Abstract:
The invention provides an electrical contact device, a pre-assembly for producing the electrical contact device, and a method of forming the electrical contact device. The electrical contact device includes a plurality of fine pitch electrical leads disposed in parallel spaced apart relation. An insulating member encapsulates portions of the electrical leads which extend from opposite sides of the insulating member. The insulating member retains the electrical leads in position and electrically isolated from one another. The contact device is used to facilitate connection with the leads of an IC package.

Description:
This application is a divisional of application Ser. No. 09/511,692 filed on Feb. 23, 2000, now U.S. Pat. No. 6,625,885 which is a divisional of Ser. No. 09/132,248, filed on Aug. 11, 1998 (now U.S. Pat. No. 6,179,659), which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrical contacts, and particularly to fine pitch electrical contacts. More particularly, the invention relates to fine pitch contacts for connecting the leads of a packaged integrated circuit (IC) to a printed circuit board, a circuit tester or the like. 
     2. Discussion of the Related Art 
     Fine pitch contacts are often used to connect packaged IC circuits to test boards, test fixtures, or the like. For example, in a known IC tester, a clam shell fixture for receiving an IC is attached to a tester circuit. The fixture includes a bottom portion having an array of leads and an upper pivoting cover portion. The packaged IC circuit is placed on the lower portion with its contacts being in contact with the array of leads. When the packaged circuit is in correct position, the lid of the clam shell is closed over the packaged IC circuit, holding the IC circuit in position with the leads of the IC circuit being connected with the arrays of leads. 
     In the past, the bottom portion of the clam shell fixture often included staggered pogo pins as the leads. The pogo pins were miniature upside down pogo sticks installed in a plastic or ceramic clam shell. Each pin was mounted in the clam shell with a tiny spring, with the case holding the spring in place. Another type of known IC tester uses a finely machined fixture that contains parallel metal slides disposed in slots at the correct pitch. In this arrangement, the outer portion of the slides provided the contact with an IC package for testing. 
     While conventional contacts for connecting with the leads of an IC package for testing or other purposes have proven to be adequate, they are also often structurally complex and expensive to produce. 
     In addition, conventional contacts tend to be application specific. That is, if the leads from the IC circuit package require a different length, the fine pitch lead package must be redesigned to accommodate the new length. Moreover, the contacts are typically at the same pitch as the leads of the IC package making it difficult sometimes to connect the contacts to test and other circuits. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages of conventional lead packages by providing a simple and inexpensive conductor package which can connect with the leads of an IC package to interface those leads with other circuits for testing or other purposes. The conductor package has an insulating member and an array of individual leads extending in opposite directions from the insulating member. The insulating member may be part of an insulating frame which has one or two insulating members, each insulating member containing its own array of individual leads extending from opposite sides thereof. 
     Each array of leads is adapted for permanent or removable connection to the leads of an IC package as well as to the leads of a circuit board or a test fixture. The conductor package may also be used to mount and connect packaged IC&#39;s to other packaged IC&#39;s, if desired. 
     The invention also provides a unique method for fabricating a pre-assembly for making a final conductor package, as well as the final conductor package itself. In another aspect the invention also provides a pre-assembly incorporating a pre-punched lead frame having molded insulation areas to facilitate manufacture of the conductor package. 
     These and other features and advantages of the invention will become more apparent from the following detailed description of preferred embodiments of the present invention which is provided in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a fine pitch electrical contact package constructed according to the present invention. 
     FIG. 2 is a plan view of a conducting lead frame used to form the FIG. 1 structure. 
     FIG. 3 is a plan view of the conducting lead frame of FIG. 2 with encapsulating material added thereto. 
     FIG. 4 is a plan view of the conducting lead frame of FIG. 3 with portions of the metal framework removed. 
     FIG. 5 is a section view taken along lines  5 — 5  of FIG.  4 . 
     FIG. 6 is a plan view of an alternative configuration of the fine pitch electrical contact package. 
     FIGS. 7,  8  and  9  are section views similar to FIG. 5 illustrating alternative configurations of the leads of the fine pitch electrical contact package. 
     FIG. 10 is a partial plan view of the contact package of FIG. 1 with the fine pitch electrical leads fanned out on one side of an insulating member. 
     FIGS. 11,  12 , and  13  illustrate use of various embodiments of the invention with IC packages. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a electrical contact package  10  constructed in accordance with a first embodiment of the present invention. It includes a plurality of regularly spaced electrical conductors held rigidly in position by an insulating member  14 . Each of the separate conductors has two leads  28   a  and  28   b  which respectively extend from opposite sides of insulating member  14 . The leads  28   a ,  28   b  are held rigidly in place by member  14 , as they extend out from opposite sides of insulating member  14  and can be bent to meet the requirements of many different circuit packages. The leads  28   a  on one side of the member  14  may be made longer than the leads  28   b  on the opposite side of insulating member  14 . The leads  28   a  may also be bent into a different configuration than leads  28   b.    
     The manner in which the electrical contact package  10  is formed is illustrated by FIGS. 2-4. The electrical contact package  10  includes a conducting frame  12 , illustrated in FIG. 2, and an insulating frame  14  which is added to predetermined portions of the conducting frame  12  to form the pre-assembly  22  illustrated in FIG.  3 . Predetermined portions of the conducting frame  12  are removed from the FIG. 3 pre-assembly to yield the electrical contact package  10 , illustrated in FIGS. 4 and 5. 
     Referring back to FIG. 2, the conducting frame  12  includes an outer conducting frame  16 , an inner conducting frame  18 , a plurality of conducting frame connectors  20 , a plurality of electrical leads  28   a  and  28   b , and a plurality of electrical lead connecting strips  32 . The inner and outer conducting frames  16 ,  18  are connected to each other by the plurality of frame connectors  20 . The inner and outer frames  16 ,  18  and the frame connectors  20  cooperate to define a plurality of frame slots  26 , that is, areas where no conductors are present. The plurality electrical leads  28   a  and  28   b  are disposed in parallel arrangement and are connected to each other and to the inner frame  18  by the plurality of connecting strips  32 . The connecting strips  32  are preferably disposed orthogonally to the electrical leads  28   a ,  28   b  and divide each electrical lead into a first end portion  28   a,  a second end portion  28   b , and a center portion  40 . The center portions of the electrical leads  28  cooperate with the connecting strips  32  to define a plurality of inner frame slots  46 . The FIG. 2 structure is formed by stamping out a thin strip of conductive material into the pattern shown in FIG.  2 . 
     As illustrated in FIG. 3, a conventional electrically insulating material, such as a plastic epoxy is applied to conducting frame  12 , for example, by transfer thermal molding. The applied insulating material forms the insulating frame  14 . The electrically insulating frame  14  includes right and left side members  50 ,  52 , respectively, top and bottom cross members  54 ,  56 , respectively, and a center bridging cross member  58 . The side members  50 ,  52  and the top and bottom cross members  54 ,  56  are formed when the electrically insulating molding material moves in and through the frame slots  26 ,  46  during the transfer molding process. When the insulating material hardens, the conducting frame  12  is rigidly retained to the insulating frame  14 . The bridging cross member  58  of the electrically insulating frame  14  are likewise formed during the transfer molding process by having the insulating material flow in and through the inner slots  46  and on both sides of the center portions  40  of the fine pitch electrical leads  28   a ,  28   b . The electrical leads  28   a ,  28   b  are rigidly held in place by the hardened insulating material. Importantly, as illustrated in FIG. 3, the connecting strips  32  are fully exposed after the bridging cross member  58  is formed. As a matter of choice, the inner and outer frames  16 ,  18  can be completely covered by the insulating material forming the left and right side members  50 ,  52  and the top and bottom cross members  54 ,  56 , or portions of the inner frame  16  and/or the outer frame  18  can be exposed. 
     As illustrated in FIG. 4, portions of the conducting frame  12  are now removed from the FIG. 3 pre-assembly  22  so that the pre-assembly  22  of FIG. 3 is converted into the electrical contact package  10  illustrated in FIG.  1 . This is accomplished by removing the connecting strips  32  from between the fine pitch electrical leads  28   a ,  28   b  by cutting or etching. Since the connecting strips  32  are the only remaining electrical connection between the individual electrical leads  28 , removing the connecting strips  32  electrically isolates the individual electrical leads  28  from each other, as illustrated in the cross section of FIG.  5 . Of course, if it is desired to have two adjacent leads carry the same signal, the connecting strips  32  connecting the two adjacent leads can be retained. If portions of the inner and outer frames  16 ,  18  were left exposed after formation of the insulating frame  14 , the exposed portions can be removed at the same time, as is illustrated in FIG.  4 . 
     FIG. 5 shows a sectional view of the FIG. 4 structure after the leads  28   a  and  28   b  are bent into a predetermined configuration for use. As shown, the longer lead  28   a  has a bend directing the distal end of lead  28   a  upward, while the shorter lead  28   b  is bent downward and includes a flat portion  28   c  for surface bonding to, for example, a printed circuit board. The FIG. 5 structure can be used as is to interconnect with IC packages or the top and bottom cross members  54  and  56  and side frames  50  and  52  can also be removed leaving just the bridging cross member  58  which now becomes the only remaining part of insulating frame  14  which supports the leads  28   a  and  28   b , as shown in FIG.  1 . 
     It will be appreciated that other arrangements of the pitch electrical leads  28   a ,  28   b  are possible. FIG. 6, for example, illustrates a second embodiment of the invention in which two separate sets of fine pitch electrical leads  28   a ,  28   b  extending from the inside to the outside of top  101  and bottom  103  cross members of a lead frame  100 . 
     Advantageously, the fine pitch electrical leads  28  can be bent to any desired configuration after they are set in the insulating material. FIGS. 7-9 illustrate possible alternate lead configurations to that illustrated in FIG.  5 . In FIG. 7, the longer leads  28   a′  are curved in the form of a C curve in an upward direction, while in FIG. 8 the longer leads  28   a ″ have a right angle bend and extend straight up. In FIG. 9 the distal end of the longer leads  28 ′″ also extend straight up after undergoing two bends. FIG. 7 also illustrates a circuit package  102  which is placed on the electrical leads  28   a ′ for testing. 
     Another embodiment of the present invention is illustrated in FIG. 10, wherein the electrical leads  28   d  are fanned out to provide a different pitch on opposite sides of the supporting insulating member  58 . 
     It will be understood that conventional stamping and punching techniques can be used to stamp out the conducting frame  12  from a thin strip of conducting material and bend the leads  28   a ,  28   b . Likewise, conventional encapsulation techniques can be used to form the insulating frame  14  on the conducting frame  12 . Conventional etching or machining techniques can also be used to remove the connecting strips  32  from between electrical leads  28 . Any exposed portions of the inner and outer frames  16 ,  18  that should be removed can also be removed using these techniques. 
     One or both sides of the insulating member  14  may also be coated with a conductor  203 , if desired, as also shown in FIG.  5 . 
     FIGS. 11,  12  and  13  illustrate potential uses for the invention. FIG. 11 shows the FIG. 6 embodiment of the invention mounted, e.g., by soldering, on top of an IC package  207  to facilitate access to IC package leads for testing or other purposes. The IC package  207  is surface mounted, e.g. by soldering to a printed circuit board  207 . FIG. 12 illustrates the FIG. 1 embodiment of the invention mounted in cantilevered fashion to an IC package  207 , while FIG. 13 illustrates the FIG. 6 embodiment bonded to an IC package  207 . Many other arrangements are also possible. The electrical contact package shown in FIG. 1 can also be cut to any desired length needed for a particular application. 
     The above descriptions and drawings are only illustrative of the preferred embodiments of the invention, and are not intended to describe all changes and modifications which can be made, but which are still part of the invention. Accordingly, the invention is not to be considered as limited by the foregoing description, but is only limited by the scope of the appended claims.