Voltage regulator attach for high current chip applications

A voltage regulator. The voltage regulator includes an interposer having, on a first side, a plurality of electrical connections suitable for coupling to a printed circuit board (PCB). The interposer also includes at least one power plane and at least one ground plane, wherein each of the power and ground planes is coupled to one or more of the electrical connections. The voltage regulator further includes a DC-DC converter that is electro-mechanically attachable to and detachable from the interposer. The interposer includes a socket, on a second side, that is suitable to receive two or more electro-mechanical connecting members of the DC-DC converter. When the DC-DC converter is attached to the interposer, at least one of the electromechanical connecting members is electrically coupled to a power plane of the interposer, while at least one other one of the electromechanical connecting members is electrically coupled to the ground plane.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to electronic systems, and more particularly, power distribution in electronic systems.

2. Description of the Related Art

The increasing ability to provide integrate more circuits on an integrated circuit (IC) die has resulted in much great processing power for devices such as microprocessors, digital signal processors, and other types of IC's. The greater processing power requires, in turn, higher pin counts and greater power requirements. Since there is a trend towards lower voltages, the increased processing power results in higher current requirements.

Many types of modern packaged integrated circuits, such as processors, ASIC's, multi-chip modules, and so forth, require large amounts of current into and out of their respective packages during operation. Current requirements of 200-300 amperes are not uncommon. These high current requirements can pose significant challenges in providing the required conductive paths for power and ground. More particularly, it is difficult to distribute these amounts of current laterally through power and ground planes in a traditional printed circuit board. A printed circuit board (PCB) capable of carrying such large amounts of current requires several thick, heavy layers of copper or other suitably conductive material. The use of these heavy conductive layers can cause difficulty in drilling holes through the PCB (e.g., for plated through holes). Complications in signal routing can also arise, and the thermal characteristics of such a PCB can also make soldering components more difficult.

SUMMARY OF THE INVENTION

A voltage regulator is disclosed. In one embodiment, the voltage regulator includes an interposer having, on a first side, a plurality of electrical connections suitable for coupling to a printed circuit board (PCB). The interposer also includes at least one power plane and at least one ground plane, wherein each of the power and ground planes is coupled to one or more of the electrical connections. The voltage regulator further includes a DC-DC converter that is electro-mechanically attachable to and detachable from the interposer. The interposer includes a socket, on a second side, that is suitable to receive two or more electromechanical connecting members of the DC-DC converter. When the DC-DC converter is attached to the interposer, at least one of the electro-mechanical connecting members is electrically coupled to a power plane of the interposer, while at least one other of the electromechanical connecting members is electrically coupled to the ground plane.

An electronic assembly is also disclosed. In one embodiment, the electronic assembly includes a PCB and an IC package mounted to a first footprint on a first side of the PCB. A voltage regulator is mounted to a second side of the PCB, and is configured to provide power to an IC in the IC package. The voltage regulator includes an interposer having a plurality of electrical connections mounted to a footprint on the second side of the PCB and opposite the IC package. The interposer also includes a power plane and a ground plane. The power plane is electrically coupled to at least one of the electrical connections, while the ground plane is coupled to at least one other of the plurality of electrical connections. The voltage regulator further includes a DC-DC converter that is electro-mechanically coupled to the interposer. The DC-DC converter is electro-mechanically attachable to and detachable from the interposer. The interposer includes a socket configured to receive two or more electromechanical connecting members from the DC-DC converter. One of the electromechanical connecting members is electrically coupled to the power plane, while another one of the electromechanical connecting members is coupled to the ground plane.

A method for assembling an electronic assembly according to the disclosure herein includes soldering an IC package to a first side of a PCB, and coupling a voltage regulator to a second side of the PCB. Coupling the voltage regulator includes soldering an interposer to the second side of the PCB in a location opposite of the IC package. Coupling the voltage regulator further includes coupling a DC-DC converter to the interposer, wherein the interposer includes a socket configured to receive two or more electromechanical connecting members of the DC-DC converter, and wherein the DC-DC converter is electro-mechanically attachable to and detachable from the interposer. The operations of soldering the IC package and soldering the interposer are each performed prior to said coupling the DC-DC converter.

Accordingly, the method and apparatus disclosed herein enables a high-current voltage regulator to be attached to a PCB in order to distribute power to an IC mounted on the opposite side of the PCB. The method and apparatus split the voltage regulator into two different units, the interposer and the DC-DC converter. The interposer has a small thermal mass, and is thus suitable for soldering to the PCB. The DC-DC has a significantly greater thermal mass (due to the high current requirements), and is thus not suitable for soldering to a PCB. Instead, the DC-DC converter is electro-mechanically attached to the interposer via a socket in a manner that does not include soldering subsequent to soldering the interposer to the PCB. The DC-DC converter may be coupled to the interposer by bolts, pin-and-socket connector, surface-to-surface mating pints (e.g., a compression mounted land grid array), a flexible PCB portion that could be built as part of the DC-DC converter PCB (a ‘rigid-flex’ solution), or a cable-to-board connection.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and description thereto are not intended to limit the invention to the particular form disclosed, but, on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling with the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a drawing of one embodiment of an electronic assembly having a two-piece voltage regulator. In the embodiment shown, electronic assembly10includes a motherboard PCB (printed circuit board)50with a processor chip package20mounted to a first side and a voltage regulator100mounted to a second side. Processor chip package20includes a processor die15mounted thereon. It should be noted that embodiments having multiple chips coupled to processor chip package20are possible and contemplated, and as such, processor chip package20may be a multi-chip module (MCM). In this particular embodiment, a heat sink25is coupled to processor die15in order to disburse heat during operation.

Processor chip package20is coupled to motherboard50via a plurality of solder balls35arranged to form a ball-grid array (BGA). Embodiments utilizing pads forming a land-grid array (LGA) are also possible and contemplated (e.g., elastomeric connections, solder bumps, etc.). If the thickness of motherboard50permits, embodiments utilizing pins forming a pin-grid array (PGA), which corresponding plated-through holes are also possible and contemplated. Some of the solder balls are electrically connected to voltage regulator100through motherboard50. Other solder balls (such as those on the periphery in this example) may be part of signal path upon which signals are conveyed to and/or from processor chip package20via motherboard50. In some cases, solder balls that provide no electrical connection may also be present.

Voltage regulator100includes two primary components: an interposer101and a DC-DC converter105. Because of their relative thermal masses, these two components are attached separately in electronic assembly10. Interposer101, in the embodiment shown, is coupled to motherboard50by a plurality of solder balls135, which form a second BGA that may be directly opposite of the BGA formed by the BGA on the first side where processor chip package is attached. As noted above, elastomeric connections or other types of electrical connection used in conjunction with an LGA, or pins in a PGA may also be used. Generally speaking, any type of electrical connection suitable for coupling interposer101to a PCB such as motherboard101may be used where solder balls135are shown inFIG. 1.

A number of solder balls135are electrically connected to corresponding solder balls35by vertical vias55. The vertical vias55in the embodiment shown provide a direct electrical path between the solder balls35and solder balls135, with no horizontal component. This may allow for cleaner and more direct power and ground distribution to processor chip package20(and thus, processor die15) than could otherwise be achieved by distributing power and ground horizontally through power and ground planes in motherboard50.

Interposer101has a relatively low thermal mass, such that it is suitable for soldering to the PCB that is motherboard50. In contrast, DC-DC converter105has a relatively large thermal mass that makes it unsuitable for soldering. Thus, while interposer101is coupled to motherboard50by soldering, DC-DC converter105in this embodiment is mechanically coupled to the interposer101without soldering or other means requiring heat (embodiments wherein the attachment requires some localized heating are also possible and contemplated). This coupling of DC-DC converter105to interposer101may take place subsequent to the soldering operations wherein interposer101is attached to motherboard50. Although not shown inFIG. 1, interposer101includes a socket that is configured to receive a plurality of electromechanical connecting members of DC-DC converter105. This arrangement will be discussed in further detail below.

The coupling of voltage regulator100(including both portions) to motherboard50may be secured by fasteners111. In this embodiment, fasteners111are threaded fasteners (e.g., bolts) that extend through the housing of DC-DC converter105, through interposer101, through motherboard50, and to heat sink25. This is but one of many possible arrangements for using fasteners to secure voltage regulator100to motherboard50, and other arrangements may be used per specific design requirements.

The arrangement of electronic assembly10shown inFIG. 1allows a voltage regulator configured to sourcing and sinking (through ground) a large amount of current to be assembled in direct contact with the motherboard upon which a processor (or other integrated circuit) is mounted. This may allow more efficient power delivery to one or more integrated circuits in the chip package that have high current requirements (e.g., 300 amperes in one example). Instead of attempting to solder a high-current voltage regulator directly to a PCB (which may be difficult, if not impossible), or distribute power from a remote voltage regulator, the configuration enables the high-current voltage regulator to be placed as close as possible to the consumer of its power, with minimal impact on the design of the PCB, while also minimizing the amount of inductive impedance introduced into the power distribution system. Power distribution and signal routing in motherboard50may be simplified by such an arrangement. Furthermore, the arrangement may allow for a greater volumetric density of high-current demanding devices on the PCB.

Turning now toFIG. 2, a drawing of one embodiment of an interposer structure comprising the first portion of the voltage regulator shown inFIG. 1is shown. Interposer101includes the plurality of solder balls as discussed above, on a first side, and a socket153mounted externally on a second side of a laminate structure102. Embodiments are also possible and contemplated wherein socket153is integral to laminate structure102. Socket153is configured for receiving connecting members of a corresponding DC-DC converter, such as that discussed above with respect toFIG. 1.

Laminate structure102includes at least one power plane150and one ground plane151in the embodiment shown. Embodiments having a plurality of power and ground planes are possible and contemplated. Power plane150is electrically coupled to various ones of solder balls135by electrical connections155-P. Similarly, ground plane151is electrically coupled to other ones of solder balls135by electrical connections155-G. Power plane150is also electrically coupled to corresponding receptacles in socket153by electrical connections156-P. Ground plane151is electrically coupled to corresponding receptacles in socket153by electrical connections156-G. Laminate structure102may also include additional layers, such as dielectric layers as well as surface layers. In general, laminate structure102may be any type of laminate structure having various layers including at least one ground plane and at least one power plane.

Interposer101includes a plurality of decoupling capacitors152mounted on laminate structure102. The decoupling capacitors in the embodiment shown are surface-mounted capacitors, although capacitors coupled using pins soldered into plated through holes may also be used in other embodiments. Decoupling capacitors152are each electrically coupled between power and ground (i.e. between the power and ground planes), and provide a low impedance path to shunt power plane noise to ground.

FIG. 3AandFIG. 3Bare drawings of one embodiment of the interposer101showing a top view and a bottom view, respectively. In the top view ofFIG. 3A, interposer101includes the laminate structure102, which has a plurality of solder balls135thereon that are arranged to form a BGA footprint134. In coupling interposer101to motherboard50, each of the solder balls may be temporarily melted to form a solder connection with corresponding BGA surface pads on motherboard50. As previously noted, other embodiments may utilize other types of electrical connections suitable for coupling laminate structure102of interposer101to a PCB such as motherboard50.

A plurality of decoupling capacitors152are also mounted on the top side of laminate structure102. In this particular example, decoupling capacitors152are surface mount capacitors, although embodiments utilizing non-surface mount capacitors are also possible and contemplated.

Holes112are also present in laminate structure102to allow for the passage of fasteners111. In some embodiments, holes112may be threaded. The number of holes112may vary from one embodiment to the next, depending on the number of fasteners to be used. Embodiments having no holes112(and thus not having fasteners passing through) are also possible and contemplated.

InFIG. 3B, interposer101includes socket153mounted to the bottom side of laminate structure102. Socket153in this particular arrangement includes two receptacles157-P for receiving corresponding connecting members of DC-DC converter105, through which power is provided. Receptacles157-P are electrically coupled to power plane150. Receptacles157-G are also configured to receive corresponding connecting members of the DC-DC converter, and provide an electrical connection to ground plane151.

As shown inFIG. 3B, interposer101may include additional decoupling capacitors152that are surface mounted on the bottom side of laminate structure102. As previously noted, embodiments utilizing non-surface mount capacitors are also possible and contemplated.

FIG. 4AandFIG. 4Bare drawings of one embodiment of a DC-DC converter of the voltage regulator100ofFIG. 1showing side and bottom views, respectively. As shown inFIG. 4A, DC-DC converter105includes a housing106. The various electrical components of the DC-DC converter105are contained within housing106.

DC-DC converter105also include electromechanical connecting members160-P and160-G. These electromechanical connecting members are configured for insertion into corresponding receptacles of socket153, and provide both an electrical and a mechanical connection between DC-DC converter105and interposer101. With respect to the electrical connections, connecting members160-P provide electrical connection through which power is conveyed to interposer101, and eventually, to an integrated circuit coupled to the other side of a PCB. Connecting members160-G provide a corresponding return path in the form of a ground connection.

In the embodiment shown, the mechanical connection formed using electro-mechanical connecting members160-P and160-G is one such that DC-DC converter105is detachable from interposer101without any de-soldering or other process that requires heat. In some cases, fasteners (such as fasteners111shown extending through housing106) may need to be removed, but otherwise no additional operations need to be performed. Thus, DC-DC converter105may be quickly attachable to and detachable from interposer101. However, it should be noted that embodiments are also possible and contemplated wherein the attachment of the DC-DC converter is more permanent than that explicitly described herein.

FIG. 4Billustrates a bottom view of DC-DC converter105. Electro-mechanical connecting members160-P and160-G are arranged in such a manner as to correspond to the receptacles of socket153of interposer101. DC-DC converter may be initially coupled to interposer101by inserting the electromechanical connecting members into their corresponding receptacles of socket153.

It should be noted that connecting members in other arrangements may also be used in various embodiments. For example, another embodiment could use pins arranged in a pin-grid array, with a socket on an interposer having corresponding receptacles for receiving the pins. In general, any arrangement that is suitable to the particular application may be used. Furthermore, in some embodiments, the group of connecting members may include one or more that enable a connection to be made only in the correct orientation. This may prevent coupling of power connections to a ground plane, and vice versa.

FIG. 4Cis another drawing of one embodiment of the DC-DC converter105in a schematic representation. In this embodiment, DC-DC converter105is a multiphase DC-DC converter. A multiphase DC-DC converter includes a plurality of square wave generators214(one for each phase), wherein the output of each of the square wave generators provides a portion of the DC output. In this particular example, VRM10is a six-phase DC-DC converter. A first phase105-1provides the DC output from 0 to 60 degrees, a second phase105-2provides the DC output from 60 to 120 degrees, and so forth. Such multiphase DC-DC converters are commonly used in high-current, low voltage applications, as the stress on individual components is distributed among the phases instead of being concentrated in a single phase. An external power source (not shown) may be coupled to DC-DC converter105in order to supply power.

Embodiments are also possible and contemplated wherein multiple DC-DC converters105may be used, each separately attached to the interposer. Such an embodiment may allow separation of the phases provided by each of the multiple DC-DC converters. For example, a first DC-DC converter could provide phases 1, 3, and 5 (of a total of 6 phases), while a second DC-DC converter could provide phases 2, 4, and 6.

Each square wave generator214of DC-DC converter105is coupled between a sum node and a reference node. More particularly, the sum node is that node where the DC output voltage is present during operation of DC-DC converter105, while the reference node is a node to which the DC output voltage is referenced to (e.g., the ground node). The sum node is electrically coupled to each of the one or more electro-mechanical connecting members160-P. The reference node is electrically coupled to each of the one or more electromechanical connecting members160-G.

A working inductor212is coupled between the positive output of each square wave generator214and the sum node. A first capacitance may be coupled between the sum node and the reference node. The first capacitance may be implemented using one or more capacitors211mounted to one or more circuit boards that provide the phases105-1to105-6.

It should be noted that the DC-DC converter105discussed in reference toFIG. 4Cis exemplary, and other types of DC-DC converters may also be used. For example, while the DC-DC converter105disclosed herein is a multi-phase DC-DC converter, other embodiments utilizing a single-phase DC-DC converter are also contemplated.

FIG. 5is a flow diagram of one embodiment of a method for assembling the electronic assembly ofFIG. 1. Method500begins with the soldering of an integrated circuit (IC) package to a PCB (505). A socket may be soldered to an interposer (510), wherein the interposer is a first component of a voltage regulator assembly. Operation510may be skipped if the socket is integral to a laminate structure of the interposer. The first component of a voltage regulator assembly may also be soldered to the PCB in a location opposite of the IC package (515). As used herein, the term “opposite” can be considered to be on the other side of the PCB in a position that is approximately the same lateral position of the IC package. It is also noted that the soldering operations for the IC package, the socket, and the interposer (to the PCB) may be performed concurrently.

Subsequent to soldering the interposer to the PCB, a second component of the voltage regulator, a DC-DC converter may be coupled to the interposer (via the socket, in embodiments so arranged) (520). Since the DC-DC converter has a thermal mass that makes it unsuitable for soldering, it is electro-mechanically coupled to the interposer without soldering. Following the coupling of the DC-DC converter to the interposer, it may be secured to the electronic assembly (525) using fasteners (e.g., such as fasteners111as discussed above).

It should be noted that while the examples presented above have been directed to a system having a processor coupled to a motherboard, the disclosure is not so limited. In general, the disclosure presented herein may apply to any electronic system having one or more integrated circuits that consume a large amount of current mounted on a PCB, and in turn, requires a power source having the capability to deliver the required current.

While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Any variations, modifications, additions, and improvements to the embodiments described are possible. These variations, modifications, additions, and improvements may fall within the scope of the inventions as detailed within the following claims.