Abstract:
Apparatus and methods for reducing circuit board flexing is presented. The apparatus is fastened to a printed circuit board to provide rigid support for reducing bending and flexing. In one embodiment, a rigid frame is provided that is adapted to be fastened to one or more components and to be fastened to a printed circuit board. The frame is adapted to elevate the attached component from the PCB surface allowing components to be mounted on the PCB therewith. The frame is adapted to occupy minimal printed circuit board surface area so as not to displace electronic components. In another embodiment, an elongated truss-like stiffener is provided that is adapted to be fastened to one side of the printed circuit board and adapted to span the printed circuit board. The elongated stiffener is adapted to have an open structure to minimize cooling flow disturbance and weight. The elongated stiffener includes a plurality of legs forming a truss-like structure. The stiffener supports the printed circuit board to resist bending and flexing stresses. In yet another embodiment, a combination of one or more stiffeners and one or more frames are provided such that the printed circuit board resists bending and flexing stresses.

Description:
RELATED APPLICATIONS  
       [0001]    This application is a divisional application of Ser. No. 09/619,725, filed Jul. 20, 2000, entitled “PRINTED CIRCUIT BOARD STIFFENER.” 
     
    
     
       TECHNICAL FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to the field of printed wiring boards and, more particularly, to mechanical stiffener apparatus and methods for rigidifying printed circuit boards.  
         BACKGROUND  
         [0003]    Modem high performance computers contain a number of printed circuit boards (PCB) to carry and interconnect the various integrated circuit chips and other components that make up the computer system. Computers may be configured to have one or more subsystems, each in its own right a computer, that are interconnected into a larger, greater capacity computer. Each subsystem may contain basically the same components assembled in a chassis. Within a given subsystem, there may be, among others, a processor board, a power board, and any number of secondary or daughter boards that are carried upon a support structure within the subsystem chassis. These subsystems of boards are carried in racks in the computer chassis.  
           [0004]    Processor boards are so named as they have attached to them one or more processors, or central processing units (CPU). The CPU is an integrated circuit (IC) chip that is considered the “brains” of the computer. The processor board serves as a communication medium for the exchange of electrical signals among the one or more attached processors and other electrical components attached to the processor boards, daughter cards, and other components. The processor board itself is sometimes referred to as a backplane, mother board, system board, or mainboard, depending on its function and configuration.  
           [0005]    The processor board is a printed circuit board. A PCB is a relatively thin, flat sheet structure. The PCB may be made of laminations of reinforced fiberglass or plastic and metallic interconnects which electrically link the components attached to the board. As flat sheets, PCBs are subject to bending and flexing stresses depending on the weight of the attached components and the method used to attach the PCB to the chassis.  
           [0006]    Some state of the art processors are an assembly consisting of a processor module and a power conditioning module with attached heatsink. These assemblies are relatively large and heavy, wherein the structural integrity of the PCB comes into question. The localized weight of the processor assembly, combined with the combined weight of the other components assembled onto the processor board, requires that the PCB be able to support handling, assembly and other stresses within acceptable limits of flexure without compromising the structural integrity of the PCB. Excessive loading will have a detrimental effect on the integrity of the electrical component interconnects and may result in failure of the electrical system.  
           [0007]    To mitigate the effects of deflection, support structures for resisting longitudinal and lateral flexing have been attached to PCBs. A processor board is commonly supported to some degree by the mounting bolts used for mounting the processor board to the chassis. Supplemental support is sometimes provided by rigidity enhancers laterally or longitudinally disposed across the processor board. These rigidity enhancers have taken various forms.  
           [0008]    Common disadvantages with lateral and longitudinal rigidity enhancers include electrical component interference, cooling air flow blockage and deflection, and lack of strength to support a PCB with attached processor assemblies. Improved lateral and longitudinal rigidity enhancers are needed that minimize electrical component interference, minimize the blockage of cooling air flow, and have sufficient strength to support a fully loaded PCB.  
           [0009]    Additionally, for a given printed circuit board size, the large processor assemblies take up considerable surface area of the board. In some cases, components which are commonly attached to the PCB are moved to other locations on the board or moved entirely off the board onto daughter boards. As a consequence, the distances between electrical components become large which is detrimental to the performance of the system as a whole.  
           [0010]    Processor assembly mounting structures have been used in the art to support the processor module and power conditioner module as an assembly. These structures have taken the form of a frame that supports the outside edge of the processor assembly. The processor module and power conditioner module are electrically connected, and the assembly is mounted onto the frame. Fasteners are used between the frame and the PCB to mount the processor assembly to the PCB. The frames elevate the processor assembly from the surface of the PCB allowing the attachment of additional electrical components onto the PCB surface that would have been covered by the processor assembly if directly attached. The state of the art processor assembly mounting frame requires considerable PCB surface area, limiting the number of electrical components capable of being attached to the PCB.  
           [0011]    There is a need in the art for PCB stiffeners and processor assembly mounting apparatus and methods to address the disadvantage of large processors crowding out electrical components on the processor board as well as being able to minimize the bending and flexing stresses on the PCB due to the weight of the processor assemblies and other components.  
         SUMMARY  
         [0012]    The above-mentioned disadvantages associated with large and heavy processor assemblies mounted on printed circuit boards, and other disadvantages, are addressed by the present invention and will be understood by reading and studying the following specification.  
           [0013]    In particular, the present invention is directed to apparatus and methods for enhancing processor board rigidity by providing processor board stiffeners and processor assembly mounting frames adapted to mount on a processor board surface. The stiffeners and mounting frames resist deflection of the processor board due to the weight of the processor assembly and other components. The mounting frame, additionally, provides accommodation for additional electrical components to be attached to the PCB by elevating the processor assembly off of the PCB, thus providing additional PCB surface area for the attachment of components.  
           [0014]    One embodiment in accordance with the present invention includes a mounting frame adapted to attach to the periphery of a component for assembly on to a PCB. The mounting frame is a frame-like structure having external dimensions configured to support an attached electrical component or components. The mounting frame comprises a plurality of legs, a cross leg, a rectangular opening, a partial rectangular opening, a plurality of through-holes, and a plurality of pilot holes. The plurality of legs includes an inwardly extending lip. The inwardly extending lip provides additional support material for supporting the attached components while minimizing the PCB surface area covered by the frame. The mounting frame is relatively thin but rigid. The legs of the mounting frame, in combination with the cross leg, define a rectangular opening and a partial rectangular opening. The partial rectangular opening is adapted to accommodate a component attached to the circuit board. A plurality of pilot holes is provided which are adapted to accommodate mounting means for attachment of the mounting frame to a printed circuit board (PCB). A plurality of through-holes is provided and adapted to accommodate mounting means for attachment of one or more electrical components to the mounting frame.  
           [0015]    In an alternative embodiment, the mounting frame is adapted such that the mounting frame peripheral edge substantially conforms to the outer dimensions of the electrical component. The mounting frame peripheral edge overlaps the electrical component bottom surface, such that when the mounting frame is placed against the electrical component bottom surface, the mounting frame rests upon the outer portion of the bottom surface. The fastening means is adapted to make use of the through-holes to fasten the mounting frame to the electrical component.  
           [0016]    In one embodiment, the peripheral edge of the electrical component overlaps the perimeter of the mounting frame. In an alternative embodiment, the peripheral edge of the mounting frame overlaps the perimeter of electrical component.  
           [0017]    One embodiment in accordance with the present invention includes a truss-like stiffener having external dimensions adapted to support an attached printed circuit board having attached components. The stiffener is relatively thin but rigid. The stiffener comprises a plurality of legs which define a plurality of openings. The stiffener has a fastening surface which is adapted to accommodate a fastening means for fastening to a PCB. The openings are provided such as to not significantly impede the flow of cooling fluid.  
           [0018]    In one embodiment in accordance with the present invention, the legs may be formed as an integral unit from a solid sheet of flat stock material. The legs may be formed by, among other methods, machining, cutting, and extruding. In another embodiment, the legs are formed as separate units of stock material and subsequently fastened into the truss-like configuration. The legs may be fastened together by, among other methods, welding, brazing, gluing, and screwing.  
           [0019]    In another embodiment in accordance with the present invention, the stiffener is made from a material that is thermally conductive. In this embodiment, the stiffener may be used as part of a heat dissipation system. In another embodiment, the stiffener is made from a material that is electrically conductive. In this embodiment, the stiffener may be used as part of a power or grounding system. In another embodiment, the stiffener is made from an electrically insulative material to minimize electrical shorting.  
           [0020]    In one embodiment in accordance with the present invention, stiffeners and mounting frames are used in combination to rigidify the PCB. Two stiffeners are positioned on one side of the PCB, in this example, while the opposite side of the PCB has attached one or more mounting frames. The two stiffeners are positioned perpendicular to the long dimension of the mounting frames. The stiffeners span substantially the width of the PCB.  
           [0021]    The present invention reduces the deflection to an acceptable amount in an efficient and economic manner which does not interfere with other electrical components or cooling flow requirements. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 illustrates a mounting frame, in accordance with one embodiment of the present invention.  
         [0023]    [0023]FIG. 2 illustrates a cross sectional view of the mounting frame of FIG. 1, in accordance with one embodiment of the present invention.  
         [0024]    [0024]FIG. 3 illustrates a cross sectional view of the mounting frame of FIG. 1, in accordance with one embodiment of the present invention.  
         [0025]    [0025]FIG. 4 illustrates a cross sectional view of the mounting frame of FIG. 1, in accordance with one embodiment of the present invention.  
         [0026]    [0026]FIG. 5 illustrates the mounting frame of FIG. 1 as assembled to a processor assembly, in accordance with one embodiment of the present invention.  
         [0027]    [0027]FIG. 6 illustrates a cross sectional view of the mounting frame of FIG. 1 as assembled to a processor assembly, in accordance with one embodiment of the present invention.  
         [0028]    [0028]FIG. 7 illustrates a side exploded view of an embodiment of the mounting frame of FIG. 1 with a processor assembly and a printed circuit board, in accordance with one embodiment of the present invention.  
         [0029]    [0029]FIG. 8 illustrates a cross sectional view of the mounting frame of FIG. 1 as assembled to a processor assembly and a printed circuit board, in accordance with one embodiment of the present invention.  
         [0030]    [0030]FIG. 9 illustrates a printed circuit board stiffener, in accordance with one embodiment of the present invention.  
         [0031]    [0031]FIG. 10 illustrates a side exploded view of the mounting frame of FIG. 1, a plurality of board stiffeners, a processor assembly and a printed circuit board, in accordance with one embodiment of the present invention.  
         [0032]    [0032]FIG. 11 illustrates a top view of a printed circuit board with attached stiffeners, in accordance with one embodiment of the present invention.  
         [0033]    [0033]FIG. 12 illustrates a bottom view of a printed circuit board with attached mounting frames, in accordance with one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0034]    The following detailed description refers to the accompanying drawings which form a part of the specification. The drawings show, and the detailed description describes, by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be used and mechanical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. Like reference numbers refer to similar items in all the figures.  
         [0035]    [0035]FIG. 1 depicts mounting frame  10 , in accordance with an embodiment of the present invention. Mounting frame  10  is a frame-like structure having external dimensions adapted to support an attached electrical component or components, which will be described subsequently. Mounting frame  10  comprises a plurality of legs  12 , cross leg  13  rectangular opening  16 , partial rectangular opening  14 , a plurality of through-holes  19 , and a plurality of pilot holes  18 . Mounting frame  10  is relatively thin but rigid. Legs  12  of mounting frame  10 , in combination with cross leg  13 , define a rectangular opening  16  and a partial rectangular opening  14 . A plurality of pilot holes  18  are provided. Pilot holes  18  are adapted to accommodate mounting means for attachment of mounting frame  10  to a printed circuit board (PCB). A plurality of through-holes  19  are provided and adapted to accommodate a mounting means for attachment of one or more components to mounting frame  10 .  
         [0036]    In one embodiment, legs  12  and cross leg  13  are formed as an integral unit from a solid sheet of flat stock material. In another embodiment, legs  12  and cross leg  13  are formed by, among other methods, machining, cutting, and extruding. Legs  12  and cross leg  13  also may be formed as separate units of flat stock material and subsequently fastened into the configuration as illustrated in FIG. 1. Legs  12  and cross leg  13  may be fastened together by, among other methods, welding, brazing, gluing, and screwing.  
         [0037]    The dimensions and configuration of mounting frame  10  can take many forms depending on the configuration of the one or more attached components. In the embodiment illustrated in FIG. 1, partial rectangular opening  14  is provided to accommodate an electrical component on the PCB. In other embodiments, partial rectangular opening  14  would not be necessary and other configurations may be used, among others, such as two complete rectangles or one rectangle. It is understood that the configuration of legs  12  and cross leg  13  can take many forms without departing from the scope of the invention.  
         [0038]    In the embodiment illustrated in FIG. 1, pilot holes  18  and through-holes  19  are provided to aid in fastening the mounting frame to components and to the PCB. Pilot holes  18  and through-holes  19  are provided for the fastening means and maybe not provided or take other forms for different fastening means. An example of fastening means not requiring pilot holes  18  and through-holes  19  include, among others, clips, adhesive, and brazing.  
         [0039]    In one embodiment of a method of use, in accordance with the present invention, an electrical component is attached to mounting frame  10  by a fastening means. In one embodiment, the electrical component is a processor assembly consisting of a processor module and a power conditioner. The processor module and power conditioner are assembled and are in electrical communication via a male/female connector. The processor assembly is mounted onto mounting frame  10  by a fastening means. The assembled processor assembly and mounting frame  10  are then mounted to the PCB with a fastening means. An embodiment of the method of use of mounting frame  10  will be presented subsequently.  
         [0040]    Mounting frame  10  may be fabricated from any material, such as rigid plastic or metal. In some embodiments, it may be desirable to make mounting frame  10  electrically conductive. In other embodiment, it may be desirable to make mounting frame  10  electrically insulative. The choice of material for mounting frame  10  will be determined by the application of the invention.  
         [0041]    [0041]FIG. 2 presents a cross-sectional view of mounting frame  10  on section line  22  shown in FIG. 1, in accordance with one embodiment of the present invention. Mounting frame  10  includes an inwardly extending lip  20 . Inwardly extending lip  20  provides additional support material for supporting the attached electrical components while minimizing the surface contact area between mounting frame  10  and the PCB, as will be discussed subsequently. Leg  10  includes top surface  12 , intermediate surface  21  and bottom surface  11 . The distance between intermediate surface  21  and bottom surface  11  is adapted to provide clearance for attached components under inwardly extending lip  20  and an attached component.  
         [0042]    The manufacture of mounting frame  10  to include inwardly extending lip  20  will be determined by the material from which mounting frame  10  is fabricated. For some materials, such as, among others, metal and plastic, the inwardly extending lip  20  may be machined from a blank of material. In other materials, such as, among others, plastic and fiberglass, it can be produced as part of a molding or lay-up process. Inwardly extending lip  20  may also be a component which must be assembled to resemble the illustration of FIG. 2, without departing from the scope of the invention.  
         [0043]    [0043]FIG. 3 presents a view of mounting frame  10  on section line  3 - 3  shown in FIG. 1, in accordance with one embodiment of the present invention. Visible in the illustration is a cross section of mounting frame  10 , including inwardly extending lip  20 , further including pilot hole  18 . Pilot hole  18  is provided to accommodate a fastening means for fastening mounting frame  10  to a printed circuit board. Such fastening means may include, among others, fasteners such as screws and bolts. Pilot hole  18  may be threaded to accommodate threaded fasteners.  
         [0044]    [0044]FIG. 4 presents a view of mounting frame  10  on section line  4 - 4  shown in FIG. 1, in accordance with one embodiment of the present invention. Visible in the illustration is a cross section of mounting frame  10 , including inwardly extending lip  20 , further including through-hole  19 . Through-hole  19  is provided in inwardly extending lip  20  to accommodate an attachment means for attaching mounting frame  10  to a component. Such attachment means may include, among others, fasteners such as screws and bolts.  
         [0045]    The fastening means applied to fasten mounting frame  10  to components or PCBs, will determine how mounting frame  10  will be adapted to accommodate such fastening means. In some embodiments, the fastening means may not require that mounting frame  10  have pilot holes  18  as shown in FIG. 2, and similarly, throughholes  19  as shown in FIG. 4. The fastening means may consist of, among others, bonding, brazing, and clipping.  
         [0046]    [0046]FIG. 5 depicts a bottom view of mounting frame  10  of the embodiment of FIG. 1 as coupled to electrical component assembly  52 , in accordance with one embodiment of the present invention. Mounting frame  10  is removably coupled component assembly  52 . In this illustration, component assembly  52  consists of a first component  53  and a second component  54 . In one embodiment, first component  53  is a processor module and second component  54  is a power conditioner for the processor module. The first component  53  and the second component  54  are in electrical communication through a male/female close-fit coupling  55 . In one embodiment, mounting frame  10  is adapted such that the mounting frame peripheral edge substantially conforms to the outer dimensions of the electrical component assembly  52 , such that leg top surface  12  abuts the bottom surface of electrical component assembly  52 . In such a configuration, when mounting frame  10  is placed against the bottom surface of electrical component assembly  52 , leg top surface  12  rests upon the outer portion of the bottom surface of electrical component assembly  52 . The fastening means is adapted to make use of through-holes  19  to fasten mounting frame  10  to electrical component assembly  52 .  
         [0047]    In one embodiment, in accordance with the present invention, the peripheral edge of electrical component assembly  52  overlaps the perimeter of mounting frame  10 . In another embodiment, the peripheral edge of mounting frame  10  overlaps the perimeter of electrical component assembly  52 . The exact orientation of the electrical component assembly  52  in relationship to mounting frame  10  will depend on the size and weight of electrical component assembly  52 . Similarly, the dimensions of legs  12  will depend on the size and weight of the attached electrical components.  
         [0048]    [0048]FIG. 6 depicts a view of mounting frame  10  and electrical component assembly  52  on section line  6 - 6  shown in FIG. 5, in accordance with an embodiment of the present invention. A cross section of mounting frame  10 , including inwardly extending lip  20  and through-hole  19 , and a cross-section of electrical component assembly  52  is shown. Through-hole  19  is provided in inwardly extending lip  20  to accommodate an attachment means  15  for fastening mounting frame  10  to electrical component assembly  52 . Such attachment means  15  may include, among others, fasteners such as screws and bolts.  
         [0049]    [0049]FIG. 7 depicts a side elevation exploded view of mounting frame  10  of the embodiment of FIG. 1, electrical component assembly  52 , and PCB  50 . Mounting frame  10  is disposed between electrical component assembly  52  and PCB  50  as would be configured when assembled. In one embodiment of the method of the present invention, mounting frame  10  is coupled to electrical component assembly  52 , and then mounting frame  10  is coupled to PCB  50 . Alternatively, mounting frame  10  is coupled to PCB  10  first, and then to electrical component assembly  52 .  
         [0050]    [0050]FIG. 8 depicts a cross sectional view of mounting frame  10 , electrical component assembly  52 , and PCB  50  on section line  8 - 8  of the embodiment of FIG. 7. A cross-sectional view of mounting frame  10 , including inwardly extending lip  20  and pilot hole  18 , a cross-sectional view of electrical component assembly  52 , and a cross-sectional view of PCB  50  is shown. Pilot hole  18  is provided in mounting frame  10  to accommodate attachment means  17  for fastening mounting frame  10  to PCB  50 . Such attachment means may include, among others, fasteners such as screws and bolts.  
         [0051]    In one embodiment, through-holes  19  and pilot holes  18  are not provided in mounting frame  10 . Fastening means for this configuration include, among others, bonding, brazing, welding, and gluing.  
         [0052]    When mounting frame  10  is fastened to PCB  50 , the portion of PCB  50  under inwardly facing lip  20  may be populated with electrical components.  
         [0053]    [0053]FIG. 9 depicts stiffener  60  in accordance with one embodiment of the present invention. Stiffener  60  is a truss-like structure having dimensions adapted to support an attached printed circuit board. Stiffener  60  is relatively thin but rigid. Legs  62  define a plurality of triangular openings  66 . Stiffener  60  has a fastening surface  68  which is adapted to accommodate a fastening means for fastening to a PCB. Triangular openings  66  are adapted such as to not significantly impede the flow of cooling fluid, as will be subsequently discussed.  
         [0054]    Stiffener  60  may be formed as an integral unit from a solid sheet of flat stock material with cut-outs defining legs  62 . Legs  62  may be formed by, among other methods, machining, cutting, and extruding. Legs  62  also may be formed as separate units of stock material and subsequently fastened into the configuration as illustrated in FIG. 9. Legs  62  may be fastened together by, among other methods, welding, brazing, gluing, and screwing. Stiffener  60  may be die-cast, routed or otherwise manufactured. Stiffener  60  may be formed of sheet metal, cast metal, plastic, graphite, fiberglass, or any material well suited for stiffening the processor board.  
         [0055]    The dimensions and configuration of stiffener  60 , as well as the configuration of legs  62  with respect to one another, is dependent on the distribution and weight of the components contained on the PCB. In one embodiment, a partial triangular opening is provided to accommodate and span over an electrical component on the PCB. In other embodiment, legs  62  are arranged to form diamond-shaped openings. These are just examples and other arrangements of legs  62  are possible without deviating from the scope of the invention.  
         [0056]    Stiffener  60  may be fabricated from any material, such as, among others, rigid plastic or metal. In some embodiments, it may be desirable to make the stiffener thermally or electrically conductive. In other embodiments, it may be desirable to make stiffener  60  electrically insulative. The choice of material for stiffener  60  will be determined by the application if the invention.  
         [0057]    It can be understood that the actual shape of stiffener  60  could be altered to accommodate differing requirements. For example, the height and length of stiffener  60  is adapted to accommodate the size of the board and the space of the chassis. Further, the configuration of legs  62  may define rectangular or trapezoid apertures, among others, to accommodate differing strength requirements. It is also to be understood that the thickness of stiffener  60  could vary as well.  
         [0058]    Stiffener  60  is mounted firmly to the processor board in such a way that stiffener  60  supports the PCB against deflection and warping. In one embodiment, stiffener  60  is mounted perpendicular to the surface of the PCB. In one embodiment, stiffener  60  is mounted perpendicular to and substantially parallel to one of the edges of the PCB. In another embodiment, a plurality of stiffeners  60  are used in parallel relationship to each other spanning the PCB.  
         [0059]    It is to be understood that stiffeners  60  may be used on any type of PCB that requires board stiffeners to support attached components.  
         [0060]    [0060]FIG. 10 depicts a side elevation exploded view of mounting frame  10  and stiffeners  60 , electrical component assembly  52 , and PCB  50 , in accordance with an embodiment of the present invention. Two stiffeners  60  are positioned on PCB  50  on the opposite side of PCB  50  from mounting frame  10 , and perpendicular to the long dimension of mounting frame  10 . Stiffeners  60  are positioned perpendicular to the width of mounting frame  10  adding additional support under electrical component assembly  52 . Stiffeners  60  span substantially the width of PCB  50 .  
         [0061]    Stiffener  60  may be mounted on the bottom side or the top side of the PCB according to the requirements of the configuration. Stiffeners  60  may be mounted in any of a variety of methods including bolts, epoxy, and cement.  
         [0062]    In one embodiment, in accordance with the present invention, one or more stiffeners  60  are adapted to be mounted on the component side of a PCB  50 . In an alternative embodiment, one or more stiffeners  60  are mounted to the back side of PCB  50 . Stiffener  60  is adapted for avoiding interference with metal runs, solder joints, as well as components.  
         [0063]    In some applications it will be difficult to relocate all of the electrical components attached to the PCB to allow room for stiffener  60  to span the entire length of PCB  50  continuously. Therefore it is understood that stiffener  60  can have missing legs  62  or gaps, allowing stiffener  60  to span above the subject components.  
         [0064]    The mounted stiffeners  60  are adapted to a height such that they do not interfere with chassis assembly, generally no higher than the height of the tallest component attached to PCB  50  but are of sufficient height to provide the required support to PCB  50 .  
         [0065]    In one embodiment of the combination mounting frame  10  and stiffener  60 , stiffener  60  provides lateral rigidity while the mounting frame provides longitudinal rigidity.  
         [0066]    [0066]FIGS. 11 and 12 are provided to illustrate the method of use of the present invention as applied to an advanced processor board configuration. In this example, electronic components are attached to both sides of processor board  115 . In FIG. 11, processor board  115  is a modified McKinley (Intel Corporation, Santa Clara, Calif.) protocol processor board. Two HUB chip sets  125  and other attached components are on processor board top side  117 . Two stiffeners  60  are disposed in the longitudinal direction of board  115 , with HUB chip sets  125  disposed between the two stiffeners  60 . Stiffeners  60  are positioned perpendicular to processor assembly mounting frame  10 , shown in FIG. 10, and are located opposite to processor module  54  of processor assembly  52 .  
         [0067]    [0067]FIG. 12 illustrates four processor assemblies  152  and their corresponding mounting frames  110  coupled to processor board back side  113 .  
         [0068]    The heavy weight and size of the McKinley processor assembly  153  presents a unique structural challenge for processor board  115 . The weight of the McKinley processor assembly  153  can cause deflection in an unsupported processor board  115 . The present invention reduces the deflection to an acceptable amount, in an efficient and economic manner which does not interfere with other electrical components or cooling flow requirements.  
         [0069]    The above-described embodiments are merely illustrative of those suitable for carrying out the objectives of the present invention, and are not intended to represent a comprehensive and exclusive list of such embodiments.  
       CONCLUSION  
       [0070]    Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention.