Preparation method of TCR-adjustable low-cost thick-film resistor

Abstract

The invention discloses a preparation method of a TCR-adjustable low-cost thick-film resistor, and the method comprises the following steps: slurry preparation: respectively mixing and stirring a slurry A, a slurry B and a slurry C with a diluent by using a stirrer to obtain uniform slurry; cleaning the substrate; carrying out direct-writing printing and sintering curing, and carrying out direct-writing printing on the slurry A, the slurry B and the slurry C with different temperature coefficients on an aluminum oxide ceramic substrate to form a continuous conductive circuit; and laser resistance trimming: carrying out accurate laser processing on a specific area through a laser resistance trimming machine according to requirements so as to change the resistance value of the specific area, thereby obtaining the required TCR value of the thick-film resistor. According to the application, the three materials with different temperature coefficients A, B and C can be directly written and printed on the aluminum oxide ceramic substrate through a direct-writing printing technology to form the continuous conductive circuit, and then the resistance of the B and C areas in the conductive circuit is adjusted by using laser, so that the purpose of adjusting the TCR is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of TCR adjustment of thick film resistors, and in particular to a method for preparing a low-cost thick film resistor with adjustable TCR. Background Art

[0002] The temperature coefficient of resistance (TCR) is a physical quantity that describes the characteristics of resistance changing with temperature, and is used to measure the sensitivity of resistors to temperature. Different types of resistor materials have different temperature coefficients, and their applications are therefore different. At present, materials with large temperature coefficients of resistance are often used in temperature sensors, thermistors, and in building filter circuits, current limiting circuits, etc. because their resistance changes significantly with temperature. Materials with small temperature coefficients of resistance are often used in precision resistors, standard resistors, electronic components, and other fields that require high stability and reliability because they can maintain relatively stable resistance values ​​under various temperature conditions. Therefore, the preparation of resistors with adjustable TCR is of great significance and can greatly broaden their scope of application.

[0003] In the prior art, such as the patent with publication number CN117586003A "A ZnO / C composite ceramic resistor with adjustable temperature coefficient and its preparation method", the main structure of the application is a ZnO core and conductive carbon particles distributed on the surface of the core. There are two conductive paths, one is the zinc oxide semiconductor ceramic conductive path showing a negative temperature coefficient characteristic, and the other is the conductive carbon particle conductive path at the grain boundary showing a positive temperature coefficient characteristic. The two effects are combined to change the C content to form a temperature coefficient B value that is adjustable within 1000-4500; but there are the following defects in the TCR adjustment process: the temperature coefficient B value is adjusted once and has a small adjustable range, and it is necessary to change the C content to adjust it, and it is difficult to control the precise adjustment of the temperature coefficient of the thermistor by changing the C content.

[0004] Another example is the patent with publication number CN112268632A, "A metal thin film thermal resistor with adjustable temperature coefficient and resistant to high temperature of 1000℃". This application prepares a Pt film or Rh-doped Pt film with a thickness of 0.5μm-2μm on a ceramic substrate, and adjusts the temperature coefficient within the range of 3700ppm / k-3851ppm / k by varying the Rh doping mass fraction in the Rh-doped Pt film. The thermal resistor prepared with the Rh-doped Pt film has high temperature resistance and can achieve stable measurement of an ambient temperature of 1000℃.

[0005] Another example is the patent "A platinum resistance temperature sensor" with publication number CN116380275A. This application electrically connects at least two conductive materials with different resistivities at the same temperature to form a complete platinum wire circuit, so as to achieve reproducibility and stability of temperature measurement by the platinum resistor as time or temperature changes.

[0006] The above inventions all adjust TCR during the preparation process, and TCR cannot be adjusted after the product is prepared, so the flexibility of TCR adjustment is poor.

[0007] In addition, in order to obtain different TCRs, the above invention requires the preparation of different samples, the preparation process is complex and costly, and the adjustable range of TCR is small.

[0008] The present invention provides a low-cost method for preparing a thick film resistor with a precisely controllable temperature coefficient of resistance, which can directly adjust the TCR of the product once or multiple times according to various needs, and has a large adjustable range, greatly broadening its application field. Summary of the invention

[0009] The object of the present invention is to provide a method for preparing a low-cost thick film resistor with adjustable TCR, so as to solve the problem of poor TCR adjustment effect of thick film resistors in the prior art.

[0010] The purpose of the present invention can be achieved through the following technical solutions:

[0011] A method for preparing a low-cost thick film resistor with adjustable TCR comprises the following steps:

[0012] Step S1, slurry preparation, using a stirrer to mix and stir the three slurries A, B, and C with a diluent to obtain a uniform slurry;

[0013] Step S2, cleaning the substrate, using acetone, alcohol and deionized water to ultrasonically clean the alumina ceramic substrate in sequence, and then blowing it dry with dry nitrogen to remove residual liquid on the surface of the substrate;

[0014] Step S3, direct writing printing and sintering and curing, printing the slurry with the highest sintering temperature among the three slurries prepared in step S1 onto the substrate of step S2 according to a predetermined pattern and path, and placing it in an annealing furnace for sintering and curing, and similarly preparing the other two slurries of the three slurries on the substrate in descending order of sintering temperature and sintering and curing, so that the three slurries with different temperature coefficients A, B, and C are directly written and printed on the alumina ceramic substrate to form a continuous conductive circuit;

[0015] Step S4, laser resistance trimming, according to the need, a laser resistance trimming machine is used to perform precise laser processing on a specific area on the conductive circuit to change its resistance value, thereby obtaining the required TCR adjustment value of the thick film resistor.

[0016] As a further solution of the present invention: the TCR of slurry A prepared in step S1 is 2000-4000 ppm / °C, the TCR of slurry B is -50-100 ppm / °C, and the TCR of slurry C is 6000-8000 ppm / °C.

[0017] As a further solution of the present invention: the three slurries A, B and C prepared in step S1 include but are not limited to metal slurries, alloy slurries or other conductive slurries.

[0018] As a further solution of the present invention: the TCR of the A slurry is 3000ppm / °C.

[0019] As a further solution of the present invention: the TCR of the B slurry is 25ppm / °C.

[0020] As a further solution of the present invention: the TCR of the C slurry is 7000ppm / °C.

[0021] As a further solution of the present invention: in step S3, direct writing printing is to complete the printing pattern and path on the substrate by mechanical extrusion, and the slurry dripping amount, position or extrusion shape can be accurately controlled to achieve high-precision printing.

[0022] As a further solution of the present invention: during laser resistance trimming in step S4, the area formed by the type B slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and obtain the required TCR adjustment value of the thick film resistor.

[0023] As a further solution of the present invention: during laser resistance trimming in step S4, the area formed by the C type slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and obtain the required TCR adjustment value of the thick film resistor.

[0024] Beneficial effects of the present invention:

[0025] (1) The present application can directly print three materials with different temperature coefficients, A, B, and C, on an alumina ceramic substrate to form a continuous conductive circuit through direct writing printing technology, wherein A, B, and C are materials with TCR of 2000-4000ppm / ℃, -50-100ppm / ℃, and 6000-8000ppm / ℃, respectively, and then use a laser to adjust the resistance of regions B and C in the conductive circuit to achieve the purpose of adjusting TCR;

[0026] (2) The low-cost thick film resistor of the present application is TCR-adjusted after the product is manufactured, so TCR adjustment has excellent flexibility;

[0027] (3) The present application can directly adjust the TCR of the product once or multiple times according to various needs, and the adjustable range is large, which greatly broadens its application field;

[0028] (4) The present application uses direct writing or printing to prepare thick film resistors, which has simple requirements for equipment and environment, and does not use expensive vacuum equipment, so the preparation cost is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] Figure 1 is a flow chart of the present invention;

[0031] Figure 2 It is a schematic diagram of the principle of the direct writing printing step of the present invention;

[0032] Figure 3 It is a schematic diagram of forming a conductive circuit in the sintering and solidification step of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in the description of the present invention, the meaning of "multiple" and "several" is at least two, for example two, three, etc., unless otherwise clearly and specifically defined.

[0035] See also Figures 1 to 3 As shown, the present invention is a method for preparing a low-cost thick film resistor with adjustable TCR, comprising the following steps:

[0036] Step S1, slurry preparation, use a stirrer to mix the three slurries A, B, and C with the diluent to obtain a uniform slurry; to obtain a uniform slurry for subsequent printing; it should be understood that the selection and proportion of the diluent will affect the fluidity, viscosity and printing performance of the slurry, and the ratio of the slurry to the diluent in this step is proportioned as needed.

[0037] In a specific implementation manner, the TCR of the A slurry prepared in this step is 2000-4000ppm / ℃. When used, when the temperature changes by 1℃, the resistance value of the A slurry will relatively change by 2000-4000ppm / ℃ (i.e., 0.2% to 0.4%). The resistance value of the A metal material is relatively sensitive to temperature changes and is suitable for application scenarios that require a certain temperature sensitivity; the TCR of the B slurry is -50-100ppm / ℃, and the resistance value of the B metal material changes very little with temperature, and the variation range is between -0.005% and 0.01%, which indicates that the B metal material has extremely high stability when the temperature changes, and is suitable for application scenarios that require highly stable resistance values; the TCR of the C slurry is 6000-8000ppm / ℃, and the resistance value of the C metal material is very sensitive to temperature changes. When the temperature changes by 1℃, the resistance value will relatively change by 6000-8000ppm / ℃ (i.e., 0.6% to 0.8%), and the C metal material is suitable for application scenarios that require high temperature sensitivity, such as temperature sensors.

[0038] In a specific embodiment, the three slurries A, B and C prepared in this step include but are not limited to metal slurries, alloy slurries or other conductive slurries.

[0039] In a specific embodiment, for example, the TCR of slurry A is 3000ppm / ℃; the TCR of slurry B is 25ppm / ℃; the TCR of slurry C is 7000ppm / ℃; among them, the B metal material has extremely high stability when the temperature changes, and the TCR of slurry C is nearly 1-3 times greater than the TCR of slurry A.

[0040] Step S2, substrate cleaning, using acetone, alcohol and deionized water to ultrasonically clean the alumina ceramic substrate in sequence, and then blowing it dry with dry nitrogen to remove the residual liquid on the surface of the substrate; when removing the residual liquid on the surface of the substrate in this step, the cleanliness of the substrate surface can be ensured.

[0041] Step S3, direct writing printing and sintering and curing, the slurry with the highest sintering temperature among the three slurries prepared in step S1 is printed onto the substrate of step S2 according to a predetermined pattern and path, and is placed in an annealing furnace for sintering and curing. Similarly, the other two slurries among the three slurries are prepared on the substrate in order of sintering temperature from high to low and sintered and cured, so that the three slurries with different temperature coefficients A, B, and C are directly printed on the alumina ceramic substrate to form a continuous conductive circuit.

[0042] In a specific embodiment, direct writing printing in this step uses mechanical extrusion to complete the printing pattern and path on the substrate, which can accurately control the slurry dripping amount, position or extrusion shape, thereby achieving high-precision printing; the direct writing printing technology is simple to operate, easy to quickly form, and has a low overall process cost; during the printing process, the extrusion amount, position and speed of the material need to be accurately controlled to ensure the accuracy and continuity of the conductive circuit; the selection of sintering temperature and time in the sintering and curing step should be determined according to the characteristics of the material and the required performance.

[0043] Step S4, laser resistance trimming, according to the need, the specific area on the conductive circuit is precisely laser processed by a laser resistance trimming machine to change its resistance value, so as to obtain the required thick film resistor TCR adjustment value; this step uses a laser beam to cut off the circuit in a specific area of ​​the conductive circuit, thereby changing the overall resistance value.

[0044] In a specific implementation, during laser resistance trimming in this step, the area formed by the B-type slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and reduce the required TCR value of the thick film resistor; the specific implementation process is as follows: Since the TCR of the area formed by the B-type slurry is small, the resistance changes very little when the temperature rises. According to the calculation formula of the TCR of the thick film resistor: TCR = (R100-R0) / [R0*(T100-T0)], R0 increases, R100 is almost unchanged, and the TCR will become smaller at this time. Therefore, R0 (initial resistance) increases, while R100 (resistance at 100°C) is almost unchanged. According to the calculation formula of TCR, the TCR of the overall thick film resistor will become smaller at this time. Therefore, by adjusting the resistance of the B area, the purpose of reducing TCR can be achieved.

[0045] In a specific implementation, during laser resistance trimming in this step, the area formed by the C-type slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and obtain the required increase in the TCR value of the thick film resistor; the specific implementation process is as follows: Since the TCR of the area formed by the C-type slurry is relatively large, the resistance will increase significantly when the temperature rises. Therefore, when the resistance of the area formed by the C-type slurry increases, its proportion in the overall circuit resistance increases, causing the overall TCR to be biased toward the TCR value of the area formed by the C-type slurry. At this time, the overall TCR is larger than the TCR of the area formed by the main A-type slurry, that is, the purpose of increasing the TCR is achieved. Therefore, the degree of resistance increase in the C area can be adjusted to achieve precise adjustment of the overall TCR.

[0046] The present application can detect and verify the precise adjustment of the overall TCR, and the specific operation is as follows: use a high-precision resistance measuring instrument to measure the resistance of the printed conductive circuit, record the initial resistance value and the resistance change at different temperatures; according to the measured resistance value and temperature change, use the TCR calculation formula TCR = (R i-R0) / [R0*(T i-T0)] to calculate the TCR value of the overall circuit, where R0 is the initial resistance, T0 is the initial temperature, Ri is the resistance at the moment of temperature change, and T i is the precise temperature value at the moment of temperature change; so as to compare the calculated TCR value with the expected target. If it does not meet the requirements, fine-tune the laser adjustment parameters according to the error analysis, and re-perform laser resistance adjustment until a satisfactory TCR value is reached.

[0047] It should be understood that the present application can achieve precise printing and TCR adjustment of continuous conductive circuits with different TCR materials through direct writing printing technology and laser adjustment of resistance; this technology provides a new way to prepare electronic devices with specific resistance-temperature characteristics.

[0048] By adopting the preparation method of the present application, three materials with different temperature coefficients A, B, and C are directly printed on an alumina ceramic substrate to form a continuous conductive circuit through direct writing printing technology. A, B, and C are materials with TCR of 2000-4000ppm / ℃, -50-100ppm / ℃, and 6000-8000ppm / ℃, respectively. Then, a laser is used to adjust the resistance of regions B and C in the conductive circuit to achieve the purpose of adjusting TCR, and the application fields are more diversified.

[0049] It should be understood that the present application can directly adjust the TCR of the product once or multiple times according to various needs, and the adjustable range is large, which greatly broadens its application field; the low-cost thick film resistor of the present application is TCR adjusted after the product is prepared, so the TCR adjustment has excellent flexibility; the present application uses printing or printing to prepare thick film resistors, which has simple requirements for equipment and environment, and does not use expensive vacuum equipment, so the cost is lower.

[0050] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail above in conjunction with the accompanying drawings. In the above description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described above, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed above. In addition, the various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a low-cost thick film resistor with adjustable TCR, characterized in that: The following steps are involved: Step S1, slurry preparation, using a stirrer to mix and stir the three slurries A, B, and C with a diluent to obtain a uniform slurry; Step S2, cleaning the substrate, using acetone, alcohol and deionized water to ultrasonically clean the alumina ceramic substrate in sequence, and then blowing it dry with dry nitrogen to remove residual liquid on the surface of the substrate; Step S3, direct writing printing and sintering and curing, printing the slurry with the highest sintering temperature among the three slurries prepared in step S1 onto the substrate of step S2 according to a predetermined pattern and path, and placing it in an annealing furnace for sintering and curing, and similarly preparing the other two slurries of the three slurries on the substrate in descending order of sintering temperature and sintering and curing, so that the three slurries with different temperature coefficients A, B, and C are directly written and printed on the alumina ceramic substrate to form a continuous conductive circuit; Step S4, laser resistance trimming, according to the need, a laser resistance trimming machine is used to perform precise laser processing on a specific area on the conductive circuit to change its resistance value, thereby obtaining the required TCR adjustment value of the thick film resistor.

2. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 1, characterized in that: The TCR of the A slurry prepared in step S1 is 2000-4000 ppm / °C, the TCR of the B slurry is -50-100 ppm / °C, and the TCR of the C slurry is 6000-8000 ppm / °C.

3. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 2, characterized in that: The three slurries A, B and C prepared in step S1 include but are not limited to metal slurries, alloy slurries or other conductive slurries.

4. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 2, characterized in that: The TCR of the A slurry is 3000 ppm / °C.

5. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 2, characterized in that: The B slurry TCR is 25 ppm / °C.

6. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 2, characterized in that: The C slurry TCR is 7000 ppm / °C.

7. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 2, characterized in that: In step S3, direct writing printing uses mechanical extrusion to complete the printing pattern and path on the substrate, which can accurately control the slurry dripping amount, position or extrusion shape, thereby achieving high-precision printing.

8. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 7, characterized in that: During laser resistance trimming in step S4, the laser resistance trimming machine can perform precise laser processing on the area formed by type B slurry and / or the area formed by type C slurry to change their resistance values, thereby obtaining the required thick film resistor TCR adjustment value.

9. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 8, characterized in that: During the laser resistance trimming in step S4, the area formed by the type B slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and obtain the required TCR adjustment value of the thick film resistor.

10. The method for preparing a low-cost thick film resistor with adjustable TCR according to claim 8, characterized in that: During the laser resistance trimming in step S4, the area formed by the C type slurry is precisely laser processed by a laser resistance trimming machine to increase the resistance of the area and obtain the required TCR adjustment value of the thick film resistor.

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