# Patent

## Title
Apparatus and method for embedding components in small-form-factor, system-on-packages

## Abstract

According to various aspects of the present disclosure, devices and methods are disclosed that include communication platform including a small form factor platform having a system-on-package architecture. The system-on-package architecture may be arranged as a stack of layers including: a first layer of the stack of layers having a first conformable material; a second layer of the stack of layers having a second conformable material; a third layer of the stack of layers having a third material, wherein the first conformable material and the second conformable material are more flexible than the third material; and one or more electronic components embedded within the stack of layers, wherein the one or more electronic components are configured to process a received wireless signal.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 13/542,086 filed on Jul. 5, 2012, which is a continuation of U.S. patent application Ser. No. 12/642,220 filed on Dec. 18, 2009, the contents of both of which are hereby incorporated by reference in their entireties. This application is related to U.S. patent application Ser. Nos. 12/642,315 and 12/642,423, both filed on Dec. 18, 2009, the contents of both of which are hereby incorporated by reference in their entireties.


BACKGROUND
1. Field of the Invention
The present invention relates generally to integrated circuit design, and more particularly, to a small-form-factor (SFF), system-on-package (SOP) architecture having one or more of improved performance, integrated thermal management and interference mitigation within the SFF-SOP environment.
2. Description of the Related Art
Mobile platforms are getting smaller in size and incorporating more electronic and wireless functionalities for efficient communications. In order to include all the desired electronic functionalities into the future small-form-factor (SFF) mobile platforms, embedded system-on-package (SOP) architectures are being developed.
Currently different active component as well as passive component embedding techniques are being developed using multilayer substrate materials and cavities. Device embedding techniques are being developed using low-cost materials which are not good for embedding radio-frequency (RF) functionalities. Some approaches to embed ‘integrated-passive-devices’ are being developed which may increase the cost of manufacturing and assembly, which tends to minimize the purpose of using low-cost material system. Moreover, RF-performance and size-reduction remains difficult to achieve for multi-standard wireless systems. RF-IPDs (Integrated Passive Devices) are also being utilized on silicon, low temperature co-fired ceramic (LTCC), glass or other materials and embedded into the low-cost material systems for RF connections. This potentially increases the cost of assembly and manufacturing considerably and degrade/changes the performance of complex passive structures after other component embedding or shielding in close proximity.
On the other hand, high-performance materials are being utilized which are perceived to have higher cost than digital-substrate materials. These materials can embed complex RF passive designs in multilayer material environment. Thermal and noise management issues are not yet solved in the current SOP structures. The conventional electromagnetic band-gap (EBG) structures for noise-mitigation in the SFF-SOP environment will tend to consume significant space and will increase the overall SOP size. Both of these approaches also suffer from cross-talk thermal issues.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-section of a SOP with both high-performance and low-performance polymer layers to form a stack of materials in accordance with various embodiments of the present invention.
FIG. 2 shows another cross-section of a SOP with both high-performance and low-performance polymer layers to form a stack of materials in accordance with various aspects of the present disclosure.
FIG. 3a shows a cross-section of a SOP, which includes embedded isolation structures in accordance with various aspects of the present disclosure.
FIG. 3b shows vertical periodic micro-via structures A and B, taken along the lines A and B of FIG. 3a. 
FIG. 3c shows horizontal periodic structures, taken along the line C of FIG. 3a. 
FIG. 4 shows an exemplary embodiment of a device including a communication module with a SOP stack, according to various aspects of this disclosure.



DETAILED DESCRIPTION
Definitions
High-performance material: High-performance material is a material that provides superior electrical properties including low loss and low coefficient of thermal expansion (CTE) characteristics versus the properties of a low-performance material.
In accordance with various aspects of the present disclosure, an apparatus is disclosed that includes a small form factor mobile platform including a system-on-package architecture, the system-on-package architecture arranged as a stack of layers including a first layer having a first conformable material; a second layer having a second conformable material or any other rigid organic material; a third layer having a third material; and one or more electronic components embedded within the stack of layers, wherein the first conformable material, the second conformable material, or both are configured to allow high frequency signal routing.
In accordance with various aspects of the present disclosure, the apparatus can further include a heat dissipating element configured dissipating heat generating from one or more electronic components, wherein the heat dissipating element is arranged between the first and the second layers. The heat dissipating element can include a high-conductivity material, such as metal, or a directional conductor. The high-conductivity metal can be selected from the group consisting of copper, aluminum, KOVAR, which is a heatsink material, bronze, silicon-carbide or other materials such as gold or silver and the directional conductor can include graphite that is configured to dissipate heat along a two-dimensional plane. Moreover, the apparatus can include features wherein the first conformable material and the second conformable material are the same material or are different materials. Further, the apparatus can include features wherein the first conformable material, the second conformable material, or both include a polymer, such as a liquid crystal polymer or can be a rigid organic or polymer material.
In accordance with various aspects of the present disclosure, the apparatus can further include a vertical filtering structure arranged between the one or more electronic components. The vertical filtering structure can include stacked via patterns, arranged in a periodic arrangement of the vertical filtering structure that can define a filtering characteristic. The apparatus can include features wherein the vertical filtering structure is configured to filter or isolate radio-frequency noise, harmonics of digital noise, or both produced by the one or more electronic components. Moreover, the apparatus can include features wherein the third material is different than the first and the second conformable materials.
In accordance with various aspects of the present disclosure, a method is disclosed that includes forming a small form factor mobile platform including a system-on-package architecture, the system-on-package architecture arranged as a stack of layers including providing a first layer of a first conformable material; providing a second layer of a second conformable material; providing a third layer of a third material; and embedding one or more electronic components within the stack of layers, wherein the first conformable material, the second conformable material, or both are configured to allow high frequency signal routing.
In accordance with various aspects of the present disclosure, the method can include arranging a heat dissipating element between the first and the second conformable materials, wherein the heat dissipating element can be arranged between the first and the second layers. The first conformable material and the second conformable material can be the same material or different materials. For example, the first or second conformable material, or both can include a polymer, such as a liquid crystal polymer or can be a rigid organic or polymer material. The heat dissipating element can include a high-conductivity material, such as metal, or a directional conductor, wherein the high-conductivity metal can be selected from the group consisting of copper and aluminum and the directional conductor can include graphite that is configured to dissipate heat along a two-dimensional plane.
In accordance with various aspects of the present disclosure, the method can include arranging a vertical filtering structure between the one or more electronic components, wherein the vertical periodic filtering structure includes stacked via patterns. The arrangement of the vertical filtering structure can be periodic and define a filtering characteristic, wherein the vertical filtering structure is configured to filter or isolate radio-frequency noise, harmonics of digital noise, or both produced by the one or more electronic components. The vertical filtering can be combined with the horizontal periodic filtering as allowed by the small-form-factor SOP in consideration.
These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various FIGS. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
FIG. 1 shows a cross-section of a SOP with both high-performance and low-performance polymer layers to form a stack of materials in accordance with various aspects of the present disclosure. The heterogeneous stackup, shown generally at 100, includes one or more layers of high-performance material 105, and one or more layers of low-performance material 110. By way of a non-limiting example, the high-performance material 105 may be a polymer, such as a liquid crystal polymer (LCP), Rogers RXP or any other material that exhibits superior electrical properties compared to those of low-performance material 110 over a wide frequency range. Low loss tangent is a factor for the high-performance material 105 and is directly related to circuit signal losses and quality or Q factor. Because of these characteristics, the high performance materials, such as LCP, allow for high frequency signal routing and passives. The low-performance material 110 may include a polymer, such as ABF (Ajinomoto Build-up Film), FR4, BT or any other organic materials.
The high-performance materials 105, like LCP, may be more flexible or pliable than the low-performance material 110. This flexibility of the high-performance material 105 allows these layers to conform around electrical components, such that the electrical components may be embedded between layers of the high-performance material. In some aspects, a particular layer of the stackup may include both the high-performance material 105 and low-performance material 110. In this case, the electrical and/or the RF component may be arranged within layers of a high-performance material and adjacent to low-performance materials on a particular layer of the SOP.
By way of a non-limiting example, the stackup as shown in FIG. 1 can be less than 0.5 mm thick. The vertical dimension of the SOP may be reduced by thinning the substrates. In this case, the embedded IC designs, if necessary, may be optimized to include the effect of thin substrates as well as polymer material environments.
In some aspects, the stackup can be a homogeneous stackup that includes only one type of layers. For example, stackup can include layers of the high-performance material or layers of low-performance material.
The stackup may include different active ICs components 115, including different electrical and/or radio-frequency components, that may be arranged between layers of high-performance material 105. By way of a non-limiting example, the different electrical ICs may include a power amplifier (PA) 120 such as GaAs PA. Moreover, the different radio frequency ICs may include a combination chipset of two highly integrated ICs such as RFIC and BB/MAC IC 125, which may operate under the IEEE 802.11n and IEEE 802.11a/b/g standards. Other chipset operating under different wireless standards may also be used. These ICs are not limited to those used in wireless application, but can include ICs such as memory, general purpose processors, or application specific ICs and System-on-Chips (SOCs). The stackup may also contain one or more passive components 130 that may be either a radio-frequency (RF) component that consume (but does not produce) energy, or a component that is incapable of a power gain. Examples of RF passive components may include capacitors, inductors, resistors, transformers, high-rejection multiband RF filters, multiplexers and baluns. Other passive components, such as an antenna 135, can be embedded within layers of the multilayer metals to achieve higher RF-performance. RF-signals from the silicon-integrated single chip such as RFIC 125 may be routed using the layers of high-performance materials 105 whereas digital signals may be routed using the layers of low-performance materials 110 through metal lines 140.
In various aspects of the present disclosure, a rolled version of high-performance liquid crystal polymer (LCP) materials may be used for embedding RF-actives and develop embedded RF-passives using the LCP-multi-metal-substrate layer structures. The rolled versions of LCP are typically less expensive than the original LCP materials. This allows the SOP form-factor (all x-, y-, z-directions) to be minimized by designing the optimized high-performance passive components in the LCP-type layers around the embedded active components. The LCP-type materials will allow the substrate materials to conform around the embedded active components and reduce the need for any surface protection around the embedded active components. Thin layers of LCP (≦25 μm thick) type materials may be used as re-distribution layers for efficient RF, analog- and digital-signal distribution to achieve small-form-factor. Lower-cost ABF-type materials may be used in the stackup to embed additional digital functionalities.
In some aspects of the present disclosure, a SOP stack of layers (e.g., as shown in FIG. 1) may be considered as having “small-form-factor” if at least one dimension of the overall SOP stack is less than or equal to around 0.5 mm. In some aspects of the present disclosure, a SOP stack of layers (e.g., as shown in FIG. 1) may be considered as having “small-form-factor”) if the thickness of each layer of high performance material and/or low performance material is less than or equal to around 25 μm. However, the foregoing stack and layer dimensions are not limiting to establish what is considered as “small” form factor. In some embodiments, the “small”-ness of the SOP stack may be defined in terms of devices (or categories of devices) within which the SOP stack is implemented. For example, with regard to desktop or laptop computers, an SOP stack may be considered as having small form factor if it can be implemented within a “netbook” computer. Similarly, for mobile devices, an SOP stack may be considered as having small form factor if it can be implemented within a cellular phone or a wearable device (e.g., glasses, wrist watch, etc.).
In some aspects of the present disclosure, layers of high performance material 105 and/or low performance material 110 in stack up 100 (of a SOP) may be flexible enough such that the layers are fully or partially foldable in one or more dimensions (e.g., in one or more of x-, y- and z-dimensions) without being fractured or broken due to folding. In such embodiments, active and/or passive components (e.g., components 115, 130, etc.) arranged between the layers of the SOP stack may be configured in a folded arrangement in a similar manner as the layers themselves. The operational functionality of the layers and components arranged therewithin in the folded arrangement may remain the same (and as such, unaffected) as in the unfolded arrangement (e.g., as shown in FIG. 1). An embodiment with the folded layers and component configuration may be used within an electronic device, such as a mobile device (a smartphone, a tablet computer, etc.), that may itself be configured to have different sizes or form factors. For example, such an electronic device may have a first form factor as a tablet computer (with screen size of around 8-10 inches), and may be configured with flexible/foldable screen and outer body such that the device can be reconfigured into a smaller second form factor as a smartphone (with screen size of around 4 or 6 inches). Within this exemplary electronic device, the SOP stack may be arranged such that, in the first “tablet” form factor, the layers and electronic components between the layers are in the unfolded configuration (e.g., as shown in FIG. 1), and in the second “smartphone” form factor, the layers and electronic components between the layers are in a folded configuration to be accommodated and operational (with the same functionalities) within the smaller form factor of the device.
In some aspects of the present disclosure, the SOP stack (e.g., as shown in FIG. 1) may be implemented within an RF front end (or communication module) of radio receivers and/or other transceiver ICs, as shown in FIG. 4. For example, the SOP stack may be embedded within the RF front end or communication module of (multi-) radio receivers of wireless devices such as tablet computers, wearable computing devices, cellular phones (based on well-known cellular technologies such as CDMA, EDGE, UMTS, OFDM, LTE, etc.), Wi-Fi receivers (based on well-known various IEEE 802.11 standards), etc. Generally, in a radio receiver circuit/module, the RF front end may include circuitry between the antenna and the first intermediate frequency (IF) stage. The RF front end may include components in the receiver that process the signal at the original incoming radio frequency, before the signal is converted to a lower intermediate frequency (IF). For example, the RF front end may include an impedance matching circuit, a band-pass filter (BPF), an RF filter, an RF amplifier, a local oscillator (LO), a mixer, and/or other components. Further, in radio receivers implemented within wireless devices such as tablet computers, wearable computing devices, cellular phones, Wi-Fi receivers, etc., the RF front end may include components from the antenna of the device to an analog-to-digital converter (ADC), which digitizes the signal for, e.g., IF filtering, demodulation, etc. Accordingly, in some embodiments, one or more of these RF front end components (e.g., in a multi-radio receiver) may be implemented within the layers of the SOP stack, as discussed above with regard to FIG. 1.
In accordance with various aspects of the present disclosure, the SOP as shown at 100 may be modified by including one or more heat dissipating elements. The one or more heat dissipating elements may be arranged within a homogenous stack of materials, such as a stack of materials having only high-performance material or only low-performance material. The one or more heat dissipating elements may also be arranged within a heterogeneous stack of materials, such as a stack having both high- and low-performance material. As shown in FIG. 1, the one or more heat dissipating elements, such as heatsink materials 150, can be arranged near the high-power active components to dissipate the heat generated by the active component. In a non-limiting example, the heat dissipating elements are in a layer above, or directly on top of, the active component. The heat dissipating element may be arranged between layers of the high-performance material or between layers of the high- and low-performance material. The heat dissipating elements may be a high-conductivity material, such as metal, and can include copper, aluminum, KOVAR (KOVAR is a trademark of Carpenter Technology Corporation and is a nickel-cobalt ferrous alloy designed to be compatible with the thermal expansion characteristics of borosilicate glass in order to allow direct mechanical connections over a range of temperature) and silicon carbide (SiC), or a directional conductor such as graphite, which dissipates heat in a two-dimensional (x-, y-) plane. Combination of different heat dissipaters and stacked via patterns, discussed further below, can be utilized for realizing optimal heat sinking structures. By this arrangement of the one or more heat dissipating elements within the small-form-factor SOP, the need for an external heat sink may be reduced or eliminated.
In accordance with various aspects of the present disclosure, thin sheets of thermal materials may be embedded in the LCP type materials due to the conformable properties of high-performance LCP. The thin sheets of copper, graphite, KOVAR, silicon-carbide, brass and other materials with good thermal properties may be embedded under ICs with high-power dissipation (such as PA) to enable thermal management within the SOP architectures and still maintain SFF properties. The LCPs can be set around the materials to conform and create SOPs without any voids or gaps. Graphite materials disperse heat in the X-Y direction and may be embedded in certain cases to spread the heat to thermal dissipators/metal-vias, discussed further below, to take the heat out from the embedded SOP structure.
FIG. 2 shows another cross-section of a SOP with both high-performance and low-performance polymer layers to form a stack of materials in accordance with various aspects of the present disclosure. FIG. 2 is similar to FIG. 1, but shows power amplifier 120, GaAs PA, mounted on top of the substrate. For small IC components such as GaAs PA, they need not be embedded since they do not occupy a large area on the substrate. A molding layer 205 may be arranged over the top-mounted component to encapsulate and protect the SOP.
FIG. 3a shows a cross-section of a SOP, which includes embedded isolation structures in accordance with various aspects of the present disclosure. The embedded isolation structures are configured and arranged to reduce noise coupling and crosstalk issues in a very small form factor SOP. Similar to the heat dissipating structure described above, the isolation structure may be arranged within a homogenous stack of materials, such as a stack of materials having only high-performance material or only low-performance material. Also, the isolation structures may also be arranged within a heterogeneous stack of materials, such as a stack having both high- and low-performance material. ICs are shown in FIG. 3a, IC1 (305), IC2 (310) and IC3 (315), arranged among the high-performance materials of the SOP. Also, one or more passive components 320 are shown embedded within layers of the high-performance material. Isolation structures 325 may be embedded within the SOP to reduce noise coupling and crosstalk issues in the SOP.
FIG. 3b shows vertical periodic micro-via structures A and B, taken along the lines A and B of FIG. 3a. The vertical micro-via structures 330 are configured and arranged to reduce element-to-element noise-coupling/crosstalk. The characteristic of the crosstalk isolation can be tuned by changing the periodicity of the vertical structures. FIG. 3c shows horizontal periodic isolation structures 335, taken along the line C of FIG. 3a. Both the vertical and horizontal structures may be combined to create improved isolation in the complete SOP environment. These isolation structures may be used to surround the radio or digital functional blocks in order to isolate the RF noise as well as harmonics of digital noise.
In some aspects of the present disclosure, faraday cages and horizontal electronic bandgap (EBG) structures using patterned metals may be used for the isolation structures. Moreover, the vertical periodic structures may also be combined with the horizontal EBG metal patterns to form effective noise reducers around desired parts of the SOP.
Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

## Claims

1. A device comprising:
a physical communication module configured to at least receive and process wireless radio frequency (RF) signals, the physical communication module comprising:
a physical platform arranged as a stack of layers comprising:
a first layer of the stack of layers having a first conformable material;
a second layer of the stack of layers having a second conformable material;
a third layer of the stack of layers having a third material, wherein the first conformable material and the second conformable material are different than the third material; and
one or more electronic components embedded within the stack of layers, wherein the one or more electronic components are configured to process a received wireless signal before a frequency of the wireless signal is converted to a lower frequency at the device,


wherein the stack of layers and the one or more electronic components are arranged to be in a folded configuration associated with a first form factor of the device, and in an unfolded configuration associated with a second form factor, different than the first form factor, of the device.

2. The device according to claim 1, further comprising:
a heat dissipating element configured to dissipate heat generating from the one or more electronic components.

3. The device according to claim 2, wherein the heat dissipating element is arranged between the first layer and the second layer.

4. The device according to claim 1, wherein the first conformable material and the second conformable material are the same material.

5. The device according to claim 1, wherein the first conformable material and the second conformable material are different materials.

6. The device according to claim 1, wherein the first conformable material, the second conformable material, or both include a polymer.

7. The device according to claim 1, wherein a thickness of the first layer, or the second layer, or both is less than or equal to 25 μm.

8. The device according to claim 1, wherein a thickness of the stack of layers is less than 0.5 mm.

9. The device according to claim 1, further comprising:
an isolation structure arranged within the stack of layers, and configured to reduce noise generated by any of the one or more electronic components, crosstalk between at least two of the one or more electronic components, or both.

10. The device according to claim 9, wherein the isolation structure includes a plurality of elements arranged in a periodic configuration, wherein an operational characteristic of the isolation structure is adaptable based on a period of the periodic configuration of the plurality of elements.

11. The device according to claim 1, wherein the one or more electronic components comprise at least one of an antenna, an impedance matching circuit, a band-pass filter (BPF), an RF filter, an RF amplifier, a local oscillator (LO) or a mixer.

12. A method comprising:
receiving and processing wireless radio frequency (RF) signals at a physical communication module of a device, wherein the physical communication module comprises:
a physical platform arranged as a stack of layers comprising:
a first layer of the stack of layers having a first conformable material;
a second layer of the stack of layers having a second conformable material;
a third layer of the stack of layers having a third material, wherein the first conformable material and the second conformable material are different than the third material; and
one or more electronic components embedded within the stack of layers, wherein the one or more electronic components are configured to process a received wireless signal before a frequency of the wireless signal is converted to a lower frequency at the device,


wherein the stack of layers and the one or more electronic components are arranged to be in a folded configuration associated with a first form factor of the device, and in an unfolded configuration associated with a second form factor, different than the first form factor, of the device.

13. The method according to claim 12, wherein the one or more electronic components comprise at least one of an antenna, an impedance matching circuit, a band-pass filter (BPF), an RF filter, an RF amplifier, a local oscillator (LO) or a mixer.

14. The method according to claim 12, wherein a thickness of the first layer, or the second layer, or both is less than or equal to 25 μm.

15. The method according to claim 12, wherein a thickness of the stack of layers is less than 0.5 mm.