Electrode printing and burning processing method
By adding pre-sintering treatment between electrode printing and firing processes, the problem of hollow protrusions during firing process is solved, and a more uniform pore distribution and better silver paste and glass attachment are achieved. Focus on improving the overall performance of the electrode.
Patent Information
- Application Number
- CN202411384367.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2024-12-31
AI Technical Summary
During the existing electrode printing and firing process, hollow protrusions will occur on the surface of the silver paste layer during the firing process, affecting the accuracy of subsequent slice processes and resistance concentration measurement results.
Add pre-sintering treatment between electrode printing and firing process, and decompose and burn out the organic carrier in the silver paste paste slurry through a high-temperature nitrogen oven to ensure sufficient glue discharge and avoid high temperature during firing process hollow bulge.
Through pre-sintering treatment, a more uniform pore size and better silver paste and glass distribution are obtained, which improves the adhesion and conductivity of the electrode, solves the problem of surface unevenness, and improves the overall performance of the electrode.
Smart Images
Figure CN119230229A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrode processing, and in particular relates to an electrode printing and burning processing method. Background Art
[0002] The electrode printing and firing process generally involves multiple process links such as slurry, printing, leveling, drying, and firing. Each process link contains many process control parameters, among which the most important ones are slurry and firing process.
[0003] In the existing electrode printing and firing process, it is found that hollow protrusions will be generated on the surface of the printed silver paste layer during the firing process. These hollow protrusions will affect the subsequent slicing process and cause problems such as dispersion of resistance concentration measurement results. Summary of the invention
[0004] The purpose of the present invention is to provide an electrode printing and burning processing method, which can at least solve some of the defects existing in the prior art.
[0005] To achieve the above object, the present invention adopts the following technical solution:
[0006] An electrode printing and burning method comprises the following steps:
[0007] S1, applying silver paste to the end surface of the electrode substrate, and leveling and drying;
[0008] S2, performing a pre-sintering and debinding treatment on the electrode substrate coated with the silver paste in step S1;
[0009] S3, performing sintering treatment on the electrode substrate pre-sintered and debinding treated in step S2.
[0010] Furthermore, the pre-sintering and debinding treatment process in step 2 is as follows: the electrode substrate coated with the silver paste is placed in a high-temperature nitrogen oven, and the heating rate of the high-temperature nitrogen oven is set according to the composition of the organic carrier in the silver paste, so that the organic carrier in the silver paste is completely decomposed, burned and discharged; after the combustion reaction is completed, the electrode substrate is cooled to room temperature.
[0011] Furthermore, the pre-burning and binder removal treatment time is 1.5 to 4 hours.
[0012] Furthermore, when the organic carrier in the silver paste is pine alcohol and ethyl cellulose, the first stage: first quickly heat up to 250°C, and the heating rate is 20-30°C / min, the second stage: continue to heat up to 400°C, and the heating rate is 1-10°C / min, the third stage: keep warm at 400°C for 5-20min, the fourth stage: cool from 400°C to 180°C, and the cooling rate is 1-10°C / min, the fifth stage: take out the electrode substrate from the high-temperature nitrogen oven after 180°C, and cool the electrode substrate to room temperature.
[0013] Furthermore, the sintering treatment process in step S3 is as follows: first, the electrode substrate after pre-sintering and binder removal treatment is heated to the decomposition and combustion temperature of the organic carrier in the silver paste, and then heated to the melting temperature of the glass powder in the silver paste, and then the electrode substrate is slowly cooled along with the sintering furnace.
[0014] Furthermore, the sintering treatment time is 1.5 to 2 hours.
[0015] Furthermore, the time for the electrode substrate to be heated to the decomposition and combustion temperature of the organic carrier in the silver paste is 20 to 40 minutes, and the time for the temperature to be heated from the decomposition and combustion temperature of the organic carrier to the melting temperature of the glass powder in the silver paste is 70 to 100 minutes.
[0016] Furthermore, the electrode substrate is a PTC electrode sheet or a varistor electrode.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] (1) The electrode printing and firing method provided by the present invention increases the debinding time of the organic carrier in the silver paste by adding a pre-burning debinding process between the silver paste printing and firing infiltration processes, so that the organic carrier can be fully debinded, thereby avoiding the formation of hollow protrusions on the electrode surface due to the higher temperature and aggravated gas exhaust in the subsequent high-temperature firing infiltration process. This effectively solves the problem of uneven surface of the electrode printing and firing process in the prior art.
[0019] (2) The pore size at the electrode cross section obtained by the electrode printing and burning processing method of the present invention is more uniform, so that a better resistance concentration can be obtained; and the silver paste and glass phase of the electrode are evenly distributed, and the adhesion is better.
[0020] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the process of electrode printing and firing processing of the present invention;
[0022] Figure 2 is a temperature curve diagram of pre-sintering and binder removal treatment in an embodiment of the present invention;
[0023] Figure 3 1 and 2 are SEM microscope images of the samples in the embodiments of the present invention after the pre-burning debinding process and before the pre-burning debinding process, wherein (a) and (c) are SEM images of the samples without the pre-burning debinding process at different magnifications, and (b) and (d) are SEM images of the samples after the pre-burning debinding process at different magnifications. DETAILED DESCRIPTION
[0024] 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.
[0025] like Figure 1 As shown, this embodiment provides an electrode printing and burning method, comprising the following steps:
[0026] S1. Apply silver paste to the end surface of the electrode substrate, and perform leveling and drying.
[0027] Among them, the silver paste is composed of three parts: silver powder, glass powder, and organic carrier. The control points of silver powder are in shape, size and silver content, which mainly affect conductivity; the control points of glass powder are in content and material type. There are two kinds of material systems generally selected, lead-containing system and bismuth-containing system, which mainly affect adhesion and the formation of electrode glass phase; the control points of organic carrier are in composition and proportion. Commonly used materials are pine oil alcohol and ethyl cellulose, which are mainly used to control the viscosity of the paste, so that the finishing paste is convenient for printing and leveling. Of course, for different electrodes, the composition of glass powder and organic carrier in the silver paste and the proportion of each component will be different, and the specific design will be based on actual needs. In this embodiment, the specific process of silver paste coating, leveling and drying is the prior art, which will not be repeated here.
[0028] S2, performing a pre-sintering and debinding treatment on the electrode substrate coated with the silver paste in step S1.
[0029] Specifically, the pre-sintering and debinding process is as follows: the electrode substrate coated with silver paste is placed in a high-temperature nitrogen oven, and the heating rate of the high-temperature nitrogen oven is set according to the composition of the organic carrier in the silver paste, so that the organic carrier in the silver paste is completely decomposed, burned and discharged; after the combustion reaction is completed, the electrode substrate is cooled to room temperature in preparation for the subsequent sintering process.
[0030] In this embodiment, a pre-firing and debinding process is added to burn and debind the organic carrier in the silver paste, thereby preventing the organic carrier from being subjected to higher temperatures during the sintering process, which intensifies the exhaust and causes protrusions to form on the electrode surface. Based on this, the pre-firing and debinding treatment time is designed to be 1.5 to 4 hours in this embodiment.
[0031] Due to the different organic carrier components in the silver paste, the temperature, time and heating rate of pre-burning and debinding are designed to be different, so as to ensure that all the components of the organic carrier can be fully decomposed, burned and debinded.
[0032] As a specific implementation method, when the organic carrier components in the silver paste are pine alcohol and ethyl cellulose, the first stage: first quickly heat up to the decomposition temperature of pine alcohol, 250°C. Since the temperature continues to rise subsequently, the pine alcohol can be fully decomposed and burned. Therefore, a relatively high heating rate can be designed for this stage. Specifically, the heating rate for this stage is designed to be 20-30°C / min; the second stage: continue to heat up to the decomposition temperature of ethyl cellulose, 400°C. During this process, the heating rate slows down, and the heating time is increased to ensure that the pine alcohol can be completely decomposed and burned. At the same time, the ethyl cellulose can burn slowly, the gas generation rate slows down, and only small bubbles are formed inside the slurry. Specifically, the heating rate for this stage is designed to be 1-10°C / min; the third stage: keep warm at 400°C for 5-20min to ensure that the ethyl cellulose can be fully burned; the fourth stage: cool down from 400°C to 180°C, and the cooling rate is 1-10°C / min; the fifth stage: take out the electrode substrate from the high-temperature nitrogen oven after 180°C, and the electrode substrate is cooled to room temperature.
[0033] S3, performing sintering treatment on the electrode substrate pre-sintered and debinding treated in step S2.
[0034] Specifically, the burning infiltration treatment process is as follows:
[0035] a) First, the electrode substrate after pre-sintering and debinding treatment is heated to the decomposition and combustion temperature of the organic carrier in the silver paste. In the conventional sintering process, it is mainly used as the debinding process of the silver paste, that is, the volatilization, decomposition, carbonization and combustion of the organic carrier. In this embodiment, due to the addition of the pre-sintering and debinding process, the heating process of the sintering treatment can further ensure the sufficiency of the silver paste debinding. At the same time, compared with the heating and debinding process in the conventional sintering process, the heating process of the sintering treatment in this embodiment can accelerate its heating rate, thereby improving the efficiency of the sintering treatment process.
[0036] b) Continue to raise the temperature to the melting temperature of the glass powder in the silver paste, the glass powder melts, and a part of it forms a glass phase with the silver powder, which can adhere well to the electrode substrate. The melting temperature of the glass powder is generally 750-900℃.
[0037] c) The electrode substrate is cooled slowly along with the sintering furnace to prevent the electrode substrate from bursting due to rapid cooling.
[0038] Optionally, the sintering treatment time is 1.5 to 2 hours, wherein the time for the electrode substrate to be heated to the decomposition and combustion temperature of the organic carrier in the silver paste is 20 to 40 minutes, and the time for the temperature to be heated from the decomposition and combustion temperature of the organic carrier to the melting temperature of the glass powder in the silver paste is 70 to 100 minutes.
[0039] In this embodiment, the electrode substrate may be, but is not limited to, a PTC electrode sheet or a varistor electrode. Thus, the electrode printing and burning processing method of this embodiment can be applied to different electrode preparation processes to solve the problem of protrusions on the electrode surface affecting conductivity during the existing burning and infiltration process.
[0040] The effect of the electrode printing and burning process of the present invention is described below by means of a specific embodiment, and the specific process is as follows:
[0041] S1. After the electrode substrate is dried after printing the silver paste, the samples are divided into two groups, A and B, wherein the organic carrier in the silver paste is ethyl cellulose and pinene alcohol.
[0042] S2. Place the samples of group B in a high temperature resistant sintering tray and place it in a high temperature nitrogen furnace for pretreatment; Figure 2 As shown, the total pretreatment process setting time is 2 hours: ① room temperature ~ 250 ° C, 10 minutes; ② 250 ~ 400 ° C, 50 minutes; ③ 400 ° C insulation for 10 minutes; ④ 400 ~ 180 ° C, 50 minutes; ⑤ room temperature environment cooling to room temperature.
[0043] S3. Put the samples of groups A and B into the infiltration furnace for infiltration at the same time.
[0044] S4. The samples of groups A and B after infiltration were analyzed by SEM microscope. The results are as follows: Figure 3 shown.
[0045] Depend on Figure 3 It can be seen that there are through pores in the samples of group A, while the through pores in the cross section of the samples of group B disappear after pretreatment, and the pores between the silver electrodes become obviously more uniform. The bumps on the surface are solid particles and do not affect subsequent processing.
[0046] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.
Claims
1. An electrode printing and burning method, characterized in that: The steps include: S1, applying silver paste to the end surface of the electrode substrate, and leveling and drying; S2, performing a pre-sintering and debinding treatment on the electrode substrate coated with the silver paste in step S1; S3, performing sintering treatment on the electrode substrate pre-sintered and debinding treated in step S2.
2. The electrode printing method according to claim 1, characterized in that: The pre-sintering and debinding treatment process in step 2 is as follows: the electrode substrate coated with the silver paste is placed in a high-temperature nitrogen oven, and the heating rate of the high-temperature nitrogen oven is set according to the composition of the organic carrier in the silver paste, so that the organic carrier in the silver paste is completely decomposed, burned and discharged; after the combustion reaction is completed, the electrode substrate is cooled to room temperature.
3. The electrode printing method according to claim 2, characterized in that: The pre-burning and binder removal treatment time is 1.5 to 4 hours.
4. The electrode printing method according to claim 2, characterized in that: When the organic carrier in the silver paste is pine alcohol and ethyl cellulose, the first stage: first quickly heat up to 250°C, and the heating rate is 20-30°C / min; the second stage: continue to heat up to 400°C, and the heating rate is 1-10°C / min; the third stage: keep warm at 400°C for 5-20min; the fourth stage: cool from 400°C to 180°C, and the cooling rate is 1-10°C / min; the fifth stage: take out the electrode substrate from the high-temperature nitrogen oven after 180°C, and cool the electrode substrate to room temperature.
5. The electrode printing method according to claim 1, characterized in that: The sintering treatment process in step S3 is as follows: first, the electrode substrate after pre-sintering and binder removal treatment is heated to the decomposition and combustion temperature of the organic carrier in the silver paste, and then heated to the melting temperature of the glass powder in the silver paste, and then the electrode substrate is slowly cooled along with the sintering furnace.
6. The electrode printing method according to claim 5, characterized in that: The sintering treatment time is 1.5 to 2 hours.
7. The electrode printing method according to claim 6, characterized in that: The time for the electrode substrate to be heated to the decomposition and combustion temperature of the organic carrier in the silver paste is 20 to 40 minutes, and the time for the temperature to be heated from the decomposition and combustion temperature of the organic carrier to the melting temperature of the glass powder in the silver paste is 70 to 100 minutes.
8. The electrode printing method according to claim 1, characterized in that: The electrode substrate is a PTC electrode sheet or a varistor electrode.