Security protection device and device protection system

Abstract

To provide a security protection device and a device protection system that make it possible to reduce the visibility of protective wiring patterns and simplify the security structure.SOLUTION: A security protection device covers a logic device mounted on an electronic substrate. The security protection device includes a base member made of a non-conductor and having transparency, a base pattern, and a wiring pattern. The base pattern is made of a metal having lower conductivity than the wiring pattern. The wiring pattern includes a circuit wiring section in which a first circuit section in which a first resistance pattern and a second resistance pattern are connected in series, and a second circuit section in which a third resistance pattern and a fourth resistance pattern are connected in series are connected in parallel. The circuit wiring section forms a bridge circuit with a resistance component of the logic device, the resistance component being connected between a connection point between the first resistance pattern and the second resistance pattern and a connection point between the third resistance pattern and the fourth resistance pattern.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a security protection device and a device protection system for protecting a device mounted on an electronic board. [Background technology]

[0002] In an environment where multiple companies and personnel are involved in product development, there are concerns about the risk of confidential information leaking or unexpected risks (so-called incident risks) due to careless mistakes or lack of security awareness by employees. Furthermore, in recent years, there has been an increase in cases where internal company personnel intentionally leak internal information. In order to protect highly confidential information under these circumstances, it is urgent to popularize an environment in which unauthorized persons cannot access technology development boards, etc.

[0003] In view of these circumstances, integrated circuits and the like are equipped with security protection devices such as protective shields to enhance security. The main types of protective shields used in integrated circuits are static shields and dynamic shields. A static shield is an internal protection technology that physically shields an IC core from the outside by laying out strips of plate-like material. A dynamic shield is an internal protection technology that detects physical interference with an IC core. Both types of protective shields are incorporated into and mounted on an IC core during the integrated circuit manufacturing process (pre-process) (see, for example, Patent Documents 1 and 2).

[0004] Patent Document 1 discloses a technology for detecting when dynamic shield wiring (geometric wiring) arranged on the surface of an IC card microcomputer is cut. Patent Document 2 discloses a semiconductor device having a meander-shaped wiring conductor and a meander-shaped dummy wiring conductor arranged nearby on the surface opposite to the surface on which the electronic circuit is formed, and a detection circuit for detecting a short circuit between the wiring conductor and the dummy wiring conductor. Furthermore, for example, conventional security chips used in financial institution cards and transportation cards incorporate a protective shield for detecting tampering in a pre-process of IC chip manufacturing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-206680 [Patent Document 2] Japanese Patent Publication No. 2022-99881 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional protective shields such as those disclosed in Patent Documents 1 and 2 cannot reduce the motivation to analyze because the wiring pattern can be easily seen from the outside. Furthermore, such conventional protective shields require a separate component for detecting breaks, shorts, etc. in the wiring pattern, which makes the structure complicated.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a security protection device and a device protection system that reduce the visibility of protective wiring patterns and simplify the security structure. [Means for solving the problem]

[0008] A security protection device according to one embodiment of the present invention is a security protection device mounted to cover a logic device mounted on an electronic board, and includes: a transparent, plate-shaped base member made of a non-conductor; a base pattern formed on a surface of the base member facing the logic device; and a wiring pattern formed on the base pattern. The base pattern and the wiring pattern are arranged at least in an area facing the logic device. The base pattern is formed of a metal having a lower conductivity than the wiring pattern and in a similar arrangement to the wiring pattern. The wiring pattern includes a circuit wiring portion connected in parallel to a first circuit portion in which a first resistor pattern connected to the positive side of a power supply device and a second resistor pattern connected to the negative side of the power supply device are connected in series; and a second circuit portion in which a third resistor pattern connected to the positive side of the power supply device and a fourth resistor pattern connected to the negative side of the power supply device are connected in series. The circuit wiring portion forms a bridge circuit between a connection point between the first resistor pattern and the second resistor pattern and a connection point between the third resistor pattern and the fourth resistor pattern.

[0009] A device protection system according to one aspect of the present invention includes the security protection device described above and a logic device mounted on an electronic board and covered by the security protection device. [Effects of the Invention]

[0010] According to the present invention, a base pattern is interposed between the base member and the wiring pattern, and the resistance component of the logic device mounted on the electronic board forms a bridge circuit together with the wiring pattern, thereby reducing the visibility of the protective wiring pattern and achieving a simplified structure for security purposes. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing an example of a state in which a security protection device according to an embodiment of the present invention is mounted on an electronic board; [Figure 2]FIG. 2 is a configuration diagram illustrating the wiring pattern side of the security protection device of FIG. 1. [Figure 3] FIG. 2 is a schematic cross-sectional view taken along line NN in FIG. [Figure 4] 2 is a circuit diagram illustrating a bridge circuit configured by the security protection device of FIG. 1 etc. and a resistance component of a logic device. FIG. [Figure 5] 10A and 10B are explanatory diagrams conceptually illustrating area expansion by a spiral portion based on a right-angled triangle in a circuit wiring portion according to an embodiment of the present invention; [Figure 6] FIG. 10 is a schematic diagram showing another wiring pattern (basic configuration example) of the security protection device according to the embodiment of the present invention. [Figure 7] 10 is a schematic diagram showing another wiring pattern (application example) in the security protection device according to the embodiment of the present invention. FIG. [Figure 8] 10 is a configuration diagram showing another example of a state in which the security protection device according to the embodiment of the present invention is mounted on an electronic board. FIG. [Figure 9] 1 is an explanatory diagram illustrating a dummy wiring section including a disconnection section (gap) of a security protection device according to an embodiment of the present invention; [Figure 10] 10 is an explanatory diagram illustrating, at a lower magnification, the location of a disconnection (gap) in the dummy wiring portion of FIG. 9 and its surroundings. FIG. [Figure 11] 2 is a block diagram illustrating a schematic example of the functional configuration of the logic device shown in FIG. 1 etc. FIG. [Figure 12] FIG. 10 is an explanatory diagram illustrating an example of a state in which a wiring pattern analysis is performed on the security protection device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiment A security protection apparatus and a device protection system according to an embodiment of the present invention will be described with reference to Figures 1 to 12. In each figure (with some exceptions), x, y, and z axes are shown to clarify the correspondence between components. In some figures, some reference numerals are omitted to avoid complexity.

[0013] As illustrated in FIGS. 1 and 8, the security protection device 100 is mounted so as to cover a logic device 80 mounted on an electronic board 90. The security protection device 100 has a transparent, plate-shaped base member 10 made of a non-conductor (insulator), and a base pattern 20 formed on the surface of the base member 10 facing the logic device 80. The base member 10 may be a colorless, transparent member, or a colored, transparent member. The transparency of the base member 10 may be adjusted as appropriate depending on the application situation, etc.

[0014] 2, 3, 6, and 7, the security protection device 100 has a wiring pattern 30 formed on a base pattern 20. The security protection device 100 is disposed so that the surface on which the base pattern 20 is formed faces the electronic board 90, and is mounted on the electronic board 90 so that the surface opposite the base pattern 20 faces outward. Therefore, when the security protection device 100 is mounted on the electronic board 90 as shown in FIGS. 1 and 8, the wiring pattern 30 cannot be seen from the outside. The base pattern 20 and the wiring pattern 30 are disposed in at least an area facing the logic device 80, and also play a role in obstructing the visibility of the logic device 80.

[0015] The electronic substrate 90 has a wiring pattern formed on at least one surface, and various electronic components including the logic device 80 are mounted thereon. The electronic substrate 90 is a concept that includes packages such as semiconductor packages. The logic device 80 is, for example, an FPGA (Field Programmable Gate Array), and the design of the logic circuit can be rewritten after the fact. In other words, the logic device 80 is a device whose logic circuit structure can be changed and redefined depending on the application. The logic device 80 is mounted on the electronic substrate 90 using a joining material 81 such as solder.

[0016] The base member 10 is formed, for example, from a glass substrate. The base pattern 20 is formed of a metal with lower conductivity (higher resistance) than the wiring pattern 30 and in the same arrangement as the wiring pattern 30. The base pattern 20 also functions to increase the connection strength between the base member 10 and the wiring pattern 30. The base pattern 20 is formed, for example, from chromium (Cr). Considering reverse engineering using chemicals, the material for the base pattern 20 is preferably a metal that dissolves and peels off in the same way as copper. Experiments using chemicals to peel the base pattern 20 and the wiring pattern 30 from the base member 10 confirmed that, in the case of gold and copper, even when the copper was completely peeled off, the gold remained on the base member 10. In the security protection device 100, it is preferable to perform plasma treatment on one side of the base member 10 and form the base pattern 20 thereon to increase the adhesion of the base pattern 20. The wiring pattern 30 is made of, for example, copper (Cu) and is formed on the surface of the base pattern 20 .

[0017] Here, the "similar arrangement" of the base pattern 20 and the wiring pattern 30 includes not only a case where the pattern shapes thereof are completely identical, but also a case where the wiring pattern 30 includes a disconnection (e.g., disconnection portion V) or a case where the wiring elements of the wiring pattern 30 are thinner than the base elements of the base pattern 20. An example of a configuration in which the wiring elements of the wiring pattern 30 are thinner than the base elements of the base pattern 20 is a case where multiple wiring elements are formed on a single base element. In this way, by concealing the wiring pattern 30 with the base pattern 20, it is possible to create an illusion of the connection details of the wiring pattern 30, such as when a portion that appears connected from the surface is not connected on the wiring pattern 30 side, or when what appears to be a single wire is actually multiple wires on the wiring pattern 30 side.

[0018] As illustrated in Fig. 3, the device protection system 200 includes a security protection apparatus 100 and a logic device 80. The logic device 80 is mounted on an electronic board 90 and covered by the security protection apparatus 100. In other words, the security protection apparatus 100 is disposed facing the surface of the logic device 80 opposite to the side mounted on the electronic board 90, so as to cover the entire surface. Fig. 3 shows only a schematic configuration of the base pattern 20, wiring pattern 30, etc., and omits, for example, gaps between the base pattern 20 and wiring pattern 30, wiring on the electronic board 90, etc.

[0019] 4, the wiring pattern 30 has a circuit wiring section 40 in which a first circuit section 41 and a second circuit section 42 are connected in parallel. The first circuit section 41 is formed by connecting a first resistor pattern R1 connected to the positive side of a power supply device 95 in series with a second resistor pattern R2 connected to the negative side of the power supply device 95. The second circuit section 42 is formed by connecting a third resistor pattern R3 connected to the positive side of the power supply device 95 in series with a fourth resistor pattern R4 connected to the negative side of the power supply device 95.

[0020] The device protection system 200 configures a bridge circuit (a so-called Wheatstone bridge circuit) with a first resistor pattern R1, a second resistor pattern R2, a third resistor pattern R3, a fourth resistor pattern R4, and a resistance component R5 of the logic device 80. That is, the circuit wiring unit 40 configures a bridge circuit with the resistance component R5 of the logic device 80 connected between connection point B and connection point D. Connection point B is a point where the first resistor pattern R1 and the second resistor pattern R2 are connected. Connection point D is a point where the third resistor pattern R3 and the fourth resistor pattern R4 are connected. Connection point A is a point where the first resistor pattern R1 and the third resistor pattern R3 are connected, and is connected to the positive side of the power supply device 95. Connection point C is a point where the second resistor pattern R2 and the fourth resistor pattern R4 are connected, and is connected to the negative side of the power supply device 95.

[0021] 2, one end 1a of the first resistor pattern R1, one end 3a of the third resistor pattern R3, one end 2a of the second resistor pattern R2, one end 4a of the fourth resistor pattern R4, the other end 3b of the third resistor pattern R3, and the other end 4b of the fourth resistor pattern R4 are each formed in a brush-like shape in a plan view. In the circuit wiring section 40, one end 1a of the first resistor pattern R1 and one end 3a of the third resistor pattern R3 are adjacent to each other, one end 2a of the second resistor pattern R2 and one end 4a of the fourth resistor pattern R4 are adjacent to each other, and the other end 3b of the third resistor pattern R3 and the other end 4b of the fourth resistor pattern R4 are adjacent to each other, and the brush portions of the adjacent ends are arranged alternately. 2 has an other-end pad 12b consisting of the other end 1b of the first resistor pattern R1 and the other end 2b of the second resistor pattern R2. Note that the dashed line indicating the boundary between the other end 1b and the other end 2b in FIG. 2 is for convenience's sake.

[0022] The device protection system 200 has a coupling conductor 70a that connects one end 1a and one end 3a and is joined to the positive side of the power supply 95, and a coupling conductor 70b that is joined to the other end pad 12b and one end of the logic device 80. The device protection system 200 has a coupling conductor 70c that connects one end 2a and one end 4a and is joined to the negative side of the power supply 95, and a coupling conductor 70d that connects the other end 3b and the other end 4b and is joined to the other end of the logic device 80.

[0023] Because the connecting conductors 70a to 70d have the same configuration, they will be hereinafter referred to collectively as connecting conductor 70. The security protection device 100 is connected to four conductive portions 91 on the electronic substrate 90 via the four connecting conductors 70. The connecting conductors 70 are made of resistors made of ceramic, for example. It is preferable to use resistors with as low a resistance value as possible for the connecting conductors 70. The above-mentioned connection point A corresponds to the connecting conductor 70a, connection point B corresponds to the connecting conductor 70b, connection point C corresponds to the connecting conductor 70c, and connection point D corresponds to the connecting conductor 70d.

[0024] More specifically, the linking conductors 70a to 70d are connected at connection points A, B, C, and D, respectively, using conductive resin (not shown). Furthermore, the linking conductors 70a to 70d are each connected to a conductive section 91 on the electronic substrate 90 via a joining member (not shown) such as solder. The conductive section 91 to which the linking conductors 70b and 70d are joined is connected to the logic device 80 via wiring on the electronic substrate 90. Resin 83 is filled between the electronic substrate 90 and the security protection device 100. As the resin 83, a synthetic resin such as resin can be suitably used.

[0025] [Shapes of the circuit wiring portion 40 and the dummy wiring portion 50] Next, examples of the shapes and variations of the circuit wiring section 40 and the dummy wiring section 50 in a plan view will be described with reference to Figures 1, 2, and 5 to 8. The wiring patterns 30 illustrated in Figures 2, 6, and 7 each have a circuit wiring section 40 and a dummy wiring section 50. The circuit wiring section 40 and the dummy wiring section 50 are formed in the same arrangement as the base pattern 20.

[0026] In the circuit wiring section 40, each resistor pattern (first resistor pattern R1, second resistor pattern R2, third resistor pattern R3, and fourth resistor pattern R4) is formed so that multiple wiring elements extending linearly with a predetermined width are connected to form a continuous line at different angles at their ends. That is, in the portion of the base pattern 20 corresponding to each resistor pattern, multiple base elements extending linearly with a predetermined width are connected to form a continuous line at different angles at their ends, and the circuit wiring section 40 is formed in that portion. Each resistor pattern may include a partially branched portion. Similarly, the base pattern 20 may include a partially branched portion.

[0027] In the first resistor pattern R1, the second resistor pattern R2, the third resistor pattern R3, and the fourth resistor pattern R4, slit-like gaps are formed between adjacent, parallel wiring elements that are not connected to each other. The width of each wiring element and the width of the slit-like gap in the circuit wiring section 40 are set based on factors such as external visibility and the desired resistance value of each resistor pattern. Each resistor pattern preferably includes a spiral portion in which multiple wiring elements of a predetermined width are connected in a spiral shape, folding back on themselves and exiting to the outside. The spiral portion is where the multiple wiring elements are connected in a continuous line.

[0028] In the circuit wiring section 40 illustrated in Figures 2, 6, and 7, each resistor pattern includes at least one spiral portion in which a plurality of wiring elements having a predetermined width are connected in a spiral shape that folds back inward and exits outward to form a right-angled triangle in a plan view. For example, in the circuit wiring section 40 of Figure 2, the first resistor pattern R1 has one spiral portion, the second resistor pattern R2 has two spiral portions, the third resistor pattern R3 has three spiral portions, and the fourth resistor pattern R4 has six spiral portions. Note that in Figures 6 and 7, the first resistor pattern R1 to the fourth resistor pattern R4 are not distinguished from each other and are given the common symbol "R."

[0029] If the spiral portion has a right-angled triangular outer shape, it becomes easy to allocate each resistor pattern to the area to be covered on the electronic board 90 when designing the wiring pattern 30, thereby effectively reflecting the ideal resistance value ratio (e.g., 1:2:3:6) between the resistors in the bridge circuit. Furthermore, depending on the area and shape of the area to be covered, the area in which the circuit wiring portion 40 is disposed can be flexibly expanded without changing the resistance value ratio between the resistors in the bridge circuit, as shown in FIG. 5, for example. In other words, by employing multiple spiral portions that are the same shape and have a right-angled triangular shape in a plan view, the circuit wiring portion 40 can be designed with improved convenience.

[0030] 2, the spiral portions included in the first resistor pattern R1, the second resistor pattern R2, the third resistor pattern R3, and the fourth resistor pattern R4 are combined in pairs, and are arranged so that the long sides of the right-angled triangular portions face each other to form a rectangular shape in plan view. By combining spiral portions having a right-angled triangular shape in plan view in this way, it is possible to form a wiring pattern 30 with few gaps using only the circuit wiring portion 40, or even if it includes almost no dummy wiring portion 50, as shown in FIG.

[0031] 2 and 6, each resistor pattern may be arranged to form a rectangle as a whole, but is not limited to this. For example, as shown in FIG. 7, a dummy wiring section 50 may be formed that includes a triangular section S having a shape similar to a spiral section having a right-angled triangle shape in a plan view. The triangular section S in FIG. 7 is formed by connecting multiple dummy wiring elements having a predetermined width in a spiral shape that folds back inside and exits outside to form a right-angled triangle shape in a plan view. The triangular section S may be formed by connecting multiple dummy wiring elements in a continuous manner, or may have a break (gap) in the middle, but it is preferable that it be formed so that it appears continuous from the outside.

[0032] In this case, one or more spiral portions in each resistor pattern and one or more triangular portions S in the dummy wiring portion 50 may be combined in a balanced manner so that the entire wiring pattern 30 has, for example, a rectangular shape. For example, as shown in FIG. 7, the wiring pattern 30 may have one or more spiral portions and one or more triangular portions S combined one-to-one, with the long sides of the right-angled triangles facing each other, forming a rectangular shape in a plan view. That is, the spiral portion included in each resistor pattern may be combined with another spiral portion or with a triangular portion S. However, the dummy wiring portion 50 may also have two triangular portions S combined with each other, with the long sides of the right-angled triangles facing each other, forming a rectangular shape in a plan view.

[0033] The dummy wiring section 50 is formed so as not to contact the circuit wiring section 40 and is composed of one or more dummy elements. The triangular section S described above is an example of a dummy element. The dummy elements are formed in a shape corresponding to the empty space between spiral sections, the outside of the circuit wiring section 40, or gaps, so as to at least obstruct the visibility of the logic device 80. For example, if an empty area W where no circuit wiring section 40 is placed occurs during the design stage, as shown in FIG. 7, a dummy element may be placed there as appropriate. The dummy wiring section 50 may have a non-conductive pattern (not shown) that is isolated from others and does not conduct electricity, and an open-circuit detection pattern (not shown) that serves as an open-circuit detection circuit.

[0034] FIG. 2 illustrates examples of dummy elements, such as a plurality of connected spiral patterns, a simple loop pattern, and a plurality of connected linear patterns. FIG. 6 illustrates a linear pattern as a dummy element. FIG. 7 illustrates examples of dummy elements, such as a triangular portion S and a meandering pattern that extends in a meandering manner. The dummy wiring section 50 may include a zigzag pattern as a dummy element. The dummy wiring section 50 may include a rectangular pattern as a dummy element.

[0035] Here, the security protection device 100 has circuit patterns (base pattern 20 and wiring pattern 30) printed on the surface of the base member 10 by forming patterns using metal particles. That is, in the security protection device 100, the area and shape of the base pattern 20 and wiring pattern 30 can be adjusted to match the size, shape, and layout of the device to be protected on the electronic board 90. For protecting multiple devices, the security protection device 100 may be formed with the base pattern 20 and wiring pattern 30 so as to cover part or all of each device. FIG. 8 shows an example in which the base pattern 20 and wiring pattern 30 are designed to protect a logic device 80 and another device 85. The other device 85 is, for example, a memory. In this way, the security protection device 100 can be flexibly designed according to the size, shape, and layout of the object to be protected. The diverse combinations of pattern shapes reduce visibility from the outside and increase the difficulty of analysis.

[0036] As shown in FIG. 9 , the wiring pattern 30 may have a disconnection V in a portion of the dummy wiring section 50 that interrupts electrical continuity. However, the base pattern 20 is formed continuously across the disconnection V. The disconnection V may be formed as a slit of several microns. As shown in FIGS. 1 and 8 , when the security protection device 100 is mounted on the electronic board 90, the disconnection V in the wiring pattern 30 is hidden by the base pattern 20, making it impossible to determine the disconnection state of the wiring pattern 30 from the outside. In addition, even if the wiring pattern 30 can be viewed directly, if the disconnection V is a slit of several microns, its presence cannot be recognized, as shown in FIG. 10 . Furthermore, in the security protection device 100 of this embodiment, the wiring pattern 30 is formed of extremely thin copper wiring as a precision polishing measure, and its thickness is basically less than 1 / 100 of the thickness of the base member 10, making accurate analysis by probing difficult.

[0037] Next, the functional configuration of the logic device 80 will be described with reference to Fig. 11. Fig. 11 is a functional block diagram illustrating a schematic example of the configuration of the logic device 80. The logic device 80 has a communication unit 80a, a control unit 80b, a first storage unit 80c, an analysis processing unit 80d, and a second storage unit 80e.

[0038] The communication unit 80a is an interface through which the control unit 80b or the analysis processing unit 80d communicates with external devices via wired or wireless communication. The first storage unit 80c stores various information, including the operation program of the control unit 80b. The second storage unit 80e stores various information, including the operation program of the analysis processing unit 80d. The first storage unit 80c and the second storage unit 80e are configured with RAM (Random Access Memory), ROM (Read Only Memory), PROM (Programmable ROM) such as flash memory, or SSD (Solid State Drive). The control unit 80b executes the main arithmetic processing of the logic device 80 and is configured with a CPU (Central Processing Unit) or GPU (Graphics Processing Unit). The control unit 80b processes data and signals sent from the analysis processing unit 80d as needed and has the function of protecting the logic device 80. For example, the control unit 80b stops operation, displays and lights up warnings, and outputs alerts in response to feedback and command signals from the analysis processing unit 80d. From a security standpoint, the control unit 80b is configured not to be involved in the determination process by the analysis processing unit 80d. The control unit 80b may have a function of protecting data by encryption.

[0039] The analysis processing unit 80d has a function of constantly acquiring data from connection points B and D, comparing it with profile data, and feeding back the comparison results to the control unit 80b. The analysis processing unit 80d may have a function of determining where an abnormality occurs in each resistance pattern in the bridge circuit and classifying the type of abnormality. The analysis processing unit 80d may have a function of detecting an abnormality such as a break in each location or a detour wiring using a focused ion beam (FIB) or the like. The analysis processing unit 80d may be configured to monitor the state of the break detection pattern and notify the control unit 80b when a break is detected. The analysis processing unit 80d may have various functions for detecting abnormalities within the substrate of the logic device 80, such as a temperature abnormality determination function, a noise abnormality determination function, a Vin abnormality determination function, and a dispersion abnormality determination function. The analysis processing unit 80d is configured with a processor such as a CPU or a GPU.

[0040] As described above, in the security protection device 100 of this embodiment, the base pattern 20 is interposed between the base member 10 and the wiring pattern 30, and the resistance component R5 of the logic device 80 mounted on the electronic substrate 90 forms a bridge circuit together with the wiring pattern 30. This reduces the visibility of the protective wiring pattern, simplifying the security structure. Specifically, the security protection device 100 has the base pattern 20, which is similarly arranged as the wiring pattern 30, formed on the transparent surface of the base member 10 facing the logic device 80, creating a three-dimensional mounting structure consisting of the base member 10, the base pattern 20, and the wiring pattern 30. Therefore, the base pattern 20 obscures the wiring pattern 30 from the front side, making it impossible to see. Furthermore, because the resistance component R5 of the logic device 80 forms a bridge circuit, any attempt to approach it from the outside would result in irreparable physical damage. This reduces the visibility of the electronic substrate 90 and increases the difficulty of analyzing the wiring pattern 30. Furthermore, the security protection device 100 does not need to be provided with a separate component for detecting breaks or short circuits in the wiring pattern.

[0041] The bridge circuit formed between each resistance pattern of the circuit wiring section 40 and the resistance component R5 of the logic device 80 may be an unbalanced bridge circuit rather than a perfect bridge circuit in which the current flowing through the resistance component R5 is set to zero. If the security protection device 100 is manufactured based on an unbalanced bridge circuit, manufacturing errors in pattern formation, etc. can be tolerated, thereby reducing manufacturing costs. Furthermore, the unbalance of the bridge circuit may be used as an individual feature, allowing for individual identification of the security protection device 100.

[0042] The circuit wiring section 40 is formed by connecting multiple linear wiring elements with a predetermined width at different angles. For example, the first resistor pattern R1, the second resistor pattern R2, the third resistor pattern R3, and the fourth resistor pattern R4 may each include a spiral portion in which multiple wiring elements with a predetermined width are connected in a spiral shape, folding back inward and exiting outward, or a meandering pattern. Each of the figures illustrates a spiral portion in which multiple wiring elements with a predetermined width are connected in a spiral shape, folding back inward and exiting outward, to form a right-angled triangle in plan view. However, the outer shape of the spiral portion is not limited to a right-angled triangle, and various shapes such as an equilateral triangle, an isosceles triangle, a rectangle, or a regular hexagon can be used. That is, each resistor pattern may also include a spiral portion in which multiple wiring elements with a predetermined width are connected in a spiral shape, folding back inward and exiting outward, to form a polygonal shape in plan view. In this way, by spreading the pattern shape over the entire surface, the appearance can increase the deterrent effect against reverse engineering.

[0043] Each resistor pattern may include two right-angled triangular spiral portions (hereinafter referred to as right-angled triangular portions) arranged such that the long sides of the right-angled triangular portions face each other, forming a rectangular shape in a plan view. If each resistor pattern is configured to have multiple right-angled triangular portions as a whole, combining these portions makes it easy to design patterns that cover rectangular areas of various sizes. Furthermore, if each resistor pattern is designed so that the total number of right-angled triangular portions included in the resistor pattern is an even number, it is possible to construct a rectangular pattern based on a combination of right-angled triangular portions, as shown in Figures 2 and 6. Furthermore, combining right-angled triangular portions makes it easy to reflect the ideal resistance value ratio between each resistor in the bridge circuit in the configuration of each resistor pattern. Furthermore, the security protection device 100 can easily be scaled to suit various devices to be protected, making it suitable for protecting any part on the electronic board 90.

[0044] The wiring pattern 30 may have a dummy wiring section 50 formed so as not to come into contact with the circuit wiring section 40. In the design stage of the circuit wiring section 40, if the desired resistance value in the bridge circuit is obtained but there is insufficient area to cover the logic device 80, etc., or if gaps occur in the area to be covered, a visually complete pattern can be constructed by filling in the dummy elements of the dummy wiring section 50.

[0045] The dummy wiring portion 50 may include a triangular portion S in which a plurality of dummy wiring elements having a predetermined width form a right-angled triangle shape in a plan view and are connected in a spiral shape that turns back inside and exits to the outside. In this way, a rectangular pattern can be constructed in combination with the right-angled triangle portion. That is, the wiring pattern 30 may be arranged by combining one or more right-angled triangle portions and one or more triangular portions S in a one-to-one manner, with the long sides in the right-angled triangle shapes facing each other so that the combination forms a rectangular shape in a plan view. Incidentally, when a tester is applied or a hole is drilled at a broken portion such as the broken portion V of the disconnection detection pattern, a change in resistance value or physical damage that cannot be recovered is caused. Therefore, it can be said that the security protection device 100 has strong security performance against physical attacks.

[0046] By the way, as in Patent Document 2, when a wiring conductor for security protection is provided on the surface of the semiconductor substrate opposite to the electronic circuit, complicated processing such as drilling holes in the substrate is required, and the structure becomes complicated. In this regard, since the security protection device 100 is configured as described above, simplification of the mounting structure to the electronic substrate 90 can be realized.

[0047] <X-ray analysis> When an analyst performs a physical analysis of an object, the first thing to do is to confirm the wiring status non-destructively. As a general method in such physical analysis, X-ray analysis is known. Therefore, X-ray analysis was actually performed using the experimental security protection device 100. As a result, it was confirmed that the base pattern 20 and the wiring pattern 30 were not shown. This is presumably because the X-ray absorption rates of the base pattern 20 and the wiring pattern 30 are extremely low. Incidentally, the security protection device 100 has a two-layer structure of the base pattern 20 and the wiring pattern 30, and the base pattern 20 that can be seen visually and the wiring pattern 30 that is a conductor are not necessarily the same pattern. Therefore, even if the base pattern 20 could be visually recognized, it would be difficult to know the exact pattern shape of the wiring pattern 30.

[0048] <Observation of temperature distribution using a thermal camera> In addition, a wiring pattern analysis was performed on the security protection device 100 using a thermal camera based on temperature distribution (outside temperature: room temperature). Specifically, as shown in FIG. 12 , the temperature distribution was observed before power-on, 3 seconds after power-on, 6 seconds after power-on, 9 seconds after power-on, 12 seconds after power-on, 15 seconds after power-on, 20 seconds after power-on, 25 seconds after power-on, and 30 seconds after power-on (actually color photographs). Heat generation from the logic device (FPGA) located below the security protection device 100 is visible in the center of the photograph, and the heat distribution reveals the layout state of the logic functions integrated in the logic device 80. Thus, even with wiring pattern analysis, no heat generation from the security protection device 100 was confirmed, meaning that analysis of the wiring pattern 30 would be difficult. The heat-generating element at the bottom right is the power supply device 95 (power supply IC) located on the electronic board 90.

[0049] <Electromagnetic field measurement> Furthermore, an impact analysis on the security protection device 100 was performed using an electromagnetic field probe. Specifically, an experimental security protection device 100 was used to measure the electromagnetic field conditions of the electronic board 90 (including the logic device 80) and the area around the security protection device 100 after power-on. When the entire electronic board 90 was measured using the electromagnetic field probe, 87.26 dBμV was measured around the power supply device 95 (power supply IC) on the board. However, the overall level was generally uniform at around 65 dBμV, which was insufficient to identify the wiring pattern 30. Similarly, when measurements were focused on the security protection device 100, a relatively high value (96.75 dBμV) was measured around the power supply device 95 (power supply IC). However, the upper part of the security protection device 100 was generally uniform at around 67 dBμV, which was insufficient to identify the wiring pattern 30. In other words, the impact analysis using the electromagnetic field probe did not reveal any electromagnetic field abnormalities caused by the security protection device 100.

[0050] The above-described embodiments are merely specific examples of a security protection device and a device protection system, and the technical scope of the present invention is not limited to these embodiments. For example, in the above embodiments, the logic device 80 is an FPGA. However, the logic device 80 may be another programmable logic device (PLD) or a combination of a PLD and another device. For example, when the logic device 80 includes a PLD, the security protection device 100 can be applied to an electronic board 90 equipped with an ASIC or ARM, whose logic circuit structure cannot be reconfigured, to protect the ASIC or ARM. The security protection device 100 may be a device that can be retrofitted to the electronic board 90, or may be combined with the logic device 80 on the electronic board 90 to form a device protection system 200.

[0051] 2 illustrates an example in which one end of the first resistor pattern R1, one end of the third resistor pattern R3, one end of the second resistor pattern R2, one end of the fourth resistor pattern R4, the other end of the third resistor pattern R3, and the other end of the fourth resistor pattern R4 are each formed in a brush-like shape in a plan view, and the brush portions of adjacent ends are arranged alternately, but this is not intended to be limiting. Various shapes may be adopted for the ends of each of the resistor patterns, taking into consideration factors such as the bonding strength with the connecting conductor 70 and ease of manufacturing. While FIG. 3 illustrates a columnar connecting conductor 70, this is not limiting, and the connecting conductor 70 may be formed of one or two wire-like conducting wires.

[0052] 1 and 8 show an example in which the base pattern 20 and the wiring pattern 30 are arranged over the entire area facing the logic device 80, but this is not limiting, and the base pattern 20 and the wiring pattern 30 may be arranged over a portion of the area facing the logic device 80. However, the base pattern 20 and the wiring pattern 30 should preferably occupy at least three-quarters of the area facing the logic device 80, and it is more preferable to arrange them so that they are slightly larger than the entire area. [Explanation of symbols]

[0053] 10 base member, 20 base pattern, 30 wiring pattern, 40 circuit wiring section, 41 first circuit section, 42 second circuit section, 50 dummy wiring section, 70, 70a to 70d connecting conductor, 71 conductive resin, 75, 81 joining member, 80 logic device, 80a communication section, 80b control section, 80c first memory section, 80d analysis processing section, 80e second memory section, 83 resin, 85 other device, 90 electronic board, 91 conductive section, 95 power supply device, 100 security protection device, 200 device protection system, R1 first resistor pattern, R2 second resistor pattern, R3 third resistor pattern, R4 fourth resistor pattern, R5 resistance component, A to D connection points, 1a, 2a, 3a, 4a one end, 1b, 2b, 3b, 4b other end, 12b other end pad.

Claims

1. A security protection device that is mounted to cover a logic device mounted on an electronic board, a transparent plate-shaped base member made of a non-conductor; a base pattern formed on a surface of the base member facing the logic device; a wiring pattern formed on the base pattern, the base pattern and the wiring pattern are disposed at least in an area facing the logic device, The base pattern is the wiring pattern is formed of a metal having a lower conductivity than the wiring pattern and in the same arrangement as the wiring pattern; The wiring pattern is a circuit wiring section in which a first circuit section in which a first resistor pattern connected to the positive side of the power supply device and a second resistor pattern connected to the negative side of the power supply device are connected in series, and a second circuit section in which a third resistor pattern connected to the positive side of the power supply device and a fourth resistor pattern connected to the negative side of the power supply device are connected in series are connected; The circuit wiring portion is A security protection device that forms a bridge circuit between a connection point between the first resistance pattern and the second resistance pattern and a resistance component of the logic device that is connected between a connection point between the third resistance pattern and the fourth resistance pattern.

2. The circuit wiring portion is 2. The security protection device according to claim 1, wherein a plurality of wiring elements extending linearly with a preset width are formed so as to be continuous at their ends at different angles.

3. 3. The security protection device according to claim 2, wherein the first resistance pattern, the second resistance pattern, the third resistance pattern, and the fourth resistance pattern each include a spiral portion in which a plurality of the wiring elements are connected in a spiral shape, folding back on the inside and exiting to the outside.

4. 3. The security protection device according to claim 2, wherein the first resistance pattern, the second resistance pattern, the third resistance pattern, and the fourth resistance pattern each include a spiral portion in which a plurality of the wiring elements are connected in a spiral shape that folds back on the inside and exits to the outside so as to form a right-angled triangle in a planar view.

5. The security protection device of claim 4, wherein the spiral portions included in the first resistance pattern, the second resistance pattern, the third resistance pattern, and the fourth resistance pattern are combined in pairs and arranged so that the long sides of the right-angled triangles face each other and the set forms a rectangular shape in a planar view.

6. The circuit wiring portion is 6. The security protection device according to claim 1, wherein an unbalanced bridge circuit is formed between the logic device and a resistance component of the logic device.

7. The wiring pattern is 6. The security protection device according to claim 1, further comprising a dummy wiring portion formed so as not to come into contact with said circuit wiring portion.

8. The wiring pattern is a dummy wiring portion formed so as not to come into contact with the circuit wiring portion; The dummy wiring portion is 5. The security protection device according to claim 4, wherein a plurality of dummy wiring elements having a predetermined width include triangular portions connected in a spiral shape that folds inward and exits outward to form a right-angled triangle in a plan view.

9. The wiring pattern is 9. The security protection device of claim 8, wherein one or more spiral portions and one or more triangular portions are combined one-to-one, and the long sides of the right-angled triangles face each other, forming a rectangular shape in a plan view.

10. A security protection device according to any one of claims 1 to 5; the logic device mounted on the electronic board and covered by the security protection device.

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