Abstract:
A method of securing an electronic package to a circuit board includes the step of providing a retainer having a locating cavity defined therein. The method further includes the step of positioning the electronic package within the locating cavity so that the electronic package is fixed in relationship to the retainer. Moreover, the method includes the step of securing the retainer in fixed relationship to the circuit board so as to sandwich the electronic package between the retainer and the circuit board. The securing step is performed after the positioning step. An apparatus for securing an electronic package to a circuit board is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to an electronic package, and more particularly to a method and apparatus for securing an electronic package to a circuit board. 
     Electronic packages typically include a number of integrated circuits which are housed within a plastic or ceramic package. Such packages, hereinafter referred to as “electronic packages”, are generally rectangular or square in shape and include a plurality of conductive pads on a bottom surface thereof. The conductive pads may be arranged in a grid-like pattern to increase number or density of the conductive pads which may be included in the electronic package. One such type of grid-like pattern arrangement is referred to as a ball grid array package. In a ball grid array package, a finely-pitched matrix of spheroid- or ball-shaped conductive pads extend outwardly from the bottom surface of the electronic package. 
     A circuit board, such as a printed circuit board or a printed circuit assembly, to which the ball grid array package is to be mounted includes a corresponding number of conductive pads which are arranged in a similar matrix as the matrix of ball-shaped conductive pads included in the ball grid array package. 
     In order to mount the ball grid array package to the circuit board, a small quantity of a conductive metal alloy such as solder is placed on the conductive pads of the circuit board prior to placing and aligning the conductive pads of the ball grid array package thereon. Thereafter, the circuit board and the ball grid array package thereon are heated to a temperature which is greater in magnitude than the melting point of the solder thereby fusing the ball-shaped conductive pads of the ball grid array package to the conductive pads of the circuit board. 
     Although soldering the ball grid array package to the circuit board yields a strong, reliable mechanical and electrical connection, it may be undesirable if it becomes necessary at a later time to remove the ball grid array package from the circuit board. In particular, if it becomes necessary to repair or replace the ball grid array package that is soldered to the circuit board, the circuit board must again be heated to a temperature which is greater in magnitude than the melting point of the solder in order to remove the ball grid array package from the circuit board. Such re-heating of the circuit board may reduce the useful life of both the circuit board and the various other components secured thereto. 
     Soldering the electronic package is particularly undesirable during the development stages of a given electronic assembly. This is true since the various integrated circuits within the ball grid array package may require several design iterations during the development thereof. Hence, upon each occasion that the design of one of the integrated circuits is altered, the ball grid array package must be unsoldered, and a ball grid array package containing a revised version of the integrated circuit is thereafter soldered to the circuit board. As described above, such unsoldering and re-soldering may damage and/or destroy the circuit board and the other components secured thereto, thereby disadvantageously lowering yields and raising costs associated with the development of the electronic assembly. Moreover, the position of the electronic package on the circuit board and/or the configuration of the electronic package itself may prevent the electronic package from being removed from the circuit board in manner which does not irreparably damage the circuit board and/or the other components secured thereto. Hence, upon each occasion that the design of one of the integrated circuits is altered, the entire electronic assembly may have to be discarded thereby disadvantageously raising costs associated with the development of the electronic assembly. 
     To this end, a number of electronic package securing mechanisms such as sockets or other similar mechanical clamps have been developed to hold or otherwise secure an electronic package to a circuit board without the use of solder on the conductive pads of the electronic package. However, many of the electronic package securing mechanisms which have heretofore been designed are mechanically complex. Moreover, many of the electronic package securing mechanisms which have heretofore been designed require precision placement and alignment thereof on the circuit board by the use of expensive automated placement machines such as “pick and place” machines. 
     What is needed therefore is a method and apparatus for securing an electronic package to a circuit board which does not require the use of solder. In addition, what is needed is a method and apparatus for securing an electronic package to a circuit board which is relatively simple and inexpensive. Moreover, what is needed is a method and apparatus for securing an electronic package to a circuit board which does not require the use of automated placement machines. What is further needed is a method and apparatus for securing an electronic package to a circuit board which enables fast and simple removal and replacement of the electronic package. 
     SUMMARY OF THE INVENTION 
     In accordance with a first embodiment of the present invention, there is provided a method of securing an electronic package to a circuit board. The method includes the step of providing a retainer having a locating cavity defined therein The method further includes the step of positioning the electronic package within the locating cavity so that the electronic package is fixed in relationship to the retainer. Moreover, the method includes the step of securing the retainer in fixed relationship to the circuit board so as to sandwich the electronic package between the retainer and the circuit board. The securing step is performed after the positioning step. 
     In accordance with a second embodiment of the present invention, there is provided an apparatus for securing an electronic package to a circuit board. The apparatus includes a retainer securable to the circuit board. The retainer has a locating cavity defined therein. The electronic package is positionable within the locating cavity. The locating cavity is configured to prevent movement of the electronic package relative to the retainer when the electronic package is positioned within the locating cavity. The electronic package has a number of first conductive pads. The circuit board has a number of second conductive pads. The number of first conductive pads contacts the number of second conductive pads when (1) the electronic package is positioned within the locating cavity, and (2) the retainer is secured to the circuit board. 
     In accordance with a third embodiment of the present invention, there is provided an apparatus for securing an electronic package to a circuit board. The apparatus includes a retainer having a locating cavity defined therein. The retainer is securable to the circuit board. The electronic package is positionable within the locating cavity. The apparatus further includes a cloth interposer having anisotropic properties. The cloth interposer is positionable between the electronic package and the circuit board when the electronic package is sandwiched between retainer and the circuit board. 
     It is therefore an object of the present invention to provide a new and useful method for securing an electronic package to a circuit board. 
     It is also an object of the present invention to provide an improved method for securing an electronic package to a circuit board. 
     It is moreover an object of the present invention to provide a new and useful apparatus for securing an electronic package to a circuit board. 
     It is a further object of the present invention to provide an improved apparatus for securing an electronic package to a circuit board. 
     It is yet further an object of the present invention to provide a method and apparatus for securing an electronic package to a circuit board which does not require the electronic package to be soldered to the circuit board. 
     It is moreover an object of the present invention to provide a method and apparatus for securing an electronic package to a circuit board which is relatively simple and inexpensive. 
     It is also an object of the present invention to provide a method and apparatus for securing an electronic package to a circuit board which does not require the use of automated placement machines. 
     It is a further object of the present invention to provide a method and apparatus for securing an electronic package to a circuit board which enables fast and simple removal and replacement of the electronic package. 
     The above and other objects, features, and advantages of the present invention will become apparent from the following description and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded cross-sectional view a first embodiment of an electronic package securing assembly which incorporates the features of the present invention therein (Note: the electronic packages  14 ,  15  are not shown in cross-section for clarity of description); 
     FIG. 2A is an enlarged bottom elevational view of the electronic package  14  of the securing assembly of FIG. 1; 
     FIG. 2B is a side elevational view of the electronic package  14  of FIG. 2A; 
     FIG. 3A is an enlarged bottom elevational view of the electronic package  15  of the securing assembly of FIG. 1; 
     FIG. 3B is a side elevational view of the electronic package  15  of FIG. 3A; 
     FIG. 4 is a reduced fragmentary top elevational view of the circuit board of the securing assembly of FIG. 1; 
     FIG. 5 is a reduced bottom elevational view of the retainer of the securing assembly of FIG. 1; 
     FIG. 6 is a cross sectional view taken along the line  6 — 6  of FIG. 5, as viewed in the direction of the arrows; 
     FIG. 7 is a reduced bottom elevational view of the back plate of the securing assembly of FIG. 1; 
     FIG. 8 is an exploded perspective view of a second embodiment of a electronic package securing assembly which incorporates the features of the present invention therein (Note: the printed circuit patterns, including the conductive pads  30   a ,  30   b  have been removed from the circuit board  16  for clarity of description); 
     FIG. 9 is an enlarged bottom elevational view of the locator of the securing assembly of FIG. 8; 
     FIG. 10 is a cross sectional view taken along the line  10 — 10  of FIG. 9, as viewed in the direction of the arrows; and 
     FIG. 11 is an enlarged bottom elevational view of the compressing plate of the electronic package securing assembly of FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Referring now to FIGS. 1-7, there is shown an electronic package securing assembly  10 . The securing assembly  10  includes an retainer  12 , a number of electronic packages  14 ,  15 , a circuit board  16 , a back plate  18 , a number of bolts  20 , and a number of nuts  22 . 
     The electronic packages  14 ,  15  are configured in a ball grid array packaging arrangement as shown in FIGS. 2A,  2 B,  3 A, and  3 B. In particular, the electronic packages  14 ,  15  include a number of sphere- or ball-shaped conductive pads  26  extending outwardly from a bottom surface  14   e ,  15   e , respectively, thereof. Each of the electronic packages  14 , 15  further includes a housing  24 . The housing  24  is made from an insulative material such as plastic or ceramic. Moreover, the ball-shaped conductive pads  26  are electrically coupled in a known manner to a number of integrated circuits  28  encapsulated within the housing  24 . 
     The circuit board  16  may be any known printed circuit board, printed circuit assembly, or the like. The circuit board  16  may be single-sided, double-sided, or multi-layered in construction. The circuit board  16  includes a number of surface mount type conductive pads  30   a ,  30   b  as shown in FIG.  4 . It should be appreciated that the size and position of the conductive pads  30   a ,  30   b  correspond with the size and position of the ball-shaped conductive pads  26  of the electronic packages  14 , 15 , respectively. 
     Moreover, the circuit board  16  has a number of board apertures  32   a-f  defined therein as shown in FIG.  4 . It should be appreciated that the position of each of the conductive pads  30   a ,  30   b  may be measured relative to a center point  33  of the board aperture  32   a . In particular, the location of a given conductive pad  30   a  or  30   b  may be defined as a first predetermined distance in the x-direction, and a second predetermined distance in the y-direction from the center point  33  of the board aperture  32   a.    
     As shown in FIGS. 5 and 6, the retainer  12  is rectangular in shape and is an integrally formed single part that may be constructed of either plastic or metal. The retainer  12  further has a number of retainer apertures  34   a-f  defined therein. As shown in FIG. 1, the retainer apertures  34   a-f  respectively align with (1) the board apertures  32   a-f  defined in the circuit board  16 , and (2) a number of plate apertures  36   a-f  defined in the back plate  18 . 
     One of the bolts  20  is positioned in each of the board apertures  32   a-f , the retainer apertures  34   a-f , and the plate apertures  36   a-f , and thereafter is threadingly engaged by the nuts  22  in order to secure the retainer  12  to a top surface  16   a  of the circuit board  16 , while also securing the back plate  18  to a bottom surface  16   b  of the circuit board  16 . 
     As shown in FIGS. 5-6, the retainer  12  has a pair of locating cavities  17 , 19  defined therein. The locating cavities  17 , 19  define a number of cavity sidewalls  17   a-d , and  19   a-d , respectively. The cavity sidewalls  17   a-d ,  19   a-d  are configured to secure and position the electronic packages  14 , 15 , respectively. In particular, the size and location of the cavity sidewalls  17   a-d ,  19   a-d  are configured to conform closely to a number of outer edges  14   a-d ,  15   a-d , respectively, defined by the electronic packages  14 , 15 , respectively (see FIGS.  2 A and  3 A). It should be appreciated that when the electronic packages  14 , 15  are secured within the locating cavities  17 , 19 , respectively, the outer edges  14   a-d ,  15   a-d  contact the sidewalls  17   a-d ,  19   a-d  thereby enabling the electronic packages  14 , 15  to be snap-fit or similarly secured within the locating cavities  17 , 19 , respectively. 
     From the previous discussion, it should be appreciated that the size and location of the locating cavities  17 , 19  may be used to align the ball-shaped conductive pads  26  of the electronic packages  14 , 15 , respectively, relative to the conductive pads  30   a ,  30   b , respectively, of the circuit board  16 . More specifically, once the electronic packages  14 , 15  are positioned in the locating cavities  17 , 19 , respectively, the position of each of the ball-shaped conductive pads  26  may be measured relative to a center point  38  of the retainer aperture  34   a  (see FIG.  5 ). In particular, the location of each of the ball-shaped conductive pads  26  of the electronic packages  14 ,  15  may be defined as a first predetermined distance in the x-direction, and a second predetermined distance in the y-direction from the center point  38  of the retainer aperture  34   a . Hence, the location of each of the ball-shaped conductive pads  26  of the electronic packages  14 ,  15  may also be predetermined in order to align with a corresponding conductive pad  30   a ,  30   b , respectively, when the retainer  12  and the electronic packages  14 ,  15  are secured the circuit board  16 . 
     Each of the locating cavities  17 ,  19  includes an engagement surface  17   e ,  19   e , respectively, as shown in FIG.  5 . When the bolts  20  are tightened, the retainer  12  and hence the engagement surfaces  17   e ,  19   e  are urged in the general direction of arrow C of FIG. 1 thereby causing the engagement surfaces  17   e ,  19   e  to contact an upper surface  14   f ,  15   f , respectively, of the electronic packages  14 ,  15 . 
     An interposer  40  (see FIG. 1) may be used to enhance the mechanical and electrical contact between the electronic packages  14 ,  15  and the circuit board  16 . More specifically, the interposer  40  may be sandwiched between the ball-shaped conductive pads  26  of the electronic packages  14 ,  15  and the conductive pads  30   a ,  30   b , respectively, of the circuit board  16 . The interposer  40  is a elastomeric cloth material having anisotropic properties, and may be particularly useful for maintaining a reliable mechanical and electrical connection between the ball-shaped conductive pads  26  of the electronic packages  14 ,  15  and the conductive pads  30   a ,  30   b , respectively, of the circuit board  16  despite any warpage or similar deformities that may be present in either the circuit board  16  or the retainer  12 . Such an anisotropic material electrically conducts along a single axis, but does not conduct along any other axes. For example, the interposer  40  conducts along the axis defined by the general direction of arrow A of FIG. 1, but does conduct along any other axis (e.g. an axis defined by the general direction of arrow B of FIG.  1 ). Such a material is advantageous in that it does not have to be placed or otherwise positioned on the circuit board  16  by a high precision placement machine such as a “pick and place” machine. For example, the interposer  40  may be purchased in a roll or in pre-cut strips, and may thereafter be placed or otherwise positioned by hand on the conductive pads  30   a ,  30   b  of the circuit board  16  prior to the attachment thereto of the electronic packages  14 ,  15  and the retainer  12 . One such material which may be suitable for use as the interposer  40  of the present invention is a part number ZC01507E-100 “Z-Axis Elastomer” which is commercially available from W.L. Gore and Associates, Inc. of Elkton, Md. 
     In operation, the interposer  40  may first be positioned on the conductive pads  30   a ,  30   b  of the circuit board  16 . Thereafter, the electronic packages  14 ,  15  may be positioned on the interposer  40  in a position in which each of the ball-shaped conductive pads  24  is proximate a corresponding conductive pad  30   a ,  30   b . Thereafter, the retainer  12  may be lowered onto the electronic packages  14 ,  15 , in order to position and secure the electronic packages  14 ,  15  within the locating cavities  17 ,  19 , respectively. 
     Once the retainer  12  is positioned on the circuit board  16 , the bolts  20  are inserted through the retainer apertures  34   a-f  and the board apertures  32   a-f . Thereafter, the back plate  18  is positioned on the bottom surface  16   b  of the circuit board  16  by advancing the bolts  20  through the plate apertures  36   a-f . Thereafter, the nuts  22  are threadingly engaged with the bolts  20 . 
     It should be appreciated that a downward or retaining force is exerted on the electronic packages  14 ,  15  when the bolts  20  are tightened. The bolts  20  may be further tightened in order to increase the retaining force being exerted on the electronic packages  14 ,  15 , whereas the bolts  20  may be loosened to decrease the retaining force being exerted on the electronic packages  14 ,  15 . 
     In order to remove the electronic packages  14 ,  15  from the circuit board  16 , the nuts  22  are first removed from the bolts  20 . Thereafter, the bolts  20  are removed thereby allowing the retainer  12  to be lifted away from the circuit board  16 . Once the retainer  12  is lifted away from the circuit board  16 , the electronic packages  14 ,  15  may then be removed. Thereafter, the same or different electronic packages  14 ,  15  may be secured to the circuit board  16  in the manner previously discussed. 
     Alternatively, the electronic packages  14 ,  15 , respectively, may first be secured within the locating cavities  17 ,  19  of the retainer  12  prior to securing the retainer  12  to the circuit board  16 . In particular, the electronic packages  14 , 15 , may be friction-fit or otherwise secured in the locating cavities,  17 ,  19 . Thereafter, the bolts  20  and the nuts  22  may be used to secure the retainer  12  to the circuit board  16  in the manner previously discussed. 
     Referring now to FIGS. 8-11, there is shown an electronic package securing assembly  50 . The same reference numerals are used in FIGS. 8-11 to designate common components which were previously discussed in regard to FIGS. 1-7. Therefore, no further discussion thereof is warranted. 
     The securing assembly  50  is essentially the same as the securing assembly  10 , except that the retainer  12  has been replaced with a number of separate components. More specifically, the securing assembly  50  includes a locator  52  and a number of spacers  74 ,  75 . As shall be discussed in more detail below, the locator  52  and the spacers  74 ,  75  collectively function equivalently as the retainer  12  of the securing assembly  10 . 
     The securing assembly  50  further includes a number of bolts  53 . The bolts  53  are installed from the bottom surface  16   b  of the circuit board  16  through the board apertures  32   a-f  of the circuit board  16  (see FIG.  4 ). Thereafter, the bolts  53  are received through a number of locator apertures  58   a-f  defined in the locator  52  (see FIG.  9 ). As shown in FIG. 8, a number of standoffs  60  and nuts  62  are secured to a threaded shaft portion  53   a  of each of the bolts  53  thereby securing the locator  52  to the circuit board  16 . 
     As shown in FIG. 9, the locator  52  has a number of locating cavities  55 ,  57  defined therein. As with the locating cavities  17 ,  19  of the retainer  12 , the locating cavities  57 ,  59  define a number of cavity sidewalls  57   a-d , and  59   a-d , respectively. The cavity sidewalls  57   a-d ,  59   a-d  are configured to secure and position the electronic packages  14 ,  15 , respectively. In particular, the size and location of the cavity sidewalls  57   a-d ,  59   a-d  are configured to conform closely to the outer edges  14   a-d ,  15   a-d , respectively, defined in the electronic packages  14 ,  15 , respectively. It should be appreciated that when the electronic packages  14 ,  15  are secured within the locating cavities  57 ,  59 , respectively, the outer edges  14   a-d ,  15   a-d  contact the sidewalls  57   a-d ,  59   a-d  thereby enabling the electronic packages  14 , 15  to be secured within the locating cavities  17 , 19 , respectively. 
     From the previous discussion, it should be appreciated that the size and location of the locating cavities  57 ,  59  may be used to align the ball-shaped conductive pads  26  of the electronic packages  14 , 15 , respectively, relative to the conductive pads  30   a ,  30   b , respectively, of the circuit board  16 . More specifically, once the electronic packages  14 , 15  are positioned in the locating cavities  57 ,  59 , respectively, the position of each of the ball-shaped conductive pads  26  may be measured relative to a center point  56  of the locator aperture  58   a  (see FIG.  9 ). In particular, the location of each of the ball-shaped conductive pads  26  of the electronic packages  14 , 15  may be defined as a first predetermined distance in the x-direction, and a second predetermined distance in the y-direction from the center point  56  of the locator aperture  58   a . Hence, the location of each of the ball-shaped conductive pads  26  of the electronic packages  14 , 15  may also be predetermined in order to align with a corresponding conductive pad  30   a ,  30   b , respectively, when the retainer  12  and the electronic packages  14 , 15  positioned therein are secured the circuit board  16 . 
     The securing assembly  50  further includes a compressing plate  66 . The compressing plate  66  has a number of plate apertures  68   a-f  defined therein, as shown in FIG.  11 . The plate apertures  68   a-f  receive the bolts  53  therein (see FIG.  8 ). A bottom surface  66   a  of the compressing plate  66  contacts the nuts  62  thereby supporting the compressing plate  66 . A number of locking nuts  70  are also received onto the threaded shaft portion  53   a  of the bolts  53  thereby securing the compressing plate  66  thereto. 
     As shown in FIG. 8, each of the spacers  74 ,  75  includes a metal upper portion  74   a ,  75   a , and a rubber lower portion  74   b ,  75   b , respectively. The spacers  74 ,  75  are urged in the general direction of arrow D of FIG. 8 thereby urging the electronic packages  14 ,  15 , respectively, into contact with the circuit board  16 . More specifically, the compressing plate  66  has a number of compressing holes  76  defined therein (see FIG.  11 ). A compressing bolt  78  is positioned in each of the compressing holes  76  as shown in FIG.  8 . As the compressing bolts  78  are tightened, the compressing bolts  78  contact the metal upper portion  74   a ,  75   a , of the spacers  74 ,  75 , respectively, thereby urging the rubber lower portion  74   b ,  75   b , of the spacers  74 ,  75 , respectively, in the general direction of arrow D of FIG.  8  and into contact with the upper surface  14   f ,  15   f  of the electronic packages  14 ,  15 , respectively. As the electronic packages  14 ,  15  are urged in the general direction of arrow D of FIG. 8, the ball-shaped conductive pads  26  of the electronic packages  14 ,  15  are likewise urged into mechanical and electrical contact with the conductive pads  30   a ,  30   b , (see FIG. 4) respectively, of the circuit board  16 . It should therefore be appreciated that the compressing bolts  78  may be used to alter the retaining force being exerted on the upper surfaces  14   f ,  15   f  of the electronic packages  14 ,  15 , respectively. In particular, if the compressing bolts  78  are tightened, the retaining force exerted on the electronic packages  14 ,  15  will be increased, whereas if the compressing bolts  78  are loosened, the retaining force exerted on the electronic packages  14 ,  15  will be decreased. 
     Prior to placing the electronic packages  14 , 15  within the locating cavities  55 ,  57 , respectively, the interposer  40  (not shown in FIG. 8, but see FIG. 1) may first be positioned within each of the locating cavities  55 ,  57 . In particular, the interposer  40  may be positioned within the locating cavities  55 ,  57  (i.e. on the conductive pass  30   a ,  30   b ) prior to placing and aligning the ball-shaped conductive pads  26  of the electronic packages  14 ,  15 , respectively, into contact with the conductive pads  30   a ,  30   b.    
     In operation, the bolts  53  are first installed from the bottom surface  16   b  of the circuit board  16 . Thereafter, the locator  52  is lowered onto the circuit board  16  by advancing the bolts  53  through the locator apertures  58   a-f . Then, the interposer  40  may be positioned on the conductive pads  30   a ,  30   b  of the circuit board  16 . Thereafter, the electronic packages  14 ,  15  may be positioned on the interposer  40  within the locating cavities  55 ,  57  in a position in which each of the ball-shaped conductive pads  24  is proximate a corresponding conductive pad  30   a ,  30   b . The rubber lower portions  74   b ,  75   b , respectively, of the spacers  74 ,  75  may then be lowered onto, and into contact with, the upper surfaces  14   f ,  15   f , respectively, of the electronic packages  14 , 15 . 
     The compressing plate may then be lowered onto the nuts  62  by advancing the bolts  53  through the plate apertures  68   a-f . Thereafter, the locking nuts  70  are threadingly engaged with the bolts  53  thereby securing the compressing plate  66  thereto. Once the compressing plate  66  is secured to the bolts  53 , the compressing bolts  78  are inserted through the compressing holes  76 . 
     It should be appreciated that a downward or retaining force is exerted on the electronic packages  14 ,  15  when the compressing bolts  78  are tightened. The compressing bolts  78  may be further tightened in order to increase the retaining force being exerted on the electronic packages  14 ,  15 , whereas the compressing bolts  78  may be loosened to decrease the retaining force being exerted on the electronic packages  14 ,  15 . 
     In order to remove the electronic packages  14 ,  15  from the circuit board  16 , the compressing bolts are first loosened. Thereafter, the locking nuts  70  are removed from the bolts  53 . After which, the compressing plate  66  may be lifted away from the bolts  53 , and thereafter the spacers  74 ,  75  may be removed. Once the spacers  74 ,  75  are lifted away, the electronic packages  14 ,  15  may then be removed. Thereafter, the same or different electronic packages  14 ,  15  may be secured to the circuit board  16  in the manner previously discussed. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 
     Although the bolts  20 ,  53  and the nuts  22 ,  62 ,  70  have been described as a manner in which the retainer may be secured to the circuit board  16  and have significant benefits in their use in the present invention, many of the advantageous of the present invention may be achieved by the use of other types of fasteners. For example, the retainer may be secured to the circuit board by using a clamp or other similar fastening device. 
     It should be appreciated that the back plate  18  (see FIG. 1) may be integrated into another component associated with an electronic assembly. For example, the back plate  18  may be integrated into a chassis associated with the electronic assembly, as opposed to being provided as a separate, discrete component. 
     In addition, although the securing assembly  10  (see FIG. 1) has been described as including the back plate  18  and has significant benefits in its use in the present invention, many of the advantageous of the present invention may be achieved without the use of the back plate  10 . In particular, the bolts  20  may be threadingly engaged into the circuit board  16  thereby eliminating the need for the back plate  18 . 
     Moreover, although the securing assembly  50  has been described to include the spacers  74 ,  75  and has significant benefits in their use in the present invention, many of the advantageous of the present invention may be achieved without the use of the spacers  74 ,  75 . For example, the compressing bolts  78  may be provided with rubber tips and be urged into contact with the upper surfaces  14   f ,  15   f  of the electronic packages  14 ,  15 , respectively.