WO2017171757A1

WO2017171757A1 - Electromagnetic haptic actuator integral with a multilayer substrate

Info

Publication number: WO2017171757A1
Application number: PCT/US2016/025033
Authority: WO
Inventors: Georgios C. Dogiamis; Feras EID
Original assignee: Intel Corporation
Priority date: 2016-03-30
Filing date: 2016-03-30
Publication date: 2017-10-05

Abstract

An electromagnetic haptic actuator is described that is integral with a multilayer substrate. In one example, the haptic actuator has an inductive coil formed in a package substrate material, an elastic membrane over the coil, a magnet on the membrane, and a power plane to supply a drive signal to move the magnet towards and away from the coil.

Description

ELECTROMAGNETIC HAPTIC ACTUATOR INTEGRAL

WITH A MULTILAYER SUBSTRATE

FIELD

The present description relates to haptic actuators and in particular to an electromagnetic haptic actuator formed in a multilayer substrate material.

BACKGROUND

Haptic actuators are used in many handheld devices to provide feedback to a user during operation of the device. For example, in many portable phones, the device is made to vibrate when a call is received or in many touchscreen devices, such as tablets and smartphones, the device is made to vibrate when a touch is registered by the phone on the touchscreen. Haptic actuators are also used in game controllers to provide feedback to the user. Haptic actuators provide haptic feedback to enhance the user experience and in some cases to emulate the experience of operating a mechanical device.

The most common haptic feedback is provided by the vibration of the entire device using a bulky motor to acknowledge an interaction with the user. This provides a single global haptic feedback signal. With a single haptic actuator, the response of most devices is limited to this single type of actuation. The haptic feedback can be varied in duration, amplitude and rhythm but remains a global haptic feedback, since the entire device is being actuated. Designers seek to enhance the user experience of wearable and other consumer products, such as phones, tablets etc., by using more variations of haptic feedback. One such enhancement is to localize the vibration to a specific location, for example a location on a user's hand for smartphones or tablets or a user's wrist for smartwatches and fitness bands.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

Figure 1 is a cross-sectional side view diagram of a haptic actuator built within a substrate according to an embodiment.

Figure 2 is a top plan view diagram of a haptic actuator built within a substrate according to an embodiment.

Figure 3 is a cross-sectional side view diagram of an alternative haptic actuator built within a substrate according to an embodiment. Figure 4 is a cross-sectional side view diagram of a further alternative haptic actuator built within a substrate according to an embodiment.

Figure 5 is a cross-sectional side view diagram of a further alternative haptic actuator built within a substrate according to an embodiment.

Figure 6 is a process flow diagram of forming a haptic actuator within a substrate according to an embodiment.

Figure 7 is a block diagram of a computing device suitable for use with embodiments.

DETAILED DESCRIPTION

The approach described herein allows for localized tactors. The tactors may be built on a millimeter or micrometer scale. Such haptic actuators with a small form factor can provide independent localized actuation of different locations on a user's skin. The small localized tactors allow for many new usage examples. As an example, different hand or wrist locations may be used for different notifications according to a preset classification of notifications.

Different locations may indicate different priorities, different senders, different types of messages, etc. Spatially distributed actuators may also be used to transfer a sensation of texture to the user.

The skin actuation has certain characteristics that make it easier to be perceived by the human user. The frequency of actuation and the skin displacement are parameters in that respect. As an example, human perception thresholds at the fingertips lie at 0-200Hz and at skin displacements of 10-200μιη. Tire higher the vibration frequency, the smaller is the required skin displacement for the vibration to be perceived by a user. Frequencies above 200Hz are increasingly difficult to perceive. Another important characteristic of human haptic perception, is the fact that different body locations exhibit different perception thresholds. Tire displacement of the actuator determines the maximum achievable skin displacement by the actuator.

Another characteristic for the design of haptic actuators is a two-point discrimination threshold. This is the smallest perceivable spatial resolution on a person's skin and is around 2mm at the fingertips for static mechanical stimulations. In other words a typical human fingertip cannot distinguish between two different statically stimulated points if they are less than 2mm apart. The person will perceive the two stimulation points as being the same point. For other parts of the body two different points may require different separation distances to be distinguishable.

Haptic actuators may be produced using semiconductor packaging and assembly technology. A part of the tactors may be made using photolithographically defined vias in a chip packaging material. The actuators operate based on an electromagnetic principle similar to a solenoid. The solenoids have an in-package inductor, an optional soft-magnetic material to concentrate magnetic field lines, and a magnet to operate as an armature or an actuator embedded in a suspended membrane.

AC (Alternating Current) is sent through an in-package inductor creating a varying magnetic field, which drives the magnet to oscillate around a predefined axis. The magnet directly or indirectly physically moves an object (such as the user's skin) to create the haptic input. This input may be a response to a user command or an alert for received status, message, or other changes. The oscillation amplitudes and actuation forces may be selected based on fulfilling the characteristics of human perception described before.

In some embodiments, the described haptic actuator may have lower power consumption than other small tactors due to the decreased electrical resistance of the inductor traces. The device may be produced within a very small volume and a very low z-height compared to, for example, a typical LRA (linear resonant actuator) with a z-height of about 3mm. The described actuator may easily be fabricated in high volumes for lower cost.

Figure 1 is a cross-sectional side view diagram of an actuator built within a substrate, for example a semiconductor packaging substrate. The actuator is particularly suitable for use as a haptic actuator or tactor but embodiments are not so limited. A magnet 102 is fastened onto or embedded in an elastic layer 104. The magnet may be made of neodymium iron boron (NdFeB), samarium cobalt (SmCo), or any other suitable material. The elastic layer is attached onto a package substrate material 1 6. The material of the elastic membrane may be selected to provide the desired mechanical characteristics, for example natural frequency , maximum vertical displacement, actuation force, etc. for the particular coil and cavity.

The package substrate material may be formed of any suitable organic dielectric material such as an epoxy resin with embedded wiring layers. Other suitable materials include flame retardant 4 (FR4), resin-fiiled polymers, prepreg (e.g., pre impregnated, fiber weave impregnated with a resin bonding agent), polymers, silica-filled polymers, or any of a variety of other suitable package substrate materials.

The inductor 1 8 is formed in the package substrate and is coupled at one end to a first power plane 112 with external connections to a power supply through a solder ball or land grid array 114 and at the other end to a second power plane 1 16 which is coupled through external connections 1 18 to the power supply. An AC drive signal sent thru the external connections 114, 118 to the inductor 108 creates a varying or alternating magnetic field in the vertical z-direction. The magnet 102, which lies into the generated magnetic field, is therefore actuated in the z~ direction as well, since the magnetic field from the inductor applies a force to the magnet 102. The inductor surrounds a cavity 110 at its center that serves as an air core.

The size and shape of the cavity may be adapted to suit different actuator designs. As an example, when the substrate 106 is a dielectric material , then the cavity may be made much smaller. The cavity accommodates the mechanical oscillation of the magnet 1 2 on the vertical z-axis or, in other words, provides room for the magnet to move, so that the size of the cavity may be based on the vertical displacement of the magnet. The magnetic field from the inductor applies a force to the magnet 102. The inductor coil 108 and magnet 102 form a linear actuator or solenoid that is controllable through the applied AC drive signal.

The magnet 102 is attached to or embedded in the elastic layer 104 that is free to move in the vertical direction, and the system may be designed so that the mechanical resonant frequency of vibration of the elastic layer matches the applied electrical frequency of the AC drive signal. This allows the magnet and the elastic layer to start vibrating with large amplitudes at lower power, creating any desired displacement.

In this diagram, the in -package coil 108 is shown consisting of 5 layers (M=5) but other numbers of layers and turns may be selected to suit different form factors, different drive signals, magnetic field strength, and different desired actuation parameters. The cavity below the magnet accommodates the mechanical oscillation of the magnet on the z-axis.

Figure 2 is a top view diagram, of the tactor of Figure 1. The inductor 208 has two turns per layer (N=2) within the substrate 206 but it is not limited to N=2. More or fewer turns may be used, depending on the coil geometry and the desired magnetic field. The cavity 210 below the elastic member is shown as rectangular and provides sufficient clearance for the movement of the magnet 202 which is centered over the cavity. However, the shape of the cavity may be circular or any other shape and does not have to be rectangular. The elastic membrane is shown as rectangular, but may be circular or any other shape and it may cover the entire cavity or only a part of the cavity.

Figure 3 is a cross-sectional side view diagram of an alternative tactor in a substrate. As in Figure 1, a substrate 306 has an embedded coil 308 with five layers and two concentric turns each. The coil is connected to power planes 312, 316 that are coupled to a power supply through connections 314, 318. A cavity 310 within the substrate provides room for a magnet 302 fastened to an elastic membrane 304 to move toward and away from the coil. The elastic membrane is over the cavity and attached on the sides or periphery to the package substrate 306.

The cavity in this example is partially filled with a soft-magnetic material 320 in the core of the coil. The soft magnetic material acts as a magnetic field-line concentrator at the center of the coil. This allows a larger magnetic flux to pass through the attached magnet 302 on top of the coil which in turn will increase the force applied to the magnet. This provides for a larger vertical displacement or better power efficiency. The soft-magnetic core of the inductor is optional and can be, for example, screen printed or directly dispensed in the cavity.

The soft magnetic material acts in a manner similar to an iron core for a rigid magnet.

The soft material allows for thermal expansion and contraction while still providing a magnetic field concentrating effect. A variety of different materials may be used including nickel-based alloys, and cobalt-based materials, such as CoNi, CoPt, and cobalt manganit.es. The soft material may alternatively be a polymer with microparticles or nano-particles made from suitable magnetic materials.

Figure 4 shows an alternative embodiment in which the elastic material holding the magnet is attached to a beam or cantilever device 422 in the top most layer of the package substrate 408. This allows the magnet to be more robustly anchored to the package compared to the configuration in Figure 1. In addition, the support beams allow the mechanical resonant frequency of the membrane-magnet-beam system to be widely tuned by selecting the physical structure of the support beams.

As in the other diagrams, a coil 408 is formed in a substrate 406. The coil is connected to power planes 412, 416 which may be coupled to an external drive signal or power supply through pads or lands 414, 418. A cavity 410 is formed below the magnet 402 to allow the magnet to move vertically as the haptic actuator.

Figure 5 is a cross-sectional side view diagram similar to Figure 4 in which a soft magnetic material 520 has been added to the cavity 510. An inductor 508 formed from, a set of coils or windings is formed in a substrate 506 around a cavity 5 10. An elastic membrane 504 with an embedded magnet 502 is attached over a support beam or cantilever 522. The inductor coils are connected to power planes 512, 516 that are connected to an external drive signal or power supply through connectors 514, 518.

In this example, the magnet is shown as having an upper rod 522 extending from the main body. Such a rod may be used to engage another object or to serve directly as a contact surface against the skin of a user. The magnet may be formed in a variety of different shapes and be made of a variety of different materials. In some embodiments, there is a lower rod (not shown) to extend into or toward the cavity. This provides additional material closer to the coil. Since the magnet operates as the armature of the solenoid, if the armature extends closer to or into the coil, then the force applied to the magnet by the magnetic field of the coil will be stronger. The shape of the magnet, the beam and the coil may be adapted to suit the desired coil current, actuation force, contact area, and displacement for the intended haptic effect.

The force through the armature magnet along the z-axis is proportional to the magnetic field strength produced by the coil and the surface area of the magnet. Therefore the movement of the armature is related to the surface area of the magnet. The shape of the magnet may be adapted to provide different amounts of feree. While a rectangular magnet is shown, a round or cylindrical magnet may be used.

While the support beams are shown in this cross-sectional view as rectangular and extending over the cavity as a single rod from each side of the cavity, however, they are not limited to this configuration. The support beams may extend over the cavity from three or four points of the cavity perimeter. The support beams may also be in the form of a round flange or lip that surrounds the cavity on all sides. Other shapes may also be used. Alternatively, the support beams may be formed integral with the elastic membrane.

The elastic membrane shown in the diagrams may be fabricated using a variet - of different polymer materials including PDMS (Polydimethylsiloxane), TPU (Thermoplastic Polyurethane) or metals shaped to have a suitable mechanical response, such as a spring constant. The membrane may be in the form of a leaf spring or a more complex structure. The mechanical resonance of the magnet-membrane system is, in part, a function of the spring constant of the membrane structure whether polymer or metal. The mechanical resonance is also affected by the dimensions of any support beams, cantilevers, other physical support structures, and the physical structure of the membrane.

While the coils are shown as being connected through pads or lands to a power supply, the power supply may be in a power controller or current sourcing die that is attached to the substrate. Since the substrate is a package substrate any type and number of dies may be attached to the s ubstrate either on the same side of the substrate as the elastic membrane or on the opposite side.

The coils of the inductor may be formed in a variety of different ways. As an example, the coils may be formed on each layer of the substrate independently. Each layer of coils has interconnects between the inductor layers. The interconnects may be formed by cylindrical vias. The interconnects may alternatively be defined lithographically to follow the shapes of the inductor turns. This will increase the overall inductor stack thickness and thus reduce the total coil resistance, enhancing the power efficiency.

In Figures 1-5, the inductor coil has two turns per layer of coils. The coils are ail formed in the package substrate. The number of layers and the number of turns per layer may be adapted to suit space, heating, power, and other constraints. The number of layers affects the total resistance that the tactor exhibits and the total magnetic field that the tactor generates. The magnetic field H at the center of the coil is given by H= M*N*I/(4*RD) where M is the number of layers, N is the number of turns/layer, 1 is the current thru the inductor, and RD the coil radius. Measurements and this formula show that for a constant M*N product more layers and less turns per layer produce a stronger field at the same current. In the same way, they produce the same magnetic field at a lower current. By reducing the applied current, there is less Joule heating in the operation of the tactor. In many implementations, the tactors are only operated for very short duty cycles so that power consumption and heating may not be important.

The structures described above may be fabricated using any of a variety of different processes. Figure 6 is an example process flow? diagram for constructing a tactor as described herein. At 601 a first dielectric layer of the substrate is deposited. The dielectric may be an epoxy resin film, organic dielectric film or any of a variety of other suitable dielectric laminate materials as mentioned above.

At 602 a first metal layer is formed to create a first coil of the inductor. The metal layer may be formed in different ways including plating, printing, or screen printing.

At 603 a second dielectric layer is deposited and patterned over the patterned metal layer. The patterning of the dielectric allows for vertical metal interconnects to be formed. These interconnects allow the first coil layer to be connected to the next coil layer. In the examples of Figures 1 and 3-5, the structure includes power planes and a ball, pad, or other type of connection array . These structures may be made in the same way as at 601, 602, and 603 before the first coil of the inductor is patterned.

At 604 a second metal layer is patterned to create the second layer of coils for the inductor. This second metal layer is formed in the same or similar way as the first one at 602.

At 605 the patterning of metal and dielectric is repeated as many times as necessary to build up the rest of the metal layers for additional coils with interconnects and dielectric layers in between. The entire structure is then covered in a top dielectric layer.

At 606 a central cavity is optionally formed within the coils of the inductor. Some of the dielectric material is removed from the substrate to empty the core of the inductor. This may be done, for example, by laser or plasma etching. This operation is optional. Instead of creating a cavity in the substrate of the lower package, the magnet and membrane may be assembled above the top of the inductor coils leaving some spacing between the bottom of the magnet or elastic layer and the top of the package substrate underneath. If there is sufficient spacing from the top of the package substrate material, then the magnet is still able to oscillate without interference from the substrate that includes the coil.

At 607 a soft magnetic material is optionally added to partially fill the cavity. The material may be added into the cavity in different ways. In one example, a photoresist is applied to cover the rest of the substrate, leaving the cavity open. The material is then deposited over the cavity with enough thickness for the intended amount of filling. Alternatively the soft magnetic material may be dispensed in the cavity.

At 608, the rest of the cavity may be filled with a sacrificial material. If there is no soft magnetic material, then this will be the only material in the cavity. Tire sacrificial material may be used for providing a mechanically stable substrate for the rest of the processing steps.

At 609 a beam or cantilever is optionally formed over the cavity to cany the elastic membrane. This component may also be formed by patterning and depositing. The particular shape and thickness of the support beam will be determined based on the desired structural characteristics and the mechanical resonance frequency.

At 610 the elastic membrane is then formed over the cavity, either directly or over the beam or cantilever. The elastic membrane may take any desired form and may be made of an elastomeric material, such as a polymer, a metal or another suitable material.

At 611, the magnet is attached to the elastic membrane. Alternatively, the magnet can be attached to any patterned beams, cantilevers, or other support structures (609). Alternatively, the elastic membrane may be formed around the magnet (embedded magnet).

At 612 the sacrificial material in the cavity is removed to release the elastic membrane and the support beams, if any. The sacrificial material may be used as structural support and to provide a surface upon which the elastic membrane or the support beams are formed during processing. After these structures are formed, then the sacrificial material may be removed so that the elastic material and support beams, if any, are free to move up and down or towards and away from the coil. A thermally decomposable sacrificial material may be removed, for example, by heating. This opens up the cavity and allows the membrane to move in the z- direction to provide a haptic actuation.

As mentioned above, photolithography techniques may be used to form more precise shapes and thicker lines. Thick routing lines may be used to fonn the inductor and then shaped vias may be used to couple a lower inductor line to an upper inductor line. As such, the cross- sectional area of the inductor lines can be greatly increased. The increased cross-sectional area of the inductor line significantly improves the DC resistance (RDC) of the resulting coil. Figure 7 illustrates a computing device 100 in accordance with one implementation of the invention. The computing device 100 houses a hoard 2. The board 2 may include a number of components, including but not limited to a processor 4 and at least one communication chip 6. The processor 4 is physically and electrically coupled to the board 2. In some implementations the at least one communication chip 6 is also physically and electrically coupled to the board 2. In further implementations, the communication chip 6 is pari of the processor 4.

Depending on its applications, computing de vice 100 may include other components that may or may not be physically and electrically coupled to the board 2. These other components include, but are not limited to, volatile memory (e.g., DRAM) 8, non-volatile memory (e.g., ROM) 9, flash memory (not shown), a graphics processor 12, a digital signal processor (not shown), a crypto processor (not shown), a chipset 14, an antenna 16, a display 18 such as a touchscreen display, a touchscreen controller 20, a haptic actuator array 21 , a battery 22, an audio codec (not shown), a video codec (not shown), a power amplifier 24, a global positioning system (GPS) device 26, a compass 28, an accelerometer (not shown), a gyroscope (not shown), a speaker 30, a camera 32, and a mass storage device (such as hard disk drive) 10, compact disk (CD) (not shown), digital versatile disk (DVD) (not shown), and so forth). These components may be connected to the system board 2, mounted to the system board, or combined with any of the other components.

The communication chip 6 enables wireless and/or wired communications for the transfer of data to and from the computing device 100. The term "wireless" and its derivatives may be used to describe circuits, devices, systems, metiiods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communication chip 6 may implement any of a number of wireless or wired standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, Ethernet derivatives thereof, as well as any other wireless and wired protocols that are designated as 3G, 4G, 5G, and beyond. The computing device 100 may include a plurality of communication chips 6. For instance, a first communication chip 6 may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second

communication chip 6 may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others. The processor 4 of the computing device 100 includes an integrated circuit die packaged within the processor 4. In some implementations of the invention, the packages that include the processor, memory devices, communication devices, or other components may include one or more haptic actuators as described herein, if desired. Alternatively the haptie actuators 21 may be formed on substrates independent of any particular die and connected to drive and control electronics through wires, system board traces, or in another way or a combination of ways, the haptic actuators 21 may be mounted in a location where a user is likely to touch the device. The actuators may be placed in several different locations and formed on several different substrates. The term "processor" may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into oilier electronic data that may be stored in registers and/or memory.

In various implementations, the computing device 100 may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set- top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device 100 may be any other electronic device that processes data.

Embodiments may be adapted to be used with a variety of different types of packages for different implementations. References to "one embodiment", "an embodiment", "example embodiment", "various embodiments", etc., indicate that the embodiment(s) of the invention so described may include particular features, structures, or characteristics, but not every

embodiment necessarily includes the particular features, structures, or characteristics. Further, some embodiments may have some, all, or none of the features described for other embodiments.

In the following description and claims, the term "coupled" along with its derivatives, may be used. "Coupled" is used to indicate that two or more elements co-operate or interact with each other, but they may or may not have intervening physical or electrical components between them.

As used in the claims, unless otherwise specified, the use of the ordinal adjectives "first", "second", "third", etc., to describe a common element, merely indicate that different instances of like elements are being referred to, and are not intended to imply that the elements so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be com bined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the specific location of elements as shown and described herein may be changed and are not limited to what is shown. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do ail of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

The following examples pertain to further embodiments. The various features of the different embodiments may be variously combined with some features included and others excluded to suit a variety of different applications. Some embodiments pertain to an apparatus that has the haptic actuator has an inductive coil formed in a package substrate material, an elastic membrane over the coil, a magnet on the membrane, and a power plane to supply a drive signal to move the magnet towards and away from, the coil.

In further embodiments the package substrate material comprises layers of organic dielectric material and one or more layers of a conductive material between the layers or dielectric material.

In further embodiments the organic dielectric material comprises one of layers of epoxy resin, resin-filled polymers, and silica-filled polymers.

In further embodiments the elastic material comprises polydirnethylsiloxane,

thermoplastic polyurethane or a metal.

Further embodiments include a cavity in the substrate material below the elastic membrane and surrounded by the coil, the cavity to allow the magnet to move toward the coil.

In further embodiments coil is formed in layers, a first layer being farthest from the membrane and wherein the cavity extends to the first layer through the substrate material.

In further embodiments the cavity is filled at least in part with a soft magnetic material.

In further embodiments the soft magnetic material comprises at least one of a nickel- based alloy, a cobalt-based material, CoNi, CoPt, and cobalt manganites.

In further embodiments the soft magnetic material comprises a polymer with particles.

Further embodiments include a beam over the coil, wherein the elastic membrane is attached to the beam, the beam providing structural support to the elastic membrane.

in further embodiments the drive signal generates a magnetic field in the coil that actuates the magnet. In further embodiments the magnet is embedded in the elastic membrane.

Some embodiments pertain to a method that includes forming a first dielectric layer of a package substrate material, depositing a conductive layer of a coil o ver first dielectric layer, forming a via to the conductive layer, depositing a second dielectric layer of the package substrate material over the coil and the via, repeating patterning and depositing of additional conductive layers, and forming a via to form a multilayer coil in the package substrate material, and depositing an elastic membrane over the multilayer coil having a magnet, so that the magnet is configured to be actuated by a magnetic field generated by the coil.

Further embodiments include removing package substrate material from within the coil to form a cavity surrounded by the coils.

Further embodiments include filling at least a part of the cavity with a soft magnetic material.

Further embodiments include patterning a photoresist material over the first dielectric layer before depositing the first conductive layer and stripping the photoresist to form a conductive coil.

Further embodiments include attaching the magnet to the elastic membrane by- embedding the magnet in the deposited elastic membrane.

Further embodiments include wherein attaching an elastic membrane comprises forming a polyme laye over the cavity.

Further embodiments include forming a beam over the cavity and wherein depositing the elastic membrane comprises depositing the elastic membrane over the beam.

Some embodiments pertain to a wearable computing system that includes a processor to perform computations, a communication chip coupled to the processor to receive information from an external device, and a tactor coupled to the processor to generate a haptic response in response to the received information, the tactor having an inductive coil formed in a package substrate material, an elastic membrane over the coil, a magnet on the membrane, and a power plane to supply a drive signal to move the magnet towards and away from the coil.

Claims

CLAIMS:

1. An apparatus comprising:

an inductive coil formed in a package substrate material;

an elastic membrane over the coil;

a magnet on the membrane; and

a power plane to supply a drive signal to move the magnet towards and away from the coil.

2. The apparatus of Claim 1, wherein the package substrate material comprises layers of organic dielectric material and one or more layers of a conductive material between the layers or dielectric material.

3. The apparatus of Claim 1 or 2, wherein the organic dielectric material comprises one of layers of epoxy resin, resin-filled polymers, and silica-filled polymers.

4. The apparatus of Claim 1, 2, or 3, wherein the elastic material comprises polydimethylsiloxane, thermoplastic polyurethane or a metal.

5. The apparatus of any one or more of the above claims, further comprising a cavity in the substrate material below the elastic membrane and surrounded by the coil, the cavity to allow the magnet to move toward the coil.

6. The apparatus of Claim 5, wherein the coil is formed in layers, a first layer being farthest from the membrane and wherein the cavity extends to the fi rst layer through the substrate material.

7. The apparatus of Claim 5, wherein the cavity is filled at least in part with a soft magnetic material.

8. The apparatus of Claim 7, wherein the soft magnetic material comprises at least one of a nickel-based alloy, a cobalt-based material, CoNi, CoPt, and cobalt manganites.

9. The apparatus of Claim 7, wherein the soft magnetic material comprises a polymer with particles.

10. The apparatus of any one or more of the above claims, further comprising a beam over the coil, wherein the elastic membrane is attached to the beam, the beam providing structural support to the elastic membrane.

11. The apparatus of any one or more of the above claims, wherein the drive signal generates a magnetic field in the coil that actuates the magnet.

12. The apparatus of any one or more of the above claims, wherein the magnet is embedded in the elastic membrane.

13. A method comprising:

forming a first dielectric layer of a package substrate material;

depositing a conducti ve layer of a coil over first dielectric layer;

forming a via to the conductive layer;

depositing a second dielectric layer of the package substrate material over the coil and the via;

repeating patterning and depositing of additional conductive layers, and forming a via to form a multilayer coil in the package substrate material; and

depositing an elastic membrane over the multilayer coil having a magnet, so that the magnet is configured to be actuated by a magnetic field generated by the coil.

14. The method of Claim 13, further comprising removing package substrate material from within the coil to form a cavity surrounded by the coils.

15. The method of Claim 14, further comprising filling at least a part of the cavity with a soft magnetic material.

16. The method of any one or more of claims 13-15, further comprising patterning a photoresist material over the first dielectric layer before depositing the first conductive layer and stripping the photoresist to form a conductive coil.

17. The method of any one or more of claims 13-16, further comprising attaching the magnet to the elastic membrane by embedding the magnet in the deposited elastic membrane.

18. The method of any one or more of claims 13-17, wherein attaching an elastic membrane comprises forming a polymer layer over the cavity.

19. The method of Claim 14, further comprising forming a beam over the cavity and wherein depositing the elastic membrane comprises depositing the elastic membrane over the beam.

20. A wearable computing system comprising:

a processor to perform computations;

a communication chip coupled to the processor to receive information from an external device; and

a tactor coupled to the processor to generate a haptic response in response to the received information, the tactor having an inductive coil formed in a package substrate material, an elastic membrane over the coil, a magnet on the membrane, and a power plane to supply a drive signal to move the magnet towards and away from the coil.

21. ^'The system of Claim 20, further comprising a cav ity in the package substrate material below the membrane and containing a soft magnetic materia] .