15° to 75° from horizontal can be used with about 45° being preferred.  
         [0023]    Either before the injector  14  is placed in the workpiece carrier  10 , or while the injector  14  is supported in the workpiece carrier  10 , a connector terminal assembly  38  is attached to the fuel injector  14 . The connector terminal assembly  38  includes a pair of connector terminals  42   a,    42   b  molded into a plastic retainer clip  46 . The retainer clip  46  includes a clip portion  50  and a body portion  54 . The clip portion  50  is generally C-shaped and is sized to be mounted on the outer cylindrical surface  34  of the extension tube  30 . The body portion  54  is generally rectangularly shaped and supports the connector terminals  42   a,    42   b.    
         [0024]    As shown in FIG. 1, the connector terminals  42   a,    42   b  include respective terminal portions  58   a,    58   b  extending in one direction from the retainer clip  46 , and respective terminal portions  62   a,    62   b  extending in the opposite direction from the retainer clip  46 . The terminal portion  62   a,    62   b  of each connector terminal  42   a,    42   b  is sized and configured as desired to extend to the location where an external power supply (not shown) is connected to the fuel injector  14  (typically at an overmolded connector socket—not shown). As a result, the terminal portions  62   a,    62   b  can be made in a variety of shapes. The terminal portion  58   a,    58   b  of each illustrated connector terminal  42   a,    42   b  is about 2 mm wide to substantially correspond to the width of the injector terminals  26   a,    26   b.  The terminal portions  58   a,    58   b  are each about 5.5 mm long from a distal end  64  to the point where each terminal portion  58   a,    58   b  extends from the body portion  54  of the retainer clip  46 . Those skilled in the art will recognize that the dimensions given for the injector terminals  26   a,    26   b  and connector terminals  42   a,    42   b  can be varied as desired depending on the specific fuel injector  14  or other device being soldered.  
         [0025]    As best seen in FIG. 3, the terminal portions  58   a,    58   b  further include respective apertures  66  that extend through the entire thickness of the connector terminals  42   a,    42   b.  Each illustrated aperture  66  is generally rectangular in shape and is defined by four interior sidewalls  70   a - 70   d.  Also, each aperture  66  is about 1.5 mm wide and about 0.75 mm long. Other sizes and shapes can be used for the aperture  66 . The aperture  66  can be formed using any suitable machining techniques, including, but not limited to, stamping, punching, cutting, grinding, milling, and the like.  
         [0026]    The terminal portions  58   a,    58   b  also include respective notches  74  formed in the respective distal ends  64 . Like the apertures  66 , the notches  74  extend through the entire thickness of the connector terminals  42   a,    42   b.  As best seen in FIG. 3, each illustrated notch  74  is defined by three interior sidewalls  78   a - 78   c.  Also, each notch  74  is about 1.5 mm wide and about 1.4 mm long. Other sizes and shapes can be used for the notch  74 . The notch  74  can be formed using any suitable machining techniques, including, but not limited to, stamping, punching, cutting, grinding, milling, and the like.  
         [0027]    The aperture  66  and the notch  74  of terminal portions  58   a,    58   b  are positioned such that a strip  82  separates the notch  74  and the aperture  66  on each respective connector terminal  42   a,    42   b.  As will be described in more detail below, the separation between the aperture  66  and the notch  74  helps ensure that the heat source does not directly contact or strike the solder wire  80  used for soldering together the terminals  26   a,    42   a,  and  26   b,    42   b.  The dimensions of the strip  82  can vary as dictated by the dimensions of the connector terminals  42   a,    42   b,  the apertures  66 , and the notches  74 .  
         [0028]    The connector terminal assembly  38  is installed on the injector  14  by first snapping or sliding the clip portion  50  of the retainer clip  46  onto the extension tube  30 . The retainer clip  46  is then positioned on the outer cylindrical surface  34  so that the terminal portions  58   a,    58   b  of the connector terminals  42   a,    42   b  are generally aligned with and in overlapping relationship with the injector terminals  26   a,    26   b,  respectively, in preparation for soldering. For reasons that will become evident below, the overlapping relationship will include the terminal portions  58   a,    58   b  of the connector terminals  42   a,    42   b  being positioned outside or on top of the injector terminals  26   a,    26   b  with respect to the fuel injector  14 . The terms “outside”, “top”, “bottom”, “under”, “over”, and the like, as used herein and in the appended claims, are for purposes of description only and are not intended to imply any particular orientation.  
         [0029]    In order to achieve the desired overlapping relationship of the connector terminals  42   a,    42   b  and the injector terminals  26   a,    26   b,  the retainer clip  46  (and therefore the connector terminals  42   a,    42   b ) is both axially and rotationally aligned on the fuel injector  14  relative to the injector terminals  26   a,    26   b.  For axial alignment, the fuel injector  14  includes a shoulder  86  that provides a stop or abutment surface against which the clip portion  50  is positioned. In the illustrated embodiment, the shoulder  86  is defined by the interface where the extension tube  30  is inserted into the main body of the injector  14 . When the clip portion  50  abuts the shoulder  86  on the injector  14 , there is about a 3 mm axial overlap of the terminal portions  58   a,    58   b  and the injector terminals  26   a,    26   b.  Moving the retainer clip  46  along the outer cylindrical surface  34  of the extension tube  30  and into abutting relation with the shoulder  86  will occur sometime prior to the actual soldering process, and can occur immediately when the retainer clip  46  is placed on the injector  14  or anywhere else during the automated process upstream of the soldering station. In the illustrated embodiment, axial alignment of the connector terminal assembly  38  occurs before the fuel injector  14  is placed on the workpiece carrier  10 .  
         [0030]    During installation of the connector terminal assembly  38  onto the injector  14 , the connector terminal assembly  38  is also generally oriented in rotational alignment with respect to the injector  14  to achieve the desired overlapping relationship of the terminal portions  58   a,    58   b  and the injector terminals  26   a,    26   b.  Once the connector terminal assembly  38  is mounted on the injector  14 , the workpiece, comprised of the injector  14  and the attached connector terminal assembly  38 , is placed in the workpiece carrier  10 . Each workpiece carrier  10  includes (see FIGS. 1 and 2) a first pair of side arms  90  that engage opposite sides of the retainer clip  46  for substantially preventing unwanted movement (both axial and rotational) of the clip  46 . The first pair of side arms  90  engage the retainer clip  46  along the clip portion  50  and are resiliently biased to engage opposite sides of the clip portion  50 , and as a result, the side arms  90  must be actuated to disengage the clip portion  50 . Any suitable fixture or workpiece carrier  10  that performs these steps may be used to support the workpiece, comprising the fuel injector  14  and connector terminal assembly  38 .  
         [0031]    Sometime after the fuel injector  14  is placed in the workpiece carrier  10 , and prior to soldering, rotational alignment of the terminal portions  58   a,    58   b  and the injector terminals  26   a,    26   b  is performed. This rotational alignment ensures the proper overlapping relationship between the terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b,  relative to their width dimensions. The rotational alignment is accomplished using (see FIG. 1) a second pair of side arms  94  that engage outer side surfaces  95  of terminal portions  58   a,    58   b,  and outer side surfaces  96  of the injector terminals  26   a,    26   b  to rotate the clip portion  50  on the outer cylindrical surface  34  of the injector  14 . In the illustrated embodiment, the workpiece carrier  10  encounters the second pair of side arms  94  upstream of the soldering station.  
         [0032]    Before the second pair of side arms  94  engages the respective terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b,  the first pair of side arms  90  on the workpiece carrier  10  is disengaged from the clip portion  50  by a mechanism (not shown) engaged by the workpiece carrier  10  as the workpiece carrier  10  moves with the conveyor belt. After the first pair of side arms  90  is disengaged, the second pair of side arms  94  moves into position to engage the respective terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b.  As shown in FIG. 1, the arms of the second pair of side arms  94  move equidistantly toward one another to engage the outer side surfaces  95  of terminal portions  58   a,    58   b,  and the outer side surfaces  96  of the injector terminals  26   a,    26   b.  This action rotates the retainer clip  46  on the extension tube  30  to rotationally align the respective terminal portions  58   a,    58   b  with the injector terminals  26   a,    26   b  for soldering.  
         [0033]    Next, the second pair of side arms  94  disengages the respective terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b,  and the first pair of side arms  90  is again biased to engage the clip portion  50  to secure the retainer clip  46  in an aligned orientation on the fuel injector  14  (see FIG. 2). FIG. 1 illustrates the connector terminal assembly  38  exploded from the extension tube  30 , however, as previously explained, the connector terminal assembly  38  is attached to the extension tube  30  of the fuel injector  14  upon rotational alignment. The connector terminal assembly  38  is shown exploded from the extension tube  30  for illustrative purposes only.  
         [0034]    Generally, both axial and rotational alignment of the terminals  26   a,    42   a,  and  26   b,    42   b  is required before the terminals  26   a,    42   a,  and  26   b,    42   b  can be soldered. This process can occur at any point along the conveyor belt before the fuel injector  14  reaches the soldering station. For example, the mechanisms that initiate axial and rotational alignment can be positioned in the soldering station, or immediately upstream of the soldering station, such that only a short distance and/or time period exists between alignment and soldering.  
         [0035]    When the injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b  are properly aligned, the overlapping relationship between the terminal portions  58   a,    58   b  and the injector terminals  26   a,    26   b  is such that the aperture  66  and notch  74  of each of the terminal portions  58   a,    58   b  completely overlap or overlie the respective injector terminals  26   a,    26   b.  In other words, when the terminal portions  58   a,    58   b  and the injector terminals  26   a,    26   b  are in overlapping relationship, each aperture  66  provides access through the respective terminal portion  58   a,    58   b  to the respective underlying injector terminal  26   a,    26   b.  Likewise, each notch  74  provides access to the respective underlying injector terminal  26   a,    26   b.  As previously mentioned, the illustrated axial overlap between the terminal portion  58   a,    58   b  and the injector terminals  26   a,    26   b  is about 3 mm, recognizing that the amount of axial overlap can vary as desired.  
         [0036]    Also, a small gap (not shown) exists between the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b  after axial and rotational alignment. The target gap is between about 0.2 mm and 0.25 mm; however, during production, the range of acceptable values widens between about 0.1 mm and 0.4 mm. The gap allows melted solder wire  80  to flow between the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b.  Thus, upon cooling and solidification, a soldered joint  97  is formed that electrically and mechanically connects the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b.  Alternatively, the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b  may be positioned in overlapping engagement such that no gap exists between the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b.  Therefore, melted solder wire  80  may only flow within the notches  74  of the terminal portions  58   a,    58   b  to electrically and mechanically connect the respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b  near the interface of the notches  74  and respective injector terminals  26   a,    26   b.    
         [0037]    After axial and rotational alignment of the connector terminal assembly  38 , the fuel injector  14  is transported to a soldering position within the soldering station, where the injector terminal  26   a  and terminal portion  58   a  are soldered together in the manner described below with respect to the injector terminal  26   b  and terminal portion  58   b.  After the terminal portion  58   a  and the injector terminal  26   a  are soldered together to form the soldered joint  97 , the fuel injector  14  is transported by the conveyor belt so that terminal portion  58   a  and injector terminal  26   a  are moved away from the soldering position, and terminal portion  58   b  and injector terminal  26   b  are moved to the soldering position for soldering. FIGS.  2 - 3  illustrate the injector terminal  26   b  and terminal portion  58   b  in the soldering position with the soldered joint  97  already completed between injector terminal  26   a  and terminal portion  58   a.  Alternatively, dual soldering stations may exist such that respective injector terminals  26   a,    26   b  and terminal portions  58   a,    58   b  may be soldered together simultaneously, rather than separately.  
         [0038]    The soldering process will now be described with respect to the injector terminal  26   b  and terminal portion  58   b.  As shown schematically in FIG. 2, a heat source, such as a laser  98 , is fixedly positioned relative to the ground while the conveyor belt transports the fuel injector  14  relative to the laser  98 . When the injector terminal  26   b  and terminal portion  58   b  are in the soldering position, a beam  102  emanating from the laser  98  will be substantially perpendicular to the outside surface of the terminal portion  58   b,  and will pass through the aperture  66  to strike the injector terminal  26   b.  Alternatively, the laser  98  may be positioned at any other angle relative to the terminal portion  58   b,  provided the beam  102  will pass through the aperture  66  and strike the injector terminal  26   b.  The laser  98  can be any commercially available laser capable of being used for the laser soldering process, including, but not limited to, a solid-state laser, a gas laser, an excimer laser, a dye laser, and a semiconductor laser. Alternatively, if dual soldering stations (not shown) are to be used, a second laser (not shown) will be positioned in the second soldering station similarly to the laser  98  in the first soldering station.  
         [0039]    The laser  98  is configured to substantially concentrate the laser beam  102  through the aperture  66  in the terminal portion  58   b  such that the laser beam  102  is directly striking the injector terminal  26   b.  Between about 10% and 30%, and believed to be about 20%, of the energy of the laser beam  102  is absorbed by the injector terminal  26   b,  thereby directly heating the injector terminal  26   b.  A portion of the laser beam  102  is diffusively reflected (see FIG. 3) by the surface of the injector terminal  26   b  and strikes the sidewalls  70   a - 70   d  that define the aperture  66 , thereby also heating the terminal portion  58   b.  The reflected portion  106  of the beam  102  contains the balance of the beam&#39;s energy, between about 70% and 90%, and believed to be about 80%. Also, some of the reflected portion  106  of the beam and its associated heat energy will be lost to the environment. The configuration and method shown in FIG. 3 promotes a substantially homogenous heating of both the terminal portion  58   b  and the injector terminal  26   b,  which decreases the temperature gradient throughout and between the injector terminal  26   b  and terminal portion  58   b.  As a result, solder flow between the terminal portion  58   b  and the injector terminal  26   b  is promoted and a higher quality soldered joint  97  is possible.  
         [0040]    The soldering station further includes a source of solder wire  80 , such as a solder feeding machine  110 , which is shown schematically in FIG. 2. Any suitable automatic solder feeding machine  110  can be used as the source of solder wire  80 . Like the laser  98 , the solder feeding machine  110  is fixedly positioned relative to the ground, while the conveyor belt transports the fuel injector  14  relative to the solder feeding machine  110 . When the injector terminal  26   b  and terminal portion  58   b  are in the soldering position, the solder wire  80  is fed automatically from the solder feeding machine  110 . The solder wire  80  is fed at an angle relative to the injector terminal  26   b  and terminal portion  58   b,  however, the solder wire  80  is preferably fed substantially vertically relative to the conveyor belt so that gravity can facilitate the feeding of the solder wire  80  and the subsequent solder flow. Typically, solder wire  80  having a diameter between about 0.5 mm and 1.5 mm is used. As shown in FIG. 3, the end  114  of the solder wire  80  is fed to the injector terminal  26   b  and terminal portion  58   b  such that the end  114  of the solder wire  80  substantially engages both the injector terminal  26   b  and the notch  74  of the terminal portion  58   b.  The sidewalls  78   a - 78   c  guide and locate the end of the solder wire  80  into position with respect to the injector terminal  26   b  and terminal portion  58   b.  Alternatively, if dual soldering stations (not shown) are to be used, a second solder feeding machine (not shown) will be positioned in the second soldering station similarly to the solder feeding machine  110  in the first soldering station.  
         [0041]    Upon the laser beam  102  striking the injector terminal  26   b  and the terminal portion  58   b,  only about 500 milliseconds are required to achieve a substantially homogeneous temperature distribution between the injector terminal  26   b  and terminal portion  58   b.  The solder wire  80  is then fed to the injector terminal  26   b  and terminal portion  58   b  such that the solder wire  80  is guided to the proper location by the notch  74 . Soon after contacting the interface between the injector terminal  26   b  and the sidewalls  78   a - 78   c  of the notch  74 , the solder wire  80  melts and forms a solder pool (not shown). Through the wetting behavior of the solder pool, the solder pool spreads over and between the injector terminal  26   b  and terminal portion  58   b.  After about two seconds, the solder wire  80  is removed and the laser  98  is deactivated. Then, within about 500 milliseconds, the solder pool cools to form a soldered joint  97 . The separation strip  82  of the terminal portion  58   b  ensures that the laser beam  102  does not directly strike the end  114  of the solder wire  80 .  
         [0042]    After the terminal portions  58   a,    58   b  have been soldered to the respective injector terminals  26   a,    26   b,  the fuel injector  14  is transported by the conveyor belt away from the soldering station to various additional assembly, manufacturing, and/or testing stations.  
         [0043]    The terminal portions  58   a,    58   b,  as previously described, preferably embody both an aperture  66  and a notch  74  as features to aid in the method of soldering of the present invention. However, those skilled in the art will recognize that either feature may be used independently of one another in alternate embodiments of the present invention. In one alternate embodiment of the present invention (not shown), the terminal portions  58   a,    58   b  only include apertures  66  therein to allow a beam  102  to pass through the apertures  66  and strike the injector terminals  26   a,    26   b  to achieve the homogeneous heating described above. After the terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b  are heated by the beam  102 , solder wire  80  is fed to the terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b  in any suitable manner, such that the solder wire  80  (and subsequent solder pool) comes into contact with both terminal portion  58   a  and injector terminal  26   a,  and both terminal portion  58   b  and injector terminal  26   b.    
         [0044]    In another alternate embodiment of the present invention (not shown), the terminal portions  58   a,    58   b  only include notches  74  therein to guide the solder wire  80  as it is fed to the respective terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b.  The terminal portions  58   a,    58   b  and injector terminals  26   a,    26   b  may be heated by a non-contacting heat source, such as the previously described beam  102 , or a contacting heat source, such as a soldering iron (not shown), prior to application of the solder wire  80 .  
         [0045]    Various features of the invention are set forth in the following claims.