Abstract:
A power interconnection system comprising a plurality of z-axis compliant connectors passing power and ground signals between a first circuit board to a second circuit board is disclosed. The interconnection system provides for an extremely low impedance through a broad range of frequencies and allows for large amounts of current to pass from one substrate to the next either statically or dynamically. The interconnection system may be located close to the die or may be further away depending upon the system requirements. The interconnection may also be used to take up mechanical tolerances between the two substrates while providing a low impedance interconnect.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    The Present application is a Continuation Application of U.S. patent application Ser. No. 11/749,070, entitled “System And Method For Processor Power Delivery And Thermal Management, filed 15 May 2007. 
         [0002]    The &#39;070 application is a Continuation Application of U.S. patent application Ser. No. 10/401,103, entitled “Method For Supplying A Z-Axis Ultra Low Power Impedance Interconnection Between A DC-To-DC Converter And A Processor,” filed 25 Mar. 2003, now abandoned. 
         [0003]    The &#39;103 application is a Continuation Application of U.S. patent application Ser. No. 10/036,957, entitled “Ultra-Low Impedance Power Interconnector System For Electronic Packages,” filed 20 Dec. 2001. 
         [0004]    The &#39;957 application is a Continuation-In-Part Application of U.S. patent application Ser. No. 09/432,878, entitled “Inter-Circuit Encapsulated Packaging For Power Delivery,” filed 2 Nov. 1999, now U.S. Pat. No. 6,356,448. 
         [0005]    The &#39;957 Application is also a Continuation-In-Part Application of U.S. patent application Ser. No. 09/785,892, entitled “Apparatus For Providing Power To A Microprocessor With Integrated Thermal And EMI Management,” filed 16 Feb. 2001, now U.S. Pat. No. 6,452,113. 
         [0006]    The &#39;957 Application is also a Continuation-In-Part Application of U.S. patent application Ser. No. 09/885,780, entitled “Inter-Circuit Encapsulated Packaging,” filed 19 Jun. 2001, now abandoned. The &#39;780 application is a Continuation Application of U.S. patent application Ser. No. 09/353,428, entitled “Inter-Circuit Encapsulated Packaging,” filed 15 Jul. 1999, now U.S. Pat. No. 6,304,450. 
         [0007]    The &#39;957 Application is also a Continuation-In-Part of U.S. patent application Ser. No. 09/727,016, entitled “EMI Containment Using Inter-Circuit Encapsulated Packaging Technology,” filed 28 Nov. 2000, now abandoned. 
         [0008]    The &#39;016 Application claims the benefit of the following U.S. Provisional Patent Applications: 
         [0009]    U.S. Provisional Patent Application No. 60/167,792, entitled “EMI Containment Using Inter-Circuit Encapsulated Packaging Technology,” filed 29 Nov. 1999; 
         [0010]    U.S. Provisional Patent Application No. 60/171,065, entitled “Inter-Circuit Encapsulated Packaging Technology,” filed 16 Dec. 1999; 
         [0011]    U.S. Provisional Patent Application No. 60/183,474, entitled “Direct Attach Power/Thermal With Incep Technology,” filed 18 Feb. 2000; 
         [0012]    U.S. Provisional Patent Application No. 60/187,777, entitled “Next Generation Packaging For EMI Containment, Power Delivery, And Thermal Dissipation Using Inter-Circuit Encapsulated Packaging Technology,” filed 8 Mar. 2000; 
         [0013]    U.S. Provisional Patent Application No. 60/196,059, entitled “EMI Frame With Power Feed-Throughs And Thermal Interface Material In An Aggregate Diamond Mixture,” filed 10 Apr. 2000; 
         [0014]    U.S. Provisional Patent Application No. 60/219,813, entitled “High-Current Microprocessor Power Delivery Systems,” filed 21 Jul. 2000; and 
         [0015]    U.S. Provisional Patent Application No. 60/232,971, entitled “Integrated Power Distribution And Semiconductor Package,” filed 14 Sep. 2000. 
         [0016]    The &#39;957 Application is also a Continuation-In-Part Application of U.S. patent application Ser. No. 09/798,541, entitled “Thermal/Mechanical Springbeam Mechanism For Heat Transfer From Heat Source To Heat Dissipating Device,” filed 2 Mar. 2001, now abandoned. 
         [0017]    The &#39;541 Application claims the benefit of U.S. Provisional Patent Application No. 60/186,769, entitled “Thermacep Spring Beam,” filed 3 Mar. 2000. 
         [0018]    The &#39;957 Application is also a Continuation-In-Part Application of U.S. patent application Ser. No. 09/910,524, entitled “High Performance Thermal/Mechanical Interface For Fixed Gap References For High Heat Flux And Power Semiconductor Applications,” filed 30 Jul. 2001, now abandoned. 
         [0019]    The &#39;524 Application claims the benefit of U.S. Provisional Patent Application No. 60/219,506, entitled “High Performance Thermal/Mechanical Interface,” filed 20 Jul. 2000. 
         [0020]    The &#39;957 Application is also a Continuation-In-Part Application of U.S. patent application Ser. No. 09/921,153, entitled “Vapor Chamber With Integrated Pin Array,” filed 2 Aug. 2001, now U.S. Pat. No. 6,490,160. 
         [0021]    The &#39;153 Application (&#39;160 Patent) claims the benefit of the following U.S. Provisional Patent Applications: 
         [0022]    U.S. Provisional Patent Application No. 60/222,386, entitled “High Density Cicrular “PIN” Connector For High Speed Signal Interconnect,” filed 2 Aug. 2000; and 
         [0023]    U.S. Provisional Patent Application No. 60/222,407, entitled “Vapor Heatsink Combination For High Efficiency Thermal Management,” filed 2 Aug. 2000. 
         [0024]    All the above-identified Patent Applications (and, where applicable, Patents) are hereby incorporated by reference herein in their entireties. Additionally, the following Patent Applications (and, where applicable, Patents) are also hereby incorporated herein by reference in their entireties: 
         [0025]    U.S. patent application Ser. No. 09/353,428, entitled “Inter-Circuit Encapsulated Packaging,” filed 15 Jul. 1999, now U.S. Pat. No. 6,304,450; 
         [0026]    U.S. patent application Ser. No. 09/432,878, entitled “Inter-Circuit Encapsulated Packaging For Power Delivery,” filed 2 Nov. 1999, now U.S. Pat. No. 6,356,448; 
         [0027]    U.S. patent application Ser. No. 09/785,892, entitled “Apparatus For Providing Power To A Microprocessor With Integrated Thermal And EMI Management,” filed 16 Feb. 2001, now U.S. Pat. No. 6,452,113; 
         [0028]    U.S. Provisional Patent Application No. 60/1,67,792, entitled “EMI Containment Using Inter-Circuit Encapsulated Packaging Technology,” filed 29 Nov. 1999; 
         [0029]    U.S. Provisional Patent Application No. 60/171,065, entitled “Inter-Circuit Encapsulated Packaging Technology,” filed 16 Dec. 1999; 
         [0030]    U.S. Provisional Patent Application No. 60/183,474, entitled “Direct Attach Power/Thermal With Incep Technology,” filed 18 Feb. 2000; 
         [0031]    U.S. Provisional Patent Application No. 60/186,769, entitled “Thermacap Spring Beam,” filed 3 Mar. 2000; 
         [0032]    U.S. Provisional Patent Application No. 60/187,777, entitled “Next Generation Packaging For EMI Containment, Power Delivery, And Thermal Dissipation Using Inter-Circuit Encapsulated Packaging Technology,” filed 8 Mar. 2000; 
         [0033]    U.S. Provisional Patent Application No. 60/196,059, entitled “EMI Frame With Power Feed-Throughs And Thermal Interface Material In An Aggregate Diamond Mixture,” filed 10 Apr. 2000; 
         [0034]    U.S. Provisional Patent Application No. 60/219,506, entitled “High Performance Thermal/Mechanical Interface,” filed 20 Jul. 2000; 
         [0035]    U.S. Provisional Patent Application No. 60/219,813, entitled “High-Current Microprocessor Power Delivery Systems,” filed 21 Jul. 2000; 
         [0036]    U.S. Provisional Patent Application No. 60/222,386, entitled “High Density Circular “PIN” Connector For High Speed Signal Interconnect,” filed 2 Aug. 2000; 
         [0037]    U.S. Provisional Patent Application No. 60/222,407, entitled “Vapor Heatsink Combination For High Efficiency Thermal Management,” filed 2 Aug. 2000; and 
         [0038]    U.S. Provisional Patent Application No. 60/232,971, entitled “Integrated Power Distribution And Semiconductor Package,” filed 14 Sep. 2000. 
     
    
     BACKGROUND OF THE PRESENT APPLICATION 
       [0039]    The Present Application relates generally to systems and methods for interconnecting electronic packages and in particular to a power interconnection system mating between substrates to enable a low impedance disconnectable power delivery path between the power source and the load of an electronic package. 
         [0040]    High-speed microprocessor packaging must be designed to provide increasingly small form-factors. Meeting end user performance requirements with minimal form-factors while increasing reliability and manufacturability presents significant challenges in the areas of power distribution, thermal management and electromagnetic interference (EMI) containment. 
         [0041]    To increase reliability and reduce thermal dissipation requirements, newer generation processors are designed to operate with reduced voltage and higher current. Unfortunately, this creates a number of design problems. 
         [0042]    First, the lowered operating voltage of the processor places greater demands on the power regulating circuitry and the conductive paths providing power to the processor. Typically, processors require supply voltage regulation to within 10% of nominal. In order to account for impedance variations in the path from the power supply to the processor itself, this places greater demands on the power regulating circuitry, which must then typically regulate power supply voltages to within 5% of nominal. 
         [0043]    Lower operating voltages have also lead engineers away from centralized power supply designs to distributed power supply architectures in which power is bused where required at high voltages and low current, where it is converted to the low-voltage, high-current power required by the processor from nearby power conditioning circuitry. 
         [0044]    While it is possible to place power conditioning circuitry on the processor package itself, this design is difficult to implement because of the unmanageable physical size of the components in the power conditioning circuitry (e.g. capacitors and inductors), and because the addition of such components can have a deleterious effect on processor reliability. Such designs also place additional demands on the assembly and testing of the processor packages as well. 
         [0045]    Further exacerbating the problem are the transient currents that result from varying demands on the processor itself. Processor computing demands vary widely over time, and higher clock speeds and power conservation techniques such as clock gating and sleep mode operation give rise to transient currents in the power supply. Such power fluctuations can require changes of thousands of amps within a few microseconds. The resulting current surge between the processor and the power regulation circuitry can create unacceptable spikes in the power supply voltage 
         [0046]    (e.g., dv=I*R+L*di/dt) 
         [0047]    The package on which the device (die) typically resides must be connected to other circuitry in order for it to communicate and get power into and out of the device. Because the current slew-rates may be very high, a low impedance interconnection system is often needed to reduce voltage excursions between the power source and load which, if left unchecked, may cause false switching due to the reduced voltage seen at the load from a large voltage drop across the interconnect. 
         [0048]    The technology of vertically stacking electronic substrates has been utilized for a number of years. As one example, U.S. Pat. No. 5,734,555, issued to McMahon (which is hereby incorporated by reference herein) discloses a method by which a circuit board containing power conversion elements is coplanar located over a circuit board containing an integrated circuit. The interconnect between the power conversion substrate and the integrated circuit substrate utilizes pins which do not provide a low impedance power path to the integrated circuit. Further, the McMahon device cannot be easily disassembled because the pins are permanently connected to the substrates. As another example, U.S. Pat. No. 5,619,339, (which is hereby incorporated by reference herein) issued to Mok discloses a printed circuit board (PCB) is vertically displaced over a multi-chip module (MCM) with electrical communication between the two substrates (the PCB and the MCM) established by a compliant interposer which contains “fuzz buttons” which communicate with pads located on each substrate. Although such an approach does provide for disassembly of the two substrates, e.g., the MCM and the PCB, the approach does not provide for large ‘Z’ axis compliance to accommodate manufacturing tolerances, and does not teach the use of a contact design that is capable of handling large amounts of DC current. Further, this design requires the use of a compliant interposer. In order to handle such large amounts of current, the number of contacts would have to be increased dramatically, which would increase the inductance between the source and the load device. Furthermore, such a large array of such contacts would require a large amount of force to be applied to maintain contact and will not result in a space-efficient design. 
         [0049]    From the foregoing, it can be seen that there is a need for a low impedance power interconnect between the power dissipating device and the power source. It can also be seen that this impedance must be low in inductance and resistance throughout a wide frequency band in order to ensure that the voltage drops across the interconnect are mitigated across it during dynamic switching of power. It can also be seen that the interconnect should provide large ‘z’ axis compliance and permit separation of the assembly without desoldering or similar measures. 
       SUMMARY OF THE PRESENT APPLICATION 
       [0050]    To address the requirements described above, the Present Application discloses an apparatus for providing power to a power dissipating device. The apparatus comprises a first circuit board and a second circuit board, and a plurality of compliant conductors disposed between first circuit board and the second circuit board. 
         [0051]    The first circuit board includes a power conditioner circuit, and a first side and a second side having a plurality of first circuit board contacts thereon. The first circuit board contacts include a first set of first circuit board contacts communicatively coupled to a first power conditioner circuit connector and a second set of first circuit board contacts communicatively coupled to a second power conditioning circuit connector. 
         [0052]    The second circuit board includes the power dissipating device mounted thereto and a plurality of second circuit board contacts disposed on a first side of the second circuit board facing the second side of the first circuit board. The second circuit board also includes a first set of second circuit board contacts communicatively coupled to a power dissipating device first connector and a second set of second circuit board contacts communicatively coupled to a second connector of the power dissipating device. 
         [0053]    The plurality of z-axis compliant conductors includes a first set of z-axis compliant conductors disposed between the first set of first circuit board contacts and the first set of second circuit board contacts and a second set of z-axis compliant conductors disposed between the second set of first circuit board contacts and the second set of second circuit board contacts. 
         [0054]    The first set of first circuit board contacts, the first set of z-axis compliant conductors, and the first set of second circuit board contacts define a plurality of first paths from the first circuit board to the second circuit board and wherein the second set of circuit board contacts, the second set of z-axis compliant conductors, and the second set of second circuit board contacts define a plurality of second paths from the first circuit board to the second circuit board. 
         [0055]    The Present Application provides a spring-like structure which disconnectably connects between two or more substrates (such as a printed circuit board or IC package) whereby the connection is disconnectable at least on one of the two sides. The interconnection system provides for an extremely low impedance through a broad range of frequencies and allows for large amounts of current to pass from one substrate to the next either statically or dynamically. The interconnection system may be located close to the die or may be further away depending upon the system requirements. The interconnection may also be used to take up mechanical tolerances between the two substrates while providing a low impedance interconnect. Due to the low impedance connection, the design permits the displacement of bypass capacitors on the circuit board having the power dissipating device, and placement of these capacitors on the circuit board having the power conditioning circuitry, resulting in ease of manufacturing and improved reliability of the power dissipating device assembly. 
         [0056]    The Present Application reduces or eliminates the need for supporting electronic components for the power dissipating device on the substrate, since the interconnect impedance between the power source and the electronic device is sufficiently low so that all or most of the supporting electronics can be located on the substrate containing the power source. Since the Present Application does not use any socket connectors to supply power to the device, such socket connectors are freed to provide additional signals. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0057]    The organization and manner of the structure and operation of the Present Application, together with further objects and advantages thereof, may best be understood by reference to the following Detailed Description, taken in connection with the accompanying Figures, wherein like reference numerals identify like elements, and in which: 
           [0058]      FIGS. 1A and 1B  are diagrams showing exploded views of the interconnection system as placed between two substrates, e.g., a voltage regulator module (VRM) mounted over a power dissipating device; 
           [0059]      FIGS. 1C-1E  are diagrams showing different electrical arrangements of the contacts; 
           [0060]      FIGS. 2A-2C  are diagrams showing exploded views of the interconnection system as placed between a processor substrate and a motherboard, the interconnection system occurring on the sides of the processor substrate; 
           [0061]      FIG. 2D  are diagrams depicting a view of section A-A of  FIG. 2C ; 
           [0062]      FIGS. 3A-3C  are diagrams showing a simple stackup cross-section of the interconnection system as placed between two substrates; 
           [0063]      FIGS. 4A and 4B  are diagrams showing an embodiment of a cantilever beam that may be used to implement the z-axis compliant contacts; 
           [0064]      FIGS. 5A-5D  are diagrams showing further embodiments of a cantilevered beam in which the different features of the beam construction are utilized to reduce the connection inductance of the compliant contacts; 
           [0065]      FIG. 6A  is an isometric view of an assembly showing multiple pairs of z-axis compliant conductors arranged in two rows within an insulating frame structure; 
           [0066]      FIG. 6B  is an isometric view of a pair of spring contacts in a scissor configuration; 
           [0067]      FIG. 6C  is a section view showing how spring contacts arranged in a scissor configuration can be used to interconnect the first and second circuit boards; 
           [0068]      FIG. 6D  is a plan view of the substrate in the embodiments illustrated in  FIGS. 6A-6C ; 
           [0069]      FIG. 6E  is a diagram illustrating an another embodiment of the z-axis compliant conductors and contact pads on the first circuit board; 
           [0070]      FIG. 6F  is a diagram illustrating another embodiment of the Present Application in which a continuous linear contact pads on the second circuit board are used without opposing scissor configuration z-compliant conductors; 
           [0071]      FIG. 6G  illustrates an embodiment of the Present Application wherein the z-axis compliant conductors are not permanently affixed to any contacts on either the first circuit board or the second circuit board, thus permitting easy disassembly; 
           [0072]      FIG. 6H  is a diagram presenting another embodiment of the Present Application in which an x-axis compliant conductor interfaces with edge contacts on the second circuit board; 
           [0073]      FIG. 6I  is a diagram presenting another embodiment of the z-axis compliant conductors having reduced impedance; 
           [0074]      FIG. 6J  is a diagram presenting a cross section of the embodiment illustrated in  FIG. 6I ; 
           [0075]      FIG. 7  is a plan view illustrating another embodiment of the Present Application utilizing multiple rows of z-axis compliant conductors; 
           [0076]      FIG. 8  is a diagram presenting a prior art stack up arrangement of a microprocessor substrate; 
           [0077]      FIG. 9  is a diagram presenting an improved power distribution system made possible by the Present Application; 
           [0078]      FIG. 10  is a diagram illustrating an embodiment of the Present Application wherein the power conditioning unit is partitioned to provide multiple power signals, each differing in phase, and each being distributed to different sides of the power dissipating device; 
           [0079]      FIG. 11A  is a diagram of a section view of direct power attachment to a substrate; 
           [0080]      FIG. 11B  is a top view of  FIG. 11A ; 
           [0081]      FIG. 11C  is a diagram of a blow-up of a section of view A-A in  FIG. 11A ; 
           [0082]      FIG. 12  is a diagram of a split-wedge washer; 
           [0083]      FIG. 13  is a diagram that shows the attachment of a section of  FIGS. 11C and 12  combined; 
           [0084]      FIG. 14  is a diagram of a high level assembly view; 
           [0085]      FIG. 15  is a diagram of a low inductance frame standoff; 
           [0086]      FIG. 16  is a diagram of an assembly view with low inductance standoff and interface board; 
           [0087]      FIG. 17  is a diagram of a cross section view with low inductance standoff and interface board; and 
           [0088]      FIG. 18  is a diagram of an exploded view of  FIG. 16 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0089]    While the Present Application may be susceptible to embodiment in different forms, there is shown in the Figures, and will be described herein in detail, specific embodiments, with the understanding that the disclosure is to be considered an exemplification of the principles of the Present Application, and is not intended to limit the Present Application to that as illustrated. 
         [0090]    In the illustrated embodiments, directional representations—i.e., up, down, left, right, front, rear and the like, used for explaining the structure and movement of the various elements of the Present Application, are relative. These representations are appropriate when the elements are in the position shown in the Figures. If the description of the position of the elements changes, however, it is assumed that these representations are to be changed accordingly. 
         [0091]    The Present Application describes a low impedance interconnection system operably placed between the two substrates whereby the interconnect is either placed to one side of the device or devices or the interconnect system circumferentially surrounds these elements. 
         [0092]    When a load change occurs in operation on one of these devices, a voltage will occur across the interconnect that can be described as shown below: 
         [0093]    DELTA. .times. .times. V=L .times. .differential. I Step .differential. t+RI Step 
         [0094]    wherein .DELTA. V is the voltage across the interconnection system, L is the series loop inductance of the interconnect, R is the interconnect resistance, and I.sub.step is the step-change in load current. 
         [0095]    As shown above, the output voltage change .DELTA. V increases linearly with the loop inductance L. Further, where rapidly changing currents are involved (as is the case with step changes in current, it is critically important that the interconnect system provides for a low inductance between the two substrates. During such a current step, reducing the loop inductance L reduces the .DELTA. V that results from current changes, thus allowing power to be efficiently delivered from the current source to the load. 
         [0096]      FIGS. 1A and 1B  are diagrams illustrating a structure  10  which provides a power path from a power conditioning circuit to a high performance electronic power dissipating device via a plurality of paths, thus yielding very low impedance. The structure  10  comprises a main board assembly  14 , an electronic assembly  13  having a high performance electronic power dissipating device, a power conversion assembly  12  and a heat dissipating assembly  11 . 
         [0097]    The electronic assembly  13  comprises a power dissipating device such as a microprocessor  134  assembled onto printed circuit board (PCB) or substrate  130  (hereinafter, the terms “printed circuit board”, “circuit board” and “substrate” are used interchangeably). The circuit board  130  includes one or more circuit traces which deliver power to the die of the microprocessor  134 . The circuit board  130  also includes circuit traces which route signals to a matrix of pins  131  communicatively coupled to microprocessor  134  I/O connectors. The microprocessor  134  is typically provided with a thermally conductive lid  133  in which the inside surface of the lid is in close thermal contact with the top of the die of the electronic device and the perimeter of the lid is sealed and attached to the surface of the substrate  130 . Although the package described herein is provided with a lid the Present Application does not preclude the use of unlidded package construction methods. 
         [0098]    The signal pins  131  engage with a socket  141  which is mounted to a main board  140  both of which are a part of main board assembly  14 . Signals from the main board assembly  14  are dispersed to other electronic devices to form a complete operating unit such as a computer. Other methods may be employed to route the signals from the substrate  130  to the main board  140  which may not utilize either pins or sockets. 
         [0099]    The circuit board  130  includes a plurality of contacts  132 . The contacts  132  can include power contacts and/or ground contacts. The power and ground contacts are communicatively coupled to power connectors or pads  135 - 137  of the power dissipating device  134 , respectively. 
         [0100]      FIGS. 1C-1E  disclose several embodiments of the Present Application showing different electrical arrangements of the contacts  132 . In one embodiment, the power contacts include positive polarity power contacts  132 A that are communicatively coupled to a positive polarity power connector or pad  135  on the power dissipating device  134  and negative polarity power contacts  132 B that are communicatively coupled to a negative polarity power connector or pad  136  on the power dissipating device  134 . The ground contacts  132 C are communicatively coupled to a ground connector or pad  137  of the power dissipating device  134 . 
         [0101]    In one embodiment of the Present Application (illustrated in  FIGS. 1D and 1E ), the power contacts  132 A and/or  132 B are interleaved with the ground contacts  132 C. In  FIG. 1D , each power contact  132 A and/or  132 B is adjacent a ground contact  132 C, and each ground contact  132 C is adjacent a power contact  132 A and/or  132 C. In another embodiment of the Present Application, the positive polarity power contacts  132 A are interleaved with negative polarity power contacts  132 B in the same way. The foregoing interleaved or alternating design substantially reduces undesirable electrical impedance of the power path. 
         [0102]    In the embodiments shown in  FIGS. 1A  and B, the contacts  132  are disposed around the perimeter of the electronic device and are a part of the substrate structure  130 . 
         [0103]    The substrate  130  generally comprises a number of conductive layers that are used to route both signals and power and ground. When routing power, layer pairs adjacent to each other form a very low electrical interconnect impedance between the power pads  132  and the die power and/or ground connectors (e.g. pads) of the electronic device  134 . These layer pairs are connected to the power pads  132  in a closely coupled arrangement to the planes. A further description of the conductive layers and their arrangement with respect to the z-axis compliant conductors  124  is presented in conjunction with  FIGS. 3A-3C  below. 
         [0104]    A power conversion assembly  12  is disposed directly above (along the z-axis) the electronic assembly  13 . This assembly  12  comprises an interconnect substrate commonly referred to as a printed circuit board (PCB)  120 , a power conversion circuit having components  121  such as switching transistors, transformers, inductors, capacitors, and control electronics; output capacitors  123  and a compliant conductor assembly  122  having a plurality of z-axis compliant conductors  124 . These power conversion components can be segmented according to the VRM circuit topology to optimize the impedance and power flow through the power conditioning circuitry. For example, in the case of a multiphase VRM, the topology of the VRM can be designed to provide one or more of the phases, each at the appropriate connector, thus minimizing the interconnect impedance and the required circuit board real estate. The plurality of z-axis compliant conductors  124  circumscribe and interface with the contacts  132  on the electronic assembly  13  to provide a conductive path between the power conversion assembly  12  and the electronic assembly  13  having very low inductance. Further, the conductor assembly  122  permits the power conversion assembly  12  and the electronic assembly  13  to be disassembled and separated without desoldering. 
         [0105]    A significant advantage to injecting power to the power dissipating device in a circumferential manner is that the current in any portion of the power planes of the substrate used to deliver power to the power dissipating device can be reduced significantly. As an example, if four compliant contact assemblies are located on each of the four sides adjacent to the power dissipating device, then, the maximum plane current is one-quarter the total current of the device assuming that the current in the device has a uniform current density at its interface to the substrate. Furthermore, the path length is significantly lower than other methods to deliver power to the substrate further reducing the voltage drop in the power delivery planes of the substrate (see, for example, U.S. Pat. No. 5,980,267, which is hereby incorporated by reference herein). Generally, the power delivery regulation budget is fixed and the power planes of the power dissipating device substrate are adjusted to maintain the desired budget either by increasing the number of planes or increasing the thickness of the planes as the current is increased or the budget is decreased. Circumscribed power delivery provides for significant reductions in both plane thickness and/or total number of planes. 
         [0106]    In the illustrated embodiment, the conductors  124  of the conductor assembly  122  are attached (e.g. soldered or bonded) to the substrate  120 . Further, the conductors  124  of the conductor assembly  122  are electrically coupled to the contacts  132  of substrate  130  through mechanical pressure applied to urge the substrate  120  towards the substrate  130 . 
         [0107]    Other variations of this structure are possible. As an example, the compliant conductor assembly  122  could be permanently attached to substrate  130  with contact pads on substrate  120  or, contact pads could be place on both substrates  120  and  130  and the compliant contact could provide pressure contacts to both substrates. Note that some of the interconnect compliant contacts may be used for control and sense interfaces between the power circuitry in assembly  12  and the electronic assembly  13 . Finally, note that substrate  120  has an aperture to allow for the lid  133  to pass through and thermally couple to the heatsink assembly  11 . 
         [0108]    In the past, it has been necessary to position bypass capacitors on substrate  130  to provide for the transient current demands of the electronic device on the substrate. This has reduced the reliability of the electronic assembly  12  which is relatively much more expensive than the other assemblies. Thus, it is desirable to increase the reliability of this assembly to the highest degree possible. Because the interconnect inductance of the compliant contacts  122  is extremely low it is possible to position the necessary bypass capacitors  123  on the power conversion substrate  120 . Further, note that these capacitors  123  are located directly above the conductor assembly  122  reducing the interconnect path length between the connector and the capacitors  123  (thus decreasing the impedance) to approximately the thickness of the substrate  120 . 
         [0109]    Heatsink assembly  11  is used to remove heat from both the electronic assembly  13  and the power conversion assembly  12 . Heatsink assembly  11  comprises a finned structure  100 , which is attached or is a part of base  111 . Heat slug or mesa  112  is attached to or is a part of base  111  and is used to both disperse heat from the lid  122  and to mechanically conform to the proper vertical displacement between the lid of the microprocessor  134  and the heat sink base  111 . Thermal interface materials may be used to thermally couple the lid  133  and the mesa  112  to the heatsink base  111  and the substrate  120 /power components  121 . The heatsink base  111  may also comprise cavities to accommodate any components on the top side of substrate  120  such as capacitors  123 . 
         [0110]      FIGS. 2A and 2B  illustrate a structure  15  which is similar to structure  10  except the power conversion circuit components are located directly on the main board assembly  18 . The structure comprises the main board assembly  18 , a high performance electronic assembly  17  and a heat dissipating assembly  16 . 
         [0111]    Electronic assembly  17  is similar to electronic assembly  13  with substrate  170 , lid  171  and pin matrix  172 . However, contacts  173 , which can be used as power pads, are located on the bottom side of substrate  170 . In the illustrated embodiment, the contacts are disposed around the perimeter of the electronic device  172 . 
         [0112]    Main board assembly  18  comprises a main board  180  with power conversion components  181  making up a power conditioner circuit and compliant conductor assembly  182  having a plurality of z-axis compliant conductors  185  circumscribing a socket  183 . As was the case with assembly  13 , bypass capacitors  184  are placed on main board  180  directly under and in electrical communication with the z-axis compliant conductors  185 . Heat sink assembly  16  is disposed above and is thermally coupled to the electronic assembly  17 . The heat sink assembly  16 , which removes heat from the electronic assembly  17 , comprises a finned structure  160  and base  161 . 
         [0113]    Thermal interface material can be used between the base  161  and the lid  171  to thermally couple the base  161  and the lid  171 . Thermal energy may also be removed from the power conversion components  181 . This can be accomplished by providing a thermal conduction path from the bottom of the main board to an adjacent chassis surface. This can also be accomplished by simply providing sufficient airflow around these components so as to directly cool them. It is also noted that as was the case with the embodiments illustrated in  FIGS. 1A and 1B , where ultimate electrical performance is not needed, compliant conductor assembly  182  and power components  181  may not need to circumscribe socket  183  and may be located on less than all four sides of socket  183 . 
         [0114]      FIG. 2C  is a diagram of a structure  15  that is similar to that shown in  FIG. 2A  except that compliant conductor assembly  182  are at least partially enclosed and contained within the socket  186  which mounts to the main board  180 . This facilitates the assembly of main board assembly  18 . 
         [0115]      FIG. 2D  is a diagram presenting a section view (A-A) along one side of socket  186  showing the socket  186  and the compliant conductor  182 . The socket  186  includes a section  186 A that secures individual z-compliant conductors  182  in place by overmolding a base extension  187  of the conductors  182 . Socket  186  includes a plurality female connectors  193  which accept pins that are communicatively coupled to the power dissipating device. Each female connector is also communicatively coupled to solder balls, which are reflow soldered to circuit pads  190  on main board  180 . The power dissipating device is thus electrically connected to the main board  180 , which, as shown in  FIG. 2C , includes power components  181  for power conditioning. 
         [0116]    The base  192  of compliant contact  182  is soldered to power contact pad  189 . This is preferably accomplished during the same reflow solder step used to couple the solder balls  191  to the circuit pads  190  on the main board  180 . Not shown are power connection paths to internal layers of main board  193  from surface contact  189 . 
         [0117]      FIGS. 3A-3C  illustrate an embodiment of a stackup  30  configured to deliver power from a power conversion PCB  301  to a processor substrate  300 . It will be recalled that a preferred embodiment of power delivery is to deliver power through alternating or interleaved contacts so as to reduce the interconnect impedance. 
         [0118]      FIG. 3A  is a diagram showing a plan view of the stackup  30  with the upper PCB  300  removed, showing the arrangement of adjacent z-axis compliant conductors  305  and  321  in the x-y plane. In one embodiment illustrated, the conductors are spaced approximately 50 mils apart, to decrease impedance. Further, the illustrated z-axis compliant (or, equivalently, compliant) conductors  305  and  321  are cantilevered beams having bases that are soldered or other wise affixed to contacts (or circuit pads)  303  and  320 , respectively. The other end of the compliant contact is pressed against the contact. (or circuit pad) of the upper circuit board  300 . 
         [0119]      FIG. 3B  is a diagram illustrating a cross section (A-A) of one polarity of power delivery, e.g., the positive polarity, while  FIG. 3C  illustrates a cross section (B-B) of the negative polarity, the two sections adjacent to one another forming the preferred interleave pattern. 
         [0120]    Referring to  FIG. 3B , power conversion PCB  301  contains power layers  312  and  313  wherein layer  312  represents the negative power layer, and layer  313  represents the positive power layer the two of which are in close proximity to one another to effect a low impedance power interconnect. A plated through hole (PTH)  314  or similar conductor connects the positive power layer  313  to a surface pad  303 . Z-axis compliant contact  305  is shown as a cantilever beam having a base that is soldered  304  to surface pad  303 . The other end of the compliant contact  305  is pressed against circuit pad  302  on the surface of the substrate  300 . A bypass capacitor  322  is located below the compliant contact  305  and on the side of the first circuit board  301  opposite contact  303 . The bypass capacitor  322  includes first and second connectors such as conductive end metalization features  306  and  317 , which are surface mounted and electrically coupled to pads  307  and  316 , respectively on PCB  301 . Circuit pad  307  is connected to layer  313  through an extension of PTH  314 . Circuit pad  316  is connected to layer  312  through an inter-connector such as the illustrated blind via  315 . Preferably, the bypass capacitor  322  is disposed directly below the compliant contact and associated structure (e.g. displaced from the structure in substantially only the z-axis); as this offers lower inductance than embodiments where the bypass capacitor  322  is displaced laterally (in the x and/or y axes as well). 
         [0121]    In the illustrated embodiment, layer  308  of substrate  300  is assigned a negative power polarity while layer  309  of substrate  300  is assigned a positive power polarity Like layers  312  and  313 , in the PCB  301 , layers  308  and  309  are in close proximity to one another to achieve a low impedance power interconnect. A power dissipating device located on substrate  300  can therefore receive power through layers  308  and  309  of the substrate  300 . Circuit pad  302  is electrically connected to layer  309  through one or more blind vias  310  thus forming a low impedance interconnect from layer  313  through PTH  314  to pad  303  then through compliant contact  305  to pad  310  and then through blind vias  310  to layer  309 . Note that layers  308  and  309  are located on or near the surface of substrate  300 . This frees the substrate  300  to use the other layers (represented as layers  311 ) for signal interconnect for the power dissipating device without topological complications that arise from designs in which the power and ground layers are disposed away from the bottom surface of the substrate. 
         [0122]    Referring again to  FIG. 3C , (which illustrates a cross section (B-B) of the negative polarity, thus forming the preferred interleave pattern with the cross section A-A in  FIG. 3B ) the negative polarity power interconnect is achieved by PTH  319  connecting layer  312  to surface contact (e.g. pad)  320  adjacent the positive polarity surface contact or pad  303  on the inner side of PCB  301 . Compliant contact  321  is soldered  304  or otherwise coupled to surface pad  320  while the other end of the compliant contact  321  is pressed against (surface) layer  308  of substrate  300 . Note that contact point for compliant contact  321  is shown as a point (or more specifically, a line segment along the y-axis) on layer  308  however, this contact area may be a unique area of layer  308  in which the surface is locally processed to provide special characteristics for this contact point such as gold plating over a nickel undercoat to improve the contact characteristics of the contact. Surface pad  310  may be processed in a similar manner. 
         [0123]    Finally, capacitor  322  may be the same bypass capacitor as shown in  FIG. 3B  or an additional bypass capacitor connected to planes  312  and  313  through an extension of PTH  319  to surface pad  316  and blind via  318  to surface pad  307 . The result of the above is to provide a very low compact and low inductance compliant connection between PCB  301  and substrate  300  with the two substrates being separable. Furthermore, because the interconnection method provides for a very low inductance connection it is possible to either eliminate or considerably reduce bypass capacitors on the substrate  300  containing the power dissipating device. 
         [0124]    Because such substrates are constructed such that the interconnects between layers  308  and  309  are blind vias  310  which pass only between layer to layer and not through the entire substrate, signal layers  311  and additional power/ground layers (if any) will not be permeated with large numbers of via interconnects (such as  310 ) as would be if power entered from the top side of substrate  300 . This has the benefit of freeing up signal routing space in these layers (such as  311 ) where the number of via interconnects are substantially reduced due to the entrance of power to the bottom side of substrate  300 . 
         [0125]    The embodiment shown in  FIGS. 3A-3C  is superior to other interconnect designs wherein the capacitor is not placed below the z-axis compliant conductors and on the opposing side of the circuit board with the power conditioning circuitry. For example, if the capacitive element were placed on the second side of the first circuit board (the same side as the z-axis compliant conductor) and adjacent to the spring members, the length of the conductive path and hence the impedance of the interconnect would include not only the vias or PTHs traversing in the z-axis, but also traces or planes in the x-y plane. By placing the capacitive element  322  on the side of the circuit board opposing the z-axis compliant conductor and directly over (or under) the z-axis compliant conductor, the length of the conductive path (and hence the impedance) is substantially reduced. The conductive path length (and hence, the impedance) is further reduced by selecting the span of the capacitive element  322  and related structures (e.g. pads  307  and  316 ) to be substantially the same as the span (the length in the longitudinal, or x-axis, direction) of the z-axis compliant conductor. With the length of the conductive path minimized capacitive elements on the second circuit board (or substrate) can be removed, which improves manufacturability and reliability as well. 
         [0126]      FIGS. 4A and 4B  illustrate an isometric view of one embodiment of a U-shaped z-axis compliant conductor  40 . The conductor  40  comprises a base  401  which can be soldered or otherwise bonded to a substrate while contact surface  400  is pressed against a pad on an opposite substrate.  FIG. 4A  shows the conductor  40  in the uncompressed state while  FIG. 4B  shows the conductor in the compressed state. In the illustrated embodiment, the contact surface  400  is formed by an S-shaped portion having a curved surface. The curved surface assures that the conductor  40  presents a surface parallel to the circuit board above the contact  40 . 
         [0127]      FIGS. 5A and 5B  illustrate an isometric view of another embodiment of the z-axis compliant conductor  50 . The conductor has a base or first shaft portion  502  having a first end  504  and a second end  506  distal from the first end  504 . The base  502  is generally soldered to a substrate contact. A U-shaped bend portion  508  is coupled to the first shaft portion  502 . The U-shaped bend portion  508  includes a first end  510  adjacent and coupled to the first shaft portion second end  506  and a second end  512 . A second shaft portion  514  is coupled to the U-shaped bend portion  508 . The second shaft portion includes a first end  516  adjacent and coupled to the U-shaped portion second end  512 . Second shaft portion is adjacent and coupled to a second U-shaped bend portion  520 . The second U-shaped bend portion comprises a first end  522  adjacent and coupled to the second end  518  of the second shaft portion  514  and a second end  524 . The second U-shaped bend portion is adjacent and coupled to a third shaft portion  526  disposed between the first shaft portion  502  and the second shaft portion  514 . The third shaft portion  526  includes a first end  528  adjacent and coupled to the second end of the second U-shaped bend portion  520  and a second end  530  distal from the first end  528 . Bend portion  532  is disposed at the second end  530 . 
         [0128]    The conductor contact surface  534  is pressed against a pad on an opposite substrate. The contact beam is then wrapped around and returns to the upper surface of base  502  forming a secondary contact  536  to the base  502 . This embodiment has improved (reduced) connection inductance compared to the embodiment illustrated in  FIGS. 4A and 4B  because the mutual coupling between path  538  and path  540  is relatively low which establishes semi-independent and parallel connection paths between contact surface  534  and the base  502 . 
         [0129]      FIGS. 5C and 5D  illustrate an isometric view of still another embodiment which is similar to that described in  FIGS. 5A and 5B .  FIG. 5C  illustrates this embodiment in the uncompressed state whereas  FIG. 5D  illustrates the embodiment in the compressed state. This embodiment further comprises a third u-shaped bend portion  557  coupled to the distal end  530  of the third shaft portion  526 , a fourth shaft portion  555  coupled to the third u-shaped bend portion  557 . The fourth shaft portion  555  includes a contact portion  556  distal from the third u-shaped bend portion  557 . When compressed, the contact portion  556  establishes an additional third path between the contact point  552  and the base  502  that passes through the fourth shaft portion  555 , the third u-shaped bend portion  557  and to the base  502 . This embodiment has still further reduced inductance over the embodiment in  FIGS. 5A and 5B  because there are now three semi-independent paths  551 ,  553  and  555  between the contact surface  552  and the base  550 . 
         [0130]    Individual conductors can be grouped so as to ease assembly of the conductor onto a PCB or substrate using soldering or other joining processes. One method is to extend a surface feature (such as  401 ) of the conductor to an area outside of the active portion of the conductor which is joined to a common bar during the stamping and forming fabrication process and then to overmold this extended feature with an insulating plastic resin up to the common bar but not including the bar. The bar is then cut off leaving a set of individual isolated contacts that are mechanically joined and can be handled during assembly as one unit. 
         [0131]      FIGS. 6A-6C  illustrate another embodiment of the Present Application in which z-axis compliant conductors similar to those shown in  FIGS. 5A and 5B  are arranged in a scissor configuration. 
         [0132]      FIGS. 6A and 6C  illustrate an isometric view of the assembly  60  showing pairs of z-axis compliant conductors  600 A,  600 B,  600 C,  600 D (hereinafter alternatively referred to as first set or row of z-axis compliant conductors  600 ) and  601 A,  601 B,  601 C,  601 D (hereinafter alternatively referred to as second set or row of z-axis compliant conductors  601 ). Each of the conductors in each row  600 ,  601  of the assembly  60  comprises an interface portion  668  and  669  disposed away from the base of the conductor that is urged against the contact on the second circuit board. Further, each row  600 ,  601  of assembly  60  is preferably assigned a separate power polarity, e.g., row  601  might be assigned negative power polarity and row  600  might be assigned a positive power polarity. The conductors of the first row  600  and the second row  601  are thereby interleaved to form conductor pairs resulting in a low inductance power path. 
         [0133]    Each of the conductors  600 ,  601  are held in place by an assembly such as overmold frame assembly  602  having an outer portion  602 A and an inner portion  602 B. In the illustrated embodiment, the assembly holds the z-axis compliant conductors in place about at least a portion of the periphery of the power dissipating device. Hole  667  is an alignment feature that may be desirably placed in the molded assembly  60  to align the assembly  60  to the PCB (e.g. PCB  120 ) during soldering. 
         [0134]      FIG. 6B  illustrates an isometric View of a pair of spring contacts  600 A,  601 A in the scissor configuration. The base  612  of each contact in the row of contacts is extended to overmold  602  as described in the preceding paragraph to simplify assembly. In this arrangement, overmold outer portion  602 A and overmold inner portion  602 B are desirably joined at their respective ends to form the overmold assembly. An advantage of this configuration is that there is no resulting net torsional force about the y or z axes. 
         [0135]      FIG. 6C  is a section view (section A-A illustrated in  FIG. 6A ) presenting an example where the scissor contacts described above are arranged in a stackup  61  to deliver power from a power conversion PCB  608  to a processor substrate  609 . The circuit pads  610  on PCB  608  require isolation between adjacent pads in the y-direction, because they will have alternating positive and negative power polarities. However, of significant importance is that contacting pads  605  and  606  on the processor substrate  609  can be arranged to be a continuous linear pad in the y-direction. This provides for relaxed tolerances in the alignment of the processor substrate  609  to the power conversion substrate  608  or PCB, and reduces the net torsional force on the two substrates. Note that bypass capacitor  607  may be installed beneath the contact arrangement  61  in a manner similar to that as described in  FIG. 3 . 
         [0136]    One technique of reducing the effective inductance of a multi-conductor connector is to assign adjacent conductors opposing current polarities. The magnetic fields of the opposing currents partially cancel each other, thus reducing the effective inductance of the overall connection. However, the effectiveness of this configuration is strongly dependent upon the configuration of the multiple conductors. In a simple configuration wherein the opposing faces of adjacent conductors are relatively narrow compared to their separation, the magnetic coupling between the conductors does not provide a substantial amount of magnetic field cancellation. However, if the separation distance between the substrates in a parallel plane connection scheme such as illustrated in  FIG. 6C  is small relative to the width of the conductors, then the magnetic field coupling between the planes becomes more significant, thus resulting in a lower inductance. This effect can be enhanced by arranging the conductors in each row  600 ,  601  of the connector in an opposing configuration as shown in  FIG. 6B . Then, the current from one pair of conductors (e.g.  600 A and  601 A) now flows across each end of the connector bases and in internal planes of the substrates  608  and  609 . This current magnetically couples with the current flowing in the non-base portions of the scissored conductors ( 600 A and  601 A), reducing the overall inductance of the connection between substrates  609  and  608 . For the effective inductance of this scissored arrangement to be less than the effective inductance of a non-scissored arrangement, the angle that the conductors make with the PCB/substrate plane must be less than a particular value .theta.=f(t, w, s) wherein t is the conductor thickness (here, assumed uniform), w is the width (also assumed uniform) and s is the separation between adjacent conductors. 
         [0137]      FIG. 6D  is a plan view of substrate  609  further illustrating the concept of the continuous pads  605  and  606  that surround power dissipating device  613 . In the illustrated embodiment, the pads  605  and  606  are formed into a continuous rings, one inside the other. 
         [0138]      FIG. 6E  illustrates a variation on the scissor contact design described in  FIGS. 6A-6C . A base portion  670  of an elongated z-axis compliant conductor  630  (of a scissor pair) is soldered to pad  632  on PCB  608 . The upper cantilevered beam portion  634  of compliant conductor  630  is pressed against contact pad  631  of substrate  609  as previously described. However, in this configuration, rather than the secondary contact wrapping around and returning to the top surface of the base  502 , the contact  630  wraps around portion  635  of compliant conductor  630  returning to a separate contact pad  633  on PCB  608 . Although both contact pads  632  and  633  are in electrical communication with the same power conditioning circuit, (e.g. through vias and conductive layers in the substrate  609 ) the advantage of this configuration is that the mating surfaces  636  of contact pad  633  and contact portion  635  are not involved in the soldering process and as a consequence there is no risk that solder used to couple the base  670  of the conductor  630  to the pad  632  may flow into the contact region of the secondary contact  633 . Additionally, because the secondary contact is further removed from the initial contact path there is less mutual coupling between the two contact paths which results in a lower overall connection inductance. 
         [0139]      FIG. 6F  illustrates another embodiment of the Present Application. In this embodiment, the stackup configuration  64  includes a first and second set of U-shaped z-axis compliant conductors ( 640  and  641 , respectively) that are displaced from one another along the x-axis. The x-axis displacement allows contact pads  644  and  645  to be constructed in a continuous linear fashion on substrate  609  similar to the embodiment shown in  FIGS. 6A ,  6 B and  6 C, without requiring that the first and second set of conductors  640 ,  641  be oriented 180 degrees from each other. Z-axis compliant conductor  640  is soldered or otherwise connected to contact pad  642  on PCB  608  which is connected to one polarity of a power circuit (e.g., as shown in  FIGS. 3A-3C ) while z-axis compliant conductor  641  forward of conductor  640  and displaced from conductor  640  in the x-axis is also soldered or otherwise electrically coupled to contact pad  643  of a second polarity of a power circuit (also as shown in  FIGS. 3A-3C ). 
         [0140]    The embodiments illustrated in  FIGS. 6A-6F  have numerous advantages. First, as described above, they permit substantial misalignment between the z-axis compliant conductors and the contacts on the opposing circuit boards in the direction of the adjacent conductors (e.g. in the y-axis direction in  FIGS. 6B-F ). Second, a nearly contiguous line of vias disposed through the pad region can be used for connecting the contacts to conductive planes within the circuit board, thus allowing a lower interconnect impedance in the substrate  609 . Third, as described further below with respect to  FIGS. 6I and 6J , the arrangement shown in  FIGS. 6A-6C  allows for improved electromagnetic coupling between each spring over arrangements where each of the z-axis compliant conductors are arranged in a single row. 
         [0141]      FIG. 6G  illustrates a stackup configuration  65  in which the z-axis compliant conductor is removably attached (e.g. not soldered, bonded, or otherwise permanently attached) to either substrate  609  or PCB  608 . In this configuration insulating (plastic, for example) overmold element  652  retains compliant conductor  651 . Additional conductors (disposed in the y direction) are also retained by plastic element  652 , forming a contact assembly that can be installed at the time of assembly of substrate  609  and PCB  608 . As before, section  653  of compliant conductor  651  is pressed against contact pad  605  on substrate  609  and section  654  is pressed against contact pad  655  of PCB  608  completing one half of a power circuit between PCB  608  and substrate  609 . The other half of the power circuit is completed by the adjacent conductor (displaced from conductor  651  in the y-axis). It is also recognized that an arrangement such as that which is shown in  FIGS. 6F and 6G  may also be applied in a similar manner as to the arrangement in  FIG. 6C , with opposing or staggered conductors, using a multiple-part or shaped overmold. 
         [0142]      FIG. 6H  illustrates still another arrangement wherein a compliant conductor may be used to provide power to a power dissipating device. In this arrangement, the plurality of first circuit board contacts  664  are disposed on the edge of the first circuit board. While only a single contact  664  is shown, a plurality of contacts, electrically isolated from one another and distributed in the y-axis, are disposed on the edge of the first circuit board  609 . Section  661  of each of the x-axis compliant conductors  660  is urged against an adjacent side contact  664  which is electrically connected to internal conductive plane  662  of substrate  664 . The internal conductive plane  662  is electrically coupled to the power dissipating device (via conductive planes, vias, and the like) to feed power to a power dissipating device disposed on the substrate  664 . The other end of conductor  660  is soldered or otherwise electrically connected to contact pad  665  of PCB  608 . Electrical connection between the contact pad  665  and to power layers of the PCB  608  can be made by a combination of plated through holes, vias and interconnecting conductive layers in the PCB  608 . 
         [0143]    Only one contact is shown in the section view of  FIG. 6H . However, it will be understood that a multiplicity of compliant contacts  660  can be arranged along the y-axis and the multiple compliant contacts  660  can interface with a corresponding multiple of edge contacts  664 , each electrically isolated from the others, to form multiple power connections between PCB  608  and substrate  664 , wherein alternating contacts  664  connect to alternate polarity power plane  663 . In a preferred embodiment, the contacts  660  and related structures circumscribe all sides of substrate  664  to form a very low impedance power interconnect path between PCB  608  and substrate  664 . The conductor  660  can also be designed with a bend to restrain the first circuit board  609  in place, if desired. 
         [0144]      FIG. 6I  illustrates one embodiment of the z-axis compliant conductor design. The illustrated z-axis compliant conductor pair which form a part of a larger array of conductors. Conductor  671  carries current in of one polarity while adjacent conductor  672  carries current in an opposite polarity. As before, a practical method of assembling such an array is to join the individual conductors with an overmolded plastic resin  673  that supports the conductors  671  and  672 . Of note is that each of the conductors  671  and  672  are provided with a slit  677  and  680  which creates two separate current paths in conductors  671  and  672  over a substantial portion of the length of the conductors. These separate current paths are identified as  675 ,  676  for conductor  671  and  678  and  679  for conductor  672 . The result of this arrangement is to reduce the overall connection inductance between a PCB and a substrate. 
         [0145]    The reduced connection inductance of  FIG. 6I  can be explained by referring to  FIG. 6J  which illustrates a section view through the conductor sections as indicated by A-A. The top portion of  FIG. 6J  illustrates the arrangement where there is no slit, forming conductors  681  and  682 , whereas the bottom portion illustrates the arrangement where the slits  677  and  680  form conductors  685 ,  686 ,  687  and  688 . The inductance of each conductor,  681  or  682 , in the configuration without the slit is: 
         [0146]    L 681, 682=2 ln .times. S .times. .times. 1 0.2235 (t+W .times. .times. 1) 
         [0147]    For the configuration with the slit  677 ,  680 , the inductance of the pair of conductors  685  and  686  or  687  and  688  can be determined by calculating the inductance of each conductor and then noting that the conductor pair are in parallel with one another. The general equation for the inductance of a multi-conductor configuration where the current in all conductors is equal (this is the case since, by symmetry, a continuous set of paired contacts as shown in  FIG. 6I  must have the same current in each path) is: 
         [0148]    1=2 ln .times. GMD GMR .times. 10-7 
         [0149]    where GMD is the geometric mean distance from the first group of conductors to the second group of conductors and GMR designates the geometric mean of the individual geometric mean radii of the group together with the wire-to-wire distances among the conductors of that group. Applying the forgoing relationships yields an expression for the inductance of the conductors  685 ,  688 ,  686 ,  687  is as follows: 
         [0150]    L685, 688=.times. 2 ln .times. (S .times. .times. 2+S .times. .times. 3).times. (S .times. .times. 2+2 S .times. .times. 3) 0.2235 (t+W .times. .times. 2) S .times. .times. 3.times. 10-7 L  686  ,  687 =.times. 21n .times. S .times. .times. 2 (S .times. .times. 2+S .times. .times. 3) 0.2235 (t+W .times. .times. 2) S .times. .times. 3.times. 10-7 
         [0151]    The pair inductance then is simply L.sub.685,688 in parallel with L.sub.686,687: 
         [0152]    L pair=L  685 ,  688  L  686 ,  687  L  685 ,  688 +L  686 ,  687   
         [0153]    When the above equations are applied to practical conductor geometries, substantial reductions in inductance can be achieved by providing a slot in the contact arrangement as shown in  FIG. 6I . 
         [0154]    It is understood that in all of the previously described conductor embodiments, it is important to design the contact arrangement such as to avoid rotational forces that may be imparted to the base of the contact wherein the base is soldered to one of the substrates. The reason for this is to eliminate normal forces that are not in compression (along the z-axis) which apply a torsional force to the base portion of the conductor, and which may result in solder creepage, and ultimately the failure of the solder joint between the base of the conductor and the substrate pad. This can be accomplished by designing the conductor so that the interface portion that contacts the second circuit board contact and the base portion that contacts the first circuit board contacts are disposed substantially only along the z-axis from one another (e.g. either above or below each other, but not displaced in the x-y plane). This can be achieved, for example as demonstrated in the foregoing description where the compliant conductor beam is folded over the base of the conductor. 
         [0155]    It is also desirable to design the conductor and contacts to cooperatively interact with each other to minimize contact resistance and insure good electrical connection. This can be accomplished, for example, with the S-shaped conductor portions (such as that which is illustrated in  FIGS. 4A and 4B , or other electrical contact-enhancing designs). 
         [0156]      FIG. 7  is a diagram illustrating a plan view (looking up into PCB  120 ) of another embodiment of the Present Application. As in previous embodiments, the z axis compliant conductors, as well as the contacts on the PCB and substrate that interface with the z-axis compliant conductors are disposed about the periphery of the power dissipating device. Further, the power and ground (or positive and negative power) conductive paths formed by the conductors and contacts were interleaved to reduce inductance. In the embodiment illustrated in  FIG. 7 , the set contacts on the first circuit board and the set of contacts on the second circuit board are separated into two subsets of contacts, and the z-axis compliant conductors are separated into two subsets of conductors as well. As was the case in the embodiments discussed previously, the first subsets of the contacts on the first and second circuit boards and the z-axis compliant conductors are disposed circumferentially around the power dissipating device. However, in this embodiment, the second set of contacts on the first and second circuit boards and the z-axis compliant conductors are disposed circumferentially around the first subset of contacts on the first and second circuit boards and the z-axis compliant conductors. The result is two “rings” of circuit paths from the first circuit board, through the first subset  122 A and the second subset  122 B of z-axis compliant conductors, to the second circuit board, wherein each ring includes a plurality of interleaved ground and power paths. The multiple “rings” of contacts  122 A and  122 B, one behind and disposed circumferentially about the other, are used to achieve even lower interconnect impedance between the PCB  120  and the substrate  130 . This is accomplished at least in part because each of the multiple rows of contacts  122 A and  122 B effectively couple in parallel. 
         [0157]    One of the advantages of the Present Application is that it permits simplification of the power/ground/signal interconnect between related printed circuit boards.  FIG. 8  is a diagram illustrating a typical stackup arrangement  5  having power/ground/signal interconnect contention problems. The substrate  847  of the stackup  5  includes conductive circuit layers  831 ,  834 ,  836 ,  839 , and  841 , and insulating layers ( 832 ,  835 ,  837 ,  840 , and  842 ) reside between the circuit layers  831 ,  834 ,  836 ,  839 , and  841 . A surface layer  826  typically is used for making contact through bumps to power dissipating device  827 . The number of insulating and conducting layers may be increased or decreased depending upon the signal and power demands of the power dissipating device. 
         [0158]    In most integrated circuit packages, power enters from pins  845  disposed on the opposite side of the power dissipating device  827  and is distributed through power vias  833 ,  838  in the substrate  847 . The power dissipating device  827  has connectors for power and ground ( 828 ,  829  shown) which connect to a surface layer  826  of substrate  847 . To ensure a low impedance DC power distribution path, multiple power vias  838  and ground vias  833  must pass through substrate  847  to connect with multiple power and ground pins (e.g.  844  and  843  respectively). Power and ground is distributed from contacts  845  including lower contacts  844  and  843  (which may be a large numbers of pin connections in a socket). 
         [0159]    Power contacts  844  are coupled to one or more power planes  841  and  836  by one or more power vias  838 ,  848 , and thence to power bumps  829 . Similarly, ground contacts  843  are coupled to one or more ground planes  839 ,  834  by one or more ground vias  849  and thence to ground bumps  828 . Signal contacts, e.g.,  830 , connect to conductive signal layers  831  and then typically distribute signals to the periphery of the device through signal vias, e.g.,  825 , and then down into a signal contact, e.g.,  846 , for distribution to other components communicatively coupled to the contact  846  (for example, a motherboard). 
         [0160]      FIG. 9  is a diagram of an improved power distribution system configuration  90  in which power taps  901  are provided through the top side of substrate  923  instead of through the bottom. Power taps  901  represent where the compliant conductors make contact to the pads on the top surface of the substrate to distribute power from a power source to the power dissipating device  906  on substrate  923 . Power dissipating device  906  on substrate  923  is connected as described in  FIG. 8 , except that that power layer  908  does not require substantial via distributions to lower layers such as layers  912  arid  914 . Power enters power taps  901  whereby the power layer  902  connects to the right power tap  901 B and the ground plane  910  connects to left power tap  901 A through via  903 . Ground plane  910  then connects to vias  924 , which in turn connect to ground bumps  905  on power dissipating device  906 . Additionally, power is routed from power plane  902  to power bumps  904  on power dissipating device  906 . This completes the power distribution path for the substrate stackup  923  from the source to the load, e.g., the power dissipating device  906 . Note that for illustrative purposes, the bumps  904 ,  905  on power dissipating device  906  are raised slightly off of the power plane  902 . 
         [0161]    Signal connections from power dissipating device  906  may now be routed to one or more bumps  907 , which connect to one or more vias  915  which route to one or more signal planes  917 . Other signals may now be distributed to pin connections (or alternatively other bump interconnects such as in an interposer to substrate connection) for connection to pins (such as  921  through vias similar to  922 ) which connect to a socket-like interconnect or PCB. Ground connections  920  through vias  919  and ground plane  914  may now be used for signal reference only rather than for power distribution as well. As in  FIG. 8 , insulation layers  909 ,  911 ,  913 ,  916 , and  918  make up the rest of the substrate  923  construction. 
         [0162]    This embodiment allows for a reduction in the number of layers because that power distribution is facilitated predominately through the top two layers  908 ,  910  of substrate  923 . Additionally, since the power and ground conductive layers are disposed on a power dissipating device side of substantially all of the conductive signal layers, the passage of power through the planes of the conductive signal layers is minimized. The distribution of signals the x-y planes is also improved. This is due to elimination or reduction of the number of vias for power and ground distribution in substrate  923  that would normally have been used to connect to pins  845  as described in  FIG. 8 . Through elimination of the power and ground vias in these lower layers (utilizing the top two layers), x-y plane real estate is henceforth available for additional signal routing in the lower layer(s), e.g.,  917 . 
         [0163]      FIG. 10  illustrates an embodiment of the Present Application wherein the power conditioning circuit or module  1000  includes a plurality of power conditioning submodules  1001 A- 1001 D, which together provide a power signal having a plurality of phases. In this embodiment, the topology of the power conditioning circuit  1000  delivers power to a plurality of compliant conductors  1003  advantageously arranged to apply different phases of the power signal to different sides of the power dissipation device  1006 . The power dissipation device  1006  is shown connected to power and ground planes  1005  and  1004  located on substrate  1002 . It is understood that the power dissipation device/substrate  1006 / 1002  resides at a level either above or below the voltage regulation module  1000 . Power and ground planes  1005  and  1004  then connect to VRM  1000  through compliant conductors  1003  which circumscribe power dissipating device  1006  wherein the ground of each phase connects to ground plane  1004  and the voltage out of each phase connects to the power plane  1005 . 
         [0164]    Topologically, each phase is represented by an input voltage (VIN) to two FET switches and an L-C output circuit. In the illustrated embodiment, each phase operates 90 degrees out of phase with the other adjacent to it. Because of the organization of the phases and due to the placement of the compliant conductors  1003  one may lay out the PCB of VRM  1000  in this topological fashion which improves routing and interconnect impedance due to the partitioning of each phase about the periphery of the power dissipating device. This allows the inductors, capacitors, and electronic drive circuitry (FETs, etc.) of each phase to be logically placed adjacent to a linear compliant conductor  1003  resulting in a superior layout and interconnect scheme which is synergistic with the topology of the VRM itself. 
         [0165]      FIGS. 11A-11B  illustrate the concept for mounting power directly to a board with the use of power pin attachments to the substrate of the package. Power pins [ 1102 ,  1103 ] (e.g. power and ground) are attached electrically and mechanically to substrate  1104 . Ground return  1103  is a coaxial integrated pad which is part of  1101  and also acts as thermal heat-spreader for die  1105  which is attached thermally to  1103  through thermal interface  1106 . 
         [0166]      FIG. 11C  is a blow-up section of view A-A in  FIG. 11A , which expands on the construction of the pin attachments. Power pin  1102  is mounted to substrate  1104  through solder or press pin  1110  which connects electrically to inter-plane  1107  in substrate. Solder or press pin  1110  is connected to plated thru-hole  1109  electrically and mechanically. A dielectric insulator  1112  isolates  1102  from  1103 . The center section of  1102  is threaded for attachment to the board. Additionally, taper  1111  is constructed to allow an electrical joint attachment to the board. This will be explained below. 
         [0167]      FIG. 12  illustrates a split-wedge washer and screw fastener construction designed to electrically and mechanically attach sub-assembly [A] to sub-assembly [B]. Split-wedge washer  1217  is designed with a lip section  1219  for forcing mechanically sub-assembly [A] to [B]. Wedge section  1216  is shown along with split section  1218 . 
         [0168]      FIG. 13  shows the attachment of a section ( FIG. 11C  and  FIG. 12  combined) integrated with board  1320 . The split-wedge washer engages electrically and mechanically to the side of plated thru-hole  1322  in the board by having taper section  1111  of  1102  spread  1217  outward to force against [Z]. Simultaneously, screw fastener  1215  forces sub-assembly [A] against [B] by pulling  1217  against  1320  and bringing assembly [B] against  1320 . Inter-power plane  1321  is attached electrically to plated thru-hole  1322  which connects to power distribution on  1320 . Additionally, ground pad  1103  is attached electrically to bottom pad of  1320  (not shown) to complete electrical circuit through vias which attach to ground plane on  1320  (also not shown). 
         [0169]      FIG. 14  shows the high level assembly of [B] attaching to [A]. VRM  1424  and heatsink  1423  are attached to  1320  electrically, thermally, and mechanically as described in previous literature. Thermal interface  1425  attaches to  1320  thermally as also described in previous literature. EMI frame  1426  is shown for completeness. 
         [0170]      FIG. 15  illustrates a low inductance ‘frame’ standoff sub-assembly [C]. A sheet metal frame is bent and joined at one corner to form an outer ground frame  1525  with solder tabs for mounting permanently to one unit (either VRM board or main board). A dielectric tape  1527  is attached to this structure as an insulator. Inner frame  1526  is made in similar fashion to  1525  but carries positive going current (e.g. connected to positive terminal of power supply) to supply power to IC. Mounting holes  1528  are supplied to mount to one side of assembly to make mechanical and electrical connection. Due to the dimensions of the construction, and the current paths for the electrical interconnect, a very low inductance can be achieved resulting in a low voltage drop between the power supply and load for low frequency switching applications. 
         [0171]      FIG. 16  is an assembled view showing the construction together in an assembly with the structure mounted to an interface board  1730 . 
         [0172]      FIG. 17  illustrates the mounting to an interface board. The purpose of this board is to remove any need to mount power directly to the main board, which can improve rout ability and cost on the main board. 
         [0173]      FIG. 18  shows an exploded view of  FIG. 16 . 
         [0174]    While the foregoing embodiment is described with respect to a four phase power signal applied to each of a four-sided power dissipating device, the principles described above can be applied to embodiments with fewer or more than four sides and power signal phases, or to embodiments with non-polygonal configurations (e.g. circular, for example). 
         [0175]    In summary, the forgoing discussion discloses a low impedance power interconnect between the power dissipating device and the power source. The impedance of the power interconnect is low in inductance and resistance throughout a wide frequency band in order to ensure that the voltage drops across the interconnect are mitigated across it during dynamic switching of power. It can also be seen that the interconnect should provide large ‘z’ axis compliance. The arrangement also reduces or eliminates the need for supporting electronic components on the device substrate because the interconnect impedance between the power conditioning circuit and the device can be reduced to the point where all or most of the support electronics can be located on the substrate having the power conditioning circuit itself. 
         [0176]    The Present Application also significantly reduces contentious routing of power to the power dissipating device because the power interconnect impedance is significantly lowered and can be routed to one or more sides of the power dissipating device. 
         [0177]    Further, since the upper layers of the power dissipating device substrate are used primarily for power distribution, the area on additional layers beneath the upper layers are free for use with for signal and other conductive interconnects. These other conductive interconnects can connect other interconnects or substrates beneath or above the stackup. 
         [0178]    The foregoing description of the preferred embodiment of the Present Application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the Present Application to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. For example, the substrate contacts and compliant conductors can be disposed proximate the outer periphery of the substrates rather than proximate the power dissipating device as described herein. Further, the compliant conductors may be rigid instead of compliant, while still permitting the detachable design described herein. Also, the compliant conductors can be integrated with other assemblies such as a socket, which might be used to interconnect signals to the microprocessor. Further, more than one linear set of contacts can be arranged to circumscribe the power dissipating device in a manner to increase the total number of contacts providing power and/or ground to the device, thus reducing the overall connection inductance and increasing total current carrying capability. The z-axis compliant contacts can also be configured so as to permit acceptance of stackup height variations. 
         [0179]    It is intended that the scope of the Present Application be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the Present Application. Since many embodiments of the Present Application can be made without departing from the spirit and scope of the Present Application, the Present Application resides in the claims hereinafter appended.