Description
MODULAR CIRCUIT BOARD CONSTRUCTION .AND METHOD OF PRODUCING THE SAME
Technical Field
This invention relates generally to the construction of printed circuit (PC) boards and, more particularly, to several embodiments of a modular circuit board construction and method for producing the same wherein a plurality of sub- circuit boards or printed circuit modules are mounted and connected to either a primary circuit board or to each other, in a stacking arrangement, to provide for greater circuit design flexibility, greater circuit concentration in a smaller space, and to isolate non-similar voltage traces and circuit functions.
Background Art
Printed circuit boards are typically made up of multiple layers and are expensive to manufacture. The more layers associated with a particular circuit board, the higher the cost of manufacturing the same. Also, the number of layers associated with a particular circuit board is often times dependent upon the complexity of the circuitry associated with such board and the width, thickness and weight of the various traces forming the connectivity network for the overall board. In this regard, often times additional layers must be added to a particular circuit board in order to both house and properly route the necessary traces to the appropriate components associated with such board. This is true because the minimum voltage trace width, thickness and weight for a particular PC board is dependent upon the maximum current density that can be accommodated by that particular PC board. This means that as the current requirements for a particular circuit board increase, the width, thickness and weight of the voltage traces must correspondingly increase to accommodate the greater current. As the width, thickness and weight of the trace network associated with a particular PC board increases, the number of layers associated with such PC board also increases in order to accommodate such traces .
If the number of board layers associated with any particular circuit board can be reduced, the overall cost of manufacturing and producing that particular circuit board can likewise be reduced. For example, if the number of board layers associated with a particular PC board can be reduced from eight (8) layers to six (6) layers, it has been determined that the cost of manufacturing and producing that particular PC board can likewise be reduced by approximately 15%. Similarly, if the number of board layers associated with a particular PC board can be reduced from eight (8) layers to four (4) layers, the associated manufacturing and production costs can be reduced by approximately 35%.
Since the total number of components as well as the width, thickness and weight of the associated traces are directly related to the size and the number of layers associated with any particular circuit board, the number of board layers associated with any particular circuit board can be reduced by either reducing the number of components and/or reducing the overall trace network associated with such PC board. This can be accomplished by grouping together or concentrating various components and circuitry onto sub-circuit boards or modules, or by merely routing various trace networks across one or more sub-circuit boards or modules to relieve component and trace routing congestion with respect to the primary PC board. In this regard, if those components of a particular PC board which require a higher current and therefore wider and thicker voltage traces could be segregated onto separate sub-circuit boards, and if such sub-circuit boards could be vertically stacked and interconnected with the primary circuit board, the number of components and traces associated with the primary board can be reduced. This will reduce the overall size and number of layers associated with the primary PC board, and it will likewise reduce the overall surface area of the primary PC board since various components and circuitry can now be located on the sub-circuit boards or modules. On the other hand, if the above-described segregation and modular assembly cannot be achieved, the size and number of board layers associated with the more complex PC boards manufactured today will continue to grow and increase thereby further increasing the overall costs of manufacturing and producing such boards .
The present invention is directed to overcoming one or more of the problems as set forth above .
Disclosure of the Invention
In one aspect of the present invention, a modular circuit board construction is achieved by forming a plurality of openings or apertures through a primary circuit board and thereafter forming a plurality of sub-circuit boards or modules for interconnection with the primary board. The circuit to be embodied in the modular circuit board construction is segmented into various sub-parts or sub-assemblies and the primary circuit board will contain those components and traces which are common or less likely to change based upon the particular function and application of that particular circuit. On the other hand, each separate sub-circuit board or module can contain circuitry and components associated with a particular sub-part of the circuit, which sub-parts may include specialized functions of the overall circuit, or such modules may contain components and circuitry which are more subject to change and/or improvement.
In addition, the sub-circuit boards or modules of the present invention may also be utilized to group together or concentrate certain high current or low current components so as to reduce the overall surface area of the primary circuit board and to both improve and reduce the trace network associated therewith. Still further, some of the modules of the present invention could likewise embody optional features and controls which can be added to the primary circuit board depending upon the particular features and options selected by the end user. For example, if the primary circuit board is designed, in whole or in part, to embody the necessary electronics for controlling and operating an engine control management system for a particular group of vehicle engines, each module may contain circuitry and components which control a particular feature of the engine management control system such as controlling a particular fuel injector driver associated with the engine, or such modules may control other system features such as engine RPM during shifting, engine speed\timing, torque, enhanced diagnostics and so forth. On the other hand, the primary circuit board will embody those components and circuitry which may be common or standard to all engine control management systems for a particular group of vehicle engines regardless of any optional features chosen or regardless of the number of fuel injectors utilized.
The present sub-circuit boards or modules are also designed to be stackably arranged on either the top and/or bottom surfaces of the primary circuit board adjacent each of the plurality of openings formed therethrough so as to extend respectively across each such opening. In this regard, each opening is specifically shaped and dimensioned so as to be slightly smaller than the overall dimensions of the module positioned thereover to provide for attachment of the module to that portion of the primary circuit board which lies adjacent to the periphery of each respective opening. The physical and electrical connection between the primary PC board and any one of the present modules can be achieved by any one of a plurality of conventional means such as through the use of a solder reflow process, or by a wire-to- board connection.
Since each of the present modules is positioned and located so as to extend over, either above or below, one of the openings formed in the primary circuit board, components can be surface mounted to both planar surfaces of each particular module. Even when a pair of modules are positioned and interconnected to the primary circuit board on both opposite surfaces thereof adjacent one of the openings formed therethrough, a sufficient space or gap will exist to accommodate the respective surface components associated with the facing surfaces of the respective modules. In this situation, low profile components can likewise be selected for placement on these opposing module surfaces so as to further accommodate such arrangement. The ability to mount components on both sides of a particular module facilitates reduction of the overall surface area of the primary circuit board and provides for greater circuit concentration in a smaller area.
In another aspect of the present invention, additional sub-circuit boards or modules can be interconnected and stackably arranged on top of two or more modules already previously positioned on the primary circuit board, the space existing between the previously positioned modules accommodating the surface components associated with the newly positioned module. This stacking arrangement can continue on both the top and bottom surfaces of the primary circuit board until all of the segregated controls and features of a particular circuit or system are captured within the completed assembly. In still another aspect of the present invention, the use of a primary circuit board can be eliminated and the present sub-circuit boards or modules can be interconnected to one another in an overlapping arrangement to implement the particular circuit desired.
Modular stacking of the present sub-circuit boards or modules provides for greater circuit concentration in a smaller space; it provides for isolation of non-similar voltage traces, that is, circuits having higher current densities as compared to lower current densities; and it also allows for the injection of an epoxy or other equivalent material between the modules to strengthen the overall structure of the board. Each of the sub- circuit boards or modules will have its own number of circuit board layers which permits greater flexibility in the design of the primary circuit board as well as the overall circuit board configuration, and such modular stacking also enhances and facilitates the upgrade, add-on, and/or removal of an individual sub-circuit board without completely redesigning the primary circuit board or the resulting assembled circuit configuration.
Brief Description of Drawings
For a better understanding of the present invention, reference may be made to the accompanying drawings in which:
Fig. 1 is a partially exploded perspective view of a printed circuit board constructed according to the teachings of the present invention showing the openings or apertures of the present invention formed through the primary circuit board and a plurality of sub-circuit boards or modules positioned above and below the primary circuit board for mounting thereto;
Fig. 2 is a fragmentary cross-sectional view taken along line 2-2 of Fig. 1 showing the modules illustrated in Fig. 1 mounted to the primary circuit board;
Fig. 3 is a fragmentary partially exploded perspective view similar to Fig. 1 showing another embodiment of the present invention wherein one of the present modules is stackably positioned on top of two other modules for mounting thereto; Fig. 4 is a fragmentary cross-sectional view taken along line 4-4 of Fig. 3 showing the various modules illustrated in Fig. 3 stackably mounted to the primary circuit board; Fig. 5 is a partial side elevational view illustrating a still further extension of the present invention wherein a plurality of the present modules are stackably arranged and mounted to the primary circuit board in an overlapping modular configuration in accordance with the teachings illustrated in Fig. 3 in order to implement a predetermined circuit; and
Fig. 6 is a side elevational view of still another embodiment of the present invention wherein a plurality of the present modules are physically and electrically connected together in an overlapping arrangement in order to implement a predetermined circuit .
Best Mode for Carrying Out the Invention
Referring now to the drawings, wherein a preferred embodiment of the present invention is shown, Fig. 1 identifies a primary printed circuit board 10 which includes a plurality of openings or apertures 16, 18, 20 and 22 which have been constructed in accordance with the teachings of the present invention. The primary PC board 10 is a substantially planar member and includes top and bottom surfaces 12 and 14 respectively. The openings 16, 18, 20 and 22 are formed during the normal production cycle of the primary board 10 and each such opening extends through the board 10 between the respective top and bottom surfaces 12 and 14 as best shown in Fig. 2. Although the plurality of openings 16, 18, 20 and 22 illustrated in Fig. 1 number only four such openings, and although such openings are arranged in a particular spaced apart configuration, it is recognized and anticipated that any plurality of such openings can be designed into any particular primary PC board and that such plurality of openings can be positioned and located anywhere on the board 10 depending upon the particular design function of the circuit embodied therein and/or the particular application of that particular PC board.
The present invention also includes the formation of one or more sub-circuit boards or modules such as the modules 24, 26 and 28 illustrated in Figs. 1 and 2. Each sub-circuit board or module 24, 26 and 28 can embody circuitry and components which relate to a particular function or application for which the primary PC board 10 was specifically designed for, or one or more of such modules can be utilized to group together or concentrate certain high current or low current components so as to both reduce the overall surface area of the primary board 10 and reduce the trace network associated therewith. In this regard, one or more of the present modules could likewise be designed to function and operate solely as a trace network for a particular portion of the primary PC board 10 so as to relieve any trace routing congestion associated with the primary board 10 thereby reducing the total number of layers associated with the board 10 yet providing the necessary routeability and connectivity to the various components, sub-parts and/or sub-assemblies associated with such board. Some of the present modules could likewise embody optional features and sub-assemblies which can be added to the primary circuit board 10 depending upon the particular features and options selected by the end user, or depending upon the particular application involved. The present modules such as the modules 24, 26 and 28 are specifically designed so as to be stackably arranged on and mounted to the top and/or bottom surfaces 12 and 14 of the primary circuit board 10 adjacent each of the openings 16, 18, 20 and 22 formed therethrough as best shown in Fig. 2. In this regard, each of the present modules such as the modules 24, 26 and 28 and each of the corresponding openings formed in the primary PC board 10 such as the openings 16 and 18 are similarly shaped and dimensioned, the present modules being shaped and dimensioned so as to be slightly larger than the corresponding openings over which they will be positioned. Attaching any one of the present modules 24, 26 or 28 to the primary circuit board 10 can be achieved by any one of a plurality of conventional surface mounting means. For example, as illustrated in Figs. 1 and 2, attachment of the modules 24, 26 and 28 to the primary board 10 is achieved through the use of a plurality of solder pads or lands 30 which are strategically positioned around the perimeter of each of the respective openings 16, 18, 20 and 22 as best shown in Fig. 1 for registration with a corresponding plurality of solder pads or lands 32 which are similarly positioned around the perimeter of each of the modules 24, 26 and 28 on one or both opposite surfaces thereof as likewise illustrated in Fig. 1. The solder pads or lands 30 are positioned and located on the primary board 10 such that each solder pad or land 30 is in alignment with and will engage a respective solder pad or land 32 associated with one side portion of a corresponding module when such module is positioned over the corresponding opening on the primary board 10. When so positioned on the primary PC board 10, the respective lands 32 rest upon the corresponding lands 30 as best illustrated in Fig. 1. The solder pads 30 and 32 can be any trace or land area comprised of a material adapted to receive a solder paste material which is applied to at least some of the solder pads 30 or 32. The respective modules such as the modules 24, 26 and 28 are thereafter physically and electrically connected to the primary PC board 10 using a conventional solder reflow process .
As illustrated in Fig. 2, the modules 24 and 26 are surface mounted over the respective openings 16 and 18 to the top surface 12 of the primary board 10 whereas the module 28 is surface mounted over the opening 16 to the bottom surface 14 of the primary board 10. Use of the above-described solder pad arrangement is generally preferred for mounting the present modules to the primary PC board because such method easily lends itself to use of a standard configuration of solder pads or lands 30 and 32 for compatibility with any one of a plurality of the present modules which are specifically designed for use with the primary board 10 regardless of the size and shape of the present modules and their corresponding openings formed through the primary PC board. Nevertheless, it is also recognized and anticipated that other conventional mounting means may be utilized to surface mount the present modules to the primary board 10 such as by using a conventional wire-to- board connection, or other similar means. Since each of the present modules is positioned and located so as to extend over one of the openings formed in the primary circuit board 10 from either above or below such opening, components can be surface mounted to both planar surfaces of the present modules . This is clearly illustrated in Fig. 2 wherein module 24 is mounted over the opening 16 adjacent the top surface 12 of the primary board 10 and module 28 is mounted over the opening 16 adjacent the bottom surface 14. As further illustrated in Fig. 2, the present module 24 includes a surface mounted component 34 mounted to the lower surface thereof whereas module 28 includes surface mounted components 36 and 38 mounted to the upper surface thereof. These components can be strategically positioned and located on the respective module surfaces so as to fit within the space formed between the respective modules and the opening 16. Low profile components can likewise be selected for placement on opposing module surfaces such as the module surfaces accommodating the surface components 34, 36 and 38 (Fig. 2) so as to further ensure that all such components will be accommodated within the space or gap formed by the depth or thickness of the respective openings such as the opening 16 illustrated in Fig. 2. In this regard, it is also anticipated and recognized that spacers or other conventional means may be utilized to raise one or both of the modules 24 and/or 28 slightly above the respective planar surfaces of the primary board 10 in order to accommodate the positioning of the module components within the space formed by a corresponding opening located on the primary board. The ability to mount surface components on both opposed planar surfaces of any particular module greatly facilitates the overall reduction of the surface area associated with a primary PC board and provides for the greater concentration of various components and circuits within a much smaller area as these components and circuits can be contained within the present modules and can be stackably arranged relative to the primary board as illustrated in Fig. 2. Still greater modularity and concentration of additional components and circuits is possible as will be hereinafter explained with respect to Figs. 3-6.
For illustrative purposes only, the present modules illustrated in Figs. 1-5 are shown attached to the primary PC board 10 with respect to openings 16 and 18 only. It is recognized and anticipated that modules similar to modules 24, 26 and/or 28 can likewise be surface mounted to the board 10 adjacent the openings 20 and 22. Likewise, as previously discussed, any plurality of openings such as the openings 16-22 as well as any arrangement of such openings on a particular primary circuit board can be achieved without departing from the teachings and practice of the present invention.
Figs . 3 and 4 illustrate another embodiment and a further extension of the present invention wherein another module 40 constructed in accordance with the teachings and practice of the present invention is stackably positioned for mounting to the respective upper side edge portions of the modules 24 and 26 as illustrated. Like the modules
24, 26 and 28, the module 40 may include components surface mounted to both opposite surfaces thereof and such module similarly includes a plurality of solder pads or lands 32' strategically positioned adjacent at least its bottom surface for similar engagement with at least some of the lands 32 associated with the upper surfaces of modules 24 and 26. As best illustrated in Fig. 4, the module 40 bridges or extends across the space 42 formed by and between the primary board 10 and the modules 24 and 26, the lands 32' associated with one side edge portion of the bottom surface of the module 40 mating with the lands 32 associated with one side edge portion of the top surface of the module 24 and the lands 32 ' associated with an opposed side edge portion of the bottom surface of the module 40 mating with the lands 32 associated with one side edge portion of the top surface of the module 26. The space 42, like the openings 16, 18, 20 and 22, provides sufficient space to accommodate the surface mounted components associated with the bottom surface of module 40. Attachment of the module 40 to the modules 24 and 26 is substantially identical to the attachment of the modules 24, 26 and 28 to the primary PC board 10 and can be achieve through the use of a solder reflow process .
Fig. 4 also illustrates the attachment of still another module 44 constructed according to the teachings and practice of the present invention to the lower surface 14 of the primary PC board 10 adjacent the opening 18. The arrangement and configuration of modules 26 and 44 with respect to opening 18 is substantially identical to the arrangement and configuration of modules 24 and 28 with respect to opening 16 as previously explained.
Still further, it is also recognized and anticipated that still another module (not shown) can likewise be positioned, located and attached to portions of the modules 28 and 44 so as to bridge or extend across the space formed by and between the primary board 10 and the respective modules 28 and 44 similar to the position and location of module 40 with respect to modules 24 and 26. As will be further explained with respect to Fig. 5, this modular stacking arrangement can be continued on both surfaces 12 and 14 of the primary circuit board 10 until a particular desired completed assembly is achieved.
Fig. 5 illustrates still another embodiment and a still further extension of the present invention wherein a plurality of the present modules are modularly, stackably arranged adjacent the upper surface 12 of primary PC board 10 in a manner substantially similar to the manner described above with respect to the embodiments and configurations disclosed and illustrated with respect to Figs. 1-4. The configuration illustrated in Fig. 5 also illustrates the use of spacer members 50 to complete the modular stacking arrangement in those situations where the support of an additional module is not available. For example, a spacer 50 is utilized to support one side edge portion of module 46 such that the module 46 can bridge or extend across the space 48 located immediately above module 24. In this particular situation, one side edge portion of the module 46 rests upon and is mounted to corresponding solder pads or lands associated with one side edge portion of the top surface of module 40 and the opposite side edge portion of module 46 is mounted to corresponding solder pads or lands associated with the upper portion of spacer 50. In this regard, depending upon the complexity and number of modules positioned on a particular primary circuit board, it is also recognized and anticipated that any one of the present modules can likewise be positioned and located such that any number of its corresponding side edge portions can mate with and rest upon portions of other previously positioned modules. For example, with respect to the rectangular or square shaped module 40 illustrated in Figs. 3 and 4, such module could also be positioned and located such that either three or all four of its side edge portions mate with corresponding side edge portions of other modules located therebelow. In other words, any of the present modules 40 and 46 could be supported by any combination of spacers 50 and/or one, two, three or all four side edge portions of other modules located therebelow depending upon the particular design of the primary PC board 10 and the arrangement of the present openings such as the openings 16, 18, 20 and 22 formed therethrough. Still further, although the completed printed circuit board assembly illustrated in Fig. 5 does not include any of the present modules mounted to the lower surface 14 of the primary board 10, as discussed above with respect to Figs. 1-4, a similar modular arrangement of modules can likewise be achieved adjacent surface portion 14 of primary board 10. Fig. 6 illustrates a still further embodiment 52 of the present invention wherein a plurality of the present sub-circuit boards or modules such as the modules 54, 56, 58, 60, 62 and 64 as well as other modules are physically and electrically connected together in an overlapping arrangement in order to achieve a particular circuit configuration. In this particular embodiment, it is important to recognize that a primary PC board such as the primary board 10 illustrated in Figs. 1-5 is not utilized. Instead, the entire circuit board construction 52 is produced and assembled solely through the interconnection of a plurality of the present modules such as the modules illustrated in Fig. 6. The modular printed circuit board construction 52 illustrated in Fig. 6 can be achieved and produced as follows. The predetermined circuit to be embodied in a particular modular circuit board construction is segmented into a plurality of sub-parts or sub-assemblies. These sub-parts may include specialized functions of the overall circuit as previously explained, or such sub-parts may merely group together or concentrate certain components, circuitry, and/or trace patterns depending upon the particular circuit involved.
Once the predetermined circuit is so segregated into sub-parts or sub-assemblies, a separate sub-circuit board or module is designed and manufactured to embody each particular sub-part or sub-assembly of the circuit. Once all of the sub-circuit boards or modules representing the particular circuit are manufactured and produced, the functionality of each such module can be tested separately before actually connecting such modules to other modules as illustrated in Fig. 6. This is particularly advantageous and cost effective because bad modules can be detected before assembly of the completed circuit. Once testing of each individual module is completed, the plurality of modules comprising the predetermined circuit are physically and electrically connected to one another in an overlapping arrangement as illustrated in Fig. 6 so as to implement the predetermined circuit .
Like the modules 24, 26, 28 and 40, all of the present modules illustrated in embodiment 52 - 1 -
(Fig. 6) including the modules 54, 56, 58, 60, 62 and 64 may likewise include components surface mounted to both opposite surfaces thereof . As previously explained with reference to the printed circuit board construction illustrated in Fig. 5, the overlapping arrangement of the present modules illustrated in Fig. 6 likewise produces a plurality of spaces such as the spaces 66, 68 and 70 formed by and between the interconnected modules to accommodate the surface mounted components associated with the top and bottom surfaces of the present modules.
In similar fashion, the physical and electrical interconnection of the modules illustrated in Fig. 6 can likewise be accomplished by any one of a plurality of conventional means such as by using a conventional solder reflow process, or by a wire-to-board/module connection. In this regard, as discussed above, use of a plurality of solder pads or lands similar to the solder pads 30, 32 and 32' can likewise be strategically positioned adjacent the respective top and bottom surfaces of each of the present modules illustrated in Fig. 6 for completing a solder connection between the respective modules. Still further, the modular printed circuit board construction 52 illustrated in Fig. 6 likewise lends itself to use of spacer members such as the spacer members 50 discussed above with respect to Fig. 5 to complete the modular stacking arrangement in those situations where the support of a particular module is not available. For example, a spacer member 50 is utilized to support one side edge portion of module 60 such that the module 60 can bridge or extend across the space 66 located immediately above module 54. As with the particular module configuration illustrated in Fig. 5, any of the present modules comprising embodiment 52 could be supported by any combination of spacers 50 and/or one, two, three or all four side edge portions of other modules located therebelow depending upon the particular design of each of the respective modules and the overlapping arrangement therebetween. Use of the modular construction illustrated in Fig. 6 affords still greater flexibility in the design of any particular circuit .
In some situations, the modular arrangement of the present modules may subject the surface mounted components associated therewith to vibration problems. If this occurs, such vibration problems can be easily overcome by injecting an epoxy, or other similar material, into the space, gap or cavities formed by and between the respective modules such as the openings 16, 18, 20 and 22 illustrated in Figs. 1-3 and the spaces 42, 48, 66, 68 and 70 illustrated in Figs. 4-6. This epoxy or other equivalent material will not only stabilize the surface mounted components extending within any such space or opening thereby eliminating any potential vibration problem, but such material will likewise lend support to and strengthen the overall structure of the completed modular assembly.
Industrial Applicability
The present invention provides an efficient and effective method for reducing the overall cost associated with manufacturing and producing a particular PC board while, at the same time, allowing greater flexibility in the design of the overall circuit board including upgrading and/or adding improvements thereto. The modular circuit board construction of the present invention enables one to optimize various parts or portions of a particular circuit board, or predetermined circuit, so as to achieve greater circuit concentration in a smaller area, to isolate non-similar voltage traces and/or optimize the overall trace network associated with a particular board, and to optimize the overall size and surface area of a particular circuit board. For example, if the primary circuit board 10 illustrated in Figs. 1-4 represents an engine control management system for a particular group of vehicle engines, the components 52 and 54 as well as the overall trace network 56 illustrated in Fig. 1 could represent components and circuitry which are common or standard to the engine control management systems for all vehicle engines in that particular group regardless of the number of fuel injectors utilized for any particular vehicle engine in that group, or regardless of any available options which may be selected in a particular engine control management system over and above the standard features represented by the components and the circuitry associated with the primary board 10. On the other hand, the sub-circuit boards or modules 24, 26, 28 and 44 (Figs. 1-4) may each embody circuitry and components necessary for delivering current to and controlling the operation of a particular fuel injector associated with any one of the vehicle engines in the designated group. In the case where the engine management control system will operate and control an engine in the designated group which utilizes four fuel injectors, the primary PC board 10 can be customized to include the respective modules 24, 26, 28 and 44. In the case where the engine management control system will control and operate an engine in the group which utilizes six fuel injectors, two additional modules of the present invention can be added to the above- described modular assembly in a manner similar to adding the module 40 to the modular board construction illustrated in Figs. 3 and 4. Still further, in the case where the engine management control system will control and operate an engine in the designated group which utilizes eight fuel injectors, two additional modules similar to the modules 24, 28, 40 and 44 can be added to the modular circuit configuration described above with respect to the control and operation of six fuel injectors, these two additional modules being likewise positioned and mounted in a manner similar to the modular construction described above with respect to either Figs. 4 or 5. In all of the above-described situations, the primary PC board 10 remains unchanged and the necessary number of modules are added to the primary circuit board based upon the total number of fuel injectors associated with a particular vehicle engine. This is particularly advantageous and cost effective in that it enables one to modularly construct the engine control management printed circuit board to include the required number of modules to control and operate the required number of fuel injectors without separately designing and constructing three different engine control management PC boards and without redesigning the primary PC board 10.
The present invention is also particularly applicable and cost effective in adding other specialized functions or sub-assemblies to the basic primary PC board 10. For example, if further options or additional features available in an engine control management system are selected by an end user such as smoke control, torque control, auto fuel ratio control adjust, cold start control, speed control, engine RPM control during shifting, enhanced diagnostics and so forth, individual customized modules similar to the modules 24, 26, 28, 40 and 44 discussed above can likewise be added to the primary circuit board 10 such as in a configuration illustrated in Fig. 5, each additional module embodying the necessary electronics for controlling the operation of one or more of the optional features selected by the end user. As illustrated in Fig. 5, all of the necessary modules can be added to the primary PC board 10 so as to incorporate all of the selected optional features and sub-assemblies into the resulting printed circuit board.
In those situations where the complexity of the circuitry associated with the primary circuit board, or with some specialized sub-assemblies housed in one or more of the present modules, is so complex that additional board layers must be added to the primary circuit board in order to house and properly route the necessary traces to the appropriate components, any one of the present modules could be utilized to house the necessary trace network for delivering current to certain portions of the primary circuit board 10, or to certain high current density modules. This would serve to reduce the trace routing network associated with the primary circuit board 10 thereby reducing the number of board layers associated therewith.
Reducing the overall trace network associated with a particular circuit board such as the primary circuit board 10 can also be accomplished by grouping together or concentrating various high current components onto a particular module. This will serve to reduce the current requirements for the primary circuit board 10 thereby reducing the trace network associated therewith. This configuration will also result in reducing the width, thickness and weight of the trace network remaining on the primary circuit board 10 thereby resulting in a smaller trace network which enables the individual traces to be positioned and located closer together. This smaller trace network will also reduce the total number of board layers associated with the primary circuit board 10 since more traces can now be located on a single board layer. This again will reduce the overall cost of manufacturing and producing such board.
Besides reducing the trace network associated with a particular primary circuit board and segregating certain high current or low current components for optimal use, the present modular construction lends itself to a variety of additional advantages. For example, each of the individual modules of the present invention such as the modules 24, 26 and 28 could be manufactured separately by a multitude of different suppliers thereby optimizing the cost for each such module due to increased manufacturing competition. In addition, the functionality of each such module can be tested individually before actually attaching such modules to the primary circuit board or to other modules.
This will likewise optimize cost and improve efficiency since bad modules can be detected before assembly of the completed circuit board. In the past, the operation and functionality of any particular circuit or component would only be detected after the entire circuit board was assembled. Also, instead of manufacturing an entire circuit board having, for example, eight layers associated therewith, only those modules having a need to be constructed with eight layers would have such number of layers whereas other modules would have considerably lesser layers such as four or six layers depending upon the components and circuitry associated respectively therewith. Since the modules of the present invention are considerably smaller in overall size as compared to the primary circuit board, and since the total number of board layers typically associated with a primary circuit board can be reduced based upon all of the reasons set forth and explained above, the overall cost associated with the completed assembly is likewise reduced.
Still further, and importantly, since many of the present modules may contain components and circuitry which are more subject to change and/or improvement as compared to the standardized components and circuitry associated with the primary circuit board 10 such as the components and trace network 52, 54 and 56 illustrated in Fig. 1, the present modular construction provides for a less expensive way to upgrade or improve the overall assembled modular circuit board since only certain modules need to be upgraded or improved. This also provides a safe migration path to new technologies and/or designs such as, for example, microchip modules or smart fuel injector drivers, since such new technologies and designs can be incorporated into a module which communicates with the rest of the primary circuit board or with other modules via datalink or other means. This again completely obviates the need to completely redesign the entire primary circuit board 10.
It is also anticipated and recognized that the present modular circuit board construction described herein can be utilized to surface mount any sub-circuit board or module to any primary PC board regardless of the size, shape and function of the primary PC board, and regardless of the size and shape of the plurality of openings formed therethrough. In other words, the present modules may be sized and shaped into a variety of different sizes and configurations to accommodate different applications and so as to be compatible with any space limitations associated with the primary circuit board, and the plurality of openings or apertures formed in the primary circuit board can likewise be sized and shaped for compatibility with the associated modules without impairing the teachings and practice of the present invention. The embodiment 52 of the present invention illustrated in Fig. 6 is likewise industrially advantageous in that a predetermined circuit can be segmented into a plurality of sub-parts or sub- assemblies and a plurality of the present modules can be designed and manufactured to respectively embody the various sub-parts of the predetermined circuit such that interconnection of the various modules in a particular overlapping arrangement will implement the predetermined circuit. This embodiment obviates the need of constructing a primary circuit board and affords still greater flexibility in the design of the particular circuit involved for all of the reasons discussed above. The embodiment 52 construction also further enhances and facilitates the add-on and/or upgrade capability of the present invention without completely redesigning the primary circuit or the various modules implementing such circuit.
Other aspects, objects and advantages of the present invention can be obtained from a study of the drawings, the disclosure and the appended claims.