Security barriers and scalable methods for forming them

Abstract

A method for forming a security barrier for a protected electronic device (104) is provided. The method comprises the steps of: stacking a convertible dielectric material layer (102) on the protected electronic device (104); and converting a target portion of the convertible dielectric material layer into at least one electrical circuit structure (110, 111) having at least one measurable electrical property. The method further comprises the step of stacking a thermally stabilized material layer (112) on the convertible dielectric material layer (102).

Description

Technology Field

[0001] (Cross-reference to related applications)

[0002] This application claims the benefit of U.S. Application No. 18 / 315,035 filed on May 10, 2023, the whole of which is incorporated herein by reference. Background Technology

[0003] The present disclosure relates to anti-tampering technology, and more specifically, to a physical barrier for protection having measurable electrical properties capable of indicating unauthorized access intended to inspect and / or modify a device under protection. Inspection may include, for example, performing imaging to counterfeit the device under protection. Modification may include, for example, replacing a part with a counterfeit part that may have reduced performance and quality. Additionally, modification may include the addition of instrumentation to record intellectual property embodied in software, firmware, or data on the device under protection. For example, malware that collects information without the product owner's knowledge may be installed on the counterfeit device. For example, signs of unauthorized access may be used to assess system integrity, serve as evidence of intellectual property theft, or serve as a signal indicating a gap in the device's provenance.

[0004] According to a non-limiting aspect, a method for forming a security barrier of an electronic device to be protected is provided. The method comprises the steps of: stacking a transformable dielectric material layer on the electronic device to be protected; and converting a target portion of the transformable dielectric material layer into at least one electrical circuit structure having at least one measurable electrical property. The method further comprises the step of stacking a thermal stabilizing material layer on the transformable dielectric material layer.

[0005] According to any prior embodiment, forming a security barrier involves establishing a mixing ratio of electrically conductive nanoparticles and electrically insulative nanoparticles in a convertible dielectric material layer.

[0006] According to any prior embodiment, the electrically conductive nanoparticles include silver (Ag) nanoparticles, and the electrically insulating nanoparticles include barium strontium titanate (BST) nanoparticles.

[0007] According to any prior embodiment, the convertible dielectric material layer is cured at 80°C for 15 minutes.

[0008] According to any prior embodiment, the step of converting a target portion of a convertible dielectric material layer includes performing a selective laser sintering (SLS) process to irradiate laser energy onto the convertible dielectric material layer to convert the target portion into at least one electrical circuit structure.

[0009] According to any prior embodiment, laser energy melts electrically conductive nanoparticles together to form an electrically conductive path defining at least one electrical circuit structure.

[0010] According to any prior embodiment, electrically insulating nanoparticles electrically isolate at least one electrical circuit structure from the rest of the convertible dielectric material layer.

[0011] According to any prior embodiment, the thermal stabilization material layer includes nanoparticles that hinder the formation of additional conductive pathways within the convertible dielectric material layer.

[0012] According to any prior embodiment, the nanoparticles include boron nitride (BN) nanoparticles.

[0013] According to any prior embodiment, the thermal stabilization material layer reduces at least one of the amount and size of air voids present in the convertible dielectric material layer.

[0014] According to any prior embodiment, reducing the amount of air voids includes filling the air voids with polymerized trimethylolpropane ethoxylate triacrylate.

[0015] According to any prior embodiment, the thermal stabilization layer is cured through ultraviolet (UV) exposure to suppress further changes in the security barrier layer at temperatures below 250°C.

[0016] According to a non-limiting embodiment, a security barrier for a protected electronic device is provided. The security barrier comprises a convertible dielectric material layer on the protected electronic device. The convertible dielectric material layer comprises a plurality of conductive nanoparticles and a plurality of insulating nanoparticles. The security barrier further comprises at least one electrical circuit structure and a thermal stabilization material layer. The at least one electrical circuit structure comprises a portion of the conductive nanoparticles and has at least one measurable electrical property. The thermal stabilization material layer covers the convertible dielectric material layer comprising the at least one electrical circuit structure.

[0017] According to any prior mode, at least one measurable electrical characteristic changes with changes in the electrical circuit structure.

[0018] According to any prior embodiment, at least one measurable electrical characteristic includes at least one of resistance, capacitance, and inductance.

[0019] According to any prior embodiment, at least one electrical circuit structure is located in a target portion of a convertible dielectric material layer, and the insulating nanoparticle electrically separates at least one electrical circuit structure from the rest of the convertible dielectric material layer.

[0020] According to any prior embodiment, the convertible dielectric material layer includes other electrical circuit structures.

[0021] According to any prior embodiment, the conductive nanoparticles include silver (Ag) nanoparticles, and the insulating nanoparticles include barium strontium titanate (BST) nanoparticles.

[0022] According to any prior embodiment, the heat-stabilizing material layer comprises boron nitride (BN) material and polymerized trimethylolpropane ethoxylate triacrylate material.

[0023] According to any prior embodiment, a convertible dielectric material layer and a thermal stabilization layer are combined to form a composite substrate comprising a combination of Ag particles, BST particles and BN particles.

[0024] Additional features and benefits are realized through the description in this disclosure. Other embodiments and aspects are described in detail in this specification and are considered to be part of the claimed disclosure. For a better understanding of the benefits and features of this disclosure, refer to the description and drawings. Brief explanation of the drawing

[0025] For a more complete understanding of the present disclosure, refer now to the following brief description in connection with the accompanying drawings and detailed description, where the same reference numerals denote the same elements: FIG. 1a illustrates an electronic device after stacking layers of deformable dielectric material according to a non-limiting aspect of the present disclosure. FIG. 1b illustrates a deformable dielectric material layer formed on the surface of an electrical device according to a non-limiting aspect of the present disclosure. FIG. 2a illustrates a deformable dielectric material of FIG. 1 in which a portion of the deformable dielectric material layer is converted into an electrical circuit structure by applying a laser sintering process to the deformable dielectric material layer according to a non-limiting aspect of the present disclosure. FIG. 2b illustrates a deformable dielectric material layer after a laser sintering process that converts a portion of the deformable dielectric material layer into an electrical circuit structure according to a non-limiting aspect of the present disclosure. FIG. 2c illustrates an example of an electrical circuit structure that is a converted portion of a convertible dielectric material layer according to a non-limiting aspect of the present disclosure. FIG. 3a illustrates the electrical circuit structure of FIG. 2 after a heat-stabilizing ink is laminated onto a deformable dielectric material layer having an electrical circuit structure according to a non-limiting aspect of the present disclosure. Figure 3b shows the state after a curing process is performed on a deformable dielectric material layer containing an electrical circuit structure and a stabilizing ink is laminated thereon. FIG. 4a shows a measurement of a converted electrical circuit structure present in an unmodulated barrier layer according to a non-limiting aspect of the present disclosure. FIG. 4b shows a measurement of a converted electrical circuit structure present in a modulated barrier layer according to a non-limiting aspect of the present disclosure. FIG. 5 is a flowchart illustrating a method for manufacturing a security barrier according to a non-limiting aspect of the present disclosure. Specific details for implementing the invention

[0026] Existing solutions for creating security barriers with measurable electrical properties fall into two categories: (1) attaching a prefabricated security barrier to an electronic assembly containing the device to be protected; or (2) laminating one or more layers of material composed of a combination that form a security barrier covering the device to be protected. Solutions in the first category typically involve separately prefabricating a physical structure containing electrical circuit elements (and other functions) and attaching (mechanically and electrically) the prefabricated structure to a circuit card assembly (CCA) to cover or surround the interconnection with the device to be protected. The first category of approaches also typically requires customizing the design of the electronic assembly containing the device to be protected in order to integrate electrical and mechanical interfaces into the prefabricated cover. Practical applications of the first category of approaches are currently limited to barrier structures on the scale of a CCA; however, the scope of application can be expanded to include barrier structures attached via three-dimensional heterogeneous integration (3DHI) manufacturing methods. Considering size, weight, power, and cost (SWaP-C), the usefulness of this first category of solutions may be limited.

[0027] Solutions in the second category generally cover or surround interconnections to target devices using layers of material (which may include electrical circuit elements and other functions) that are deposited through fabrication or manufacturing processes. One or more layers are combined to form a protective barrier for the device being protected, exhibiting measurable electrical / mechanical properties. The deposition methods used in solutions of the second category are very diverse, such as 3D printing of conductive or resistive inks to create circuit structures and photolithography to deposit metal layers in integrated circuit manufacturing processes.

[0028] Various non-limiting aspects of the present disclosure provide a physical barrier for protection having measurable electrical properties capable of indicating unauthorized access to inspect and / or modify a device under protection, and a method for manufacturing the same. The security barrier comprises, for example, a deformable or convertible dielectric material such as silver-barium-strontium-titanate (Ag-BST) ink. Then, a sintering process is applied to the convertible dielectric material to convert selected portions of the dielectric material into electrically conductive structures or structures having measurable electrical properties, such as resistance, capacitance, or inductance, which can be incorporated into an electrical circuit. The sintering process may be performed, for example, using laser energy. The sintering process aims to create electrically conductive structures(s) such that the electrical properties of the structures(s) are altered or damaged due to tampering or other unauthorized attempts to physically access the device under protection. The electrical properties of a structure formed through the aforementioned process can be measured in various ways, such as, for example, by integrating the structure into an electrical circuit and comparing the circuit's electrical response with an expected electrical response (established at the time of initial manufacturing). In this manner, the present disclosure provides a method for creating a security barrier by selectively converting a portion of a dielectric material layer into a conductive structure having measurable electrical properties that change when a malicious actor attempts to access a protected device.

[0029] The security barrier method described herein is extended to individually solve a wider range of problems than could be individually solved by previously known methods. In terms of size, for example, the material properties of the aforementioned dielectric ink layer allow for the creation of security barriers for small devices, such as security barriers covering the back of a semiconductor die by sintering into an electrically conductive structure, or for large assemblies, such as single-board computers or CCAs. One or more methods described herein may be applied to various electrical devices and components, including but not limited to microelectronic manufacturing wafers, dies attached to a substrate, printed circuit board (PCB) layers, package (lid) components, and CCAs, and may be used to create security barriers for commercial-off-the-shelf (COTS) devices or assemblies as well as custom microelectronic devices or assemblies. In terms of lifecycle, for example, this method may be applied to microelectronic wafer processing, PCB manufacturing steps (to form a security barrier under the device), or finished microelectronic assemblies. Furthermore, for a single microelectronic assembly or device, extending this method allows for the creation of a single security barrier or multiple spatially distributed security barriers of different sizes. Additionally, since the transformed circuit changes can be controlled via the sintering process (e.g., software used in the sintering tool), not only component-to-component changes but also CCA-to-CCA changes can be achieved during wafer manufacturing.

[0030] Now, returning to FIGS. 1a and 1b, an electronic device (100) after a deformable dielectric material (102) has been laminated onto a surface (104) is illustrated in accordance with a non-limiting aspect of the present disclosure. As described herein, the processed electronic device (100) may include, but is not limited to, a microelectronic manufacturing wafer, a die attached to a substrate, a PCB layer, a component with packaging and / or a lid, an integrated circuit (IC) chip, and a circuit card assembly.

[0031] In FIGS. 1a and 1b, the deformable dielectric material (102) is depicted as an "insulating phase" existing before the sintering process is applied, as described in more detail below. Various lamination methods, including but not limited to direct printing, spin coating, or spraying, may be used to laminate the deformable dielectric material onto the surface (104) of the electronic device. Although a single layer of the deformable dielectric material (102) is depicted, it should be understood that additional layers of deformable dielectric material may be laminated onto the device (100) without departing from the scope of the invention.

[0032] Referring further to FIG. 1b, the deformable dielectric material is also referred to as "transformable ink" or "composite functional ink." In one or more non-limiting embodiments, the deformable dielectric material is a silver-barium strontium titanate (Ag-BST) composite ink comprising a mixture of electrically conductive silver (Ag) nanoparticles (200) and electrically insulating barium strontium titanate (BST) nanoparticles (202). According to non-limiting embodiments, the Ag nanoparticles (200) may have a size in the range of, for example, about 75 nanometers (nm) to about 85 nm, and the BST nanoparticles (202) may have a size in the range of, for example, about 80 nm to about 100 nm. In one or more non-limiting embodiments, the mixing ratio of Ag nanoparticles (200) and BST nanoparticles (202) can be optimized to obtain an insulating phase when the Ag nanoparticles (200) and BST nanoparticles (202) are first deposited on the surface (104) and undergo a curing process (e.g., curing at 80°C for about 15 minutes) to stabilize the arrangement of Ag nanoparticles (200) and BST nanoparticles (202).

[0033] Returning to FIG. 2a, the deformable dielectric material (102) is illustrated to undergo a sintering process, after which the sintered material forms a "highly conductive phase." The sintering process may include a selective laser sintering (SLS) process, which strikes a selected or targeted portion of the deformable dielectric material (102) with laser energy (106) output from a laser sintering tool (108). The laser energy (106) generates a temperature exceeding 150 °C (about 300 °F) at the targeted portion of the deformable dielectric material (102), causing the Ag nanoparticles (200) to melt and fuse, and, as illustrated in FIG. 2b, thereby converting the heated portion from an electrically insulated state to an electrically conductive state. Accordingly, a selectively modified portion of the convertible dielectric material (102) forms a conductive trace (110) having various measurable electrical properties such as resistance, capacitance, or inductance, which can be integrated into an electrical circuit. FIG. 2c illustrates the convertible dielectric material (102) after a laser sintering process. As illustrated, the targeted portion of the convertible dielectric material is converted into a serrated profile conductive trace (110) that forms a resistor.

[0034] As discussed herein, since the measurable electrical properties of a conductive trace (110) are derived from the physical properties of the trace (e.g., line width, line thickness), if the conductive trace (110) is altered due to tampering or other causes of damage, a measurable change occurs in the electrical properties of the conductive trace (110). In this way, if a sintering process is used to convert a portion of the convertible dielectric material (102) into a conductive trace (110) covering the device to be protected, a security barrier is formed, and unauthorized physical access to the device to be protected alters the physical properties of the trace (110), thereby altering the electrical properties in a measurable manner. Although a single conductive trace (110) is illustrated, it should be understood that additional conductive traces can be formed from the convertible dielectric material (102) without departing from the scope of the invention. In addition to the conductive trace, one or more conductive pads (111) may be optionally formed using the method of forming the conductive trace described herein. The conductive pad (111) may provide access to an electrical measuring tool (e.g., an ohmmeter) to facilitate measuring the electrical characteristics of a given trace (110). The conductive pad (111) described herein represents one example of electrically connecting a conductive trace to another electrical or electronic device using the method of forming a conductive trace described herein. In one or more non-limiting embodiments, the SLS process described herein may be used to form a conductive trace, which is electrically connected to an existing pad of an underlying device (104).

[0035] In one or more non-limiting embodiments, the laser sintering tool (108) may store a design layout that controls the operation of the laser sintering tool (108). Additionally, operating parameters of the laser sintering tool (108), such as laser energy power, laser wavelength, and raster speed, may be adjusted, for example, when forming an electrical circuit structure. In this way, the electrical properties of the conductive trace (110) can be adjusted to achieve target electrical properties. Additionally, the target area and / or design of the conductive trace (110) may be selected and formed accordingly. Thus, various types of conductive traces with various shapes and profiles can be formed.

[0036] In one or more non-limiting embodiments, adjusting the operating parameters of the sintering tool may make parts of the conductive trace wider or wider and thicker. The trace may be designed to generate complex impedances and may be connected to individual electronic components that are part of an assembly. By adjusting the operating parameters to configure line width, spacing, and trace thickness, one may also create arbitrarily unique barrier structures that can be utilized for authentication (integrity) and / or confidentiality strategies. The sintering tool (108) may also be programmed to perform patterned laser scans (e.g., using software), which may be dynamically changed and rapidly modified to accommodate part-to-part changes.

[0037] Now, returning to FIGS. 3a and 3b, the security barrier of FIG. 2 is illustrated after a thermally stabilized ink (112) has been laminated over a deformable dielectric material (102) and a conductive trace (110). The thermally stabilized ink (112) is formed from various non-conductive, heat-resistant materials, such as boron nitride (BN), for example, and contains nanoparticles that fill most of the air voids in the barrier layer containing the deformable dielectric material (102) and the conductive trace (110). The thermally stabilized ink (112) can be laminated using various lamination techniques, such as direct writing printing, spin coating, or spraying. Once the thermally stabilized ink (112) is laminated, it undergoes a curing process to cure the thermally stabilized ink (112). The curing process of the thermally stabilized ink (112) can be achieved by exposing the thermally stabilized ink (112) to ultraviolet (UV) energy. By curing the heat-stabilizing ink (112), changes that occur when the convertible dielectric material (102) and the conductive trace (110) are exposed to high temperatures (e.g., solder reflow) can be prevented.

[0038] Referring to FIG. 3b, the cured heat-stabilized ink (112) is described in more detail. In this embodiment, the heat-stabilized ink (112) introduces larger BN particles (206) into the air pores of a convertible dielectric material (102) having a conductive trace (110). Once cured, the BN nanoparticles prevent further melting or aggregation of Ag nanoparticles, thereby preventing the formation of additional conductive pathways that may occur due to subsequent heat exposure, etc., in locations not originally targeted in the initial SLS process, for example, in un-SLS treated areas of the convertible dielectric material (102). Thus, the combination of the heat-stabilized ink (112) and the convertible dielectric material (102) forms a composite substrate comprising a combination of Ag particles (200), BST particles (202), and BN particles (206).

[0039] UV-cured heat-stabilized ink fills air voids with polymerized trimethylolpropane ethoxylate triacrylate to reduce the amount of air voids present in the convertible dielectric material layer (102), thereby minimizing the possibility of an increase in the particle size of AG nanoparticles (200) that may occur when the heat-insulating film (112) is exposed to a subsequent heat source.

[0040] As described in this specification, an electrical circuit structure (110) created by selectively converting a convertible dielectric material layer has measurable electrical characteristics (e.g., resistance, capacitance, current output, voltage output, etc.) that change when the electrical circuit structure inside the barrier layer (110) is damaged, modulated / modulated, or compromised. In this way, modulation of the electrical device (100) can be detected by measuring the characteristics of the electrical circuit structure (110) and comparing them with expected electrical characteristics (e.g., measured at the time of initial manufacture of the electrical device).

[0041] In one or more non-limiting embodiments, the electrical characteristics or properties of the conductive trace (110) can be measured by connecting the trace and possible other circuit elements to a logic device (not shown), which is programmed to drive the formed electrical circuit and measure the electrical response. Thus, the generated subsystem can be used to compare the response measured at a specific point in the system lifecycle with the measurement response recorded at the time of manufacture.

[0042] According to another embodiment, the conductive trace (110) may be designed to detect an open circuit or short circuit that was not present at the time of initial manufacture of the electronic device (100) using an electrical measuring instrument (e.g., a probe, an ohmmeter, a voltage meter, etc.). FIG. 4 illustrates, for example, an ohmmeter measurement of an undamaged conductive trace (110) present in an undamaged barrier layer (102). In this example, the undamaged conductive trace (110) provides a finite resistance measurement of Ω. However, FIG. 4b shows an ohmmeter measurement of a conductive trace (110) damaged due to a modulation event (150). In this example, the ohmmeter indicates the damaged conductive trace as an open circuit (OC). Thus, it can be determined that unauthorized modulation and / or damage has occurred to the electrical device (100). It should be understood that damage caused by the modulation event may have caused the measured resistance to change from its original value to a different finite value, or that the measured value may have changed similarly due to the modulation event (150) even when using a different electrical measurement method.

[0043] Returning to FIG. 5, a method for manufacturing a security barrier according to a non-limiting aspect of the present disclosure is illustrated. The method begins at step (500), and at step (502), a convertible dielectric material layer is deposited on the device to be protected. As described herein, the layer is formed from a deformable Ag-BST composite ink cured at 80°C for about 15 minutes. In step (504), one or more targeted portions of the barrier layer are converted from a dielectric insulating phase to a conductive phase through a sintering process to form a conductive trace that can be integrated into an electrical circuit(s). As described herein, an SLS process may be performed using laser energy to precisely form the conductive trace. In step (506), a thermally stabilized ink is deposited on the convertible dielectric material and the conductive trace. In one or more non-limiting aspects, the thermally stabilized ink is formed from a material containing polymerized trimethylolpropane ethoxylate triacrylate and BN particles. In step (508), the heat-stabilizing ink is cured to fix the conductive trace and prevent the convertible dielectric material from further converting into a conductive phase (e.g., using UV energy). This method ends in step (510), at which point the electrical structure forms a security barrier over the device to be protected.

[0044] In the claims below, the functional element plus any means or steps, and the corresponding structures, materials, operations, and equivalents, mean any structures, materials, or operations for performing a function together with other claimed elements as explicitly claimed. The description of this disclosure is presented for illustrative and illustrative purposes, but is not intended to be limited to or comprehensive only to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments are selected and described so that those skilled in the art may understand the disclosure in various embodiments having various modifications suitable for the specific use being considered, as they best illustrate the principles and practical applications of this disclosure.

[0045] Although preferred embodiments of the present disclosure have been described, those skilled in the art will understand that various improvements and enhancements may be made now and in the future within the scope of the following claims. These claims should be interpreted to maintain adequate protection for the disclosure originally described.

Claims

Claim 1 A method for forming a security barrier for a protected electronic device, wherein the method comprises: a step of stacking a convertible dielectric material layer on the protected electronic device; a step of converting a target portion of the convertible dielectric material layer into at least one electrical circuit structure having at least one measurable electrical characteristic; and a step of stacking a thermally stabilized material layer on the convertible dielectric material layer. Claim 2 A method for forming a security barrier of a protected electronic device according to claim 1, wherein forming the security barrier comprises establishing a mixing ratio of electrically conductive nanoparticles and electrically insulating nanoparticles in the convertible dielectric material layer. Claim 3 A method for forming a security barrier for an electronic device to be protected, wherein, in paragraph 2, the electrically conductive nanoparticles comprise silver (Ag) nanoparticles and the electrically insulating nanoparticles comprise barium strontium titanate (BST) nanoparticles. Claim 4 A method for forming a security barrier of a protected electronic device, wherein, in paragraph 2, the convertible dielectric material layer is cured at 80°C for 15 minutes. Claim 5 A method for forming a security barrier for a protected electronic device, wherein, in paragraph 2, the step of converting a target portion of the convertible dielectric material layer comprises performing a selective laser sintering (SLS) process to irradiate laser energy onto the convertible dielectric material layer to convert the target portion into at least one electrical circuit structure. Claim 6 A method for forming a security barrier for a protected electronic device according to claim 5, wherein the laser energy melts electrically conductive nanoparticles together to form an electrically conductive path defining at least one electrical circuit structure. Claim 7 A method for forming a security barrier for a protected electronic device according to claim 6, wherein the electrically insulating nanoparticles electrically isolate at least one electrical circuit structure from the rest of the convertible dielectric material layer. Claim 8 A method for forming a security barrier for a protected electronic device according to claim 1, wherein the thermal stabilization material layer comprises nanoparticles that hinder the formation of additional conductive paths within a convertible dielectric material layer. Claim 9 A method for forming a security barrier for an electronic device to be protected, wherein, in claim 8, the nanoparticles comprise boron nitride (BN) nanoparticles. Claim 10 A method for forming a security barrier of a protected electronic device according to claim 1, wherein the thermal stabilization material layer reduces at least one of the amount and size of air voids present in a convertible dielectric material layer. Claim 11 A method for forming a security barrier of a protected electronic device according to claim 10, wherein reducing the amount of the air voids comprises filling the air voids with polymerized trimethylolpropane ethoxylate triacrylate. Claim 12 A method for forming a security barrier of a protected electronic device according to claim 11, wherein the heat-stabilizing material layer is cured through ultraviolet (UV) exposure to suppress further changes in the security barrier layer at a temperature of less than 250°C. Claim 13 A security barrier for a protected electronic device, wherein the security barrier comprises: a convertible dielectric material layer stacked on the protected electronic device, wherein the convertible dielectric material layer comprises a plurality of conductive nanoparticles and a plurality of insulating nanoparticles; at least one electrical circuit structure comprising a portion of the conductive nanoparticles, wherein the at least one electrical circuit structure has at least one measurable electrical characteristic; and a thermal stabilization material layer covering the convertible dielectric material layer, wherein the thermal stabilization material layer comprises at least one electrical circuit structure. Claim 14 A security barrier of an electronic device to be protected, wherein, in paragraph 13, at least one measurable electrical characteristic changes according to a change in the electrical circuit structure. Claim 15 A security barrier for an electronic device to be protected, wherein, in paragraph 14, the at least one measurable electrical characteristic comprises at least one of resistance, capacitance, and inductance. Claim 16 A security barrier for a protected electronic device according to claim 13, wherein at least one electrical circuit structure is located in a target portion of a convertible dielectric material layer, and the insulating nanoparticle electrically isolates at least one electrical circuit structure from the rest of the convertible dielectric material layer. Claim 17 A security barrier of a protected electronic device, wherein the convertible dielectric material layer comprises another electrical circuit structure in paragraph 16. Claim 18 A security barrier for an electronic device to be protected, wherein, in paragraph 13, the conductive nanoparticles comprise silver (Ag) nanoparticles and the insulating nanoparticles comprise barium strontium titanate (BST) nanoparticles. Claim 19 A security barrier of a protected electronic device, wherein, in paragraph 18, the thermal stabilization material layer comprises a boron nitride (BN) material and a polymerized trimethylolpropane ethoxylate triacrylate material. Claim 20 A security barrier for a protected electronic device according to claim 19, wherein the convertible dielectric material layer and the thermally stabilized material layer are combined to form a composite substrate comprising a combination of Ag particles, BST particles and BN particles.

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