Method and program for predicting electrical characteristics of composite material member

Abstract

The challenge is to predict the electrical characteristics associated with the current flowing in the composite member when an electric field is applied to the composite member.SOLUTION: In the first step, an internal structure model of the composite material member is prepared. In the second step, a plurality of resistance portions are defined in the internal structure model. In the third step, an electric field distribution when a voltage is applied to the internal structure model is calculated. In the fourth step, the first process and the second process are repeated until both the electric field and the resistance value converge. The first process is a process of calculating a resistance value of each of the plurality of resistance units based on a field emission phenomenon of each of the plurality of resistance units. The second process is a process of recalculating the electric field of the internal structure model based on the resistance value of each of the plurality of resistance portions 4 calculated in the first process. The fifth step calculates an electrical characteristic related to a current flowing through the internal structure model.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure generally relates to a method and program for predicting electrical properties of a composite material member, and more particularly to a method and program for predicting electrical properties of a composite material member that predicts electrical properties related to current flowing through the composite material member. [Background technology]

[0002] Non-Patent Document 1 discloses a formula for calculating a current when an electric field is applied between two electrodes in a configuration in which the two electrodes are separated by a thin insulating film. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Simmons, J. Appl. Phys. Vol.34, 1793-1803 (1963) Summary of the Invention [Problem to be solved by the invention]

[0004] The calculation formula disclosed in Non-Patent Document 1 cannot predict the electrical characteristics related to the current that flows through a composite material member when an electric field is applied to the composite material member.

[0005] An object of the present disclosure is to provide a method and program for predicting the electrical properties of a composite material member that are capable of predicting the electrical properties related to the current that flows through the composite material member when an electric field is applied to the composite material member. [Means for solving the problem]

[0006] A method for predicting electrical characteristics of a composite material member according to one embodiment of the present disclosure includes a first step, a second step, a third step, a fourth step, and a fifth step. In the first step, an internal structure model is prepared. The internal structure model is a simulation model of the composite material member. The internal structure model has a plurality of functional particles and an insulator portion covering at least a portion of each of the plurality of functional particles. Each of the plurality of functional particles includes a conductive particle and an insulating film covering the conductive particle. In the second step, a plurality of resistive portions are defined in the internal structure model, each of which is interposed between conductive particles of two adjacent functional particles among the plurality of functional particles. In the third step, an electric field distribution when a voltage is applied to the internal structure model is calculated. In the fourth step, the first and second steps are repeated until both the electric field and the resistance value converge. The first step is a step of calculating the resistance value of each of the plurality of resistive portions based on the field emission phenomenon of each of the plurality of resistive portions. The second step is a step of recalculating the electric field of the internal structure model based on the resistance values ​​of the respective resistors calculated in the first step. The fifth step is to calculate electrical characteristics related to the current flowing through the internal structure model.

[0007] A program according to one aspect of the present disclosure is a program for causing a computer system to execute the above-described method for predicting electrical properties of a composite material member. [Effects of the Invention]

[0008] The method and program for predicting the electrical properties of a composite material member according to the present disclosure make it possible to predict the electrical properties related to the current that flows through the composite material member when an electric field is applied to the composite material member. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flowchart showing a method for predicting electrical properties of a composite material member according to the first embodiment. [Figure 2]FIG. 2 is a diagram showing the configuration of an internal structure model in the method for predicting the electrical properties of a composite material member. [Figure 3] FIG. 3 is a schematic diagram of functional particles included in an internal structure model in the method for predicting electrical properties of a composite material member according to the above embodiment. [Figure 4] FIG. 4 is a model diagram including a plurality of resistor portions defined in an internal structure model in the method for predicting electrical properties of a composite material member. [Figure 5] FIG. 5 is an equivalent circuit diagram including a plurality of resistors defined in an internal structure model in the method for predicting electrical properties of a composite material member according to the above embodiment. [Figure 6] FIG. 6 is a current-applied voltage characteristic diagram predicted by the above-mentioned method for predicting the electrical characteristics of the composite material member. [Figure 7] FIG. 7 is a graph showing the resistance value-applied voltage characteristic predicted by the method for predicting the electrical characteristics of the composite material member. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments and the like will be described with reference to the drawings. The drawings referred to in the following embodiments and the like are schematic diagrams, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the size ratios and thickness ratios between the components do not necessarily reflect the actual dimensional ratios.

[0011] (Embodiment) Hereinafter, a method for predicting the electrical properties of a composite material member according to an embodiment will be described with reference to FIGS.

[0012] (1) Overview The method for predicting the electrical properties of a composite material member according to the embodiment includes a first step, a second step, a third step, a fourth step, a fifth step, and a sixth step.

[0013] In the first step, an internal structure model 1 (see FIG. 2) is prepared. The internal structure model 1 is a simulation model of a composite material member. The internal structure model 1 has a plurality of functional particles 2 and an insulator portion 3 covering at least a portion of each of the plurality of functional particles 2. As shown in FIG. 3, each of the plurality of functional particles 2 includes a conductive particle 21 and an insulating film 22 covering the conductive particle 21.

[0014] In the second step, a plurality of resistor sections 4 (see FIG. 4) are defined in the internal structure model 1. Each of the plurality of resistor sections 4 is interposed between conductive particles 21 of two adjacent functional particles 2 among the plurality of functional particles 2 in the internal structure model 1. FIG. 5 shows a schematic equivalent circuit when each of the plurality of resistor sections 4 is represented by a variable resistor symbol.

[0015] In the third step, the electric field distribution when a voltage is applied to the internal structure model 1 is calculated.

[0016] In the fourth step, the first and second processes are repeated until both the electric field and the resistance value converge. The first process is a process of calculating the resistance value of each of the plurality of resistor sections 4 based on the field emission phenomenon of each of the plurality of resistor sections 4. The second process is a process of recalculating the electric field of the internal structure model 1 based on the resistance value of each of the plurality of resistor sections 4 calculated in the first process.

[0017] In the fifth step, the electrical characteristics related to the current flowing through the internal structure model 1 are calculated.

[0018] In the sixth step, the voltage applied to the internal structure model 1 is changed, and the process returns to the third step.

[0019] (2)Details The composite material member is a member formed using a composite material in which a plurality of functional particles are densely packed in a resin, and is, for example, a powder magnetic core used in an inductor (e.g., a power choke coil).

[0020] The method for predicting the electrical properties of a composite material member is implemented, for example, in a computer system. The computer system is primarily composed of a processor and memory as hardware. The processor executes a program stored in the memory of the computer system to realize the functions of the method for predicting the electrical properties of a composite material member disclosed herein. The program may be pre-stored in the memory of the computer system, provided via a telecommunications line, or provided on a non-transitory recording medium readable by the computer system, such as a memory card, optical disk, or hard disk drive. The processor of the computer system is composed of one or more electronic circuits, including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs and LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large-scale integrations (VLSIs), or ultra-large-scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices capable of reconfiguring the connections within the LSI or the circuit partitions within the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0021] In the first step, as described above, the internal structure model 1 is prepared. More specifically, in the first step, input of structural design values ​​for the internal structure model 1 is accepted (step S1 in FIG. 1), and the internal structure model 1 of the composite material member (see FIG. 2) is constructed (step S2 in FIG. 1). The internal structure model 1 is, for example, a model in which a three-dimensional shape model constructed by generating an arbitrary number and shape of three-dimensional structures within a domain by numerical means is described as a three-dimensional voxel model. In the internal structure model 1, the material of the conductive particles 21 in each of the multiple functional particles 2 is, for example, a soft magnetic material. Examples of soft magnetic materials include iron-silicon alloys, iron-aluminum alloys, iron-aluminum-silicon alloys, iron-silicon-chromium alloys, iron-chromium alloys, iron-nickel alloys, iron-silicon-boron alloys, iron-nitrogen alloys, iron-carbon alloys, iron-boron alloys, iron-phosphorus alloys, permendur (Fe-Co), iron-cobalt-vanadium alloys, Fe-based amorphous alloys, and Fe-based nanocrystalline alloys. The insulating film 22 is, for example, an oxide film, an insulating coating, or a passivation film. Examples of oxide films include natural oxide films. The material of the insulator portion 3 of the internal structure model 1 is, for example, a resin having electrical insulation properties. The structural design values ​​include, for example, physical property values ​​according to the material of the conductive particles 21, the filling rate of the conductive particles 21, the type of the conductive particles 21, the number of the conductive particles 21, the shape of the conductive particles 21, the particle size of the conductive particles 21, the particle size distribution of the conductive particles 21, the distance between adjacent conductive particles 21, the degree of non-uniformity in the arrangement (spatial arrangement) of the conductive particles 21, physical property values ​​according to the material of the insulating film 22, the thickness of the insulating film 22, and physical property values ​​according to the material of the insulator portion 3. The type of the conductive particles 21 input as the structural design value of the internal structure model 1 may be a single type or multiple types. The thickness and material of the insulating film 22 input as the structural design value of the internal structure model 1 may also be a single type or multiple types. The insulating film 22 input as the structural design value of the internal structure model 1 may have a single layer structure or a multi-layer laminate structure.

[0022] In the second step, a plurality of resistor portions 4 are defined in the internal structure model 1 (step S3 in FIG. 1). More specifically, in the second step, a contact point or contact surface is detected for each combination of two functional particles 2 that are in contact with each other among the plurality of functional particles 2, and a resistor portion 4 including the contact point or contact surface is defined for each detected contact point or contact surface (step S3 in FIG. 1). Each of the plurality of resistor portions 4 is a portion interposed between the conductive particles 21 of two contacting functional particles 2 among the plurality of functional particles 2. In other words, each of the plurality of resistor portions 4 includes, for each combination of two contacting functional particles 2, a portion of the insulating film 22 of one of the two functional particles 2 and a portion of the insulating film 22 of the remaining functional particle 2.

[0023] The third step calculates the electric field distribution when a voltage is applied to the internal structure model 1. More specifically, the third step calculates the initial value of the electric field in the entire internal structure model 1, including each resistor portion 4 and the periphery of each resistor portion 4, when a preset initial applied voltage (e.g., 80 [V]) is applied to the entire internal structure model 1 (step S4 in FIG. 1).

[0024] In the fourth step, the first process (step S5 in FIG. 1) and the second process (step S6 in FIG. 1) are repeated until both the electric field and the resistance value converge (step S7 in FIG. 1: Yes). The first process is a process of calculating the resistance value of each of the multiple resistor sections 4 caused by the tunneling phenomenon based on the electric field of each of the multiple resistor sections 4. The second process is a process of recalculating the electric field of the internal structure model 1 based on the resistance value of each of the multiple resistor sections 4 calculated in the first process.

[0025] In the first step of the fourth step, a resistance value R is determined by calculating a tunneling current based on the intrinsic tunneling phenomenon and the field emission phenomenon (Fowler-Nordheim tunneling phenomenon) in each resistor section 4. The tunneling current in each resistor section 4 is a tunneling current that flows according to the gradient of the electric field in the resistor section 4. More specifically, in the Fowler-Nordheim tunneling phenomenon (hereinafter also referred to as FN tunneling phenomenon) in the first step of the fourth step, the resistance value of each of the multiple resistor sections 4 is calculated using a tunneling current calculation formula based on the Fowler-Nordheim equation. In this embodiment, the tunneling current calculation formula includes a term for a linear intrinsic tunneling current that exhibits linear dependence on the potential gradient and a term for a tunneling current based on the field emission phenomenon. The linear intrinsic tunneling current means a tunneling current whose current-voltage characteristics are linear. The tunneling current based on the field emission phenomenon means a current that flows due to the Fowler-Nordheim tunneling effect (Fowler-Nordheim tunneling current). In the first process of the fourth step, the resistance value of each of the plurality of resistor sections 4 is calculated, for example, by the following formula (1).

[0026]

number

[0027] In formula (1), R is the resistance value of the resistor portion 4, β is a first constant, and γ is a second constant. γ is a value determined by the thickness of the insulating layer at the contact portion, the magnitude of the potential barrier, and the interaction of solid-state electrons, with a reference value of, for example, around 10, and is greater than 0. The thickness of the insulating layer at the contact portion is the thickness of the portion interposed between the conductive particles 21 of two contacting functional particles 2 among the plurality of functional particles 2, and is the thickness of the resistor portion 4. β is a value determined by the thickness of the insulating layer at the contact portion, the magnitude of the potential barrier, the interaction of solid-state electrons, the proportion of the real contact surface that contributes to the FN tunneling phenomenon, and other factors, and is greater than 0. Furthermore, in formula (1), z is calculated using formula (2) below. In formula (2), E is the electric field applied to the resistor portion 4. Furthermore, in formula (1), R0 is the resistance determined when the applied voltage is smaller than the applied voltage when current leakage occurs in the resistor portion 4, and is the resistance determined when the intrinsic tunneling current is J DT and the voltage applied to the resistor section 4 is V, it is defined by the following equation (3).

[0028]

number

[0029]

number

[0030] The following equation (4) is used to derive equation (1).

[0031]

number

[0032] In equation (3), S is the contact area between the conductive particles 21 of the two functional particles 2 that are in contact with each other. Of the contact areas corresponding to this contact area, tunneling actually occurs in only a portion of the contact area. This portion of the contact area is called the real contact surface, and the area of ​​the real contact surface is the real contact area. The sum of all tunnel currents generated by the potential difference at this real contact surface is the tunnel current, and when the potential difference is smaller than the potential barrier at the real contact surface, the current is the intrinsic tunnel current J DT Furthermore, if the potential difference is sufficiently small, the intrinsic tunnel current J DT is determined by equation (3), which is proportional to the potential difference, with the reciprocal of R0, the sum of the contact resistances proportional to the potential difference, as the proportionality coefficient.

[0033] In equation (4), J FN is a Fowler-Nordheim current, which occurs when the potential difference at the contact surface exceeds the potential barrier of the contact surface, causing a transition from intrinsic tunneling to FN tunneling. This transition from intrinsic tunneling to FN tunneling occurs from the part of the real contact surface where the potential barrier is lowest. Since the increase in FN tunneling current relative to the potential difference is extremely large, the current concentrates at this contact point, causing even more tunneling current to flow, leading to dielectric breakdown. In other words, FN tunneling is considered only in the part of the real contact surface where the potential barrier is low. Also, in equation (4), J DT is a linear intrinsic tunnel current as described above, so equation (4) is a calculation formula based on a resistance model that takes into account both the intrinsic tunnel current and the Fowler-Nordheim current.

[0034] Such a tunnel current transitions from an intrinsic tunnel current to an FN tunnel current as the gradient of the electric field in the resistor 4 increases. However, until field emission begins in the resistor 4, the J FN is small enough that it rises rapidly after field emission occurs, and J DT Therefore, it is preferable to describe it using the model formula (4).

[0035] As described above, the second process of the fourth step is a process of recalculating the electric field of the internal structure model 1 based on the resistance values ​​of each of the multiple resistor sections 4 calculated in the first process. The reason for repeating the first and second processes in the fourth step is that the resistance value of each of the multiple resistor sections 4 is determined by field emission, but when field emission occurs through a resistor section 4, the state of the electric field around that resistor section 4 changes, and the resistance value of the resistor section 4 changes.

[0036] In the fourth step, a numerical calculation is performed using the finite volume method. In other words, in the fourth step, a numerical analysis is performed using the finite volume method to calculate the electric field distribution and the resistance value of each resistor portion 4. In the fourth step, the method of numerical calculation is not limited to the finite volume method, and other methods may be used. Also, in the fourth step, the internal structure model may be converted into a circuit model for calculation.

[0037] In the fifth step, electrical characteristics related to the current flowing through the internal structure model 1 are calculated. More specifically, in the fifth step, if both the electric field and the resistance value converge in the fourth step (step S7 in FIG. 1: Yes), the current flowing through the internal structure model 1 (see FIG. 6) is calculated, and the resistance value of the internal structure model 1 (see FIG. 7) is calculated to determine whether or not a leak has occurred (step S9). In this embodiment, in the fourth step, between steps S7 and S9, it is determined whether or not there is a resistance unit 4 in which a current exceeding a threshold (internal current) has occurred among the multiple resistance units 4 (step S8). If there is a resistance unit 4 in which a current exceeding the threshold has occurred among the multiple resistance units 4 (step S8: Yes), the resistance value of the resistance unit 4 in which a current exceeding the threshold has occurred is set as the upper limit of the resistance value of the resistance unit 4 (step S13), and the process returns to step S5; however, step S8 is not essential. When step S8 is included, taking into consideration dielectric breakdown (internal dielectric breakdown) due to minute current leakage caused by field emission in each resistor section 4, a limitation is imposed so that the resistance value of a resistor section 4 in which a current exceeding the threshold value is generated does not return to its original resistance value greater than the upper limit value after the applied voltage is applied. That is, in this embodiment, the resistance value of a resistor section 4 in which a current exceeding the threshold value is generated is limited to the resistance value at the time when the current exceeds the threshold value. Therefore, when step S8 is included, the resistance value of a resistor section 4 in which a current exceeding the threshold value is generated will not become greater than the upper limit value after step S13. Note that in this embodiment, the resistance value of a resistor section 4 in which a current exceeding the threshold value is generated is allowed to fall below the upper limit value.

[0038] In the sixth step, the voltage applied to the internal structure model 1 is changed (step S11), and the process returns to step S4. More specifically, in the sixth step, if it is determined in step S9 that there is a leak (step S9: Yes), the applied voltage at that time is recorded as the leak voltage (step S12). In addition, in the sixth step, whether it is determined in step S9 that there is a leak (step S9: Yes) or that there is no leak (step S9: No) is determined in either case, and if it is determined that the calculation termination condition is met in step S10, and if it is not met (step S10: No), the applied voltage is changed (step S11), and the process returns to step S4. In this embodiment, in step S11, for example, the applied voltage is increased by a predetermined value (e.g., 10 [V]).

[0039] In step S10, if it is determined that the calculation end condition is met (step S10: Yes), the prediction ends.

[0040] The method for predicting the electrical properties of a composite material member of this embodiment can output the predicted results of the electrical properties. The method for predicting the electrical properties of a composite material member of this embodiment can output, as predicted results of the electrical properties, data on the current-applied voltage characteristics as shown in FIG. 6 and data on the resistance-applied voltage characteristics as shown in FIG. 7, and display them on a display device (e.g., a monitor). The display device may or may not be included in the computer system described above. Figure 6 shows that the current increases nonlinearly with increasing applied voltage, and that the current increases sharply when the applied voltage exceeds 110 V.

[0041] For example, composite material components used as powder magnetic cores for inductors are made of composite materials densely packed with functional particles, including magnetic particles, and must be designed to prevent current leakage when a voltage is applied. However, in composite material components, the functional particles are densely packed and in contact with each other. Composite material components used as powder magnetic cores ensure insulation between the contacting functional particles by providing insulating films on the surfaces of the conductive particles. However, when a high voltage is applied, insulation breakdown occurs at the numerous contact points and contact surfaces, and these contacts connect to form current paths, resulting in current leakage.

[0042] In contrast, the method for predicting the electrical characteristics of a composite material member makes it possible to predict the applied voltage at which leakage current occurs in the composite material member, and to predict the withstand voltage of the composite material member.

[0043] (3) Advantages A method for predicting the electrical characteristics of a composite material member according to an embodiment includes a first step, a second step, a third step, a fourth step, and a fifth step. In the first step, an internal structure model 1 is prepared. The internal structure model 1 is a simulation model of a composite material member. The internal structure model 1 has a plurality of functional particles 2 and an insulator portion 3 covering at least a portion of each of the plurality of functional particles 2. Each of the plurality of functional particles 2 includes a conductive particle 21 and an insulating film 22 covering the conductive particle 21. In the second step, a plurality of resistor portions 4 are defined in the internal structure model 1. Each of the plurality of resistor portions 4 is located between the conductive particles 21 of two adjacent functional particles 2 among the plurality of functional particles 2 in the internal structure model 1. In the third step, the electric field distribution when a voltage is applied to the internal structure model 1 is calculated. In the fourth step, the first and second steps are repeated until both the electric field and the resistance value converge. The first step is to calculate the resistance value of each of the plurality of resistor sections 4 based on the field emission phenomenon of each of the plurality of resistor sections 4. The second step is to recalculate the electric field of the internal structure model 1 based on the resistance value of each of the plurality of resistor sections 4 calculated in the first step. The fifth step is to calculate electrical characteristics related to the current flowing through the internal structure model 1.

[0044] According to the above configuration, it is possible to predict electrical characteristics related to the current that flows through a composite material member when an electric field is applied to the composite material member.

[0045] Moreover, the method for predicting the electrical properties of a composite material member according to the embodiment further includes a sixth step, in which the voltage applied to the internal structure model 1 is changed, and the process returns to the third step.

[0046] According to the above configuration, it is possible to predict the current-applied voltage characteristics as an electrical characteristic related to the current that flows through a composite material member when an electric field is applied to the composite material member, and it is also possible to predict the occurrence of leakage current. Therefore, according to the above configuration, it is possible to predict the withstand voltage of the composite material member.

[0047] Furthermore, the method for predicting the electrical properties of a composite material member of this embodiment can be used, for example, in the structural design and material design of a powder magnetic core when the composite material member is an inductor powder magnetic core. When designing the composition, amount, particle size, etc. of the magnetic particles (conductive particles) in the powder magnetic core, information such as the presence or absence of leakage current and the applied voltage at which leakage current occurs can be fed back. Furthermore, the method for predicting the electrical properties of a composite material member of this embodiment can predict the presence or absence of leakage current in a composite material member whose current-applied voltage characteristics are not linear, as well as the withstand voltage, which is the applied voltage at which the current begins to increase rapidly. Therefore, it can also be used to determine the quality of insulation when the material and thickness of the insulating film 22 and the material and amount of the insulator portion 3 in the composite material member are tweaked.

[0048] The method described in Non-Patent Document 1 cannot predict the withstand voltage and dielectric breakdown of composite material components, and cannot estimate the nonlinear (non-ohmic) change in current value that occurs when current leaks, which is a precursor to withstand voltage leaks.

[0049] Furthermore, the method for predicting electrical properties of a composite material member according to this embodiment can be realized by a computer system executing a program. This program is a computer program for causing a computer system to execute the method for predicting electrical properties of a composite material member. This program makes it possible to predict electrical properties related to the current that flows through a composite material member when an electric field is applied to the composite material member, similar to the method for predicting electrical properties of a composite material member.

[0050] (Variation) The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0051] The composite material member is not limited to a powder magnetic core of an inductor, but may be, for example, an insulating substrate such as a resin substrate having high thermal conductivity.

[0052] The internal structure model 1 is not limited to a three-dimensional shape model, and may be described by converting it into a circuit network model.

[0053] The first step of preparing the internal structure model 1 is not limited to constructing the internal structure model 1, and data of the internal structure model 1 constructed in advance may be acquired, for example, by communication from outside the computer system.

[0054] Furthermore, the tunneling current calculation formula for calculating the resistance value of each of the multiple resistor sections 4 in the fourth step may be an approximation formula other than formula (4) as long as it includes a term for the intrinsic tunneling current and a term for the tunneling current based on the field emission phenomenon.

[0055] Furthermore, the calculation formula for the tunneling current used to calculate the resistance value of each of the multiple resistance sections 4 in the fourth step is not limited to a calculation formula including both a term for the intrinsic tunneling current and a term for the tunneling current based on the field emission phenomenon, but may be a calculation formula including at least one of a term for the intrinsic tunneling current and a term for the tunneling current based on the field emission phenomenon.

[0056] Furthermore, in the method for predicting the electrical properties of a composite material according to embodiment 1, leakage is determined, but it is not essential to determine leakage; for example, it is sufficient to simply predict the current-applied voltage characteristics within a predetermined applied voltage range.

[0057] Furthermore, the electrical property related to the current flowing through the internal structure model 1 calculated in the fifth step may be the resistivity, which is the resistance per unit volume in the internal structure model 1.

[0058] (Aspect) The present specification discloses the following aspects.

[0059] A first aspect of the method for predicting electrical characteristics of a composite material member includes a first step, a second step, a third step, a fourth step, and a fifth step. In the first step, an internal structure model (1) is prepared. The internal structure model (1) is a simulation model of the composite material member. The internal structure model (1) has a plurality of functional particles (2) and an insulator portion (3) covering at least a portion of each of the plurality of functional particles (2). Each of the plurality of functional particles (2) includes a conductive particle (21) and an insulating film (22) covering the conductive particle (21). In the second step, a plurality of resistor portions (4) are defined in the internal structure model (1). Each of the plurality of resistor portions (4) is interposed between the conductive particles (21) of two adjacent functional particles (2) among the plurality of functional particles (2) in the internal structure model (1). In the third step, an electric field distribution when a voltage is applied to the internal structure model (1) is calculated. In the fourth step, the first and second steps are repeated until both the electric field and the resistance value converge. The first step is a step of calculating the resistance value of each of the plurality of resistors (4) based on the field emission phenomenon of each of the plurality of resistors (4). The second step is a step of recalculating the electric field of the internal structure model (1) based on the resistance value of each of the plurality of resistors (4) calculated in the first step. The fifth step is a step of calculating electrical characteristics related to the current flowing through the internal structure model (1).

[0060] According to this aspect, it is possible to predict electrical characteristics related to the current that flows through the composite material member when an electric field is applied to the composite material member.

[0061] The method for predicting the electrical properties of a composite material member according to the second aspect is the same as the first aspect, and further includes a sixth step, in which the voltage applied to the internal structure model (1) after the fifth step is changed and the process returns to the third step.

[0062] A method for predicting electrical properties of a composite material member according to a third aspect is based on the method according to the second aspect. In the fourth step, the tunneling current calculation formula for calculating the resistance value of each of the plurality of resistors (4) includes a term for the intrinsic tunneling current and a term for the tunneling current based on the field emission phenomenon.

[0063] According to this embodiment, it is possible to more accurately predict the electrical characteristics of a composite material member having a nonlinear current-applied voltage characteristic.

[0064] A fourth aspect of the method for predicting electrical characteristics of a composite material member is based on the third aspect. In a fourth step, the reciprocal of the electric field applied to each of the plurality of resistors (4) is defined as z, the resistance value of each of the plurality of resistors (4) is defined as R, the first constant is defined as β, the second constant is defined as γ, and the resistance value determined when the applied voltage to each of the plurality of resistors (4) is smaller than the applied voltage when current leakage occurs is defined as R0;

[0065]

number

[0066] A method for predicting electrical properties of a composite material member according to a fifth aspect is based on the third or fourth aspect. In a fourth step, if there is a resistance part (4) among the plurality of resistance parts (4) in which a current exceeding a threshold value is generated, the resistance value of the resistance part (4) in which a current exceeding the threshold value is generated is limited to the resistance value at the time when the current exceeding the threshold value is generated as an upper limit value.

[0067] In the method for predicting the electrical properties of a composite material member according to a sixth aspect, in any one of the first to fifth aspects, the electrical properties related to current include a value of a current flowing through the internal structure model (1).

[0068] According to this aspect, it is possible to predict the value of the current flowing through the internal structure model (1).

[0069] In the method for predicting the electrical properties of a composite material member according to the seventh aspect, in any one of the first to sixth aspects, the electrical properties related to current include resistivity, which is the resistance per unit volume in the internal structure model (1).

[0070] A program according to an eighth aspect is a program for causing a computer system to execute the method for predicting electrical properties of a composite material member according to any one of the first to seventh aspects. [Explanation of symbols]

[0071] 1 Internal structure model 2. Functional particles 21 Conductive particles 22 insulating film 3 Insulator 4 Resistance part

Claims

1. 1. A method for predicting electrical properties of a composite material component, comprising: a first step of preparing an internal structure model as a simulation model of the composite material member, the internal structure model having a plurality of functional particles and an insulator portion covering at least a portion of each of the plurality of functional particles, each of the plurality of functional particles including a conductive particle and an insulating film covering the conductive particle; a second step of defining a plurality of resistive portions in the internal structure model, each of the resistive portions being interposed between conductive particles of two contacting functional particles among the plurality of functional particles; a third step of calculating an electric field distribution when a voltage is applied to the internal structure model; a fourth step of repeating a first step of calculating a resistance value of each of the plurality of resistors based on the field emission phenomenon of each of the plurality of resistors and a second step of recalculating an electric field of the internal structure model based on the resistance value of each of the plurality of resistors calculated in the first step until both the electric field and the resistance value converge; a fifth step of calculating electrical characteristics related to a current flowing through the internal structure model. A method for predicting the electrical properties of composite material components.

2. a sixth step of changing a voltage applied to the internal structural model after the fifth step and returning to the third step; The method for predicting electrical properties of a composite material component according to claim 1 .

3. a calculation formula for a tunneling current for calculating the resistance value of each of the plurality of resistors in the fourth step includes a term for an intrinsic tunneling current and a term for a tunneling current based on a field emission phenomenon; The method for predicting electrical properties of a composite material member according to claim 2.

4. In the fourth step, the reciprocal of the electric field applied to each of the plurality of resistors is defined as z, the resistance value of each of the plurality of resistors is defined as R, the first constant is defined as β, the second constant is defined as γ, and the resistance value determined when the applied voltage to each of the plurality of resistors is smaller than the applied voltage when current leakage occurs is defined as R. ０ year, [Equation 1] Perform the calculation by The method for predicting electrical properties of a composite material member according to claim 3.

5. In the fourth step, when there is a resistor in which a current exceeding a threshold value is generated among the plurality of resistors, the resistance value of the resistor in which a current exceeding the threshold value is generated is limited to an upper limit value, the resistance value at which a current exceeding the threshold value is generated. The method for predicting electrical properties of a composite material member according to claim 3 or 4.

6. The electrical characteristics related to the current include a value of a current flowing through the internal structure model. A method for predicting electrical properties of a composite material member according to any one of claims 1 to 3.

7. The electrical characteristics related to the current include resistivity, which is resistance per unit volume in the internal structure model. A method for predicting electrical properties of a composite material member according to any one of claims 1 to 3.

8. In order to cause a computer system to execute the method for predicting the electrical properties of a composite material member according to any one of claims 1 to 3, program.

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