Silver conductive paste sintering anti-sticking agent and preparation method thereof

Abstract

The present invention relates to the technical field of metal powder metallurgy, and in particular to a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The preparation method of the silver conductive paste sintering anti-sticking agent comprises the following steps: causing a silver salt to undergo a reduction reaction under the action of a reducing agent, and collecting a solid wet powder; coating the solid wet powder with a coating agent, drying, and preparing an original powder; starting at least one round of stirring and kneading granulation, adding all or part of the original powder to each round of stirring and kneading granulation, until a spherical silver powder with a particle size of 6 μm-100 μm is obtained as a silver conductive paste sintering anti-sticking agent. The prepared silver conductive paste sintering anti-sticking agent can be added to a sintered silver conductive paste to prevent the stack from burning and sticking.

Description

Technical Field

[0001] The invention relates to the technical field of metal powder metallurgy, and in particular to a silver conductive paste sintering anti-sticking agent and a preparation method thereof. Background Art

[0002] As a metal with good conductivity and oxidation resistance, silver is widely used in the electronics industry, energy, aviation and other fields. Silver powder and its electronic paste series products are the most widely used and largest precious metal products in the electronics industry, and are the basic and key functional materials for the production of various electronic components. Silver conductive paste for chip ceramic components is an important electronic material. It is widely used in the production of various ceramic capacitors, piezoelectric buzzers, thermistors, varistors and other components. It is the basic material for various home appliances, communication electronics, and electrical instruments, and has a wide range of uses.

[0003] The manufacturing technology of silver conductive paste has become more and more demanding with the continuous development of components. In addition to good adhesion, surface gloss, electrical properties and welding performance, the use process is also more important, such as stacking performance and printing process. The process of printing and sintering the silver layer of ceramic components requires large-scale stacking. The stacking process is prone to product sticking, resulting in a decrease in product qualification rate and other problems. This problem, whether light or heavy, has always plagued component and paste manufacturers. Summary of the invention

[0004] Based on this, the present invention provides a method for preparing a sintering anti-sticking agent for silver conductive paste. The prepared sintering anti-sticking agent for silver conductive paste can be added to sintering type silver conductive paste to prevent stacking from being sintered and stuck.

[0005] The technical solution is:

[0006] A method for preparing a silver conductive paste sintering anti-sticking agent comprises the following steps:

[0007] Allowing the silver salt to undergo a reduction reaction under the action of a reducing agent, and collecting solid wet powder;

[0008] The solid wet powder is coated with a coating agent and dried to prepare an original powder;

[0009] At least one round of stirring and kneading granulation is started, and all or part of the original powder is added in each round of stirring and kneading granulation to obtain spherical silver powder with a particle size of 6μm-100μm, which is used as a sintering anti-sticking agent for silver conductive paste.

[0010] In one embodiment, the particle size D50 of the silver conductive paste sintering anti-sticking agent is 6 μm-20 μm.

[0011] In one embodiment, each round of stirring, kneading and granulation lasts for 10 min to 60 min.

[0012] In one embodiment, the rotation speed of each round of stirring, kneading and granulating is 1000r / min-6000r / min.

[0013] In one embodiment, 2-5 rounds of stirring and kneading granulation are started.

[0014] In one embodiment, the coating agent is selected from at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid and myristic acid.

[0015] In one embodiment, the coating agent accounts for 0.1%-1.0% by mass of the solid wet powder.

[0016] In one embodiment, the silver salt is silver nitrate.

[0017] In one embodiment, the reducing agent is selected from at least one of ascorbic acid, glucose, hydrazine hydrate, formaldehyde and hydroxylamine hydrochloride.

[0018] The invention also provides a silver conductive paste sintering anti-sticking agent, which is prepared by the above preparation method.

[0019] Compared with the traditional solution, the present invention has the following beneficial effects:

[0020] In the present invention, solid silver wet powder is first obtained by conventional liquefaction reduction method, and then the powder is coated to avoid the solid wet powder from agglomerating and drying into silver sand and turning into coarse powder during subsequent drying treatment, which loses the processing value, and then the original powder is stirred and kneaded to granulate to obtain a spherical silver powder with a particle size D50 of 6μm-100μm. This type of spherical silver powder is large in size, and its sintering activity is slightly lower than that of the silver powder prepared by traditional liquefaction reduction. After adding it to the silver conductive slurry containing traditional silver powder, at a preset sintering temperature, the small-sized traditional silver powder as the main body completes the silver surface sintering, and the large-sized spherical silver powder is not easy to sinter, forming a support point between the sheets in the stacked state, which plays the role of a stacked physical anti-sticking sheet. Moreover, the preparation method of the present invention has a simple process, and only needs to add the steps of coating and stirring and kneading granulation on the basis of the process of traditional silver powder, which is easy to mass produce and suitable for industrial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the SEM image of the original powder prepared in Example 1;

[0022] Figure 2 This is a SEM image of the anti-sticking agent prepared in Example 1;

[0023] Figure 3 This is the SEM image of the anti-sticking agent prepared in Comparative Example 1;

[0024] Figure 4This is a SEM image of the anti-sticking agent prepared in Example 2;

[0025] Figure 5 This is the SEM image of the original powder prepared in Example 3;

[0026] Figure 6 This is a SEM image of the anti-sticking agent prepared in Example 3;

[0027] Figure 7 This is the SEM image of the anti-sticking agent prepared in Comparative Example 2. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] the term

[0031] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0032] In the present invention, the optional scope of the terms "and / or", "or / and", and "and / or" used includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, and the any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items.

[0033] In the present invention, "one or several" refers to any one, any two or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0034] In the present invention, "combinations thereof", "any combinations thereof", "any combination thereof" and the like used include all suitable combinations of any two or more of the listed items.

[0035] In the present invention, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. is based on the ability to implement the technical solution of the present invention, solve the technical problem of the present invention, and achieve the expected technical effect of the present invention.

[0036] In the present invention, “preferred” is only used to describe an implementation method or example with better effects, and it should be understood that it does not constitute a limitation on the protection scope of the present invention.

[0037] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0038] In the present invention, when a numerical range is involved, unless otherwise specified, the two endpoints of the numerical range are included.

[0039] In the present invention, when it comes to percentage content, unless otherwise specified, for solid-liquid mixing and solid-solid mixing, it refers to mass percentage, and for liquid-liquid mixing, it refers to volume percentage.

[0040] In the present invention, when it comes to percentage concentration, unless otherwise specified, it refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0041] In the present invention, when it comes to temperature parameters, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are permitted. The constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument.

[0042] Since the beginning of the production of high-temperature thick film silver paste in my country, the problem of how to prevent product sticking during the stacking process has been a problem for various silver paste manufacturers. In the past ten years, some solutions have adopted the addition of nickel powder or nickel oxide powder with a larger average particle size, which has achieved a certain anti-sticking effect. However, the main metal conductive phase of silver paste is silver. The addition of other metals will either form a glass phase similar to oxide or form an alloy phase with silver. The addition of different metals and the amount of addition will directly affect the electrical properties of components. The method of adding large-particle nickel powder improves the sticking problem while sacrificing some electrical properties, and technicians need to strike a balance between the two.

[0043] If silver powder with a larger average particle size is directly added, there may be a large difference in the sintering activity between the large-sized silver powder and the original silver paste, resulting in incompatibility, poor silver surface bonding, easy detachment of silver powder with a larger average particle size, vacancies, and decreased electrical performance. For example, large-sized silver powder prepared by conventional physical atomization is usually prepared by atomizing silver in a high-temperature molten state. The resulting silver powder basically loses its sintering activity. When added to the silver conductive paste, it will be incompatible, causing the above-mentioned problems. Moreover, large-sized silver powder prepared by conventional physical atomization methods also has problems such as high energy consumption and low yield.

[0044] The technical solution of the present invention is as follows:

[0045] A method for preparing a silver conductive paste sintering anti-sticking agent comprises the following steps:

[0046] Allowing the silver salt to undergo a reduction reaction under the action of a reducing agent, and collecting solid wet powder;

[0047] The solid wet powder is coated with a coating agent and dried to prepare an original powder;

[0048] At least one round of stirring and kneading granulation is started, and all or part of the original powder is added in each round of stirring and kneading granulation to obtain spherical silver powder with a particle size D50 of 6μm-100μm, which is used as a sintering anti-sticking agent for silver conductive paste.

[0049] In the present invention, solid silver wet powder is first obtained by conventional liquefaction reduction method, and then the powder is coated to avoid the solid wet powder from agglomerating and drying into silver sand and turning into coarse powder during subsequent drying treatment, which loses the processing value, and then the original powder is stirred and kneaded to granulate to obtain a spherical silver powder with a particle size D50 of 6μm-100μm. This type of spherical silver powder is large in size, and its sintering activity is slightly lower than that of the silver powder prepared by traditional liquefaction reduction. After adding it to the silver conductive slurry containing traditional silver powder, at a preset sintering temperature, the small-sized traditional silver powder as the main body completes the silver surface sintering, and the large-sized spherical silver powder is not easy to sinter, forming a support point between the sheets in the stacked state, which plays the role of a stacked physical anti-sticking sheet. Moreover, the preparation method of the present invention has a simple process, and only needs to add the steps of coating and stirring and kneading granulation on the basis of the process of traditional silver powder, which is easy to mass produce and suitable for industrial large-scale production.

[0050] Compared with adding large-sized nickel powder, the large-sized silver powder of the present invention is made of the same material as the main conductive phase silver of the silver conductive paste, thereby avoiding the problems caused by adding multiple materials.

[0051] Compared with the large-sized silver powder prepared by the conventional physical atomization method, the large-sized silver powder prepared by the present invention has low sintering activity, but it is consistent with the preparation process of the main conductive phase silver of the silver conductive paste, is more compatible, and will not cause the problems of silver powder falling off, vacancies, and electrical performance degradation. In addition, the preparation process is simple, the controllability is good, the product performance is adjustable, the batch production volume is large, and it is easy to scale up industrial production.

[0052] In addition, the particle size of the main conductive phase silver powder of the silver conductive paste prepared by the conventional liquefaction reduction method is generally small, and the present invention can also make up for this defect.

[0053] It can be understood that there are many specific options for preparing solid wet powder by the liquefaction reduction method of the present invention, and relatively green and environmentally friendly production processes and materials can be selected.

[0054] In one embodiment, the silver salt is silver nitrate.

[0055] Optionally, the reducing agent is selected from at least one of ascorbic acid, glucose, hydrazine hydrate, formaldehyde and hydroxylamine hydrochloride. Preferably, the reducing agent is ascorbic acid or hydrazine hydrate.

[0056] In one embodiment, when the silver salt is subjected to a reduction reaction under the action of a reducing agent, a pH adjuster is also added, and the reduction reaction is carried out in a solution, and the solvent may be water.

[0057] Optionally, the pH regulator is selected from at least one of sodium hydroxide, sodium carbonate and sodium sulfate. Preferably, the pH regulator is sodium hydroxide.

[0058] In one embodiment, the reduction reaction of the silver salt under the action of a reducing agent comprises the following steps:

[0059] (1) Weigh a reducing agent into a reaction kettle and add water to dissolve it, add a pH adjuster to adjust the pH value, add water to prepare a reducing system of a certain volume, and adjust the temperature.

[0060] (2) Weigh silver nitrate into a mixing bucket and add water to dissolve it. Add water to prepare a certain volume of silver system and adjust the temperature.

[0061] (3) Under stirring conditions, the silver system is added to the reduction system for reduction reaction, and after the reaction is complete, washing is performed to obtain solid wet silver powder.

[0062] It can be understood that the temperature of steps (1) and (2) is adjusted to a range of 10-80°C.

[0063] The solid wet silver powder can be coated by stirring and dispersing the solid wet silver powder and the coating agent, and the coating agent is added to prevent the solid wet silver powder from agglomerating and drying into silver sand and turning into coarse powder during subsequent drying treatment, thereby losing its processing value.

[0064] Optionally, the coating agent is selected from at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid and tetradecanoic acid. Preferably, the coating agent is stearic acid or oleic acid.

[0065] Optionally, the coating agent accounts for 0.1%-1.0% by mass of the solid wet powder.

[0066] After coating, drying is performed to obtain the original powder.

[0067] Optionally, the drying temperature is 55-95°C. Preferably, the drying temperature is 65-70°C.

[0068] It can be understood that the stirring and kneading granulation can be carried out in a high-speed disperser. This step obtains large-sized silver powder by physical high-energy kneading. The original powder can be added at one time for one round of stirring and kneading granulation, or it can be added in batches for multiple rounds of stirring and kneading granulation.

[0069] The invention can knead large-size silver powders of different specifications with high energy by controlling the stirring speed of the original powder, the high-speed disperser, the number of times the original powder is added in batches, and the interval time of adding materials.

[0070] In one embodiment, one round of stirring, kneading and granulation is started, and the original powder is added at one time.

[0071] In some other embodiments, 2-5 rounds of stirring and kneading granulation are started, preferably, 2-3 rounds of stirring and kneading granulation are started.

[0072] Optionally, each round of stirring, kneading and granulating time is 10min-60min. Preferably, each round of stirring, kneading and granulating time is 20min-30min.

[0073] Optionally, the rotation speed of each round of stirring, kneading and granulating is 1000r / min-6000r / min. Preferably, the rotation speed of each round of stirring, kneading and granulating is 2000r / min-3000r / min.

[0074] The present invention can also prepare silver powders of the same size but different activities and sintering properties by adjusting the initial sintering activity and particle size of the original powder.

[0075] In one embodiment, the particle size D50 of the silver conductive paste sintering anti-sticking agent is 6 μm-20 μm.

[0076] The invention also provides a silver conductive paste sintering anti-sticking agent, which is prepared by the above preparation method.

[0077] The silver conductive paste sintering anti-sticking agent can be used in sintering type silver conductive paste, and can be used together with the silver powder prepared by traditional liquefaction reduction method drying.

[0078] In the above-mentioned sintered silver conductive paste, the anti-sticking agent is prepared by adding the steps of coating and stirring, kneading and granulation on the basis of the process of traditional silver powder. It is larger in size than traditional silver powder and has lower sintering activity. The two have good compatibility. At the preset sintering temperature, the small-sized traditional silver powder as the main body completes the silver surface sintering, and the large-sized anti-sticking agent is not easy to sinter, forming a supporting point between the sheets in the stacked firing state, and playing the role of a physical anti-sticking sheet for stacking.

[0079] The following is further described in conjunction with specific examples and comparative examples. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources. The instruments used, unless otherwise specified, can all be sourced from commercial sources. The processes involved, unless otherwise specified, are all routinely selected by those skilled in the art.

[0080] Example 1

[0081] This embodiment provides a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The key parameters are shown in Table 1, and the preparation method steps are as follows:

[0082] Step 1: Weigh 580 g of ascorbic acid into a reactor, add 4 L of water to dissolve, add 120 g of sodium hydroxide, and finally add water to prepare a 6 L reduction system, and adjust the temperature to 30°C.

[0083] Step 2: Weigh 1 kg of silver nitrate into a mixing bucket and add 2 L of water to dissolve it. Finally, add more water to make a 4 L silver system and adjust the temperature to 30 °C.

[0084] Step 3: Under stirring conditions, add the silver system to the reduction system for reduction reaction, and wash after the reaction is complete to obtain a solid wet powder.

[0085] Step 4: Add 3.2 g of oleic acid to the solid wet powder (635 g) obtained in step 3, stir and disperse for 15 min, and coat the solid wet powder to obtain the original powder. The SEM image of the original powder is as follows: Figure 1 As shown, the particle size D50 of the original powder is 2.01μm, and the particle size range is 1.0μm-3.0μm. The specific surface is 0.35μm 2 / g.

[0086] Step 5: Add the above raw powder into a high-speed disperser at one time, stir and knead for granulation for 30 minutes at a speed of 2000 r / min to obtain spherical silver powder as an anti-sticking agent. The SEM image of the anti-sticking agent is as follows: Figure 2 As shown, the product particle size D50 is 10.05μm, and the specific surface area is 0.07m 2 / g.

[0087] Comparative Example 1

[0088] This comparative example provides a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The key parameters are shown in Table 1, and the preparation method steps are as follows:

[0089] Step 1: Weigh 580 g of ascorbic acid into a reactor, add 4 L of water to dissolve, add 120 g of sodium hydroxide, and finally add water to prepare a 6 L reduction system, and adjust the temperature to 30°C.

[0090] Step 2: Weigh 1 kg of silver nitrate into a mixing bucket and add 2 L of water to dissolve it. Finally, add more water to make a 4 L silver system and adjust the temperature to 30 °C.

[0091] Step 3: Under stirring conditions, add the silver system to the reduction system for reduction reaction, and wash after the reaction is complete to obtain a solid wet powder.

[0092] Step 4: Add 3.2 g of oleic acid to the solid wet powder (635 g) obtained in step 3, stir and disperse for 15 min, and coat the solid wet powder to obtain the original powder. The particle size D50 of the original powder is 2.01 μm, and the particle size range is 1.0 μm-3.0 μm. The specific surface is 0.35 μm 2 / g.

[0093] Step 5: Add the above raw powder into a high-speed disperser at one time, stir and knead to granulate for 10 minutes at a speed of 2000r / min to obtain silver powder as an anti-sticking agent. The SEM image of the anti-sticking agent is as follows: Figure 3 As shown, from Figure 3 It can be seen that the product granulation was unsuccessful and the granulation was not completed.

[0094] Example 2

[0095] This embodiment provides a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The key parameters are shown in Table 1, and the preparation method steps are as follows:

[0096] Step 1: Weigh 580 g of ascorbic acid into a reactor, add 4 L of water to dissolve, add 120 g of sodium hydroxide, and finally add water to prepare a 6 L reduction system, and adjust the temperature to 30°C.

[0097] Step 2: Weigh 1 kg of silver nitrate into a mixing bucket and add 2 L of water to dissolve it. Finally, add more water to make a 4 L silver system and adjust the temperature to 30 °C.

[0098] Step 3: Under stirring conditions, add the silver system to the reduction system for reduction reaction, and wash after the reaction is complete to obtain a solid wet powder.

[0099] Step 4: Add 3.2 g of oleic acid to the solid wet powder (635 g) obtained in step 3, stir and disperse for 15 min, and coat the solid wet powder to obtain the original powder. The particle size D50 of the original powder is 2.01 μm, and the particle size range is 1.0 μm-3.0 μm. The specific surface is 0.35 μm 2 / g.

[0100] Step 5: Add the above raw powder into the high-speed disperser in batches in three rounds, stir and knead the granules for 30 minutes in each round, and the speed is 2000r / min to obtain spherical silver powder as an anti-sticking agent. The SEM image of the anti-sticking agent is as follows: Figure 4 As shown, the product particle size D50 is 58.86μm, and the specific gravity is 0.05μm 2 / g.

[0101] Example 3

[0102] This embodiment provides a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The key parameters are shown in Table 1, and the preparation method steps are as follows:

[0103] Step 1: Weigh 140 g of hydrazine hydrate into a reactor, add 7 L of water to dissolve, add 600 g of sodium carbonate, and finally add water to prepare a 10 L reduction system, and adjust the temperature to 45 °C.

[0104] Step 2: Weigh 1 kg of silver nitrate into a mixing bucket and add 4 L of water to dissolve it. Finally, add more water to make a 5 L silver system and adjust the temperature to 45 °C.

[0105] Step 3: Under stirring conditions, add the silver system to the reduction system for reduction reaction, and wash after the reaction is complete to obtain a solid wet powder.

[0106] Step 4: Add 3.2 g of stearic acid to the solid wet powder (635 g) obtained in step 3, stir and disperse for 15 min, and coat the solid wet powder to obtain the original powder. The SEM image of the original powder is as follows: Figure 5 As shown, the particle size D50 of the original powder is 1.04μm, the particle size range is 0.6μm-1.5μm, and the specific surface is 1.21μm 2 / g.

[0107] Step 5: Add the above raw powder into a high-speed disperser at one time, stir and knead for granulation for 30 minutes at a speed of 4000 r / min to obtain spherical silver powder as an anti-sticking agent. The SEM image of the anti-sticking agent is as follows: Figure 6 As shown, the product particle size D50 is 9.08μm, and the specific surface area is 0.08m 2 / g.

[0108] Comparative Example 2

[0109] This comparative example provides a silver conductive paste sintering anti-sticking agent and a preparation method thereof. The key parameters are shown in Table 1, and the preparation method steps are as follows:

[0110] Step 1: Weigh 140 g of hydrazine hydrate into a reactor, add 7 L of water to dissolve, add 600 g of sodium carbonate, and finally add water to prepare a 10 L reduction system, and adjust the temperature to 45 °C.

[0111] Step 2: Weigh 1 kg of silver nitrate into a mixing bucket and add 4 L of water to dissolve it. Finally, add more water to make a 5 L silver system and adjust the temperature to 45 °C.

[0112] Step 3: Under stirring conditions, add the silver system to the reduction system for reduction reaction, and wash after the reaction is complete to obtain a solid wet powder.

[0113] Step 4: Add 3.2 g of stearic acid to the solid wet powder (635 g) obtained in step 3, stir and disperse for 15 min, and coat the solid wet powder to obtain the original powder. The particle size D50 of the original powder is 1.04 μm, the particle size range is 0.6 μm-1.5 μm, and the specific surface is 1.21 μm. 2 / g.

[0114] Step 5: Add the above raw powder into a high-speed disperser at one time, stir and knead to granulate for 10 minutes at a speed of 4000r / min to obtain silver powder as an anti-sticking agent. The SEM image of the anti-sticking agent is as follows: Figure 7 As shown, from Figure 7 It can be seen that the product granulation was unsuccessful and could not form a good spherical shape.

[0115] Performance Testing

[0116] Homemade sintered silver conductive paste, the paste contains:

[0117] ①60% metal components: 20% of the metal components have a specific surface area of ​​2.0-2.5m 2 / g, particle size D50 is 1.0μm-1.5μm and 80% specific surface area is 7.0-7.5m 2 / g, and a particle size D50 of 0.3μm-0.7μm.

[0118] ②33% organic component: the organic component is a resin system consisting of 15 parts of terpineol, 45 parts of butyl carbitol, 10 parts of ethyl cellulose and 30 parts of additives;

[0119] ③7% glass component: the glass component is purchased bismuth oxide system glass;

[0120] Using the large-particle silver powder prepared in the above examples and comparative examples as an anti-sticking agent, replacing the corresponding 1.5% of the metal component at an addition amount of 1.5%, and adding it to the slurry;

[0121] The above components are mixed and slurried to form the surface electrode silver paste.

[0122] The sticking rate of the sintered silver conductive paste product prepared above was tested. The testing method was as follows: the prepared silver paste was used for batch printing on piezoelectric ceramic sheets. After drying, the ceramic sheets were stacked and placed in a sintering furnace for sintering. After sintering, they were taken out and cooled, the stacked ceramic sheets were shaken apart, the sticking products were sorted, the sticking products and the total amount of products were counted, and the proportion of sticking products was calculated to obtain the sticking rate, as shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126]

[0127] Combined with Table 1, it can be seen that the quasi-spherical silver powder prepared in Examples 1-3 is added to the silver conductive paste. At the preset sintering temperature, the small-sized traditional silver powder as the main body completes the silver surface sintering, and the large-sized quasi-spherical silver powder is not easy to sinter, forming a support point between the sheets in the stacked state, which can play the role of a stacked physical anti-sticking sheet. Among them, the quasi-spherical silver powder prepared in Example 2 is large in size, and may be slurried into sheets later, which is not conducive to printing, while the silver powder of about 10μm in Example 1 and Example 3 is more suitable. In Comparative Examples 1 and 2, the kneading granulation time is short, the granulation is not completed, and the anti-sticking sheet effect is relatively poor.

[0128] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are 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.

[0129] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a silver conductive paste sintering anti-sticking agent, characterized in that: The following steps are involved: Allowing the silver salt to undergo a reduction reaction under the action of a reducing agent, and collecting solid wet powder; The solid wet powder is coated with a coating agent and dried to prepare an original powder; At least one round of stirring and kneading granulation is started, and all or part of the original powder is added in each round of stirring and kneading granulation to obtain spherical silver powder with a particle size D50 of 6μm-100μm, which is used as a sintering anti-sticking agent for silver conductive paste.

2. The method for preparing the silver conductive paste sintering anti-sticking agent according to claim 1, characterized in that: The particle size D50 of the silver conductive paste sintering anti-sticking agent is 6 μm-20 μm.

3. The method for preparing the silver conductive paste sintering anti-sticking agent according to claim 1, characterized in that: When a total of one round of stirring, kneading and granulating is started, the time of this round of stirring, kneading and granulating is 30 minutes to 60 minutes; when a total of 2 to 5 rounds of stirring, kneading and granulating are started, the time of each round of stirring, kneading and granulating is 20 minutes to 60 minutes.

4. The method for preparing the silver conductive paste sintering anti-sticking agent according to claim 1, characterized in that: The rotation speed of each round of stirring, kneading and granulating is 1000r / min-6000r / min.

5. The method for preparing the silver conductive paste sintering anti-sticking agent according to claim 1, characterized in that: Start 2-5 rounds of stirring, kneading and granulating.

6. The method for preparing the silver conductive paste sintering anti-sticking agent according to any one of claims 1 to 5, characterized in that: The coating agent is selected from at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid and myristic acid.

7. The method for preparing the silver conductive paste sintering anti-sticking agent according to claim 6, characterized in that: The mass percentage of the coating agent to the solid wet powder is 0.1%-1.0%.

8. The method for preparing the silver conductive paste sintering anti-sticking agent according to any one of claims 1 to 5, characterized in that: The silver salt is silver nitrate.

9. The method for preparing the silver conductive paste sintering anti-sticking agent according to any one of claims 1 to 5, characterized in that: The reducing agent is selected from at least one of ascorbic acid, glucose, hydrazine hydrate, formaldehyde and hydroxylamine hydrochloride.

10. A silver conductive paste sintering anti-sticking agent, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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