A design method for a thermal feedback mechanism energy conversion element chip

Abstract

The present invention discloses a design method for a thermal feedback mechanism energy conversion element chip, comprising at least the following steps: Step S1: preparing a substrate layer; Step S2: forming an insulating layer on the substrate layer; Step S3: placing an energy conversion element and at least one thermistor on the insulating layer; Step S4: establishing a parallel electrical connection between the energy conversion element and the thermistor; and Step S5: monolithically integrating the thermistor into a non-polar, two-terminal device. The thermistor is a thermally coupled resistive switch configured to assume a high-resistance or low-resistance state depending on its sensed temperature, with its high-resistance state resistance being much greater than that of the energy conversion element. The present invention eliminates heat accumulation in the energy conversion element chip through the monolithically integrated thermistor, significantly simplifying the complexity of the pyrotechnic device system and improving system reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic energy conversion elements, and in particular to a design method for an energy conversion element chip with a thermal feedback mechanism. Background Art

[0002] Explosive devices are the first, single-action element in the ignition and detonation sequence, determining the ultimate effectiveness of weapon systems and civilian explosives. The electromagnetic environment surrounding modern weapons, ammunition, and other explosive devices is becoming increasingly complex and deteriorating. The electromagnetic energy picked up by exploratory devices within these devices through leads and coupling increases the risk of accidental detonation or performance degradation, posing safety and reliability risks. While low levels of electromagnetic energy are insufficient to trigger ignition, the cumulative thermal effects can degrade exploratory performance. For example, thermal decomposition of the pyrotechnic agent can cause performance changes, leading to loss of reliability and resulting in misfires, delayed ignition, and insensitivity. When electromagnetic energy accumulates to a certain level, it can cause accidental ignition and detonation, threatening the safety of weapons and personnel. Therefore, safety requirements generally require a 1A / 1W / 5min non-fire rating or higher, and a reliability rating of 0.995-0.9999 (with a confidence level of 0.95).

[0003] In order to improve the safety performance of explosive devices, the invention patent application number 201220055188.6 discloses an electromagnetically reinforced semiconductor bridge detonator, and the invention patent application number 2012220512005.9 discloses a surface-mounted semiconductor bridge transducer device for electric explosive devices. By adding a temperature sensitive element - a negative temperature coefficient (NTC) thermistor, it is used to shunt and absorb stray energy such as electromagnetic interference, thereby eliminating the effect of thermal accumulation damage to the semiconductor bridge chip. However, this type of technology has the following shortcomings: (1) The thermal constant time of the NTC thermistor is generally in the second (s) level, such as the Japanese Murata NXFT15XV series, the thermal constant time ≤3s; Fenghua High-Tech FH-HWF series, the thermal constant time ≤20s. The action time of semiconductor bridge SCB transducers is generally in the range of 0.5us-12us, and that of metal film bridge transducers is generally in the range of 100us-1000us. The pyrotechnic system composed of transducers (SCB bridge or metal bridge film) generally has an action time requirement of milliseconds (ms), such as ≯10ms. In other words, the solution of using external commercial-grade NTC thermistors cannot provide real-time protection for pyrotechnic devices and is only suitable for long-term continuous heating, such as 1A1W5min pyrotechnic device safety current test; (2) Using NTC thermistor discrete devices and semiconductor bridge SCB transducer chips, parallel integration on the electrode plug to form a functional circuit, the process is complex and the reliability is reduced.

[0004] In addition, invention patent application number 201710544785.2 discloses an integrated semiconductor bridge transducer element that attempts to address the safety and reliability of ignition devices. This technical solution includes two or more semiconductor bridges; at least one semiconductor bridge has a different resistance value, bridge area, or bridge area shape than the other semiconductor bridges; and the semiconductor bridges are connected in series, in parallel, or in a combination of these. Taking a series connection of N bridges as an example, "each unit bridge can be designed with a different resistance value and bridge area. Bridges with larger areas and higher resistance primarily absorb electromagnetic interference energy, while bridges with smaller areas and lower resistance rapidly vaporize under input energy to generate plasma radiation, igniting the pyrotechnic agent." Basic circuit principles dictate that different resistances in a series circuit result in different energy shares. However, this technical solution cannot automatically identify and distinguish between normal ignition signals (ignition energy) and electromagnetic and other stray interference signals (electromagnetic stray interference energy). Therefore, it fails to achieve the goal of "at least one semiconductor bridge is used to absorb electromagnetic interference energy, while the other semiconductor bridges are used to convert input energy into plasma ignition energy."

[0005] In summary, to eliminate heat buildup in semiconductor bridge chips, existing technologies typically use external discrete NTC thermistors, and no integrated chip solutions exist. Existing integrated designs employ multiple semiconductor bridges with different structures, each responsible for igniting the pyrotechnic device and absorbing electromagnetic interference energy. However, this solution cannot effectively distinguish between normal ignition signals and electromagnetic interference signals.

[0006] Therefore, in view of the defects of the existing technology, it is necessary to propose a technical solution to solve the technical problems existing in the existing technology. Summary of the Invention

[0007] In view of this, it is indeed necessary to provide a design method for a thermal feedback mechanism energy conversion element chip, which can eliminate the heat accumulation of the semiconductor bridge energy conversion element or the metal film bridge energy conversion element chip (hereinafter collectively referred to as the energy conversion element chip) through a monolithic integrated thermistor, and at the same time provide real-time protection for pyrotechnics, and can automatically distinguish between normal ignition energy and electromagnetic and other interference energy.

[0008] In order to solve the technical problems existing in the prior art, the technical solutions of the present invention are as follows:

[0009] A method for designing a thermal feedback mechanism energy conversion element chip includes at least the following steps:

[0010] Step S1: preparing a substrate layer;

[0011] Step S2: forming an insulating layer on the substrate layer;

[0012] Step S3: arranging an energy conversion element and at least one thermistor on the insulating layer;

[0013] Step S4: forming a parallel electrical connection between the energy conversion element and the thermistor;

[0014] Step S5: Monolithically integrating into a non-polarity two-terminal device.

[0015] As a further improvement, the thermistor is a thermally coupled resistive switch, configured to exhibit a high resistance state or a low resistance state according to its sensed temperature, wherein the resistance value of the high resistance state is much greater than the resistance value of the energy conversion element;

[0016] When the thermistor is in a high-resistance state, its parallel branch is almost in an open-circuit state, and the circuit energy is loaded on the energy conversion element; when the thermistor is in a low-resistance state, its parallel branch is shunted to eliminate heat accumulation on the energy conversion element.

[0017] As a further improvement, the thermistor is made of a reversible metal insulator phase change material. When its sensing temperature is lower than the phase change temperature, the thermistor is in a high resistance state; and when its sensing temperature is higher than the phase change temperature, the thermistor is in a low resistance state.

[0018] As a further improvement, the thermal coupling between the energy conversion element and the thermistor is adjusted by setting a distance d between the energy conversion element and the thermistor.

[0019] As a further improvement, the distance d is set according to the chip material parameters to achieve the following: during normal ignition, the thermistor does not reach its phase change temperature within the action time of the energy conversion element.

[0020] As a further improvement, the distance d is set according to the chip material parameters to achieve the following: the time it takes for the energy generated by the transducer to be thermally coupled to the thermistor and reach the phase change temperature of the thermistor is less than the action time of the pyrotechnic system.

[0021] As a further improvement, the phase transition temperature of the thermistor is controlled by cooling / increasing the temperature by means of chemical element doping or the like.

[0022] As a further improvement, the phase change time of the thermistor is on the order of microseconds or less.

[0023] As a further improvement, a plurality of thermistors are symmetrically placed with the energy conversion element as the center.

[0024] As a further improvement, the thermistor is prepared using insulator-metal reversible phase change material VO2.

[0025] As a further improvement, the energy conversion element adopts a semiconductor bridge SCB made of heavily doped N-type polysilicon, or a metal film bridge made of a single metal or a composite metal; wherein the single metal is any one of Ti / Al / Ni / Cr / Pt / Au; and the composite metal is any one of NiCr / PtW / NiAl.

[0026] As a further improvement, the typical resistance of the energy conversion element is ∼1.0Ω.

[0027] As a further improvement, the insulating layer uses SiO2 or Si3N4 as the insulating medium.

[0028] As a further improvement, the substrate layer is made of silicon, sapphire or glass.

[0029] As a further improvement, any one or more of a protection device, a switch device or a SOC integrated circuit is monolithically integrated on the substrate layer.

[0030] Compared with the existing technology, the present invention eliminates heat accumulation in the energy conversion element chip through a monolithic integrated thermistor. Since the thermistor is made of reversible metal insulator phase change material, its phase change time is in the microsecond level, thereby enabling real-time protection of pyrotechnics. At the same time, by adopting the technical solution of the present invention, it is only necessary to reasonably set the distance d between the energy conversion element and the thermistor to automatically distinguish between normal ignition energy and electromagnetic interference energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural block diagram of the thermal feedback mechanism energy conversion element chip of the present invention.

[0032] Figure 2 This is the equivalent circuit of the thermal feedback mechanism energy conversion element chip of the present invention.

[0033] Figure 3 This is a graph showing the relationship between the resistivity change rate and phase transition temperature of common MIT materials.

[0034] Figure 4 Schematic diagram of the phase transition of VO2 material. After heating, at around 68°C, the resistance drops by more than three orders of magnitude, and the lattice symmetry changes from monoclinic to tetragonal.

[0035] Figure 5 Schematic diagram of the switching transient characteristics of the VO2 material configuration. The switching time from the "high resistance" state to the "low resistance" state is about 150us.

[0036] Figure 6 This is a flowchart of the thermal feedback mechanism energy conversion element chip design method of the present invention.

[0037] Figure 7Schematic diagram of the relationship between thermal relaxation time Δt and distance d in the R-RT system constructed by the chip of the present invention.

[0038] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0039] The technical solution provided by the present invention will be further described below with reference to the accompanying drawings.

[0040] See also Figure 6 , which shows a design method of a thermal feedback mechanism energy conversion element chip of the present invention, comprising at least the following steps:

[0041] Step S1: preparing a substrate layer;

[0042] Step S2: forming an insulating layer on the substrate layer;

[0043] Step S3: arranging an energy conversion element and at least one thermistor on the insulating layer;

[0044] Step S4: forming a parallel electrical connection between the energy conversion element and the thermistor;

[0045] Step S5: Monolithically integrating into a non-polarity two-terminal device;

[0046] The thermistor is a thermally coupled resistive switch, which is configured to be in a high resistance state or a low resistance state according to its sensed temperature, and its high resistance state resistance is much greater than the resistance of the transducer element.

[0047] The thermal coupling between the energy conversion element and the thermistor is adjusted by setting the distance d between the energy conversion element and the thermistor.

[0048] In the above technical solution, the distance d is set based on the chip material parameters to ensure that, during normal ignition, the thermistor does not reach its phase transition temperature within the transducer's operating time. The distance d is also set based on the chip material parameters to ensure that the time it takes for the energy generated by the transducer to be thermally coupled to the thermistor and reach its phase transition temperature is less than the operating time of the pyrotechnic system. Furthermore, by setting the distance d between the transducer and the thermistor, the thermal coupling between the transducer and the thermistor is adjusted. In other words, by appropriately designing the distance d, the thermal relaxation time Δt of the R-RT-substrate system is adjusted. The detailed principle is described below.

[0049] See also Figure 1, shown is a block diagram of the structure of a thermal feedback mechanism transducer chip provided by the present invention. The chip comprises at least a substrate layer 1, a transducer element 2 integrated on the substrate layer 1, and at least one thermistor 3 electrically connected in parallel with the transducer element 2. The thermistor 3 is a thermally coupled resistive switch, configured to assume either a high-resistance or low-resistance state depending on its sensed temperature. The high-resistance value of the thermistor is significantly greater than that of the transducer element. When the thermistor 3 is in the high-resistance state, its parallel branch acts as an open circuit, with all circuit energy being loaded onto the transducer element 2. When the thermistor 3 is in the low-resistance state, its parallel branch shunts current from the main circuit, eliminating heat accumulation in the chip.

[0050] See also Figure 2 , shown is the equivalent circuit of the thermal feedback mechanism energy conversion element chip of the present invention. The circuit is a non-polar two-terminal device with ports A and B. The energy conversion element 2 is the main circuit and is connected to multiple branches of thermistors 3. All of them can be manufactured using well-known microelectronic processes and are easy to integrate into a single chip.

[0051] like Figure 1 As shown, an insulating layer 4 is also provided on the substrate layer 1. The insulating layer 4 can be made of an insulating medium such as SiO2 or Si3N4. The transducer 2 and the thermistor 3 are provided on the insulating layer 4 to provide electrical isolation. The substrate layer 1 can be made of materials such as silicon, sapphire, or glass. If the substrate layer 1 is made of silicon, electronic devices such as protection devices, switching devices, and SOC integrated circuits can be further monolithically integrated with the transducer R and thermistor RT to provide protection for the pyrotechnic system and intelligent ignition control.

[0052] As a preferred solution, multiple thermistors 3 are symmetrically placed with the energy conversion element 2 as the center, so as to achieve multi-way symmetrical diversion and quickly and evenly cool the energy conversion element.

[0053] Preferably, the typical resistance of the energy conversion element 2 is 1.0Ω. The energy conversion element can be a semiconductor bridge SCB made of heavily doped N-type polysilicon, or a metal film bridge made of a single metal or a composite metal. The semiconductor bridge SCB energy conversion element made of heavily doped polysilicon material using microelectronics technology has a typical resistivity of 7.6x10 -4 Ω.cm, with typical dimensions of 100um(L)x380um(W)x2um(H). It can also be a metal film bridge transducer formed by a single metal or composite metal deposited by a microelectronic PVD process, wherein the single metal is any one of Ti / Al / Ni / Cr / Pt / Au; the composite metal is any one of NiCr / PtW / NiAl, with a typical resistivity of 1.0x10 -4 Ω.cm.

[0054] The above technical solution proposes for the first time the inventive concept of a monolithic integrated design of a transducer and thermistor. In contrast, existing technologies in the field of pyrotechnics typically employ an external discrete NTC thermistor connected in parallel to a semiconductor bridge SCB transducer chip, and no monolithic integrated technical solution has been found. Furthermore, the present invention configures the thermistor as a thermally coupled resistive switch. At room temperature, the thermistor exhibits a high resistance exceeding kΩ (high resistance), much greater than the resistance of the transducer. This parallel branch acts as an open circuit. When the temperature exceeds a certain threshold temperature Tc, the RT resistance decreases by orders of magnitude (low resistance), and the parallel branch acts as a shunt for the transducer circuit, thereby eliminating heat accumulation in the transducer. When the RT temperature returns to room temperature, the RT resistance reversibly recovers to a value exceeding kΩ.

[0055] The discrete NTC thermistors used in the prior art are mostly made of manganese-cobalt-nickel (Mn-Co-Ni) ceramic materials, which are not compatible with microelectronics processes and are not conducive to monolithic integration.

[0056] In order to overcome the above technical defects, in a preferred technical solution of the present invention, the thermistor is made of a reversible metal insulator phase change material. When its sensing temperature is lower than the phase change temperature, the thermistor is in a high-resistance state; and when its sensing temperature is higher than the phase change temperature, the thermistor is in a low-resistance state.

[0057] That is, the present invention proposes to use a class of materials with unique and reversible metal-insulator phase transition properties (MIT) to make thermistor RT. There are a large number of materials with MIT properties in nature, and theoretically all of them can be used in the chip solution designed by the present invention. Figure 3 The relationship between the resistivity change rate and phase transition temperature of common MIT materials, such as vanadium (V) oxide, niobium (Nb) oxide, europium (Eu) oxide, etc. The resistivity of vanadium oxide decreases by 10 during the phase transition process. 3 -10 5 times, the resistivity of niobium oxide decreases by 10 during the phase transition. 6 times, and the resistivity of europium oxide decreases by 10 during the phase transition. 13 The phase transition temperature varies with different MIT materials, and the same MIT material can adjust the phase transition temperature to a range of 0-1080K (-270℃--807℃) by adjusting the MIT film doping and film grain size.

[0058] The phase transition temperature of metal-insulator (MIT) materials can be manipulated by methods such as chemical doping to lower or raise the temperature. For example, the phase transition temperature of pure VO2 material is 340K (68°C). Through doping, this can be controlled to a temperature between 40°C and 70°C. Typically, VO2 material is doped with chemical elements such as W, Cu, Mo, Nb, Ti, and Fe to control the VO2 phase transition temperature. To lower the phase transition temperature, high-valent elements such as W 6+, Mo 6+, and Nb 5+ are typically doped. To raise the phase transition temperature, low-valent elements such as Cr 3+, Ga 3+, and Al 3+ are typically doped.

[0059] Furthermore, thermistors made from metal-insulator phase change (MIT) materials have phase transition times in the microsecond range or below, enabling real-time protection for explosive devices. Explosive systems require a function time in the millisecond range, such as ≤10ms. Specifically, the presence of the thermistor must not affect normal ignition functionality, yet must be able to react quickly to interference energy. In practical applications, if heat accumulation from interference energy exceeds a certain temperature, such as 80°C, the thermistor will not activate, or the thermistor will not react quickly enough. This will cause the explosive agent pressing against it to thermally decompose, causing performance changes and reducing reliability. Existing discrete NTC thermistors typically have a thermal constant time in the second range, making them incapable of providing real-time protection for explosive devices. The metal-insulator phase change (MIT) material employed in this invention has a phase transition time in the microsecond range, enabling real-time elimination of heat accumulation on the energy conversion element within the pyrotechnic system's function time, within the millisecond range, ensuring that the explosive agent mounted on the energy conversion element will not thermally decompose, thereby improving system reliability.

[0060] Existing research has shown that a temperature of no more than 80°C will not damage the pyrotechnic agent pressed on the energy conversion element R. Among the phase transition temperatures of vanadium oxides, VO is 126K (-146°C), V2O3 is 160K (-112°C), VO2 is 340K (68°C), and V2O5 is 530K (258°C), which is determined by its atomic structure. Preferably, the oxide VO2 material of the transition metal vanadium (V) is used to make the thermistor RT. During the phase change process, the material changes from a low-temperature monoclinic rutile structure to a high-temperature tetragonal rutile structure. With the transformation of the crystal structure, the electrical and optical properties of VO2 will mutate, and the mutation can be completed in picoseconds (ps) at the fastest. After theoretical research and computer simulation verification, the applicant found that VO2 material can perfectly meet the following standards of the pyrotechnic system:

[0061] (a) Initially at room temperature of 300K (T0~25℃), RT has a large resistance of more than kΩ. When the temperature exceeds a certain threshold temperature Tc, the RT resistance decreases by orders of magnitude. When the RT temperature returns to room temperature, the RT resistance reversibly recovers to more than kΩ.

[0062] (b) The RT resistance value changes by orders of magnitude. Generally, it should be >3 orders of magnitude, which is significantly better than the current discrete thermistor solution which changes by less than 1 order of magnitude.

[0063] (c) The RT resistance value transient conversion is fast, on the order of 1µs, which is significantly better than the current discrete thermistor's S-level = 1000000µs.

[0064] (d) Compatible with microelectronics technology, easy to integrate with transducer element R and other circuits.

[0065] The present invention uses VO2 for thermistor RT of the pyrotechnic system. The phase transition temperature Tc = 68°C is determined by the physical properties of VO2. Vanadium dioxide (VO2) has unique phase transition properties and can transform between an insulator and a metal. It behaves as an insulator at room temperature and behaves as a metal conductor above 68°C (Tc). The resistance change range is greater than three orders of magnitude. Figure 4 The transient characteristics diagram of the resistor is as follows: Figure 5 As shown in the figure, the thermistor RT rapidly decreases its resistance when it senses temperature Tc. Current generated by interference such as radio frequency is shunted and absorbed by the thermistor, preventing heat accumulation in the EID. This prevents damage to the transducer, alteration of the pyrotechnic agent's performance, or the possibility of accidental ignition. Under normal ignition conditions, the thermistor RT's resistance is significantly greater than the transducer R's resistance, approximately 1.0Ω, and has no impact on the pyrotechnic system's ignition performance. This fundamentally improves both the safety and reliability of the pyrotechnic device.

[0066] The preparation of VO2 thin films can be achieved using existing processes, mainly magnetron sputtering, sol-gel, chemical vapor deposition, pulsed laser deposition, etc., which are compatible with standard microelectronics processes and have been widely used in infrared thermal imaging, thermistors, thermoswitches, optical switches, laser protection and other fields.

[0067] The existing technology uses multiple semiconductor bridges with different structures to respectively perform the functions of igniting the explosive device and absorbing electromagnetic interference energy. However, this technical solution cannot effectively distinguish between normal ignition signals and electromagnetic interference signals. The technical solution of the present invention can automatically distinguish between normal ignition energy and electromagnetic interference energy by properly setting the distance d between the energy conversion element and the thermistor. The specific working principle is as follows:

[0068] (1) When the room temperature is initially 340K (T0 ~ 25°C), RT is a large resistor (in the kΩ range) connected in parallel with the transducer R (~1.0Ω). RT>>R, so the equivalent resistance at the AB port is still around ~1.0Ω. Whether it is normal ignition signal energy or electromagnetic interference energy, both act primarily on the transducer R, and there is no need to distinguish between the different types of energy.

[0069] (2) Normal ignition energy and electromagnetic interference energy are automatically distinguished in the following way: the heat of the energy conversion element R is mainly conducted to the substrate layer 1 through the heat conduction mode (the two modes of heat radiation and heat convection can be ignored in the application scenario of the present invention and do not affect the explanation of the main purpose of the principle of the present invention). The substrate layer 1 is conducted to the thermistor RT as a heat conducting medium. The physical process is determined by the Fourier heat conduction equation. By selecting the spatial distance d between the energy conversion element R and the thermistor RT, the degree of thermal coupling between the energy conversion element R and the thermistor RT can be determined. By adjusting the distance between the energy conversion element and the thermistor to d, the thermal coupling between the energy conversion element and the thermistor can be adjusted and calibrated with the thermal relaxation delay time Δt. Δt is a function of d, recorded as Δt(d). The larger the spatial distance d, the longer the thermal relaxation delay time Δt of the R-RT-substrate thermal coupling system, and the weaker the thermal coupling between the energy conversion element R and the thermistor RT. The thermal coupling degree Δt is used to automatically distinguish several operating conditions of the pyrotechnic device, as follows:

[0070] (a) Normal ignition of explosive devices usually uses constant current or CDU capacitor ignition. Taking 5A constant current ignition as an example, the resistance value of the transducer R is ~1.0Ω, RT>>R, and the ignition current flows almost entirely through the transducer R. The energy diverted by RT is almost negligible. The power on the transducer R is W = I 2 R=25W, the pyrotechnic product acts quickly and ignites normally.

[0071] Published experimental data indicates that the operating time of semiconductor bridge (SCB) transducers (R) ranges from 0.5µs to 12µs, while that of metal film bridge transducers (R) ranges from 100µs to 1000µs. By prioritizing the type of transducer (R) used in the pyrotechnic system to determine the appropriate d and different thermal relaxation times (Δt), the goal is to ensure that the heat transfer from the transducer (R) does not reach the threshold temperature (Tc) of the thermistor (RT). Consequently, RT maintains a high resistance and is inactive, allowing nearly 100% of the ignition energy to be used for ignition. This overcomes the shortcomings of existing solutions. Specifically, by setting an appropriate distance (d), the thermistor does not reach its phase transition temperature during the transducer's operating time during normal ignition. This ensures that all ignition energy is utilized in the transducer for ignition.

[0072] (b) When conducting a safety current test of 1A1W5min or a more stringent one such as 2A4W5min, or when the pyrotechnic system is in storage, for whatever reason, such as radio frequency energy generating Joule heat, causing the pyrotechnics in the system to be continuously heated and generate heat accumulation, when the temperature rise exceeds the threshold temperature Tc of RT, RT is automatically activated to divert the interference energy of the transducer R. The thermal relaxation time Δt from room temperature to Tc satisfies: the action time of the transducer R (~1us-1000us) < Δt < the action time of the pyrotechnic system (such as ≯10ms). In other words, setting a suitable distance d ensures that the time it takes for the energy generated by the transducer to be thermally coupled to the thermistor and reach the phase change temperature of the thermistor is less than the action time of the pyrotechnic system, thereby enabling real-time protection of the pyrotechnics at the millisecond (ms) level.

[0073] Therefore, when the thermal relaxation time Δt meets the above conditions, it can be ensured that: during normal ignition, RT does not play a role, and almost 100% of the ignition energy is used for ignition. When the electromagnetic interference energy accumulates to a certain threshold temperature Tc, RT is activated in real time, diverting the interference energy, so that the transducer R is not damaged and the performance of the pyrotechnic agent suppressed on it is not changed; when the temperature of the pyrotechnic system drops, RT automatically returns to the high-resistance state. RT must reversibly switch back and forth between the high-resistance and low-resistance states, with a time of nanoseconds to microseconds, which is very fast. Therefore, the presence of RT does not affect the operating time of the entire pyrotechnic system. This overcomes the problem that the existing technical solutions use discrete NTC thermistors, whose thermal constant time is generally in the second (s) level, and cannot provide real-time millisecond (ms) level protection for pyrotechnic products. It is only suitable for long-term continuous heating of more than second (s), such as the 1A1W5min pyrotechnic product safety current test.

[0074] From the above analysis, it can be seen that by adopting the technical solution of the present invention, the thermal relaxation time Δt of the R-RT-substrate thermal coupling system can be designed and controlled by the spatial distance d between the transducer R and the thermistor RT on the substrate layer 1, and a certain safety factor can be set.

[0075] See also Figure 7 , which is a schematic diagram showing the relationship between the thermal relaxation time Δt and the distance d in the R-RT-substrate system constructed by the chip of the present invention, wherein the chip structure is as follows Figure 1 As shown, the substrate layer 1 is made of Si, the insulating layer 4 is made of SiO2, the transducer 2 is a semiconductor bridge SCB made of heavily doped N-type polycrystalline silicon, and the thermistor 3 is made of VO2. Specifically, the chip has a Si substrate with dimensions of 1000um (L) x 2000um (W) x 300um (H); the insulating layer 4 has dimensions of 1000um (L) x 2000um (W) x 0.1um (H); and the transducer 2 has dimensions of 100um (L) x 380um (W) x 2.0um (H). Material parameters are shown in Table 1 below.

[0076] Table 1 Material parameters

[0077] Heat capacity at constant pressure J / (kg.K) <![CDATA[Density Kg / m 3 > Thermal conductivity W / mK Si 700 2329 141.2 polysilicon 678 2320 45 <![CDATA[SiO2]]> 966 2200 7.6

[0078] The transducer R can be regarded as a heat source. In this embodiment, the length of the transducer R is 100um and the resistance is 1.0Ω. Under the experimental conditions of simulating a 1.5A constant current safety current, the heat generation power of the transducer is 2.25W. Figure 7 As shown in the figure, with the transducer element R as the center, the heat conduction through the Si substrate reaches the thermistor. By solving the distance and time to reach the phase transition temperature (340K) of the thermistor RT, it can be found that the thermal relaxation delay time Δt of the R-RT-substrate thermal coupling system is a function of d. Figure 7 The data in are fitted into an approximate empirical formula:

[0079] Δt=2.65+2.689ln(0.51d)

[0080] Its physical explanation is similar to that of an RC series circuit. During the charging process, the voltage at the capacitor terminal gradually increases exponentially with time. Here, the thermal resistance and thermal capacitance of the equivalent R-RT-substrate thermal coupling system are connected in series.

[0081] When Δt is less than 2ms, the heat generated by the transducer element does not reach the phase transition temperature of RT. The action time of semiconductor transducers is between 0.5us and 12us, and that of metal film bridge transducers is between 200us and 1000us. Therefore, the existence of RT will not affect the normal firing of the transducer element R.

[0082] When the distance d is selected to be 14um, the RT phase transition temperature of 340K is reached in 8ms, which meets the requirement that the action time of the pyrotechnic system is ≯10ms.

[0083] The above-mentioned computer simulation results of solving the Fourier heat conduction equation through physical modeling and the finite element method have verified the technical effect of the present invention. Theoretically, the R-RT-substrate thermal coupling system of the transducer of any shape and any material can be simulated to guide specific engineering practices, so as to design the transducer chip that meets the actual needs of the pyrotechnic system.

[0084] From the above analysis, it can be seen that the technical solution of the present invention, by setting the distance d between the energy conversion element and the thermistor, ensures that during normal ignition, the thermistor does not reach its phase transition temperature within the energy conversion element's operating time. Furthermore, it ensures that the time it takes for the energy generated by the energy conversion element to be thermally coupled to the thermistor and reach its phase transition temperature is less than the operating time of the pyrotechnic system. This enables real-time millisecond-level protection of pyrotechnic devices and automatically distinguishes between normal ignition energy and electromagnetic interference energy.

[0085] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0086] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A design method for a thermal feedback mechanism energy conversion element chip, characterized in that: At least the following steps are included: Step S1: preparing a substrate layer; Step S2: forming an insulating layer on the substrate layer; Step S3: arranging an energy conversion element and at least one thermistor on the insulating layer; Step S4: forming a parallel electrical connection between the energy conversion element and the thermistor; Step S5: Monolithically integrating into a non-polarity two-terminal device; The thermistor is a thermally coupled resistive switch, which is used to present a high resistance state or a low resistance state according to its sensed temperature, and its high resistance state resistance is much greater than the resistance of the energy conversion element; When the thermistor is in a high-resistance state, its parallel branch is almost in an open-circuit state, and the circuit energy is loaded on the energy conversion element. When the thermistor is in a low-resistance state, its parallel branch is shunted to eliminate heat accumulation on the energy conversion element. The thermistor is made of a reversible metal-insulator phase change material. When its sensing temperature is lower than the phase change temperature, the thermistor is in a high-resistance state; and when its sensing temperature is higher than the phase change temperature, the thermistor is in a low-resistance state. The phase change time of the thermistor is on the order of microseconds or less.

2. The design method of the thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The thermal coupling between the energy conversion element and the thermistor is adjusted by setting the distance d between the energy conversion element and the thermistor.

3. The design method of the thermal feedback mechanism energy conversion element chip according to claim 2, characterized in that: The distance d is set according to the chip material parameters to achieve: when igniting normally, the thermistor does not reach its phase change temperature within the action time of the energy conversion element.

4. The design method of the thermal feedback mechanism energy conversion element chip according to claim 2, characterized in that: The distance d is set according to the chip material parameters to achieve: the time it takes for the energy generated by the energy conversion element to be thermally coupled to the thermistor and reach the phase change temperature of the thermistor is less than the action time of the pyrotechnic system.

5. The design method of the thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The phase change temperature of the thermistor is controlled by cooling / increasing the temperature through methods such as chemical element doping.

6. The design method of the thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The plurality of thermistors are symmetrically placed with the energy conversion element as the center.

7. The design method of the thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The thermistor is prepared by using insulator-metal reversible phase change material VO2.

8. The method for designing a thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The energy conversion element adopts a semiconductor bridge SCB made of heavily doped N-type polysilicon, or a metal film bridge made of a single metal or a composite metal; wherein the single metal is any one of Ti / Al / Ni / Cr / Pt / Au; and the composite metal is any one of NiCr / PtW / NiAl.

9. The method for designing a thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The typical resistance of the energy conversion element is .

10. The method for designing a thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The insulating layer uses SiO2 or Si3N4 as the insulating medium.

11. The design method of the thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The substrate layer is made of silicon, sapphire or glass.

12. The method for designing a thermal feedback mechanism energy conversion element chip according to claim 1, characterized in that: The substrate layer is also monolithically integrated with any one or more of a protection device, a switch device or a SOC integrated circuit.

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