GB2591840A

GB2591840A - Electronic devices comprising printed circuit boards

Info

Publication number: GB2591840A
Application number: GB2016309.3A
Authority: GB
Inventors: Sinclair Grant
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-04
Filing date: 2020-10-14
Publication date: 2021-08-11
Also published as: GB201917680D0; GB202016309D0

Abstract

Electronic device 101 comprising: a stack of printed circuit boards, PCBs 111, each PCB having two opposed main surfaces 121a, 121b (figs 3-5), each PCB main surface 121b that faces a PCB main surface 122a of another PCB of the stack 111 defines an inner surface of the stack and the other two PCB main surfaces define exterior surfaces of the stack (e.g 121a, 123b fig 4), wherein the exterior surfaces (121a, 123b) of the stack provide a casing of the electronic device; and a plurality of electronic components (e.g battery 103 , display 107) carried by at least one inner surface of the stack, wherein the plurality of electronic components are electrically connected to one another via electrically conductive paths carried by at least one inner surface of the stack. Stack may comprise two, three or four PCB’s which may be rigid PCBs and may form a sandwich, whilst the inner surfaces may be in flush contact and include a cavity 106 to house components. The PCBs may connect by adhesive double-sided tape or embedded internal mating pins. The electronic components may be accessible from an external surface. The electronic device may be a computer, gaming console, camera, mobile phone, music keyboard etc (figures 6-11). A side surface may comprise a micro-switch (206 fig 2). Other embodiments include a stack of PCBs carrying components arranged so as not to expose electronic circuitry at the exterior surfaces. In yet another embodiment a stack of PCBs carrying electronic circuitry comprise a casing defined from the first and last exterior surfaces of the PCBs, the inner surfaces carrying the electronic circuitry.

Description

ELECTRONIC DEVICES COMPRISING PRINTED CIRCUIT BOARDS

The present disclosure relates to electronic devices comprising printed circuit boards, and more particularly ctronic devices in which the electronic components constituting the electronic device are carried on the printed circuit boards

Background

consumer electronic devices are made up of a number of sensitive electronic components enclosed in a housing to p rotect the electronic components from the external environment The housing may provide mechanical protection, for example against damage, and electrical protection, for example insulation andlor shielding such as electromagnetic interference (EMI) shielding.

Seine consumer electronic devices may further include a case for protecting the outer surface of the housing and/or any externally exposed electronic components, such as displays or screens.

As examples, the housing or casingof sueheiec1ron1cdevcesprovidesthedev1ces with rigidity, 20 electrical insulation, protection of the internal parts from abrasion and/or impact and, in some cases; airflow for cooling.

Summary

According to a first aspect of the invention there is provided an electronic device comprising a stack of printed circuit boards, PCBs, each PCB having two opposed main surfaces wherein each PCB main surface that faces a PCB main surface of another PCB of the stack defines an inner surface of the stack and the other two PCB main surfaces define exterior surfaces of the stack, wherein the exterior surfaces of the stack provide a casing of the electronic device; and a plurality of electronic components carried by at least one inner surface of the stack, wherein the plurality of electronic components are electrically connected to one another via electrically conductive paths carried by at least one inner surface of the stack. -2 -

This arrangement allows for most of the electronic components to be installed on the printed circuit boards during a manufacturing process and further avoids the need for an additional outer housing for the electronic device. Avoiding the need for an additional housing for the electronic device dramatically reduces total component count and allows for an ultra-thin whilst highly robust construction A further advantage of the construction of the present disclosure is the protection provided to the plurality of electronic components by the stiffness provided to the electronic device by virtue of the laminate/stack structure. The stacked PCBs provide increased stiffness and resistance to splintering and cracking. These advantages reduce the likelihood and severity of damage to the electronic components from bending and cracking of the electronic device.

The stiffness of the device may be further improved by increasing the number of layers of each PCB in the stack of PCBs. A PCB comprising an exterior surface may comprise four layers and may have a thickness of 1.8mm. A PCB comprising two inner surfaces may comprise eight layers and may have a thickness of 0.8mm. The stack of PCBs may have a total thickness of 4mm.

Another advantage of the present invention is the provision of a slimmer electronic device with 20 improved thermal performance.

In some embodiments, the stack of PCBs may comprise two, three or four PCBs and at least one of the inner surfaces of the stack of PCBs may be in flush contact with at least one other inner surface. Such a stack of PCBs may be arranged such that it forms a PCB sandwich and may be connected to one another by atleast one of: adhesive, double sided tape, internal mating connectors. The internal mating connectors may be embedded into at least one PCB of the stack of PCBs. The components may be thereby hidden and sealed inside or between the PCBs and plagiarism of the internal arrangement and/or component constitution is made much more difficult. The electronic device may further comprise at least one heat sink which may be comprised of at least one of the PCBs or arranged between two of the PCBs in the stack. At least one of the PCBs of the stack (111) of PCBs may comprise wound copper. -3 -

Including ground copper into at least one of the PCBs of the stack, or adding other materials such as aluminium or ceramics, may provide further stiffness to the PCB(s). Including these materials in layers may improve stiffness even further.

At least two of the PCBs of the stack may be pivotally connected to one another and the PCBs may be rigid which may provide the stack as a whole with rigidity. At least one of the PCBs of the stack of PCBs may comprise multiple layers and the stack of PCBs may comprise at least one 3D printed part.

At least one inner surface of the stack of PCBs may comprise at least one cavity for housing at least one of the plurality of electronic components and at least one of the plurality of electronic components may be carried by each of the inner surfaces of the stack of PCBs. The at least one cavity may be located on an inner surface of the stack of PCBs adjacent to an inner surface of the stack of PCBs which carries the at least one electronic component such that the electronic component located on the inner surface may be accommodated by the adjacent inner surface. The cavity may, therefore, be shaped to completely or partially accommodate the at least one of the plurality of electronic components. The cavity may be depth milled using a computer-controlled router. At least one electronic component may be accessible from at least one exterior surface of the stack ofPCBs.

The electronic device may comprise an electronic computing device and, thereby, the plurality of electronic components may comprise electronic computing components. Such electronic computing components may together comprise a computer and may include the computing components necessaryto constitute a computer such as, butnotlimited to, a processor, memory and an interface. The plurality of electronic components may, alternatively or additionally, comprise at least one of the following: a screen, a battery, a mechanical push micro switch, a resistor, a capacitor, a CPU, a camera module. RFID circuitry, a UPS module, a microphone, an EMI shield, a Bluetooth module, a WIFI module, an LED, a sensor, a touch control, a haptic actuator, a camera sensor, an inductive charging receiver coil, a general purpose input/output (I/O), a keyboard. These components may be as semb led together and the electronic device may comprise any of: a gaming console, a gaming controller, a camera, a home automation controller, a door entry system, a laptop, a medical device, a mobile phone, a music keyboard, -4 -a synthesiser, a portable lighting device, a remote control, single board computer, a smart speaker, a tablet computer, a television, a vehicle dashboard, a watch.

At least one of the plurality of electronic components may comprise a system on module, SO 5 which may provide for a thinner or otherwise more compact construction.

The stack of PCBs may comprise at least one side surface which carries at least one electronic component and the at least one electronic component carried by the at least one side surface may comprise any of: a surface mounted mechanical push micro switch, an input/output stage 10 (I/O).

According to a second aspect of the present invention there is provided a caseless electronic device, wherein the device comprises a stack of PCBs carrying electronic circuitry, wherein the electronic circuitry is not exposed at exterior surfaces of the stack.

According to a third aspect of the present invention there is provided an electronic device comprising a stack of PCBs carrying electronic circuitry, wherein exposed surface of a first and a last PCB of the stack define a casingof the device and one or more surfaces within the interior stack carry the electronic circuitry.

In the context of the present disclosure, the concept of the electronic components being "carried" by or on a PCB essentially includes electronic components being provided on a PCB and/or a PCB substrate or within (or at least partially within) the PCB and/or PCB substrate.

Further, in the context of the present disclosure, the term "electronic components" includes any form of electronic or electrical component capable of being carried by a PCB including, as non-limiting examples, one or more of passive discrete components, active discrete components, integrated circuits (ICs), opto-electronic, electromechanical components (e.g. micro electromechanical devices (MEMs) and system on modules (SOM) In the context of the present disclosure, the concept of a "printed circuit board" or PCB" includes circuit boards with a substrate having the mechanical and electrically insulative and/or -5 -thermally insulative characteristics of standard PCBs known in the field and may be suitable for carrying electronic components and electrically conductive paths. Such circuit boards may, for example, adhere to [PC circuit board standards.

Brief Description of the Drawings

Embodiments of the disclosure will now be described, by way of example only, and with reference to the drawings in which: Figure 1 schematically illustrates a perspective view of an electronic device according to a 10 first embodiment of the present disclosure, Figure 2 schematically illustrates a side view of an electronic device according to a second embodiment of the present disclosure in which a side surface ofthe electronic device carries a mounted mechanical push micro switch; Figure 3 schematically illustrates a perspective view of the electronic device of Figure 1 with a PCB of the electronic device shown separated from the rest of the electronic device; Figure 4 schematically illustrates a perspective exploded view of the electronic device of the first embodiment of the present disclosure with the electronic components removed; Figure 5 schematically illustrates a side exploded view of the electronic device of the first embodiment; Figure 6 schematically illustrates a plan view of an electronic device according to a third embodiment of the present disclosure; Figures 7a to 7c schematically illustrate a side view, a plan view from the other main surface and an enlarged view, respectively, of the electronic device shown in Figure 6; Figure 8 schematically illustrates a side view of an electronic device according to a fourth 25 embodiment of the present disclosure in an open configuration, Figures 9a to 9c schematically illustrate a front view, a side view and a plan view, respectively, of the electronic device shown in Figure 8 in a closed configuration, Figures 9d and 9e schematically illustrate a side view and a plan view, respectively, of the electronic device of the fourth embodiment of the present disclosure in a closed configuration; Figures 10a to 10c schematically illustrate a front view, a side view and plan view, receptively, of an electronic device according to a fifth embodiment of the present disclosure in a closed configuration; -6 -Figures 10d and 10e schematically illustrate a side view and a plan view, respectively, of the electronic device of the fifth embodiment of the present disclosure in an open configuration; Figures 1 la to lie schematically illustrate a front view, a side view and a plan view, respectively, of an electronic device according to a sixth embodiment of the present disclosure in a closed configuration; Figures 1 1 d and 1 1 e schematically illustrate a side view and a plan view, respectively, of the electronic device of the sixth embodiment of the present disclosure in an open configuration.

Detailed Description

Figures Ito 7c show embodiments of an electronic device 101 comprising a stack of printed circuit boards (PCBs) lit In the embodiments shown in Figures he stack of PCBs Ill comprises three rigid PCBs 104, 102 105, a first outer or exterior (top as shown) PCB 104, an inner or interior PCB 102 and a second outer or exterior (bottom as shown) PCB 105. Each PCB has two opposed main surfaces. The first outer PCB 104 comp ri ses an exterior surface 121a and an inner surface 1.21b. The inner PCB 102 comprises two opposed inner surfaces 122a, 122b. The second outer PCB 105 comprises an inner surface 123a and an exterior surface 123b.

In the context of the present disclosure, the concept of "rigid P I al ishes from flexible PCBs and includes hardboard PCBs usually made out of a solid substrate material which provides the PCB with resistance to twisting. By way of example, a "thin PCB" may be understood to be a PCB with a thickness of 0.4mm but may also include PCBs of a thickness between 0.1 ram and I mm.

Flex circuits are designed to be bent e.g. twisted around corners, whereas rigid boards are fixed and are not designed for bending.

The electronic device 101 comprises a piuraliw of electronic components carried by one or more of the PCBs -7 -The electronic device 101 may be completely pre-assembled. As another po.

assemblable kit of PCBs 104, 102, 105 may be provided as a flat-pack kit of parts in which one or more of the PCBs already carries electronic components mounted to or on the PCB in a manufacturing facility or factory. These PCBs may then be assembled one on top of the other by an end user or consumer and joined together, for example by push-fit internal mating connectors embedded into the inner surfaces of the PCBs, to form a sandwich of PCBs 104, 102, 105 (similar to the construction of plywood). The PCBs may be further secured together using a suitable adhesive Such an adhesive may compromise a permanent adhesive or a temperature glue. The use of a temperature glue may allow users to gain access inside the device to carry out repairs. Although the majority of the electronic components (not shown) may be added to the PCBs during a manufacturing process so that all the end user has to do is mount the PCBS one on top of the other, some components such as a flush fitting screen 103 and battery 107 may be fitted to the PCB stack 111) by the end consumer.

As shown in Figures 3 and 5 t batte 107 may be carried on an upper inner surface 122a of the inner PCB 102 and may be arranged to provide power to the electronic components of the electronic device 10'!For example, the battery may provide power to a flush-mount display or screen 103 and possibly other electronic components carried by one or more of the PCBs. The flush-mount display or screen 103 may be carried on the inner PCB 102 and extend through a recess 106 in the outer PCB 104 such that it is flush with the exterior surface 121a of the electronic device. The display or screen 103 may comprise, for example, a TEL OLED or ePAPER module.

The second embodiment shown in Figure 2 differs from the first embodiment of Figures 1 and 3 to 5 in that the electronic device 201 further comprises two mechanical push micro switches 206 carried on a side surface of the stack of PCBs 204, 202, 205. These mechanical push micro switches 206 may b e used to power-on the electronic device 201 or provide other control of the electronic device 201. In embodiments of the present disclosure in which the electronic device 201 is a gaming console, the two mechanical push micro switches 2.06 may provide left and right shoulder buttons for gaming. -8 -

A further optional feature of the electronic device 101, shown most dearly in Figure 4, is that the exterior PCBs 104 and 105 may be slightly thicker or otherwise more robust than the 2.

PCB 102.

The inner PCB 102 may he configured for serving as a main PCB ("motherboard') for the electronic device whilst the extetior PCBs 104 and PCB 105 are con fiFpred for maintaining rigidity and providinga suitable casing,comerisingthe top exterior surface 2Ia and the bottom exterior surface 123b. These configurations enable the electronicdeviceto be thin vetmaintain, by virtue of the more rugged outer PCBs, a robust and rigid protection for the plurality of electronic components located on the inner surfaces 121b, 122a, 122b,, 123a.

The inner PCB 102 may also be nested in a recess of the inner surface 123 a of the outer PCB 105 and/or in a recess of the inner surface 121h of the outer PCB 104.

As mentioned above, the stack of PCBs Iii may be Field together using internal mating connectors or internal mating pins. Alternatively, or additionally, the PCBs may be held together with strips of double-sided tape and/or adhesive. One advantage of using internal mating connectors is that they easily clip together, another advantage is that they make good electrical contact between the PCBs. Such internal mating connectors may be push-fit or snap-fit connectors. An adhesive may be used in addition to the internal mating connectors and may reduce the likelihood of the internal mating connectors disconnecting during use, particularly in the event that the device is dropped. A further advantage of using adhesive to hold the PCBs 0 c that access to the electronic components on the inner surfaces may be restricted or rendered impossible without damaging or destroying the electronic device 101 so that any 25 attempted access may be readily determined.

Referring to Figure 4, as can be clearly seen from this Figure, the inner PCB 102 may have a cavity 130 arranged and/or configured for accommodating the battery 107 (not shown). The battery 107 may therefore be carried on and/or electrically an d mechanical ly connected to the bottom inner surface 123a. Electrical power may therefore be provided to the screen 103 by the battery 107 via electrically conductive paths carried by the inner surfaces. -9 -

Referring, to Figure 5, the majority of the electronic components of the electronic device 101 may be, where suitable, embedded within the inner PCB 105 such that the electronic components are flush with the inner surfaces 122a, 122b of the inner PCB and, therefore, hidden from view. Plaarism of the electronic components and their layout may be frustrated by embedding the electronic components in a PCB of the device in this manner.

Electronic components that may be suitable for embedding in the inner PCB 105 may include, for example, resistors, capacitors and a CPU.

Alternatively or additionally, space for adding a system-on-module (SON) may be provided within the PCB stack 111.

In some instances, where a component is too large to be embedded in a PCB, the component can protrude from an inner surface of a PCB and fit either within a cavity or recess of a PCB adjacent to the PCB on which the component is carried or inside a cavity or recess of the PCB on which the component is carried. An example of such an instance is shown in the exploded view of Figure Sin which the battery 105 protrudes from the bottom inner surface 123a and is accommodated by a cavity 130 in the inner PCB 102. The cavity may be produced by a CNC process of depth milling. This process may allow the cavities to b created whilst maintaining the structural integrity of the PCB. The cavities may be located on the PCBs comprising an exterior surface.

By virtue of the above-mentioned arrangements for accommodating the electronic components of electronic device 101, each inner surface 121b, 122a, 122b, 123a may be in flush contact with an immediately adjacent inner surface. The flush contact of the inner surfaces provides a robust construction of the stack of PCBs HI such that the electronic components are protected from impact such as when the electronic device 101 is dropped because any mechanical impact stress will be transferred from one PCB to another rather than into the sensitive electronic components.

-10 -This flush contact arrangement further provides stiffness to the PCB stack 111 which reduces the likelihood of component damage, for example solder joint breaks, which are a common failure in regular electronic PCBs with external mounted components.

This above-mentioned flush construction provides for the possibility of improved thermal management of the electronic components of the electronic device 101 because good thermal contact of the electronic components with at least one of the PCBs of the electronic device 101 or by virtue of being embedded in at least one PCB, may enable heat generated by the electronic component to be dissipated more effectively to the exterior surfaces 121a, 123b of the electronic device 101 by thermally conductive paths or portions of the PCBs. The dissipation of heat through the PCBs may be further assisted by including ground copper in the substrate of the PCB. Adding ground copper to the PCB may also provide increased stiffness. The above-mentioned flush construction provides good thermal contact over a greater surface area of the electronic components over a conventional arrangement in which electronic components may be thermally insulated by being exposed to air over a greater proportion of their surface. This construction may be further improved by providing a thermal paste around the electronic components to provide a flush seal and further reduce contact of the electronic component with air. For example, thermally conductive vias or tracks, for example formed of a metal such as aluminium, silver or gold, may be included in the substrate of at least one of the PCBs.

This feature of improved thermal performance may circumvent the requirement for an additional heat sink component. However, if necessary, to improve thermal performance even further, a heat sink may be provided, for example in the form of a copper or aluminium layer.

Embodiments of the present disclosure may include electronic components carried on at least one of the exterior surfaces 321a 3236 of the electronic device. For example, as shown in Figures 6 to 7c, circular capacitive touch controls 309 may be embedded in the top exterior surface 321a of the electronic device. These controls 309 may be flush with the top exterior surface 321a. Each circular capacitive touch control 309 may be encircled with a surface mounted LED 308 so as to indicate to the user the location of the circular capacitive touch controls 309. Such a surface mounted LED may also be embedded in the top exterior PCB.

Further, the circular capacitive touch controls 309 may be embossed with a raised circle 310 so that the user can physically feel where the circular capacitive touch controls 309 are located.

To provide tactile feedback for the actuation of the circular capacitive touch controls 309, wafer thin, haptic actuators can be embedded inside the PCB stack. Such actuators may also double as piezo speakers such that the whole electronic device itself may acts as a loudspeaker whereby the actuators resonate sound through the top and b ottom PCB s (avoiding the need for bulky speaker modules) Referring specifically to Figures 7a to 7c, the electronic device may further comprise a camera sensor 312 embedded inside the bottom exterior PCB and flush with the bottom exterior surface 323b The bottom exterior surface 323b may further carry a lens mount 313 which may be secured to the exterior surface 323b with screws or adhesive. A lens 314 may be secured to the lens mount 313 with a screw thread.

The bottom exterior surface 323b may carry further circular capacitive touch controls 309 and may also comprise a wireless inductive charging receiver coil 315. Such a coil 315 may be etched onto the bottom exterior surface 323b. The advantage of this would be to avoid the need for a conventional wireless charging coil module or additional charging ports, such as USB, which would occupy limited space on the electronic device.

In the embodiment shown in Figure 7b, a very thin Ferrite sheet (approximately 0.1mm) (not shown) may be included in a recess within the bottom PCB and located between the wireless inductive charging receiver coil 315 and the battery 107, such that the wireless inductive charging receiver coil 315 does not interfere with other electronic components of the electronic device such as Bluetooth and/or Wi-Fi modules -12 -The bottom exterior surface 3236 may further comprise an embedded RGB LED matrix 317 for showing custom messages. The LEDs may be flush with the bottom exterior surface 323b by virtue of being embedded therein.

The bottom exterior surface 323b may further comprise a row of optional general-purpose input/output (GPIO) holes 316 to allow the user to add peripherals or modify the device. Adding GPIO pins enables the user to either input to their computer program from outside the CPU or to provide the user with an output from the electronic device As shown in Figure 8, a fourth PCB 419 may be pivotally connected to the PCB stack with a hinge 418 to provide a lid top so that the electronic device has a clamshell or laptop type structure. The fourth PCB 419 may comprise a hybrid circuit board that integrates elements of hardboard and flexible circuits that are rigid at some points on the board and flexible at others. Such circuit boards may be known as flex-rigid, rigid flex or dynamic flex PCBs. The hinge 418 may comprise a flexible PCB or a ribbon cable or other flexible coupling made of, for example, polyimide or similar. The hinge may be configured to allow the fourth PCB 419 to be positioned at different angles relative to the PCB stack.

Figures 9a to 9e depict an embodiment like that shown in Figure 8 in that again a fourth PCB 20 419 which functions as a lid is pivotally attached to a stack of three PCBs by a hinge 418 as described above, As seen in Figure 9c the lid exterior surface 424a comprises an RGB LED matrix 417 embedded in the fourth PCB 419 to display a custom name and/or message.

As shown in Figure 9e, a display or screen 403 may be embedded in the lid inner surface 424b.

The top exterior surface 421a of the PCB stack may comprise a keyboard (for example a QWERTY keyboard) 409 comprising capacitive touch controls embedded in the top exterior surface 421a. Each key of the keyboard 409 may be lit with embedded LEDs similar to those -13 -described above in relation to Figure 6. Haptic actuators (not shown) may also be embedded to make the capacitive touch controls of the keyboard 409 feel more like a physical keyboard The top exterior surface 421a and the lid inner surface 424b may have a fastening mechanism to releasably secure the fourth PCB 419 to the PCB stack in the closed configuration. For example, top exterior surface 421a and the lid inner surface 424b may comprise corresponding embedded rare earth magnets 420a that mate with adjacent metal pads 420b used to removably secure the fourth PCB 419 to the PCB stack in a closed configuration.

Figures 10a to 10e shows an electronic device of similar construction to that shown in Figures 9a to 9e. However, in this embodiment the capacitive touch controls 509a, 509b are configured to provide controls for music production. For example, controls for pitch and/or amplitude modulation 509a may be carried on a lid inner surface 524b and a piano keyboard 509b may be provided on a top exterior surface 521a.

Using capacitive touch controls for the piano keys of the piano keyboard 509b allows each key to be used with added effects e.g. vibrato, pitch bend, timbre changes and other expressive effects to users. Such controls may be configured for actuation by moving fingers on the key surfaces. LEDs may also be embedded on each key area to guide and/or teach users which note(s) to play for musical arrangements.

Figures lla to 11 e show another clamshell design which differs from those of Figures 8 to 10e in that two displays 603a, 6036 are provided, one on a lid inner surface 6246 and one on a top exterior surface 621a.

Variations and Alternatives As described above, the electronic device may comprise comprising electronic components whereby at least some of the electronic components together comprise a computer.

However, an electronic device of the present disclosure may additionally or alternatively take the form of any one or more of a gaming console, a synthesiser, a gaming controller, a -14 -camera, a home automation controller, a door entry system, a laptop, a medical device (for example for patient reaction testing), a mobile phone, a music keyboard, a portable lighting device, a remote control, a single board computer, a smart speaker, a tablet computer, a television, a vehicle dashboard (for example for an automobile or bike), a watch (for example a smartwatch or fitness tracker), a robot.

The embodiments described above relate to small portable electronic devices, however, various sizes and layouts of the electronic device are considered under the present disclosure. For example, the electronic device of the present disclosure may take the form of a large wall-10 mounted device Further, embodiments of the present disclosure may comprise any number of electronic components carried on any of the PCBs. Such electronic components may include: a camera module, RFID circuitry for serial number identification, components suitable for conducting wireless electronic payments, a UPS module (for example for mobile phone functionality), miniature SMT (Surface Mount) microphones (so the device can receive voice commands, shielding (for example for EMI shielding), Bluetooth modules, Wi-Fi modules, Bluetooth antennas, Wi-Fi antennas (the Bluetooth and Wi-Fi antennas may be printed or etched onto one of the PCBs).

Bare die components (for example an IC chip or sensors without plastic, ceramic or lens casing) can be used to reduce the product thickness further.

Electronic devices of the present disclosure may further comprise optional features such as rare earth magnets that may be provided on an exterior surface of the stack of PCBs to allow the electronic device to be easily wall mounted to, for example, simple adhesive metal discs that may be secured to the wall so the electronic device may easily magnetise to the metal discs, circumventing the requirement for a bulky external wall bracket such as those used with conventional wall mounted televisions Alternatively, the electronic device may comprise metal discs that correspond and attach to wall-mounted magnets.

-15 -The embodiments of the disclosure described above relate to a method of construction in which the constituent PCBs of the stack of PCBs are pre-manufactured with at least some of the electronic components carried on the inner surfaces of the PCBs. The PCBs are then assembled together, along with any remaining electronic components, to form a stack of PCBs and the complete electronic device. However, in some alternative embodiments of the present disclosure, part or all of the stack of PCBs may be 3D printed as one complete stack with all components carried on the PCB surfaces. Additionally, or alternatively, a combination of 3D printing and/or prefabricated PCB boards may be used.

The embodiments of the disclosure described above depict electronic devices of the present disclosure comprising three and four PCBs, however, embodiments of the present disclosure may comprise only two PCBs. Further, embodiments of the present disclosure may comprise any number of PCBs, for example there may be more than one inner PCB.

In embodiments of the present disclosure, one or several of the PCBs of the stack of PCBs may comprise multiple layers For example, the exterior surfaces of the stack of PCBs may together comprise the casing for the electronic device and as such they may be provided with a coating such as polymer coating or a non-scratch coating.

In a further variation of the above-described embodiments, the plurality of electronic components may further comprise a miniature motor, such as miniature vibration motor. Such a motor may be embedded into a PCB of the stack of PCBs.

Claims

-16 -CLAIMS: An electronic device (101) comprising: a stack of printed circuit boards, PCBs (111), each PCB haying two opposed main surfaces (121a, 121b), wherein each PCB main surface (121b) that faces a PCB main surface (122a) of another PCB of the stack (111) defines an inner surface (121b, 122a, 1226, 123a) of the stack and the other two PCB main surfaces define exterior surfaces of the stack (121a, 123b), wherein the exterior surfaces (121a, 123b) of the stack provide a casing of the electronic device (101), and a plurality of electronic components (103, 107) carried by at least one inner surface of the stack (111), wherein the plurality of electronic components (103, 107) are electrically connected to one another via electrically conductive paths carried by at least one inner surface of the stack.An electronic device (101) according to claim 1, wherein the stack of PCBs comprises two, three or four PCBs.An electronic device according to any preceding claim, wherein at least one of the inner surfaces (121b, 122a, 122b, 123a) of the stack (111) of PCBs is in flush contact with at least one other inner surface (1 21b, 122a, 1 22b, 123a).An electronic device (101) according to any preceding claim, wherein at least one inner surface (12 lb, 122a, 122b, 123a) of the stack (111) of PCBs comprises at least one cavity (106) for housing at least one of the plurality of electronic components (103) 5. An electronic device (101) according to claim 4, wherein the at least one cavity (106) is depth milled using a computer-controlled router.-17 -An electronic device (101) according to any preceding claim, wherein the electronic device (101) comprises an electronic computing device.An electronic device (101) according to any preceding claim, wherein the plurality of electronic components (103, 107) comprises electronic computing components.8 An electronic device (101) according to claim 7, wherein the electronic computing components together comprise a computer.An electronic device (101) according to any preceding claim, wherein at least one of the plurality of electronic components (103, 107)is carried by each of the inner surfaces (12 lb, 122a, 122b, 123a) of the stack (111) of PCBs.10. An electronic device (101) according to any preceding claim, wherein the PCBs are rigid.11. An electronic device (101) according to any of claims 4 to 10, wherein the at least one cavity (106) is located on an inner surface (121b, 122a, 122b, 123a) of the stack (111) of PCBs adjacent to an inner surface (121b, 122a, 122b, 123a) of the stack (111) of PCBs which carries the at least one electronic component (103, 107).12. An electronic device (101) according to any preceding claim, wherein the plurality of electronic components (103, 107) comprise at least one of the following: a screen (103), a battery (107), a mechanical push micro switch (206), a resistor, a capacitor, a CPU, a camera module, REID circuitry, a GPS module, a microphone, an EMI shield, a Bluetooth module, a WTI module, an LED (308), a sensor, a touch control (309), a haptic actuator, a camera sensor (312), an inductive charging receiver coil (315), a general purpose input/output (WO) (316), a keyboard (409).13. An electronic device (101) according to any of claims 4 to 12, wherein the cavity (106) is shaped to completely or partially accommodate the at least one of the plurality of electronic components (103, 107).14. An electronic device (101) according to any preceding claim, wherein the electronic device (101) comprises any of: a gaming console, a gaming controller, a camera, a home automation controller, a door entry system, a laptop, a medical device, a mobile -18 -phone, a music keyboard, a synthesiser, a portable lighting device, a remote control, single board computer, a smart speaker, a tablet computer, a television, a vehicle dashboard, a watch.15. An electronic device (101) according to any preceding claim, wherein the stack (ill) of PCBs is arranged such that it forms a PCB sandwich.16. An electronic device (101) according to any preceding claim, wherein the stack (111) of PCBs comprises at least one side surface which carries at least one electronic component (206).17. An electronic device (101) according to claim 16, wherein the at least one electronic component carried by the at least one side surface comprises any of: a surface mounted mechanical push micro switch (206), an 1/0(316).18. An electronic device (101) according to any preceding claim, wherein the stack (111) of PCBs are connected to one another by at least one of: adhesive, double sided tape, internal mating pins.19. An electronic device (101) according to claim 18, wherein the internal mating pins are embedded into at least one PCB of the stack of PCBs (111).An electronic device (101) according to any preceding claim, wherein at least one of the PCBs of the stack (111) of PCBs comprises multiple layers.21. An electronic device (101) according to any preceding claim, wherein at least one of the PCBs of the stack (111) of PCBs comprises ground copper.22. An electronic device (101) according to any preceding claim, wherein at least two of the PCBs of the stack (111) of PCBs are pivotally connected to one another.23 An electronic device according to any preceding claim, wherein at least one electronic component (308, 309, 310) is accessible from at least one exterior surface (121a, 123b) of the stack (111) of PCBs -19 - 24. A caseless electronic device (101), wherein the device comprises a stack (111) of PCBs carrying electronic circuitry, wherein the electronic circuitry is not exposed at exterior surfaces (121a, 123b) of the stack (111).25. An electronic device (101) comprising a stack (111) of PCBs carrying electronic circuitry, wherein exposed surface (121a, 123b) of a first and a last PCB of the stack define a casing of the device (101) and one or more surfaces within the interior stack carry the electronic circuitry.