Polymer precursor ceramic low-temperature sensor electrode solder and preparation and application thereof

Abstract

The invention belongs to the technical field of temperature sensor preparation, and particularly relates to a polymer precursor ceramic low-temperature sensor electrode solder and preparation and application thereof.The electrode solder comprises nanoscale conductive ceramic powder, a liquid polymer precursor, a curing agent and the like, and the curing agent is a light curing agent or a thermal curing agent; the mass ratio of the nanoscale conductive ceramic powder to the liquid polymer precursor is (30: 70)-(70: 30), and the mass ratio of the light curing agent or the thermal curing agent to the liquid polymer precursor is (1-5): 100. The connection position of the ceramic substrate and the electrode is filled with the conductive solder, and after high-temperature pyrolysis treatment, high-stability electrical connection between the electrode and the precursor ceramic is achieved, the problem that connection between traditional metal conductive solder and conductive epoxy glue and the ceramic substrate is prone to disengagement and failure is effectively solved, and the service life of the ceramic substrate is prolonged. And the mechanical reliability and the electrical property continuity of the sensor are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature sensor preparation, and in particular relates to polymer precursor ceramic low-temperature sensor electrode solder and its preparation and application. Background Art

[0002] With the continuous development of fields such as aerospace exploration, polar scientific research and deep space exploration, higher requirements are placed on temperature sensors that can work stably in extremely low temperature environments. Polymer precursor ceramics are widely regarded as a class of highly promising high-performance temperature sensor sensitive materials due to their excellent semiconductor properties, thermal shock resistance and good mechanical properties. They are particularly suitable for temperature detection applications in extreme environments. In the applicant's previous research (see Chinese patent document with application number 2025103720089), it has been confirmed that it is particularly suitable for deep low temperature environments below -100°C, such as the night surface of the moon (as low as -170°C to -190°C) or other similar outer space environments.

[0003] In the fabrication of PDC-based temperature sensors, a reliable connection between the electrodes and the ceramic substrate is crucial for ensuring long-term stable device operation. However, traditional electrode connection methods, such as metal welding, bonding with precious metal pastes, or conductive epoxy adhesives, often suffer from thermal expansion coefficient mismatch, low-temperature embrittlement, or thermal cycling failure. These connection methods are prone to cracking, detachment, or poor conductivity under cryogenic conditions, seriously affecting sensor reliability and measurement accuracy.

[0004] Conductive ceramics, such as ITO and ZnO, have excellent electrical conductivity and are widely used as conductive thin film layers. Their thermal expansion coefficients closely match those of PDCs (polymer-derived ceramics), making them ideal electrode connection materials. However, these conductive ceramics struggle to form a stable bond directly with the PDC substrate. Without an intermediate adhesive layer, their high sintering temperatures and poor compatibility make reliable low-temperature electrical connections difficult. Therefore, there is an urgent need to develop an electrode connection solution that can both stably bond to the PDC substrate and maintain good conductivity at low temperatures. Summary of the Invention

[0005] To address these issues, the present invention innovatively prepares a composite conductive solder by mixing a polymer precursor with a conductive ceramic filler. This method not only regulates the solder's thermal expansion coefficient but also synergizes with PDCs during pyrolysis to form a continuous conductive network, achieving a strong conductive connection between the electrode and the polymer precursor ceramic. This improves the sensor's electrical stability and mechanical reliability in cryogenic environments.

[0006] To achieve the above-mentioned objectives, the present invention provides a polymer precursor ceramic low-temperature sensor electrode solder, comprising the following components: nanoscale conductive ceramic powder, a liquid polymer precursor and a curing agent, wherein the curing agent is a photocuring agent or a thermal curing agent, the mass ratio of the nanoscale conductive ceramic powder to the liquid polymer precursor is 30:70 to 70:30, and the mass ratio of the photocuring agent or thermal curing agent to the liquid polymer precursor is (1 to 5):100.

[0007] Preferably, the nano-scale conductive ceramic powder is nano-ITO powder, Nb-doped TiO2 conductive nano-powder or ZnO nano-powder.

[0008] Preferably, the liquid polymer precursor is any one of a binary polymer ceramic precursor, a ternary polymer ceramic precursor, a quaternary polymer ceramic precursor or a quinary polymer ceramic precursor.

[0009] Preferably, the photocuring agent is Irgacure 819 photoinitiator, and the thermal curing agent is dicumyl peroxide.

[0010] The polymer precursor ceramic low-temperature sensor electrode solder is prepared according to the following steps:

[0011] S1, weighing nano-scale conductive ceramic powder, liquid polymer precursor, and light curing agent or heat curing agent according to the mass ratio;

[0012] S2, stirring under heating conditions in a vacuum condition to prepare a uniform conductive solder, which is a polymer precursor ceramic low-temperature sensor electrode solder.

[0013] Preferably, the heating temperature in step S2 is 90-120°C.

[0014] Preferably, the stirring time in step S2 is 20 to 40 minutes.

[0015] Based on another object of the present invention, the application of the above polymer precursor ceramic low-temperature sensor electrode solder in the preparation of a low-temperature sensor is proposed, and the application includes the following steps:

[0016] S91, evenly filling the conductive solder to the position where the polymer precursor ceramic substrate and the electrode are connected, and performing vacuum degassing treatment to ensure good contact between the conductive solder and the surface of the polymer precursor ceramic substrate and the electrode surface;

[0017] S92, curing the conductive solder by light curing or heat curing to form a preliminary bonding structure to ensure stable embedding of the electrode, thereby pre-fixing the electrode;

[0018] S93, performing pyrolysis treatment at 800-1100°C in an inert atmosphere at a pyrolysis rate of 0.5-3°C / min for 10-60 min to obtain a low-temperature sensor having good access between the electrode and the polymer precursor ceramic matrix.

[0019] In this step, the inert atmosphere is an argon atmosphere or a nitrogen atmosphere. The pyrolysis treatment can promote the transformation of the polymer precursor into a ceramic structure, and effectively embed the conductive ceramic particles therein, constructing a continuous and stable conductive connection path, forming a ceramic-conductive ceramic-electrode integrated structure.

[0020] Preferably, the vacuum degassing treatment in step S91 lasts for 10 to 30 minutes, until the bubbles in the conductive solder are completely removed and the conductive solder is in uniform contact with the polymer precursor ceramic matrix and the electrode.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] 1. Improved electrode connection reliability: This method combines a conductive ceramic with a liquid polymer precursor to form a composite conductive solder. After pyrolysis, this solder forms a dense, continuous, integrated ceramic connection between the ceramic substrate and the electrode. Compared to traditional bonding methods using metal wires or metal pastes, this method significantly improves bond strength and interfacial stability at low temperatures, avoiding electrode cracking and detachment caused by thermal expansion mismatch.

[0023] 2. Enhanced conductivity and low-temperature stability: The conductive ceramic powder forms a continuous conductive network within the ceramic matrix. Combined with the ceramic structure generated by the pyrolysis of the polymer precursor, this creates a stable conductive path in the electrode connection area. This structure exhibits excellent electrical performance in extremely low-temperature environments, avoiding the high resistance fluctuations and poor contact associated with traditional metal soldering or silver paste connections at low temperatures.

[0024] 3. Simple Process and Ease of Integrated Manufacturing: The present invention features a concise process flow. The conductive solder preparation and application process includes conductive solder preparation, homogeneous dispersion, solder filling, pre-curing connection, and pyrolysis ceramic formation. It is easy to operate and easily automated and mass-produced. The conductive solder maintains excellent condition and is suitable for a variety of modern processing methods, including screen printing, spray coating, and injection molding. The preparation process is compatible with conventional PDC pyrolysis processes, resulting in a simple, highly repeatable process suitable for engineering deployment.

[0025] 4. Can reduce manufacturing costs: The conductive ceramic and polymer precursor materials used in the present invention are low-priced, avoiding the precious metal resources that traditional metal solders rely on, thereby effectively reducing manufacturing costs.

[0026] In summary, the present invention has the advantages of simple process, easy integrated manufacturing, and low cost, and can enhance the conductivity and low-temperature stability of the low-temperature sensor electrode connection area, which is beneficial to improving the reliability of the low-temperature sensor electrode connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1 is a process flow chart of the preparation and application of the conductive solder of the present invention in the examples.

[0028] Figure 2 This is a physical picture of the conductive solder prepared in Example 1;

[0029] Figure 3 This is a photo of the conductive solder after curing after being coated between the SiCN ceramic substrate and the platinum electrode in Example 1;

[0030] Figure 4 This is a photo of the conductive solder after sintering, in which the conductive solder in Example 1 is applied between the SiCN ceramic substrate and the platinum electrode.

[0031] Figure 5 The voltage-temperature curve of the sensor prepared in Example 1 at low temperature is shown below:

[0032] Figure 6 The curve of voltage variation at low temperature of the sensor 2 prepared in Comparative Example 1 is shown as a function of temperature. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] All raw materials used in the present invention are not specifically limited in their origin and can be purchased commercially or prepared according to conventional methods known to those skilled in the art. For example, the present invention does not specifically limit the type of liquid polymer precursor, encompassing any commercially available binary, ternary, quaternary, or quinary polymer ceramic precursors, as long as they exhibit fluidity and can be mixed with nanoscale conductive ceramic powders. The specific precursor selection criteria can be determined by selecting the same polymer precursor as the polymer precursor ceramic substrate to avoid undesirable effects on sensor performance from different precursors. It should be noted that the above criteria serve only as a guideline and are not intended to be limiting.

[0035] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts conventional purity used in the art.

[0036] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0037] like Figure 1 As shown, the present invention provides a preparation method and application of a polymer precursor ceramic low-temperature sensor electrode solder, comprising the following steps:

[0038] S1, preparation of conductive solder: nano-scale conductive ceramic powder and liquid polymer precursor are mixed with a certain amount of light curing agent or heat curing agent in a certain mass ratio and stirred at 90-120°C in a vacuum condition for 30 minutes to obtain a uniform conductive solder. This conductive solder is the polymer precursor ceramic low-temperature sensor electrode solder;

[0039] In this step, the mass ratio of the nano-scale conductive ceramic powder to the liquid polymer precursor is 30:70 to 70:30 (e.g., 30:70, 40:60, 50:50, 60:40, 70:30, etc.). The mass of the light curing agent or thermal curing agent is 1% to 5% (e.g., 1%, 2%, 3%, 4%, 4%, 5%) of the total amount of the liquid polymer precursor.

[0040] S2, solder filling: uniformly fill the conductive solder in the connection area between the electrode and the polymer precursor ceramic substrate, and ensure that the conductive solder fully penetrates and has good contact with the surface of the polymer precursor ceramic substrate and the electrode surface by vacuum degassing (processing time 10 to 30 minutes);

[0041] S3, curing pre-connection: Use light curing or heat curing to cure the conductive solder to form a preliminary bonding structure to ensure stable electrode embedding;

[0042] S4, High-Temperature Pyrolysis: In an argon or nitrogen inert atmosphere, heat the material to 800-1100°C at a rate of 0.5-3°C / min for 10-60 minutes. This converts the polymer precursor into a ceramic structure, effectively embedding the conductive ceramic particles within it, creating a continuous and stable conductive connection path and forming an integrated ceramic-conductive ceramic-electrode structure.

[0043] Example 1

[0044] The present embodiment proposes a method for preparing a polymer precursor ceramic low-temperature sensor electrode solder and its application, comprising the following steps: taking 4g of nano-ITO powder (particle size of about 50nm) and 6g of commercially available polysilazane (PSN), adding 0.12g of light curing agent Irgacure 819, and stirring at 100°C in a vacuum for 30 minutes to obtain a conductive solder with suitable viscosity and no bubbles (such as Figure 2 As shown in the figure, the polymer precursor ceramic low temperature sensor electrode solder). Then, the conductive solder is applied to the connection position between the SiCN ceramic substrate and the platinum electrode, and a vacuum box is used for degassing for 15 minutes to ensure that the conductive solder is evenly filled. After curing for 10 minutes using a light curing machine (the cured state is shown in the figure). Figure 3 ), placed in an argon atmosphere and heated to 1000℃ at a rate of 1℃ / min for 30min, and finally formed as shown in Figure 4 The integrated conductive connection structure of ceramic-conductive ceramic-platinum electrode shown is referred to as sensor 1.

[0045] Example 2

[0046] This embodiment proposes a preparation method and application of a polymer precursor ceramic low-temperature sensor electrode solder, including the following steps: first weighing 5g of polysiloxazane (PSZ) and 5g of Nb-doped TiO2 conductive nanopowder, then adding 1% of a thermal curing agent, dicumyl peroxide, and stirring and mixing at 90°C in a vacuum for 30 minutes to form a conductive solder (i.e., a polymer precursor ceramic low-temperature sensor electrode solder); then applying the conductive solder between the PSZ ceramic substrate and the nickel alloy electrode, thermally curing at 120°C for 4 hours, and then heating to 900°C at 0.5°C / min and pyrolyzing for 60 minutes to form an integrated conductive connection structure of ceramic-conductive ceramic-nickel alloy electrode.

[0047] Example 3

[0048] This embodiment proposes a preparation method and application of a polymer precursor ceramic low-temperature sensor electrode solder, comprising the following steps: weighing 4 g of polyborosilazane (PSNB), 6 g of ZnO nanopowder, and 0.8 g of a photocuring agent, Irgacure 819, and stirring them in a vacuum at 110°C for 30 minutes to form a conductive solder (i.e., a polymer precursor ceramic low-temperature sensor electrode solder); filling the conductive solder between the SiBCN ceramic and the carbon fiber electrode and evacuating the mixture for 25 minutes to remove bubbles; curing the mixture in a light curing machine for 10 minutes, and then heating the mixture to 1100°C at a heating rate of 2°C / min and pyrolyzing the mixture for 10 minutes to form an integrated conductive connection structure of ceramic-conductive ceramic-carbon fiber electrode.

[0049] Comparative Example 1

[0050] The same ceramic substrate and electrodes as in Example 1 were used, and nano silver paste was applied between the ceramic substrate and the electrodes for connection to prepare a temperature sensor, which was recorded as Sensor 2.

[0051] Figure 5 The voltage-temperature curve of the sensor prepared in Example 1 at low temperature is shown below:

[0052] Figure 6 The voltage variation curve of the sensor 2 prepared in Comparative Example 1 at low temperature is as a function of temperature;

[0053] contrast Figure 5 、 Figure 6 It can be seen from the change curve in that the sensor electrode connection area prepared by the present invention has better conductivity and low-temperature stability under extreme low-temperature environment, which can avoid the problems of large resistance fluctuation and poor contact of traditional silver paste connection method at low temperature.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A polymer precursor ceramic low-temperature sensor electrode solder, characterized in that: The invention comprises the following components: nano-scale conductive ceramic powder, a liquid polymer precursor and a curing agent, wherein the curing agent is a light curing agent or a heat curing agent, the mass ratio of the nano-scale conductive ceramic powder to the liquid polymer precursor is 30:70 to 70:30, and the mass ratio of the light curing agent or the heat curing agent to the liquid polymer precursor is (1 to 5):

100.

2. The polymer precursor ceramic low-temperature sensor electrode solder according to claim 1, characterized in that: The nano-scale conductive ceramic powder is nano-ITO powder, Nb-doped TiO2 conductive nano-powder or ZnO nano-powder.

3. The polymer precursor ceramic low-temperature sensor electrode solder according to claim 1, characterized in that: The liquid polymer precursor is any one of a binary polymer ceramic precursor, a ternary polymer ceramic precursor, a quaternary polymer ceramic precursor or a quinary polymer ceramic precursor.

4. The polymer precursor ceramic low-temperature sensor electrode solder according to claim 1, characterized in that: The photocuring agent is Irgacure 819 photoinitiator, and the thermal curing agent is dicumyl peroxide.

5. The method for preparing the polymer precursor ceramic low-temperature sensor electrode solder according to any one of claims 1 to 4, characterized in that: The steps include: S1, weighing nano-scale conductive ceramic powder, liquid polymer precursor, and light curing agent or heat curing agent according to the mass ratio; S2, stirring under heating conditions in a vacuum condition to prepare a uniform conductive solder, which is a polymer precursor ceramic low-temperature sensor electrode solder.

6. The method for preparing the polymer precursor ceramic low-temperature sensor electrode solder according to claim 5, characterized in that: The heating temperature in step S2 is 90 to 120°C.

7. The method for preparing the polymer precursor ceramic low-temperature sensor electrode solder according to claim 5, characterized in that: The stirring time in step S2 is 20 to 40 minutes.

8. Use of the polymer precursor ceramic low-temperature sensor electrode solder prepared by the preparation method according to any one of claims 5 to 7 in the preparation of low-temperature sensors.

9. The use according to claim 8, characterized in that: The steps include: S91, evenly filling the conductive solder to the position where the polymer precursor ceramic substrate and the electrode are connected, and performing vacuum degassing treatment to ensure good contact between the conductive solder and the surface of the polymer precursor ceramic substrate and the electrode surface; S92, curing the conductive solder by light curing or heat curing, thereby pre-fixing the electrode; S93, performing pyrolysis treatment at 800-1100°C in an inert atmosphere at a pyrolysis rate of 0.5-3°C / min for 10-60 min to obtain a low-temperature sensor having good access between the electrode and the polymer precursor ceramic matrix.

10. The use according to claim 9, characterized in that The vacuum degassing treatment in step S91 lasts for 10 to 30 minutes, until the bubbles in the conductive solder are completely removed and the conductive solder is in uniform contact with the polymer precursor ceramic matrix and the electrode.

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