Abstract:
A method of making a microelectronic package. The advanced microelectronic component package incorporates a specially shaped base element which holds and electrically separates the individual conductors associated with the microelectronic component(s) so that the individual conductors may be bonded to external package leads and other conductors within the package. In a first embodiment, jacketed, insulated wire is used as one winding of a toroidal transformer, while unjacketed insulated wire is used as another winding. The jacketing is stripped from the first winding and the exposed conductors are routed into channels along the sides of the base element. The unjacketed conductors are also routed into the same channels, where both conductors are bonded to the external package leads. Raised elements along the sides of the base provide the required electrical separation between the conductors during both manufacture and operation. A method of manufacturing the improved microelectronic package is also disclosed.

Description:
RELATED APPLICATION 
     This application is a divisional of U.S. patent application entitled “ADVANCED ELECTRONIC MICROMINATURE PACKAGE AND METHOD” having application Ser. No. 09/163,871, filed on Sep. 30, 1998, now U.S. Pat. No. 6,225,560, issued May 1, 2001 which claims the benefit of provisional application Ser. No. 60/066,278, filed on Nov. 25, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to microminiature electronic elements and particularly to an improved package and method of packaging for microminiature electronic components. 
     2. Description of Related Technology 
     For many years, electronic circuit boards have been fabricated by interconnecting a plurality of electronic components, both active and passive, on a planar printed circuit board. Typically, this printed circuit board has comprised an Epoxy/fiberglass laminate substrate clad with a sheet of copper, which has been etched to delineate the conduct paths. Holes were drilled through terminal portions of the conductive paths for receiving electronic component leads which were subsequently soldered thereto. 
     More recently, so-called surface mount technology has evolved to permit more efficient automatic mass production of circuit boards with higher component densities. With this approach, certain packaged components are automatically placed at preselected locations on top of a printed circuit board so that their leads are registered with, and lie on top of, corresponding solder paths. The printed circuit board is then processed by exposure to infrared, convection oven or vapor phase soldering techniques to re-flow the solder and, thereby, establish a permanent electrical connection between the leads and their corresponding conductive paths on the printed circuit board. 
     Dual in-line chip carriers are a well known embodiment of microelectronic component packages which have existed for many years. The most common example is an integrated circuit which is bonded to a ceramic carrier and electrically connected to a lead frame providing opposite rows of parallel electrical leads. The integrated circuit and ceramic carrier are normally encased in a rectangular plastic housing from which the leads extend. Typically, these dual in-line packages are mounted horizontally, i.e. with the leads extending co-planar with the printed circuit board. Such dual in-line packages have heretofore been attached to printed circuit boards by surface mounting techniques. 
     The increasing miniaturization of electrical and electronic elements and the high density mounting of such elements has created increasing problems with electrical isolation and mechanical interconnection. In particular, miniaturization and high density placement makes it more difficult to establish reliable and efficient connection between fine gauge (AWG 20 to AWG 50) copper wires and egress hardware or terminals. Presently known interconnection methods severely limit the ability to provide high density and reliable electrical and mechanical isolation between distinct egress or terminal points due to space limitations. 
     One prior art interconnection approach, as illustrated in  FIG. 1 , is to extend a fine copper wire forming the element lead and to wrap or coil it around a terminal pin of a terminal and apply solder to the connection. This configuration requires space that is not always available and does not allow adequate separation for high voltages that may be required in the circuit. Another problem with this approach is that element leads are frequently broken or sheared during a subsequent encapsulation process. In addition, the lead is also frequently broken as the result of thermal expansion and contraction of the leads and/or terminals. For reasons discussed further below, this method is particularly unsuitable when microelectronic transformers are used within the component package. Transformers are electrical components which are used to transfer energy from one alternating current (AC) circuit to another by magnetic coupling. Generally, transformers are formed by winding one or more wires around a ferrous core. A first wire acts as a primary winding and conductively couples energy to and from a first circuit. A second wire, also wound around the core so as to be magnetically coupled with the first wire, acts as a secondary winding and conductively couples energy to and from a second circuit. AC energy applied to the primary windings causes AC energy in the secondary windings and vice versa. A transformer may be used to transform between voltage magnitudes or current magnitudes, to create a phase shift, and to transform between impedance levels. 
     Another purpose for which microelectronic transformers may be used is to provide physical isolation between two circuits. For example, a transformer may be used to provide isolation between a telephone signal line in the public switched telephone network and consumer equipment such as modems, computers and telephones. The transformer must be able to withstand large voltage spikes which may occur due to lightning strikes, malfunctioning equipment, and other real-world conditions without causing a risk of electrical fire or other hazardous conditions. 
     One well-known configuration for a microelectronic transformer comprises a toroidal ferrous core. A toroidal transformer can elegantly provide any one of the above listed functions. One drawback to the use of toroidal cores relates to manufacturing; such cores are not easily manufactured nor are the resulting transformers in a convenient configuration for modem component package production techniques. Additional information about electronic microminiature packaging can be found in U.S. Pat. No. 5,015,981 entitled “ELECTRONIC MICROMINIATURE PACKAGING AND METHOD” which is assigned to the assignee hereof, and incorporated by reference herein in its entirety. 
     In addition to physical and manufacturing considerations, the electrical performance of the transformer must be considered. One means by which the electrical performance of transformers is gauged is the high-potential (hi-pot) test. A hi-pot test involves the application of AC or DC signals to the transformer to determine whether the breakdown of the core dielectric or other destructive failures occur at some chosen voltage level. A hi-pot test can also be used to demonstrate that insulation can withstand a given over-voltage condition and to detect weak spots in the insulation that could later result in in-service failures. 
     The International Electro-Technical Committee is an international standards body which develops the standards by which isolation transformers are categorized according to performance level. For example, UL-1950 and its corresponding national adaptations specify a minimum standard for dielectric breakdown between the primary and secondary windings of a transformer. In order to meet such a standard, it is critical that the primary and secondary windings are electrically isolated from one another while remaining magnetically coupled to one another through the transformer core. 
     In order to provide such electrical isolation between the primary and secondary windings, special jacketing materials have been developed to encase one or both of the primary and secondary windings. For example, UL-1950 specifies that one winding is covered with three layers of insulation material for which all combinations of two layers together pass a specified electric strength test. The second winding may be enameled copper magnet wire. The wire covered in a protective extrusion or jacket comprising three layers of insulation is referred to as reinforced insulated or jacketed wire. The protective jacket provides electrical isolation which inhibits dielectric breakdown between the windings at extended voltage ranges. One example of jacketed wiring is that manufactured by the Rubadue Wire Co. of Fontana, Calif. and incorporated in Pulse Engineering, Inc. part number 054-XIXWXXX-X. 
     The protective jacket provides insulation between the wires so long as it is in place. But in order to conductively connect the insulated conductors to external elements during the manufacturing process, a portion of the conductors must be exposed by removal of the protective jacket. The exposed conductors are not immune from dielectric breakdown and other phenomenon which may decrease the isolation performance of the resulting transformer. Isolation between the exposed conductors and the remainder of the transformer such as the ferrous core and the second winding must be accomplished by some other means. UL-1950 specifies that the additional isolation is accomplished by physical separation between the exposed conductors and other transformer elements. For example, UL-1950 specifies that the exposed portion of the conductors should be separated from the bare core and the second windings by at least 0.4 millimeters (mm) or approximately 0.016 in. (16 mils). 
     One difficulty related to the incorporation of jacketed insulated wire into a dual in-line surface mount package is maintaining the 0.4 mm clearance in a repeatable and consistent manner. The jacketed wire resists bending and may tend to spring back and, thus, move after placement. In the manufacturing environment, the assembly of packaged electronic elements is carried out in stages. In order for manufacturing to produce conforming parts, it is important that the previously assembled components remain properly in place while waiting for and during execution of additional manufacturing steps. In this case, if the wires move from the desired position, the parts may not conform to the requirements (such as the aforementioned requirement of 16 mils of spacing). 
     Based on the foregoing, it would be desirable to provide an improved microelectronic component surface mount package and method of manufacturing. Such an improved package would provide a guaranteed separation between the exposed conductors and other component elements and also provide a locking feature to hold the jacketed wire in place during the manufacturing process, thereby allowing for a more uniform and reliable product. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the aforementioned needs by providing an improved microelectronic component base and package, and method of manufacturing the same. 
     A first aspect of the invention comprises an improved microelectronic component base for use within an encapsulated component package. One embodiment, the base includes one or more internal recesses adapted to receive a microelectronic component, and an external sidewall. The sidewall incorporates a series of peripheral raised elements that each cooperate with the sidewall and a respective locking element so as to guide and retain the conductors of the microelectronic component during manufacture of the component package. The raised elements are each comprised of an outer wall and tapered divider; the outer wall, divider, and base sidewall cooperating to form a cavity within which the microelectronic component conductors are received. This arrangement secures the conductors during manufacture and further provides reliable and effective electrical separation for the conductors during manufacture and operation of the package. 
     A second aspect of the invention comprises an improved microelectronic component package incorporating the aforementioned component base. The package includes one or more microelectronic components (transformers in one embodiment) having both jacketed and unjacketed conductors wound thereon. The jacketing of the former is removed in the region of the base element sidewall to expose the underlying insulated conductors, which are routed through the channels of the base. A series of electrical leads are inserted in channels formed between adjacent raised elements so as to form an electrical connection with the individual transformer conductors. The base with installed transformer(s), conductors, and a portion of the electrical leads are ultimately encapsulated in a polymer to form the finished component package. 
     A third aspect of the invention comprises a circuit board incorporating the aforementioned microelectronic package. 
     A fourth aspect of the invention comprises an improved method of manufacturing the microelectronic component package of the present invention. The method is comprised generally of the steps of (1) winding a toroidal transformer core with a plurality of conductors, at least some of which are jacketed; (2) forming a base element with a recess as described above, (3) stripping the jacketing from a portion of the conductors in the vicinity of the base element; (4) inserting and retaining one or more of the wound toroidal transformer cores within the recess of the base element, (5) routing the jacketed conductors through the locking elements and raised elements of the base to provide mechanical restraint; (6) routing the exposed conductors through the channels of the base to provide electrical separation; (7) inserting electrical leads into the channels formed between the raised elements of the base; (8) bonding the electrical leads and exposed conductors within each channel together; and (9) encapsulating the base, toroidal core, conductors and a portion of the electrical leads to seal the package and maintain the relative positions of the aforementioned components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, objectives, and advantages of the invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein: 
         FIG. 1  is a perspective view illustrating a prior art configuration and method for attaching electrical conductors to lead posts. 
         FIG. 2  is a perspective view illustrating major components of a first embodiment of the microelectronic component package of the present invention. 
         FIGS. 3 and 4  are top and side views, respectively, of the microelectronic component base contained within the component package of FIG.  2 . 
         FIG. 5  is a front cross-sectional view of the microelectronic component base contained within the component package of  FIG. 2 , taken along  5 — 5  of FIG.  3 . 
         FIG. 6  is a partial perspective view of the component package of  FIG. 2  illustrating the relationship between the reinforced insulated wire, raised element, cavity, and electrical leads during assembly. 
         FIGS. 7 through 9  are top, side, and front cutaway views, respectively, of the fully assembled microelectronic component package of  FIG. 2  with various portions of the outer encapsulation removed to reveal the internal package components. 
         FIG. 10  is a perspective view of a second embodiment of the microelectronic component base of the present invention. 
         FIG. 11  is a partial perspective of a portion of a third embodiment of the microelectronic component base of the present invention. 
         FIG. 12  is perspective view of a portion of a circuit board incorporating the microelectronic component package of the present invention. 
         FIG. 13  is a flow diagram illustrating a first embodiment of the manufacturing process of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference is now made to the drawings wherein like numerals refer to like parts throughout. 
     Referring now to  FIG. 2 , a first embodiment of the microelectronic component package of the present invention is illustrated. The component package  100  is generally comprised of a base element  102 , one or more microelectronic components  104 , and a series of package electrical leads  120 . The finished device also includes an outer encapsulating covering (not shown in  FIG. 2 ; see discussion of  FIGS. 7 through 9  below). In the present embodiment, the microelectronic components  104  are two toroidal transformers as previously described, although it can be appreciated that other components (such as choke coils or inductors) may be used within the package, either alone or in combination. The construction and manufacture of such microelectronic components are well known in the art, and accordingly will not be described further herein, except as with respect to the jacketed electrical wire  117  utilized in conjunction with the component(s)  104 ; see detailed discussion below. 
     Referring again to  FIG. 2 , the base element  102  generally includes one or more sidewalls  108 , a bottom surface  110 , and one or more recesses  112  which are adapted to receive the aforementioned microelectronic component(s)  104  during assembly. Note that the package  100  is typically inverted from the orientation shown in  FIG. 2  when mounted on an external device (see, for example, FIG.  9 ); hence, the “bottom” surface  110  in actuality becomes the “top” surface when the package is installed. The base element  102  of the present embodiment further includes a plurality of raised elements  114  which are integrally formed with the sidewalls  108  in a vertical orientation adjacent to one another. As will be described in greater detail below, the raised elements provide four primary functions: (1) assist in the formation of a cavity  116  between the raised element  114  and the sidewall  108 , this cavity being designed to receive the jacketed wire  117  associated with the microelectronic component(s)  104 ; (2) route and separate the individual conductors  118  of the jacketed wire  117  received by the aforementioned cavity  116  so as to provide electrical isolation; (3) receive the individual conductors  118  and unjacketed wire  130  from the microelectronic component  104  within the channels  122  formed by adjacent raised elements  114 , and (4) receive electrical leads  120  within channels  122  so as to facilitate electrical contact between the individual conductors  118 , unjacketed wire  130 , and the electrical leads  120 . 
     The base element  102  is preferably constructed of a suitable molded non-conducting material; for example, a high temperature liquid crystal polymer such as that available under the part number RTP 3407-4 from the RTP Company of Winona, Minn. may be used. It will be recognized, however, that a variety of other insulative materials may be used to form the base element, depending on the needs of the specific application. 
     Referring again to  FIG. 2 , a jacketed wire  117  is wound about the toroid core  105 . The jacketed wire  117  houses two individual insulated conductors  118  within a reinforced insulation extrusion or jacket  119 . The number of conductors  118  and the configuration in which they are electrically connected depends upon the desired transform characteristics. A variety of configurations are possible in accordance with the invention. The individual conductors  118  are exposed by removing a portion of the jacket  119  during manufacture of the transformer component  104 . 
     The jacketed wire  117  used in the present embodiment may be the aforementioned RUBADUE wire having a Teflon™ or Tefzel™ fluoropolymer jacket and insulated conductors  118 , or may be an alternate construction and composition, so long as the desired electrical performance is maintained. 
     Also shown in  FIG. 2  is a unjacketed wire  130  (insulated “magnet” wire in the present embodiment) which is wound about the toroid core  105 . Also, along the upper edges of the base  102 , is a series of sidewall interstices  155 . When the package  100  is assembled, the unjacketed wire  130  is disposed through one of the interstices  155  and directly into the lead channels  122 . A portion of any insulation on the unjacketed wire  130  which extends into the channel  122  is ultimately removed during solder bonding so that a permanent electrical connection may be made between the unjacketed wire  130  and a respective one of the package leads  120 . 
       FIGS. 3-6  illustrate the construction of the base element  102  in greater detail.  FIG. 3  is a top view illustrating the cavities  116  formed between the raised elements  114  and their respective sidewalls  108 . In the present embodiment, the inner surface of the top portion  124  of the raised element  114  includes a semicircular recess  126  which is useful in receiving the common jacket  119  of the individual conductors  118 . The channels  122  formed between adjacent raised elements  114  are also clearly visible in  FIGS. 3 ,  4 , and  6 . These channels  122  receive the electrical leads  120 , and the conductors  118  and unjacketed wire  130  associated with the microelectronic components  104 , and allow for electrical connection thereof via soldering or other bonding process as shown in FIG.  6 . In the present embodiment, the base element  102  is optionally adapted to receive a portion of the electrical leads  120 ; this assists in maintaining the leads in position within the channels  122  during remaining portions of the package manufacturing process prior to encapsulation. 
     As shown in  FIGS. 4 and 6 , the raised elements  114  also each include a divider  135  which is used to route the individual conductors  118  away from one another into their respective channels  122 . The dividers therefore not only position the conductors  118  during manufacture, but also provide electrical separation. The dividers  135  include a curved or apexed top surface  137  which facilitates separation of the conductors  118 . Each divider top surface  137  forms one boundary of its respective aforementioned cavity  116 , and acts as a vertical “stop” for the jacketed wire  117  when inserted into the cavity  116 . 
     The base element  102  further includes a plurality of locking notches  140  located in the portion of the sidewall  108  adjacent to and opposite the semicircular recess  126  as shown in  FIGS. 2 ,  3 ,  4  and  6 . These notches  140  are generally semicircular in shape, and guide the jacketed wire  117  into the respective cavity  116  formed by the recess  126  and the sidewall  108 . The notches  140  further help maintain the position of the wire  117  relative to the cavity  116  and raised element  114  during subsequent manufacturing steps. Note that other shapes and configurations may be used for the notches  140 , including a “V”-shaped notch or even a hole (aperture) through the sidewall  108 . 
     As discussed above, it is also important to maintain a minimum distance between other parts of the assembly and the exposed portion of the conductors  118 . It should be noted that the configuration of the base  102  disclosed herein provides a known minimum distance between the exposed portion of the conductors  118  and other parts of the assembly. As previously described, the jacketed wire  117  passes over the sidewall  108  and through the integral locking notch  140 . The wall itself provides a minimum path length, for example, 0.020 inches, as shown in FIG.  5 . In addition, the wire  117  is also disposed within its respective cavity  116  which in the present embodiment is approximately 0.050 inches deep. The jacket  119  of the wire  117  is stripped such that when the wire  117  is fully inserted into the cavity  116 , the jacket  119  touches the top surface  137  of the divider  135 . Thus, the distance between the exposed portion of the conductors and the other components of the transformer exceed the aforementioned minimum value of 0.4 mm. Therefore, the use of the locking notches  140  and cavities  116  allow repeatable conformance with the specified standard. 
       FIG. 6  further illustrates the placement of the jacketed insulated wire  117  and component  104  when installed within the base element  102 . Note that in  FIG. 6 , the outer wall of the raised element  114  is shown transparent for illustrative purposes. As seen in this Figure, the portion of wire  117  enclosed within reinforced jacketing  119  forms a right angle over the locking notch  140  and into the cavity  116 . Due to the tendency of the reinforced jacketing  119  to resist deformation, the wire  117  presses against the semicircular recess  126  located on the inner surface of the raised element  114  which creates friction between the recess  126  and the wire  117 . The size and depth of the locking notch  140  and cavity  116  are such that a slight interference is caused between the jacket and the recess  126 . The cavity  116  is deep enough so that the jacket&#39;s resiliency does not permit the wire  117  to inadvertently come out of the cavity  116  during assembly and manufacturing. 
       FIGS. 7 through 9  are top, side and end cross-sectional views, respectively, of a fully assembled microelectronic component package according to the present invention comprising two toroid transformers within the base element  102  of  FIGS. 3 through 5 . In  FIGS. 7-9 , an overmolding  144  or casing of thermoset epoxy has been transfer molded over the base  102  assembly, leaving only the distal ends  145  of the electrical leads  120  exposed. Overmolding secures the elements permanently in place and provides additional insulation and mechanical protection. 
     Referring now to  FIG. 10 , a second embodiment of the component base  102  of the present invention is shown. The embodiment of the base  102  shown in  FIG. 10  is similar to that shown in  FIGS. 3 through 5 , with the exception that raised elements  114   a  with dividers  135  and cavities  116  (and associated locking notches  140 ) are only formed on a first side  147  of the base  102 . The raised elements  114   b  on the second side  149  are simply rectangular blocks with no dividers  135 , cavities  116 , or associated locking notches  140 . Note that the second side  149  of the base also includes a series of semicircular notches  151  which allow for passage of the unjacketed wires  130  into the channels  122  formed by the raised elements  114   b.    
     Referring now to  FIG. 11 , a third embodiment of the component base of the present invention is illustrated. The component base  102  of  FIG. 11  includes a series of raised elements  114  similar to the embodiment of FIG.  2 . However, in the embodiment of  FIG. 11 , the raised elements are comprised essentially of solid rectangular “blocks”  150  which are formed into the sidewall  108 , as opposed to the outer wall/divider arrangement previously described in connection with  FIGS. 2 through 6 . The rectangular blocks  150  accomplish routing of the wire  117  and associated conductors  118  by use of a recess and bore arrangement. Specifically, the top surface  152  of each block includes a recess  154  of semicircular cross-section which extends from the inner surface  160  of the sidewall  108  to a generally central point  162  in the top surface  152  of the block. Two or more bores  164   a ,  164   b  are located in the block  150  at oblique angles with respect to vertical, and communicate with the recess  154  at one end. As further illustrated in  FIG. 11 , two additional side recesses  166   a ,  166   b  are located in the side surfaces  168   a ,  168   b  of each block  150  which communicate with the other end of the bores  164   a ,  164   b , respectively to receive the electrical conductors  118  routed therethrough. When assembled, the jacketed wire  117  is retained by its respective the locking notch  140  and routed into the top surface recess  154 . At the outermost terminus of the top surface recess  154 , the jacketing  119  is removed from the wire  117 , and the individual conductors  118  further routed through the bores  164   a ,  164   b  and into the side recesses  166   a ,  166   b  and ultimately into their respective channel  122  where the conductors  118  can be electrically connected to the electrical lead  120  and the unjacketed wire  130  (also routed into the channel). 
     Referring now to  FIG. 12 , a circuit board assembly  400  incorporating the microelectronic component package  100  of the present invention is described. As shown in  FIG. 12 , a component package  100  is disposed upon at least one surface  402  of the circuit board  404  such that the electrical leads  120  of the package are in electrical contact with corresponding contact elements  406  on the circuit board  404 . The circuit board  404  of the present embodiment is a multi-layer board having a plurality of conductive strips  408 , vias (not shown), and contact elements  406  of the type well known and commonly used in the electronic arts. It can be appreciated, however, that any type of circuit board which allows for the interchange of electrical signals to and from component package may be used. In the present embodiment, a standard eutectic solder (such as 63% lead and 37% tin) is used to establish a permanent bond between the electrical leads  120  of the package and the contact elements  406  of the board, although other bonding agents may be used. It will further be recognized that a plurality of component packages  100  may be mounted to either side of the board  404  as needed. 
     Method of Manufacture 
     Referring now to  FIG. 13 , a method  500  of manufacturing the aforementioned microelectronic component package, including the circuit board assembly, is described in detail. 
     In the first step  502 , one or more microelectronic components are fabricated. For example, the aforementioned transformers are fabricated using a series of process steps, including fabrication of the core and winding of the insulated conductors thereon, which are well known in the art. The toroidal core  105  of the exemplary transformers is formed and subsequently wound with the jacketed wire  117  and the unjacketed wire  130  to provide the desired electrical characteristics. In the present embodiment of the method  500 , the jacketing  119  of the jacketed wire  117  is stripped as previously described such that the jacketing  119  roughly coincides with the top surface  137  of its respective raised element divider  135 . It will be appreciated, however, that the jacket may also be stripped prior to winding around the core  105  if desired, or even after the component  104  is disposed into the base  102  (see discussion of the third step  506  below). 
     Next, in the second process step  504 , the component base  102  as previously described herein is formed preferably using an injection molding process of the type well known in the polymer arts. Note that this second step  504  can be performed either prior to, after, or in parallel with the first step  502 . 
     In the third process step  506 , the microelectronic component(s)  104  fabricated in the first process step  502  are disposed within the recess(es)  112  the base element  102  using mechanical or manual means. Ideally, a small bead of silicone is placed in the bottom of each recess  112  or surrounding the component  104  to temporarily affix the respective component  106  to the base  102 . 
     Next, the jacketed wire  117  of the microelectronic component  106  is routed into the appropriate notch  140  on the sidewall  108  of the base  102  and inserted into the respective cavity  116 . The individual conductors  118  of the wire are also routed around the raised elements  114  and into their respective channels  122  in this fourth process step  508 . 
     Also as part of the process step  508 , the unjacketed wires  130  from the component  106  are routed via the sidewall interstices  155  into their respective channels  122  to ultimately permit electrical connection to the package leads  120  and the exposed portion of the wire conductors  118 . The unjacketed wires  130  are bent into the lead channels  122  and, thus, held in place by conductor&#39;s retention of the preformed shape. The ends of the unjacketed wires  130 , and individual conductors  118 , are further sized and trimmed such that they roughly coextensive and extend no further than the bottom surface  110  of the base element  102 . 
     In the next process step  510 , the package electrical leads  120  are inserted into the channels  122  and placed in physical contact with the exposed portion of the conductors  118  and the unjacketed wire  130 . This step  510  is typically accomplished using a preformed leadframe (not shown) such that all of the package leads  120  may be placed and trimmed substantially simultaneously, although other methods may be used. Fabrication and placement of the leadframe is further discussed in U.S. Pat. No. 5,015,981, incorporated herein by reference. 
     In the next process step  512 , the bottom surface  110  of the assembly is dipped partially into a flux and then into a eutectic solder pot to form a solder joint between the package leads  120 , the exposed portion of the conductors  118  of the jacketed wire  117 , and the unjacketed wire  130 . Insulation present on the ends of the wires  130  and conductors  118  is melted and stripped away immediately by the heat of the flux/solder process. 
     In process step  514 , polymer overmolding  144  is applied which encapsulates the assembly and completes the package. The details of these processes are discussed in the previously described U.S. Pat. No. 5,015,981 incorporated by reference herein. 
     In an optional process step  516 , the assembled package  100  is positioned atop a printed circuit board  404  as shown in  FIG. 12 , and the package leads  120  are soldered to the contact elements  406  of the circuit board to form a permanent electrical connection. Any number of solder or bonding processes may be used to join the package leads  120  to the contact elements  406 ; soldering using a eutectic solder as described herein is merely illustrative of these methods. 
     While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the spirit of the invention. The foregoing description is of the best mode presently contemplated of carrying out the invention. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the invention. The scope of the invention should be determined with reference to the claims.