PRINTED CIRCUIT BOARDS WITH INDUCTORS IN THE MOUNTING HOLES

Systems, apparatus, articles of manufacture, and methods are disclosed for inductors of voltage regulators that are built into and/or around mounting holes of a printed circuit board. An example apparatus includes a printed circuit board that includes a plurality of layers and a mounting hole extending through the plurality of layers, and an inductor at least partially in the mounting hole between two or more of the plurality of layers.

BACKGROUND

Electronic devices such as laptop computers include voltage regulators. Voltage regulators maintain the voltage of a power source within a range that is acceptable to the electrical components using that voltage.

In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. The figures are not necessarily to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings.

DETAILED DESCRIPTION

Electronic devices such as computers include a central processing unit (CPU) and other power consuming electrical components. Voltage regulators are used to regulate or maintain the voltage of a power source such as battery within a limit or range that is acceptable to the power consuming electrical components using that voltage. Voltage regulators are circuits that create and maintain a fixed output voltage, regardless of fluctuations in the input voltage. Voltage regulators include multiple components such as a field-effect transistor (FET), a capacitor, and an inductor. The size of a voltage regulator is proportional to the maximum current and thermal design current properties of the component the voltage regulator maintains power for. As the power and current demands of electronic devices increase, the physical size and/or number of phases of a voltage regulator also increases to meet the demand. The chassis size of the electronic device, number of fans, and/or fan sizes limit space available for voltage regulators, which limits the physical size of the voltage regulator.

In addition, CPUs, voltage regulators, and other components are mounted to a printed circuit board such as a main board. Printed circuit boards include apertures or holes to receive mechanical fasteners to couple components to the printed circuit board. Fasteners include, for example, screws, rivets, thermal mechanical loading mounting screws, etc. Some fasteners are positioned in proximity to components the fasteners mount for loading purposes. For example, thermal mechanical loading mounting screws are positioned near System on Chip (SOC) dies or packages to provide sufficient loading to die. However, the locations of the mounting holes where the fasteners are coupled may coincide with a location a voltage regulator should be positioned to deliver power efficiently to the SOC with a low load line.

Examples disclosed herein include inductors of voltage regulators that are built into mounting holes of a printed circuit board. The inductors include a core and windings or a coil (e.g., copper wire wound into a coil) around the core. In some examples, the windings or coil of the inductor are built into layers of a printed circuit board. In some examples, mechanical load screws or other fasteners can form the core. Placing the inductors of the voltage regulators in the mounting holes allows the voltage regulators to be close to the component the voltage regulator maintains power for (e.g., the SOC).

FIG.1is a cross-sectional view of a portion of an example electronic device100that includes an example printed circuit board102. The printed circuit board102includes a plurality of substrates or layers. In some examples, there are ten layers. In some examples, there are eleven layers. In some examples, there are twelve layers. In other examples, there are other numbers of layers. The printed circuit board102includes an example mounting hole104that extends through the plurality of layers of the printed circuit board102. The mounting hole104is used to mount components to the printed circuit board102.

The electronic device100also includes an example back plate106. The back plate106performs stiffening function to support the printed circuit board102. The back plate has an extension or standoff108. The standoff108extends through the mounting hole104. The standoff108receives an example fastener110. The fastener110secures a component112such as thermal module, CPU, etc. to the printed circuit board102. The standoff108includes internal threads114that mate with external threads116of the fastener110. In the illustrated example, the standoff108and the fastener110support the component112a distance above or away from the printed circuit board102. In some examples, the fastener110is a load screw. In other examples, other types of fasteners such as rivets, etc. may be used.

The electronic device100includes an example coil118that is formed in, around, and/or adjacent to the mounting hole104. In this example, the coil118is a coil structure that is formed of copper traces within and between the layers of the printed circuit board102. In the illustrated example, the coil118is formed in two or more of the layers of the printed circuit board102.

In some examples, the back plate106includes metal. In some examples, the back plate106includes silicon steel. In some examples, the fastener110includes metal. In some examples, the fastener110includes silicon steel. In some examples, the coil118includes metal. In some examples, the coil118includes copper. In some examples, the back plate106and/or the fastener110include other materials or combination of materials including ferrite, iron, other steel-based materials, etc.

The coil118surrounds at least a portion of the fastener110. In the illustrated example, the standoff108is interposed between the coil118and the fastener110. In the example ofFIG.1, the standoff108, the fastener110, and the coil118form an inductor of a voltage regulator. The fastener110and/or the standoff108act as a magnetic core for the inductor. The coil118includes an example trace or input A that is communicatively coupled to a power supply. For example, the input A may be coupled to a MOSFET of a power supply. The coil118includes an example trace or output B that is communicatively coupled to a power consuming component. For example, output B may be coupled to a power rail of an SOC. The standoff108, the fastener110, and the coil118(i.e., the inductor) work with other components of a voltage regulator to regulate the voltage and power distribution from the power supply to the power consuming component.

FIG.2is an isolated view of the coil118ofFIG.1.FIG.3is an exploded view of example layers of the printed circuit board102with the coil118ofFIG.1. The windings, coils, or turns of the coil118are stacked through the layers of the printed circuit board102. Respective windings of the coil118are connected to an adjacent winding at another layer through vias of the printed circuit board102. Each ring around the mounting hole104is considered a winding. In some examples, the coil118includes two windings. In some examples, the coil118includes a number of windings that is two less than the number of layers of the printed circuit board102. For example, if the printed circuit board102has twelve layers, the coil118may have ten windings. In some examples, the coil118is inset within the printed circuit board102such that the coil118is in the inner layers. For example, if the printed circuit board102has ten layers, the coil118can be formed in the second layer through the ninth layer (the penultimate layer). In some examples, the printed circuit board102includes twelve layers and is 1 millimeter thick, and the coil118is formed from a metal (e.g. copper) trace that is 30 microns thick.

FIG.4is an illustration of the windings of the coil118in the different layers of the printed circuit board102. The arrows inFIG.4illustrate example current flow through the coil118. The number of windings of the coil118affects the inductance of the voltage regulator and the saturation current.

FIG.5is a cross-sectional view of a portion of the example electronic device100that includes an alternative inductor and voltage regulator. In the example ofFIG.5, the electronic device includes an example coil500of an inductor that is inserted or embedded into the mounting hole104. In some examples, the coil500includes a metal insert. In some examples, the coil500includes a metal coil. In some examples, the coil500includes copper. In some examples, the coil500is held in the mounting hole104via a friction fit. In some examples, the coil500is held in the mounting hole104via an epoxy or other adhesive.

In the illustrated example, the mounting hole104of the printed circuit board102does not have internal threads to secure the fastener110. In addition, in this example, the coil500also does not have internal threads to secure the fastener110. Instead, the back plate106includes an example boss502that includes internal threads that engage the external threads116of the fastener110. In some examples, there is an example nut504to also secure the fastener110. In the example ofFIG.5, the fastener110and the coil118form an inductor of a voltage regulator. In some examples, the nut504, along with the fastener110may form part of the magnetic core of the inductor. In the example ofFIG.5, the back plate106can include other materials including, for example, nonmetal materials.

FIG.6Ais an isolated view of an example metal coil600that can be used as the coil500ofFIG.5.FIG.6Bis an isolated view of another example metal coil650that can be used as the coil500ofFIG.5. The metal coil600and the metal coil650includes ends that form the input A and output B of the coil500. As noted above, the input A is coupled to a power supply, and the output B supplies regulated voltage to a power consuming component. The metal coil600includes more windings than the metal coil650. The number of windings of the coil118affects the inductance of the voltage regulator and the saturation current.

FIG.7is a cross-sectional view of a portion of the electronic device100with the coil500ofFIG.5. In the example ofFIG.7, an example resin700is included in the mounting hole104around the coil500. The coil500is embedded in and/or surrounded by the resin700. The resin700is magnetic. In some examples, the resin700extends into the printed circuit board102between layers of the printed circuit board102. In some examples, the resin700forms a magnetic core. In the example ofFIG.7, the fastener110, the coil118, and the resin700form an inductor of a voltage regulator. The magnetic field generated by the fastener110and the coil500in the example ofFIG.5is enhanced by the resin700in the example ofFIG.7. The resin700creates a wider cross-sectional diameter of the magnetic core. Thus, the magnetic field has a larger area with the resin700than without the resin700. The larger magnetic field enhances the inductive properties of the voltage regulator.

In some examples, the resin700includes a magnetic material within a neutral (e.g., non-magnetic, non-conductive) matrix. In some examples, the matrix is a thermoplastic or thermosetting organic polymer that includes epoxy resins, polyamide resins, polyimide resins, polysulfones. Inorganic materials such as silica filler and/or silicates may also be included.

FIG.8is a flowchart representative of an example process800to form the printed circuit board102and coil500with the resin700ofFIG.7. At block802, a substate that will form the printed circuit board102is laminated to form, for example, a copper clad laminate. At block804, the mounting hole104is mechanically formed via, for example, a mechanical drill. At block806, the substrate is electroplated.

At block808, a tape809is added to the bottom of the substrate, the coil500is inserted into the mounting hole104, and the resin700is added. At block810, the tape809is removed after the resin700sets or cures. A mechanical drill removes resin700from the center of the coil500. At block812, there is further plating and etching of the printed circuit board102. At block814, an insulating ink such as solder resist and surface finishing are added to the printed circuit board102. At block816, the fastener110, back plate106, and component112are assembled.

Examples disclosed herein include inductors of voltage regulators that are built into and/or around mounting holes of a printed circuit board. In some examples, the inductors also are built into layers of a printed circuit board at, near, adjacent, and/or surrounding the mounting holes. These examples reduce the number of inductors of voltage regulators that are coupled to areas of a printed circuit board outside of the mounting holes. Thus, the regions of the printed circuit boards traditionally dedicated to inductors of voltage regulators are free to support other components and/or the size of the printed circuit board can be reduced to provide more remove for other components such as fans and/or to reduce the size of the electronic device. For example, a traditional inductor of a voltage regulator may require 1 mm2of space on a printed circuit board. With the examples disclosed herein, the inductor fits into a mounting hole that is already part of the printed circuit board. Thus, in this example, 1 mm2of space is saved without the traditional inductor.

The inductance saturated current values of examples disclosed herein may depend on the number of windings of the inductors, the materials of the fasteners, the materials of the resin, the diameter of the fastener and/or the resin, etc. For example, different silicon steels with different relative permeabilities lead to voltage regulators with difference inductance values. For example, silicon steel with relative permeabilities of50,70, and100achieve inductance values of 1.6 microhenrys (ρH), 2.2 ρH, and 3.3 μH respectively and saturation currents of 11.2 amperes (A), 8 A, and 5.6 A, respectively. These values are sufficient regulating VddQ rail (CPU voltage) and/or any other rail with similar specifications in other current and/or future platforms. Thus, these values also are sufficient to remove a traditional inductor of a voltage regulator from elsewhere on the printed circuit board.

As used herein, “approximately” and “about” modify their subjects/values to recognize the potential presence of variations that occur in real world applications. For example, “approximately” and “about” may modify dimensions that may not be exact due to manufacturing tolerances and/or other real-world imperfections as will be understood by persons of ordinary skill in the art. For example, “approximately” and “about” may indicate such dimensions may be within a tolerance range of +/−10% unless otherwise specified herein.

Example systems, apparatus, articles of manufacture, and methods are disclosed for inductors of voltage regulators that are built into and/or around mounting holes of a printed circuit board. Example 1 includes an apparatus that includes a printed circuit board that includes a plurality of layers and a mounting hole extending through the plurality of layers, and an inductor at least partially in the mounting hole between two or more of the plurality of layers.

Example 2 includes the apparatus of Example 1, including: a back plate including a standoff, the standoff inserted in the mounting hole; and a fastener coupled to the standoff.

Example 3 includes the apparatus of Example 2, wherein the fastener and standoff include a silicon steel.

Example 4 includes the apparatus of any of Examples 1-3, wherein the inductor is formed in the two or more of the plurality of layers.

Example 5 includes the apparatus of any of Examples 1-4, wherein the inductor includes a number of windings, the number of windings is two less than a number of the plurality of layers.

Example 6 includes the apparatus of any of Examples 1-5, wherein the inductor includes an input that is communicatively coupled to a power supply and an output that is communicatively coupled to a power consuming component.

Example 7 includes the apparatus of any of Examples 1-6, wherein the inductor is a metal coil.

Example 8 includes the apparatus of Example 7, wherein at least a portion of the inductor is inserted in the mounting hole.

Example 9 includes the apparatus of Example 8, wherein the inductor includes a magnetic resin between the plurality of layers and around the metal coil.

Example 10 includes the apparatus of any of Examples 1-9, wherein the inductor includes a magnetic resin between the plurality of layers.

Example 11 includes the apparatus of any of Examples 1-10, further including a fastener in the mounting hole, the fastener forming a core of the inductor, and the inductor forming a portion of voltage regulator.

Example 12 includes an inductor of a voltage regulator. The inductor of Example 12 includes: a coil in or around a mounting hole of a printed circuit board having a plurality of layers, the coil between two or more of the plurality of layers of the printed circuit board; and a fastener of metal in the mounting hole, the coil surrounding at least a portion of the fastener.

Example 13 includes the inductor of Example 12, including a standoff of a back plate, the fastener coupled to the standoff, the standoff interposed between the fastener and the coil.

Example 14 includes the inductor of Example 13, wherein the fastener and the standoff include silicon steel and the coil includes copper.

Example 15 includes the inductor of any of Examples 12-14, wherein the plurality of layers of the printed circuit board includes a first number of layers, and the coil includes a second number of windings, the second number less than the first number.

Example 16 includes the inductor of any of Examples 12-15, wherein the coil includes a first trace coupled to a power supply and a second trace coupled to a power rail.

Example 17 includes the inductor of any of Examples 12-16, wherein the coil is formed within the plurality of layers of the printed circuit board.

Example 18 includes the inductor of any of Examples 12-17, wherein the coil includes a metal insert in the mounting hole.

Example 19 includes the inductor of Example 18, wherein the coil is embedded in a magnetic resin.

Example 20 includes the inductor of Example 19, wherein the magnetic resin extends between two or more layers of the plurality of layers of the printed circuit board.