Abstract:
A method and apparatus are provided for the interconnection of multiple circuit boards within a device. A module is provided which comprises multiple circuit boards interconnected with a plurality of connectors. Modules may be interconnected to other modules using the same connectors. Circuit components are disposed on inner surfaces of the circuit boards of the module. Multiple circuit boards and modules are interconnected by contacts that do not require soldering, that permit the circuit boards and modules to be removably coupled to each other by the contacts, and that permit circuit boards to be positioned by a spaced amount that results in a small spacing between circuit boards. Enclosures are also provided, which allow modules to be configured and secured in both a horizontal and vertical direction. Thus, modules may be interconnected to other modules on each side, as well as interconnected to other modules stacked above or below the module.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a method and apparatus for interconnecting circuit boards and, in particular, to circuit boards adapted to be housed within an enclosure. This invention further relates to a method and apparatus for interconnecting circuit boards of different modules, wherein a module comprises two circuit boards. 
         [0003]    2. Statement of the Problem 
         [0004]    Circuit boards are widely used in electronic devices and systems. It is commonplace to use a plurality of circuit boards in a television, a laptop computer, a mobile telephone, an MP3 player, a digital voice recorder, etc. In general, the more complex the device, the greater number of circuit boards that are required for the device. 
         [0005]    It is a problem in the industry to use multiple boards within a device because of problems related to efficiently and economically mounting and interconnecting the multiple boards to each other. Industry standard specification PC  104  characterizes the recommended specifics of stacking or mounting a plurality of circuit boards vertically. This standard specifies that vertically stacked circuit boards must have a ½″ space between them. The component&#39;s are mounted on only one side of the circuit board and are contained within this ½″ spacing. This ½″ spacing increases the overall size of the device containing the stacked circuit boards. Thus, a device containing four circuit boards would have a height of 2″; a device with six circuit boards would have a height of 3″, etc. Compliance with this standard precludes such devices from being used in laptops, mobile telephones and other devices that must be thin to be commercially attractive. 
         [0006]    The PCI standard characterizes the requirements for devices containing a motherboard or backplane. The requirements include having a plurality of the circuit boards spaced at least ½″ from each other, connecting the circuit boards at right angles to the motherboard or backplane. Compliance with this standard precludes the use of the circuit boards and the motherboard in devices such as cell phones of a like where the devices must be thin in order to be commercially acceptable. 
         [0007]    In accordance with the PC  104  and PCI standards, electronic elements such as resistors, capacitors, coils, transformers, etc. are positioned on only one side of the board in the ½″ spacing between circuit boards. When the components are of a heat generating type, it is difficult to mount the components in this ½″ spacing because of thermal problems created by the generated heat. This in turn, may require the use of fans and the like to maintain a satisfactory temperature of the circuit boards and its components. Further, the use of motherboards connected to multiple circuit boards presents a problem protecting the boards from vibrations. 
         [0008]    It can be seen that prior art arrangements having multiple circuit boards creates problems that preclude their use in miniaturized devices. These problems include space, thermal, and vibration problems. 
       SUMMARY OF THE SOLUTION 
       [0009]    The present invention solves the above and other problems by the provision of a method and apparatus that provides for the interconnection of multiple modules and circuit boards within a device. In accordance with the invention, a module is provided which comprises multiple circuit boards interconnected with a plurality of connectors. Further, a pair of circuit boards, herein referred to as a module, may also be interconnected to other like modules. The multiple circuit boards and modules are interconnected by contacts that permit the circuit boards and modules to be removably coupled to each other, and that permit circuit boards to be positioned by a spaced amount that results in a small spacing between circuit boards. This small spacing facilitates the use of modules in miniaturized devices where small dimensions are a prerequisite to commercial success of the devices. The use of the method and apparatus of the present invention permits the use of the modules in mobile telephones, laptop computers, MP3 players, digital voice recorders, etc., where space is at a premium. This enables devices housing the circuit boards to be commercially attractive by permitting the device to have increased functionality without an increase in size. 
         [0010]    The method and apparatus of the present invention also permits the removal and insertion of modules. This permits a module to be removed for maintenance and then repaired or replaced by another module. This is particularly advantageous since it permits a working device to be easily repaired instead of being discarded since it is often not feasible to repair a single motherboard and/or a plurality of a circuit boards interconnected by wires and the like. 
         [0011]    The ability of the modules to be removed is advantageous since it permits modules to be used for different applications by inserting a combination of modules into the device to create a device having a required functionality. This feature allows a manufacturer to store generic modules that can be stored and later converted into a device having a specific functionality by the insertion of a specific combination of modules. This feature permits a manufacturer or assembler to store a fewer number of parts that can be converted to a specific use using different types of circuit boards and modules. 
         [0012]    The method and apparatus of the present invention is further advantageous in that it provides increased thermal capabilities for the module in which it is used. This is achieved by thermally coupling components to the faces of a module, with the face being in contact with surreally conductive material that dissipates heat by conduction rather than by thermal convection requiring airflow. This permits a device to use modules of smaller size since space does not have to be provided within the device to accommodate airflow or the like. 
         [0013]    The method and apparatus of the present invention is ubiquitous in that the modules are equipped with contacts along the perimeter of their top and bottom faces. This permits modules to be placed side-by-side or stacked vertically. When the modules are vertically positioned, they are interconnected to each other by engaging the perimeter contacts of stacked modules to each other. These perimeter contacts also permit modules to be horizontally positioned in the same plane and connected to each other by a thin connector sheet that enables a module to be connected to an adjacent module by pressing the connector sheet down so that its contacts interconnect the perimeter contacts of the adjacent modules. 
         [0014]    The contacts may be on one or all of the perimeters of the module. This provides great flexibility in the assembly of a device using a plurality of modules with different functionality. For example, a device can be equipped with a single pair of circuit boards (i.e., a module). Also, a device can have modules positioned in a plane and connected to each other by their perimeter contacts. A device may also have modules vertically stacked atop each other. Further, a device may have any number of horizontally interconnected modules as well as any number of vertically stacked modules. 
         [0015]    The space between the upper and lower circuit boards of a module is used to mount components on one side of each circuit board. The components may be controllably positioned on the surface of the lower and upper circuit boards of the module. The components on the upper or lower circuit boards of a module may be positioned so that a tall element on one of the circuit boards does not abut a tall element on the other circuit board. In other words, a tall element on a lower circuit board may be positioned vertically opposite a smaller element on the upper circuit board, or vice versa. The capability of positioning the elements in this manner permits a smaller spacing between two vertical circuit boards of a module, since the component&#39;s on adjacent vertical circuit boards are controllably positioned to fill the space available between the two circuit boards. 
         [0016]    In use, modules may be stacked vertically and mounted within an enclosure so that the lower surface of the bottom circuit board of the module abuts the lower surface of the enclosure. The top surface of the top circuit board of the module engages the bottom surface of the upper wall of the enclosure. This provides for increased thermal capabilities as above discussed. 
         [0017]    The invention may include other exemplary embodiments described below. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0018]    The above and other advantages and features of the invention may be better understood from a reading of the detailed description taken in conjunction with the drawings. The same reference number represents the same element on all drawings. 
           [0019]      FIG. 1  is an exploded top isometric view of a module in an exemplary embodiment of the invention. 
           [0020]      FIG. 2  is an exploded bottom isometric view of a module in an exemplary embodiment of the invention. 
           [0021]      FIG. 3  is an isometric view of a module in an exemplary embodiment of the invention. 
           [0022]      FIG. 4  is an exploded top isometric view of a 3×2 enclosure adapted to house a plurality of modules in an exemplary embodiment of the invention. 
           [0023]      FIG. 5  is an exploded bottom isometric view of a 3×2 enclosure adapted to house a plurality of modules in an exemplary embodiment of the invention. 
           [0024]      FIG. 6  is a top view of a 3×3 enclosure adapted to house a plurality of modules in an exemplary embodiment of the invention. 
           [0025]      FIG. 7  is an exploded isometric view of a multi-layered enclosure adapted to house a plurality of layers of modules in an exemplary embodiment of the invention. 
           [0026]      FIG. 8  is a side view of the connection between the two circuit boards of a module in an exemplary embodiment of the invention. 
           [0027]      FIG. 9  is a side view of two modules matingly engaged in a stacked configuration in an exemplary embodiment of the invention. 
           [0028]      FIG. 10  is a side view of two modules matingly engaged in a side-by-side configuration in an exemplary embodiment of the invention. 
           [0029]      FIG. 11  is an isometric view of a row of inside contacts in an exemplary embodiment of the invention. 
           [0030]      FIG. 12  is an isometric view of a row of outside contacts in an exemplary embodiment of the invention. 
           [0031]      FIG. 13  is an isometric view of insulator material separating the top outside contacts, the bottom outside contacts, and the inside contacts in an exemplary embodiment of the invention. 
           [0032]      FIG. 14  is an isometric view of an apparatus adapted to connect a module to an external device in an exemplary embodiment of the invention. 
           [0033]      FIG. 15  is a flow chart of a method for forming a module in an exemplary embodiment of the invention. 
       
    
    
     ASPECTS 
       [0034]    An aspect of the invention comprises a system, the system including at least one module. The module comprises a first circuit board having a component surface; a second circuit board having a component surface, the component surface of the second circuit board disposed facing the component surface of the first circuit board; and an apparatus adapted to physically and electrically couple the first circuit board and the second circuit board, and further adapted to matingly engage the module with a second module. 
         [0035]    Preferably, the apparatus for physically and electrically coupling the first circuit board and second circuit board comprises: a plurality of outside spring leaf contacts that clamp the outer sides of the first and second circuit boards along each edge of the first and second circuit boards to keep the first and second circuit boards from moving apart, each outside spring leaf contact extending beyond the outer faces of the first and second circuit boards and adapted to matingly engage contact pads on the outer faces of the module with the second module; and a plurality of inside spring leaf contacts pressed between the component sides of the first and second circuit boards along each edge of the first and second circuit boards to keep the first and second circuit boards from moving together, each inside spring leaf contact adapted to matingly engage with contact pads on the component sides of the first and second circuit boards to electronically couple the first circuit board and the second circuit board. 
         [0036]    Preferably, the apparatus for physically and electrically coupling the first circuit board and second circuit board further comprises: insulator material substantially a same length as an edge of the module, the insulator material having a plurality of slots adapted to electrically isolate each pair of matingly engaged outside spring leaf contacts and inside spring leaf contacts from other pairs of matingly engaged outside spring leaf contacts and inside spring leaf contacts. 
         [0037]    Preferably, the plurality of outside spring leaf contacts further comprises: at least one power contact; at least one ground contact; at least one control signal contact; and at least one data signal contact. 
         [0038]    Preferably, the system comprises a plurality of modules. 
         [0039]    Preferably, sizes of each edge of the first circuit board and the second circuit board are integer multiples of a base value. 
         [0040]    Preferably, the first circuit board and the second circuit board further comprise means for securing the module in place in an enclosure housing the module. 
         [0041]    Preferably, the module comprises: a cut-out on each of the four corners of the first circuit board, and a cut-out on each of the four corners of the second circuit board, the cut-outs on the first circuit board and the cut-outs on the second circuit board adapted to pass through a spacer in the enclosure housing the module to secure the module in place around the spacer. 
         [0042]    Preferably, the enclosure comprises a plurality of spacers arranged in a grid pattern, each spacer being equally spaced apart in an X-direction and a Y-direction of the enclosure, with the base value equal to a distance between centers of two of the plurality of spacers. 
         [0043]    Another aspect of the invention is a system comprising: a plurality of modules, each module comprising: a first circuit board having a component surface; and a second circuit board having a component surface, the component surface of the second circuit board disposed facing the component surface of the first circuit board; and an apparatus adapted to physically and electrically couple the first circuit board and the second circuit board and adapted to matingly engage the module with at least one of the other plurality of modules, and the system further comprising an enclosure adapted to house the plurality of modules; and a plurality of spacers coupled to the enclosure, the plurality of spacers arranged in a grid pattern, each spacer being equally spaced apart in an X-direction and a Y-direction of the grid pattern, wherein sizes of each edge of the first circuit board and the second circuit board of each module are integer multiples of a base value, the base value equal to a distance between centers of two of the plurality of spacers. 
         [0044]    Preferably, the apparatus for physically and electrically coupling the first circuit board and second circuit board comprises: a plurality of outside spring leaf contacts that clamp the outer sides of the first and second circuit boards along each edge of the first and second circuit boards to keep the first and second circuit boards from moving apart, each outside spring leaf contact extending beyond the outer faces of the first and second circuit boards and adapted to matingly engage contact pads on the outer faces of the module with the second module; and a plurality of inside spring leaf contacts pressed between the component sides of the first and second circuit boards along each edge of the first and second circuit boards to keep the first and second circuit boards from moving together, each inside spring leaf contact adapted to matingly engage with contact pads on the component sides of the first and second circuit boards to electronically couple the first circuit board and the second circuit board. 
         [0045]    Preferably, the system comprises a plurality of layers of modules housed in the enclosure, wherein at least one layer of modules is stacked atop a lower layer of modules. 
         [0046]    Preferably, the plurality of layers of modules are electronically coupled together by the outside spring leaf contacts, the outside spring leaf contacts electrically coupling a first module on a first layer and a second module on a second layer, the second module stacked atop the first module. 
         [0047]    Preferably, the system comprises an apparatus adapted to electrically couple at least one of the plurality of modules with an external device, the apparatus comprising: a cable electrically coupled to the apparatus module, the cable adapted to electrically couple the apparatus module with the external device. 
         [0048]    Another aspect of the invention are modules with footprints that are restricted to closed shapes that can be constructed by arranging segments of a unit length end-to-end such that all segments are either parallel or perpendicular to one-another and where said modules have a plurality of electrical contacts centered along the edge of at least one of said segments and extending above and below the edge such that a plurality of modules can be electrically connected to one-another by way of said contacts when said plurality of modules are stacked atop one-another. 
         [0049]    Preferably, the modules are also arranged side-by-side in a plane and connected by an apparatus that contains conductive strips where said apparatus is oriented parallel to said modules in order to mate with said perimeter contacts of both modules in order to effect electrical connection between the contacts of said modules. 
         [0050]    Another aspect of the invention is a method for forming a module, the method comprising: providing a first circuit board having a component surface; providing a second circuit board having a component surface, the component surface of the second circuit board disposed facing the component surface of the first circuit board; and positioning components on the component surface of the first circuit board and the component surface of the second circuit board to minimize un-utilized space between the first circuit board and the second circuit board. 
         [0051]    Preferably, there is a first height between the first circuit board and the second circuit board, and positioning components further comprises: positioning a first component on the component surface of the first circuit board, the first component having a second height less than the first height; determining a remaining height based on the first height minus the second height; and positioning a second component on the component surface of the second circuit board, the second component having a third height which is less than or equal to the remaining height. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0052]      FIGS. 1-15  and the following description depict specific exemplary embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects of the invention have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
         [0053]      FIG. 1  is an exploded isometric view of a module  100  in an exemplary embodiment of the invention.  FIG. 1  illustrates an internal view of the bottom of module  100 . Module  100  includes a bottom circuit board  101  and a top circuit board  102 . Top circuit board  102  has a component surface (not visible in  FIG. 1 ) which is disposed facing a component surface of bottom circuit board  102 . The component surface of bottom circuit board  102  contains components  112  and  113  of differing heights. The terms top and bottom are used for illustrative purposes only. Module  100  may be oriented in any number of directions such that bottom circuit board  101  and top circuit board  102  may be disposed in opposite positions, or may comprise opposite sides of module  100 . Module  100  includes a connector  103  adapted to physically and electrically couple bottom circuit board  101  and top circuit board  102 . To electrically couple bottom circuit board  101  and top circuit board  102 , the connector  103  comprises a plurality of inside contacts  107  that engage inside contact pads  108 A on circuit board  102  with contact pads  108 B (not visible in  FIG. 1 ) on circuit board  101 . The engagement of bottom inside contact pads  108 B and top inside contact pads  108 A will be subsequently described. As illustrated in  FIG. 1 , there are twenty-five pairs of bottom inside contacts  108 B and top inside contacts  108 A along each edge of module  100 . However, any number of pairs of bottom inside contacts  108 B and top inside contacts  108 A may be disposed along each edge of module  100  depending on desired design criteria. 
         [0054]    The coupling apparatus of module  100  may further include a plurality of outside contacts  109 A and  109 B adapted to matingly engage module  100  with another like module (not shown) to electrically couple the two modules. A portion of outside contacts  109 B and  109 A are electrically coupled to bottom outside contact pads  110 B (not visible in  FIG. 2 ) of circuit board  101  and outside contact pads  110 A of circuit board  102  respectively to electrically couple bottom circuit board  101  and top circuit board  102  with other modules. As illustrated in  FIG. 1 , there are thirteen outside contacts  109 A on the top and thirteen outside contacts on the bottom along each edge of module  100 . Thus, thirteen top outside contacts  109 A may be electrically coupled to another module on each side of module  100  and thirteen bottom outside contacts  109 B may be electrically coupled to another module on each side of module  100 . Module  100  as illustrated may be electrically coupled to eight other modules, two on each side of module  100 . 
         [0055]    Corner clips  104  are captured between circuit boards  101  and  102  when corner clip posts  105 A and  105 B pass through holes  106 A and  106 B respectively in circuit boards  102  and  101  respectively. Said corner clips hold connectors  103  to module  100  by way of tab  114  of connector  103  snapping into slot  115  of corner clip  104 . 
         [0056]    Bottom circuit board  101  includes a plurality of cut-outs  111 B on each corner of bottom circuit board  101 . Top circuit board  102  includes a corresponding plurality of cut-outs  111 A on each corner of top circuit board  102 . The cut-outs  111 A and  111 B are adapted to secure module  100  in place in an enclosure (not shown in  FIG. 1 ). The enclosure and securing of module  100  within the enclosure will be subsequently described. 
         [0057]      FIG. 3  is an isometric view of module  100  in an exemplary embodiment of the invention. More specifically,  FIG. 3  illustrates the final assembly of module  100  after bottom circuit board  101  and top circuit board  102  are physically and electrically coupled by connectors  103  and corner clips  104 . While module  100  is illustrated as a square, module  100  may be other types of parallelepipeds, such as a rectangle. 
         [0058]    To minimize a height of module  100 , components may be disposed on the inside surfaces of both bottom circuit board  101  and top circuit board  102 . Preferably, components disposed on bottom circuit board  101  and top circuit board  102  are staggered to avoid having two large components on corresponding locations of bottom circuit board  101  and top circuit board  102 . If one tall component  113  is disposed on bottom circuit board  101 , and a second tall component is disposed on top circuit board  102  immediately above the tall component on bottom circuit board  101 , then the height of module  100  may become larger than necessary. Thus, it may be beneficial to place a tall component  113  on bottom circuit board  101 , and place a short component in the corresponding location on top circuit board  102  above the tall component. Likewise, a tall component may be placed on top circuit board  102 , and a short component may be placed on bottom circuit board  101  below the tall component on top circuit board  102 . Further, if a relatively tall component is placed on either bottom circuit board  101  or top circuit board  102 , then the corresponding location on the other circuit board may be left empty to minimize the overall height of module  100 . This staggering of components is advantageous, because a minimum height of the module is kept as small as physically possible depending on the largest component that may be disposed on bottom circuit board  101  or top circuit board  102 . 
         [0059]      FIG. 4  is an isometric view of a 3×2 enclosure  400  adapted to house a plurality of modules  100  in an exemplary embodiment of the invention. Enclosure  400  comprises a bottom plate  401  and a plurality of spacers  403 . More specifically, enclosure  400  comprises twelve spacers  403 . Spacers  403  are arranged in a grid pattern, with each spacer  403  being equally spaced apart in an X-direction and a Y-direction of the grid pattern. Each module  100  has corresponding cut-outs  111  to fit within spacers  403 . Further, the size of each edge of bottom circuit board  101  and top circuit board  102  may be integer multiples of a base value. The base value is equal to a distance between the centers of two of the spacers  403 . Thus, modules  100  may be placed at any location of enclosure  400  and fit within any four spacers  403 . Connector strips  408  on circuit substrate  406  electrically couple adjacent modules  100 . Circuit plane  407  on circuit substrate  406  distributes ground to modules  100 . Thermal contact pad  405  passes through circuit substrate  406  to thermally couple bottom plate  401  to modules  100 . Holes  404  in spaces  403  accommodate fasteners (not shown) to affix top plate  402  to bottom plate  401  and to compress modules  100  with connector strips  408  and ground plane  407 . Enclosure  400  is adapted to house a total of six square modules  100 . 
         [0060]      FIG. 5  is an isometric view of a 3×2 enclosure  400  showing the inside surface of top plate  402  and circuit substrate  506 . Connector strips  508  on circuit substrate  506  electrically couple adjacent modules  100 . Circuit plane  507  on circuit substrate  506  distributes power to modules  100 . Thermal contact pad  505  passes through circuit substrate  506  to thermally couple top plate  501  to modules  100 . 
         [0061]      FIG. 6  is a top view of a 3×3 enclosure  600  adapted to house a plurality of modules  100  in an exemplary embodiment of the invention. As illustrated, enclosure  600  includes sixteen spacers  403 , and is adapted to house nine square modules  100 . However, if each edge of a module  100  is an integer multiple of a base value, modules do not need to be square shaped, but rather, may be any type of parallelepiped, or could even be other shapes, such as L-shaped or U-shaped. For example, an L-shaped module may comprise three or more 1×1 modules, and a U-shaped module may comprise five or more 1×1 modules. Exemplary dimensions of a 1×1 square module  100  are 25.6 mm×25.6 mm, with a height of 3.2 mm. Exemplary dimensions of cut-outs  111 A and  111 B of a 1×1 square module  100  have a 2 mm radius. Thus, a spacer  403  may have a 4 mm diameter to secure up to four 1×1 modules in place. 
         [0062]    As illustrated in  FIG. 6 , module  602  is a 1×2 module (e.g., is twice the length of module  100 , but the same width as module  100 ). Thus, module  602  may be 25.6 mm by 51.2 mm. Module  602  includes six cut-outs, one on each corner of module  602 , and two cut-outs  603  in the middle along the longest edge of module  602 . 
         [0063]    Module  604  is a 2×2 module (e.g., is twice the length and twice the width of module  100 ). Thus, module  604  may be 51.2 mm by 51.2 mm. Module  604  includes nine cut-outs, four on each corner of module  604 , one cut-out  605  in the center of module  604 , and one cut-out  606  in the middle of each side of module  604 . 
         [0064]    Spacers  403  have been described as arranged in a grid pattern, where each spacer  403  is spaced equally apart from other spacers  403  in both an X-direction and a Y-direction of the grid pattern. However, design criteria may dictate that some spacers  403  are not needed in the grid pattern. For example, a space in an enclosure may be selected to hold a module which is larger than a 1×1 module. Therefore, in some embodiments, a portion of the spacers  403  may be omitted from the grid pattern. For example, two adjoining spacers  403  may be placed two base value units of length apart, while other spacers  403  are placed one base value unit of length apart. This permits the utilization of the standard grid pattern, while accommodating large modules which do not require cut-outs to be placed in the middle of the component. 
         [0065]      FIG. 7  is an isometric view of a multi-layered enclosure  700  adapted to house a plurality of layers of modules  100  in an exemplary embodiment of the invention. Enclosure  700  comprises a bottom plate  701 , and a plurality of spacers  403  coupled to bottom plate  701 . Each spacer  403  is twice the height of a module  100 . A first layer of modules  100  may be placed horizontally on bottom plate  701 . A second layer of modules  100  may be vertically stacked atop the first layer of modules  100 . Stacked modules  100  are connected by outside contacts  109 . A top plate  402  is placed above the second layer of modules  100  to secure modules  100  in a Z-direction. Multi-layered enclosure  700  allows six 1×1 modules  100  to be horizontally configured in an X-direction and a Y-direction of multi-layer enclosure  700 . Additionally, multi-layered enclosure  700  allows for two layers of modules  100  to be stacked together, allowing up to twelve 1×1 modules  100  to be enclosed in multi-layered enclosure  700 . However, any number of layers may be stacked, and any number of modules  100  may be horizontally placed on each layer depending on desired design criteria. Additionally, as described in  FIG. 6 , different sized modules having edges which are integer multiples of a base value may be horizontally and vertically configured in multi-layered enclosure  700 . 
         [0066]      FIG. 8  is a side view of circuit boards  101  and  102  of module  100  being connected by inside contacts  107  of connector  103 . Circuit board  102  is clamped between spring leaf outside contacts  109 A and spring leaf inside contacts  107  of connector  103  causing electrical coupling of outside contacts  109 A to outside contact pads  110 A and electrical coupling of inside contacts  107  with inside contact pads  108 A. Circuit board  101  is clamped between spring leaf outside contacts  109 B and spring leaf inside contacts  107  of connector  103  causing electrical coupling of outside contacts  109 B to contact pads  110 B and electrical coupling of inside contacts  107  with contact pads  108 A. Thus circuit board  101  is electrically coupled to circuit board  102  through contacts  107 . 
         [0067]    Module  100  is electrically coupled to other modules using outside spring leaf contacts.  FIG. 9  is a side view of the connection between two stacked modules in an exemplary embodiment of the invention. More specifically, the left portion of  FIG. 9  illustrates two modules prior to coupling, and the right portion of  FIG. 9  illustrates two modules coupled together.  FIG. 10  is a side view of the connection between two modules laid side-by-side in the same plane. More specifically, the left portion of  FIG. 10  illustrates two modules prior to coupling, and the right portion of  FIG. 10  illustrates two modules coupled together. The side-by-side coupling uses connector strips  1002  on enclosure base  1001  to couple with contacts  109 B on the two modules. 
         [0068]    As illustrated in  FIGS. 1-3 , module  100  comprises thirteen bottom spring leaf outside contacts  109 B and thirteen top spring leaf outside contacts  109 A. In the described embodiment, these thirteen pairs of connectors comprise a power contact, two ground contacts, two control signal contacts, and eight data signal contacts for transferring 8-bit data. However, any number of contacts and configurations may be used depending on desired design criteria. 
         [0069]      FIG. 11  is an isometric view of connector  103  showing inside spring leaf contacts  107  in an exemplary embodiment of the invention. Each inside contact matingly engages with inside contact pads on the circuit boards  101  and  102  of a module  100   
         [0070]      FIG. 12  is an isometric view of connector  103  showing outside spring leaf contacts  109 A and  109 B in an exemplary embodiment of the invention. 
         [0071]      FIG. 13  is an isometric view of insulator material  1101  separating the top outside contacts, the bottom outside contacts, and the inside contacts in an exemplary embodiment of the invention. Insulator material  1101  may run substantially the length of top circuit board  102  (i.e., run the length of the edge between two cut-outs  111 B). Insulator material  1101  has a plurality of slots  1301  adapted to electrically isolate each of the plurality of bottom outside contacts  109 B. More specifically, insulator material  1101  may have thirteen slots  1301  to physically and electrically isolate each bottom outside contacts  109 B. Additionally, insulator material  1101  has a plurality of slots  1303  adapted to electrically isolate each of the plurality of top outside contacts  109 A. More specifically, insulator material  1101  may have thirteen slots  1303  to physically and electrically isolate each top outside contacts  109 A. Additionally, insulator material  1101  has a plurality of slots  1302  adapted to electrically isolate each of the plurality of inside contacts  107 . More specifically, insulator material  1101  may have twenty-five slots  1302  to physically and electrically isolate each inside contacts  107 . 
         [0072]    It may become necessary to couple an enclosure of modules  100 , or one or more modules  100  to an external device. For example, if an enclosure comprises the components of a handheld computer, then it may become necessary to couple the modules of the enclosure to a printer, input device, network connection, external storage device, etc. An exemplary embodiment of the invention comprises provisions for coupling one or more modules  100  to an external device. 
         [0073]      FIG. 14  is a view of a module enclosure  1400  connected to an external device  1401  in an exemplary embodiment of the invention. Module enclosure  1400  may house any number of modules  100 , including a plurality of layers of modules  100 . Module enclosure  1400  may also be one of a plurality of module enclosures which are vertically stacked atop one another. Module enclosure  1400  may further comprise a case for an electronic device, e.g., a handheld computer, mobile telephone, etc. External device  1401  may be a printer, external storage system, network connection, or any other type of external device connected to a computer, handheld computer or electronic device. 
         [0074]      FIG. 15  is a flow chart of a method  1500  for forming a module in an exemplary embodiment of the invention. The steps of method  1500  will be described in reference to the module of  FIGS. 1-3 . The steps of method  1500  are not all inclusive, and may include other steps not shown for the sake of brevity. 
         [0075]    Step  1502  comprises providing a first circuit board  101  having a component surface. Step  1504  comprises providing a second circuit board  102  having a component surface, the component surface of the second circuit board disposed facing the component surface of the first circuit board. Next, components on positioned on the component surface of the first circuit board and the component surface of the second circuit board to minimize un-utilized space between the first circuit board and the second circuit board. There is a first height between the first circuit board and the second circuit board. In step  1506 , a first component is positioned on the component surface of the first circuit board. The first component has a second height which is less than the first height. In step  1508 , a remaining height is determined based on the first height minus the second height. In step  1510 , a second component is positioned on the first surface of the second circuit board, with the second component having a third height which is less than or equal to the remaining height. This results in a module with minimal un-utilized space, while providing a module which may be constructed of a uniform height as other modules. 
         [0076]    Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents therein.