A gel-type brazing material for brazing and its preparation method and application

Abstract

The invention discloses a gel-type solder for brazing and a preparation method and application thereof, and relates to the technical field of electric contacts; the solder gel layer comprises the following components in percentage by mass: 80-95% of alloy solder, 0.01-10% of gelling agent, 0.05-10% of moisturizing agent, and 5-20% of ultrapure water; the mass ratio of the gelling agent to the alloy solder is (0.01-0.15):90; the invention improves the raw material components of the solder and makes it into a gel state, so that the prepared solder can be cut into appropriate sizes according to the shape and size of a component to be welded, and is more flexible and more customizable; in addition, the gel-type solder of the invention does not need to be rolled, so the preparation process is simplified, and more importantly, the production cost is saved and the safety hazard in the rolling process is avoided; further, because the gel-type solder can be accurately cut into a shape and size matching a welding part, the waste of materials is reduced, and the control of welding is more refined, and the welding accuracy is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric contacts, and in particular to a gel-type brazing material for hard brazing of contact materials with a size of ≥10*10mm, and a preparation method and application thereof. Background Art

[0002] Brazing refers to a brazing process with a brazing temperature greater than 400°C. The brazing material plays a key role in connection, electrical conduction, thermal conduction, filling and sealing, anti-oxidation and lowering the melting point during the brazing process of contact materials. It ensures the stability, reliability and good electrical properties of the welded joint and is an important auxiliary material to ensure a "seamless" brazing result.

[0003] In the process of brazing contact materials, sheet solder is widely used in the industry. However, due to the complex preparation and difficult positioning, additional flux needs to be added to assist positioning and remove oxides on the surface of the molten solder and the base material, which increases the workload. In addition, sheet solder is generally thicker (generally 0.1-0.3mm), which can easily lead to excessive materials and waste of precious metal materials. The solder is easy to overflow and even flow to the surface of the base material, affecting the appearance of the product and subsequent assembly. In severe cases, it will increase the risk of fusion welding during the use of the product. If a thinner sheet solder is developed to reduce material waste and overflow risks, the process is more difficult and the R&D cost is too high.

[0004] Solder paste is a uniform paste made by mixing a binder and brazing material powder. Since it can be applied quantitatively to the required welding parts of the workpiece by pneumatic extrusion, it has recently attracted great attention from industry personnel. However, in order to ensure the stable discharge of solder paste, the binder is often mixed with a polymer binder and a solvent, and a large amount of smoke and odor are generated during the welding process. In addition, thixotropic agents are generally added to the binder, but thixotropic agents are often not conducive to improving the welding brazing rate and are easy to introduce post-welding residues. In addition, due to the limited glue discharge position and glue discharge amount, the parent material far away from the glue dispensing position cannot be welded due to the lack of solder, and the brazing rate of large-area components to be welded is often not high. In addition, the solder paste production process often requires dozens of rolling techniques, which is dangerous and cumbersome to operate.

[0005] Therefore, further research and development is needed to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, one of the purposes of the present invention is to provide a gel-type solder for hard soldering, and by improving the raw material components of the solder and making it into a gel, the prepared solder can be cut into appropriate sizes according to the shape and size of the components to be welded, which is more flexible and customizable, and can adapt to various complex welding requirements, reducing the defects of sheet solders that have a certain shape during the preparation process and are difficult to adjust; in addition, the gel-like solder of the present invention does not need to be rolled, which simplifies the preparation process and, more importantly, saves production costs and avoids safety hazards during the rolling process; further, since the gel-like solder can be accurately cut into a shape and size that matches the welding part, the waste of precious metal materials is reduced, and at the same time the welding control is more refined, and the solder can be more accurately positioned in the area where welding is required, greatly improving the welding accuracy.

[0007] The second object of the present invention is to provide a method for preparing a gel-type solder for hard soldering as mentioned above, optimize the order of adding materials, pre-mix the two before adding the humectant and the gelling agent, and form a cross-linked structure or gel network in advance, which provides a stable foundation for subsequent standing and hardening, and can improve the initial adhesion of the solder gel layer, improve fluidity, and make it more firmly adhere to the workpiece surface; at the same time, the gelling agent can be evenly distributed in the alloy solder and other components, ensuring the overall uniformity of the gel layer, balancing many factors such as wetting performance, soldering rate, production cost, etc., forming a stable gel structure as a whole, and providing better wettability and wetting performance during the welding process.

[0008] A third object of the present invention is to provide an application of the gel-type solder for brazing as described above.

[0009] One of the purposes of the present invention is achieved by the following scheme:

[0010] A gel-type solder for hard soldering comprises a solder gel layer; the solder gel layer comprises the following components in percentage by mass: 80-95% alloy solder, 0.01-10% gelling agent, 0.05-10% moisturizing agent, and 5-20% ultrapure water; the sum of the weight percentages of the above components is 100%; the mass ratio of the gelling agent to the alloy solder is (0.01-0.15):90.

[0011] As a further illustration of the above scheme, the solder gel layer includes the following components in mass percentage: 80-86% alloy solder, 0.01-1% gelling agent, 0.05-5% moisturizing agent, and 10-20% ultrapure water; the mass ratio of the gelling agent to the alloy solder is (0.01-0.15):90; the sum of the mass percentages of the above components is 100%.

[0012] As a further illustration of the above scheme, the gelling agent is one or more of methyl cellulose, sodium hydroxymethyl cellulose, polyacrylamide, polyacrylate, sesbania gum, yellow gum, carbomer, and water glass.

[0013] As a further illustration of the above scheme, the mesh number of the alloy solder is minus 100 mesh; the alloy solder is one of Ag18CuP, Ag15CuP, Ag6CuP, Ag5CuP, Ag2CuP, CuPSnNi, and CuPSn; the Ag18CuP includes the following components by weight percentage of the raw materials: Ag17.2-18.0%, P6.0-6.7%, and the balance is Cu; the Ag15CuP includes the following components by weight percentage of the raw materials: Ag14.5-15.5%, P4.8-5.2%, and the balance is Cu; the Ag6CuP includes the following components by weight percentage of the raw materials: Ag5.8-6.2% , P7.0-7.5%, and the balance is Cu; the Ag5CuP includes the following components by weight percentage of raw materials: Ag4.8-5.2%, P6.5-7.0%, and the balance is Cu; the Ag2CuP includes the following components by weight percentage of raw materials: Ag1.8-2.2%, P6.8-7.2%, and the balance is Cu; the CuPSnNi includes the following components by weight percentage of raw materials: P6.0-7.0%, Sn6.0-7.0%, Ni4.0-6.0%, and the balance is Cu; the CuPSn includes the following components by weight percentage of raw materials: P6.0-7.2%, Sn6.0-7.0%, and the balance is Cu.

[0014] As a further illustration of the above scheme, the moisturizing agent is one or more solvent-based alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, and n-butanol.

[0015] The second object of the present invention is achieved by adopting the following technical solution:

[0016] A method for preparing the gel-type solder for brazing as described above comprises the following steps:

[0017] S1: sieve the alloy solder in the formula amount to remove the powder of 100 mesh and set aside;

[0018] S2: Add the alloy solder in S1 into a stirring device, and add 1 / 2 of the formula amount of ultrapure water to mix evenly;

[0019] S3: premix the formulated amount of moisturizer with the remaining ultrapure water, and then add it to the mixture in S2 and continue stirring;

[0020] S4: Add a gelling agent to the mixture in S3 and ensure that it is stirred evenly, and let it stand to obtain the solder gel layer.

[0021] As a further illustration of the above scheme, in S2, the stirring speed is set to 80-100 rpm / min; the stirring time is 4-5 min; in S3, the stirring speed is set to 200-250 rpm / min; the stirring time is 10-15 min.

[0022] As a further illustration of the above scheme, in S4, after adding the gelling agent, the stirring speed is set to 350-400 rpm / min; the stirring time is 20-25 min; and after stirring evenly, the mixture is allowed to stand for 0-1.5 h.

[0023] The third object of the present invention is achieved by adopting the following technical solution:

[0024] An application of a gel-type solder for brazing prepared by the above preparation method in the preparation of a solder paste, wherein the solder further comprises a release layer and a protective layer; the solder gel layer is arranged between the release layer and the protective layer; the preparation of the solder paste comprises the following steps:

[0025] 1) Preparation of release layer

[0026] Clean the release layer and set aside;

[0027] 2) Coating of solder gel layer

[0028] The prepared solder gel layer is coated on the release layer through a perforated mold by a scraper, a coater or a screen printing method;

[0029] 3) Covering of protective layer

[0030] Covering the upper surface of the solder gel layer in step 2) with a release layer or a PE film as a protective layer to obtain the solder paste;

[0031] 4) Cutting of plaster

[0032] The solder paste is cut into appropriate sizes for welding according to the size of the assembly to be welded.

[0033] As a further illustration of the above scheme, in step 2), the solder gel layer coated on the release layer through the perforated mold is a continuous gel with holes or side openings.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention makes the solder into a gel state and improves the raw material components of the solder so that the prepared solder can be cut into appropriate sizes according to the shape and size of the components to be welded, which is more flexible and customizable, and can adapt to various complex welding requirements, reducing the defects of sheet solders that have a certain shape during the preparation process and are difficult to adjust; in addition, the gel solder of the present invention does not need to be rolled, which simplifies the preparation process, and more importantly, saves production costs and avoids safety hazards during the rolling process; further, since the gel solder can be accurately cut into a shape and size that matches the welding part, the waste of precious metal materials is reduced, and the welding control is more refined, and the solder can be more accurately positioned in the area where welding is required, greatly improving the welding accuracy; on the other hand, its viscosity and gel properties help prevent the overflow and flow of the solder, especially on the vertical or horizontal welding surface, which helps to improve the aesthetics of the product and reduce the risk of the solder flowing to the unnecessary area;

[0036] 2. The present invention optimizes the components for preparing the gel solder. The alloy solder is mainly composed of self-soldering alloy solders such as Ag15CuP, Ag18CuP, CuPSnNi, etc., without the need to add additional additives such as flux to improve the fluidity, wettability and other properties of the solder. A small amount of P element in the alloy can significantly reduce the melting point, improve the wettability of the solder, help reduce the formation of surface oxides, and improve the adhesion of the solder to the base material, making it easier to melt and spread on the surface of the base material, helping to form a uniform and dense connection, and enhancing the bonding between the solder and the base material. At the same time, it can diffuse with the metal surface at the brazing temperature to achieve connection, the welding process is faster, and the welding efficiency is improved.

[0037] 3. The gel-like solder of the present invention uses sodium polyacrylate and other components as gelling agents to promote the formation of a gel of the solder, which helps to improve the adhesion and stability of welding, increase the viscosity of the solder, and make it easier to adhere and position on a vertical or horizontal surface, thereby improving the precision and control of welding; in addition, the appropriate amount of gelling agent can improve the fluidity of the solder, making it easier to apply to the part to be welded, ensuring the quality of welding, and making the solder environmentally friendly;

[0038] 4. The order of adding materials to the solder gel layer of the present invention includes first adding part of ultrapure water to preliminarily wet the alloy solder, and then premixing the two before adding the humectant and the gel promoter, so as to form a cross-linked structure or gel network in advance, which provides a stable foundation for subsequent standing and hardening, and can improve the initial adhesion of the solder gel layer, improve fluidity, and make it more firmly attached to the workpiece surface; at the same time, the gel promoter can be evenly distributed in the alloy solder and other components, ensuring the overall uniformity of the gel layer, balancing the wetting performance and soldering rate, forming a stable gel structure as a whole, and providing better wettability and wetting performance during the welding process;

[0039] 5. The present invention can apply the gel-like solder to the part to be welded at a fixed point and in a quantitative manner through the coating of the perforated die, which reduces the waste of solder, can effectively save precious metal materials, and reduce production costs; in addition, excessive solder can easily cause the solder to climb and flow to the working surface, causing various undesirable phenomena. Coating with a perforated die can accurately control the amount of solder applied, which can not only reduce the amount of solder applied and reduce costs, but also effectively prevent the occurrence of climbing, and quality defects such as poor size and inability to assemble caused by climbing and other problems, which are more critical in brazing; at the same time, a continuous body with holes is formed to ensure uniform coating of the welding part, which helps to improve the appearance quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of a mold with holes used in a preferred embodiment of the present invention for applying a gel-type brazing material for brazing;

[0041] Figure 2 Application of the present invention Figure 1 Schematic diagram of the decomposed structure of the gel layer, release layer and protective layer of the gel-type brazing material for brazing made of a perforated mold;

[0042] Figure 3 This is a schematic diagram of a mold with holes used in another preferred embodiment of the present invention for applying a gel-type brazing material for brazing;

[0043] Figure 4 Application of the present invention Figure 3 Schematic diagram of the decomposed structure of the gel layer, release layer and protective layer of the gel-type brazing material for brazing made of a perforated mold;

[0044] Figure 5 This is an ultrasonic testing diagram of the gel-type brazing material for brazing prepared in Example 2 of the present invention;

[0045] Figure 6 This is an ultrasonic detection image of the gel-type solder for brazing prepared in Comparative Example 2 of the present invention.

[0046] In the figure:

[0047] 1. Solder gel layer; 2. Release layer; 3. Protective layer; a. Mold with holes. DETAILED DESCRIPTION

[0048] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0049] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0050] like Figure 2 , 4 As shown, the present invention provides a gel-type solder for hard soldering, including a solder gel layer 1; the solder gel layer includes the following components in mass percentage: alloy solder 80-95%, gel promoter 0.01-10%, moisturizer 0.05-10%, ultrapure water 5-20%; the sum of the weight percentages of the above components is 100%; the mass ratio of the gel promoter to the alloy solder is (0.01-0.15):90.

[0051] As a further preferred embodiment, the solder gel layer 1 comprises the following components in percentage by mass: 80-86% alloy solder, 0.01-1% gelling agent, 0.05-5% moisturizing agent, and 10-20% ultrapure water; the mass ratio of the gelling agent to the alloy solder is 0.01:90; the sum of the mass percentages of the above components is 100%.

[0052] As a further preferred embodiment, the gelling agent is one or more of methyl cellulose, sodium hydroxymethyl cellulose, polyacrylamide, polyacrylate, sesbania gum, yellow gum, carbomer, and water glass.

[0053] As a further preferred embodiment, the mesh number of the alloy solder is minus 100 mesh; the alloy solder is one of Ag18CuP, Ag15CuP, Ag6CuP, Ag5CuP, Ag2CuP, CuPSnNi, and CuPSn; the Ag18CuP comprises the following components by weight percentage of raw materials: Ag17.2-18.0%, P6.0-6.7%, and the balance is Cu; the Ag15CuP comprises the following components by weight percentage of raw materials: Ag14.5-15.5%, P4.8-5.2%, and the balance is Cu; the Ag6CuP comprises the following components by weight percentage of raw materials: Ag5.8-6.2%, P7.0-7.5%, the balance is Cu; the Ag5CuP comprises the following components by weight percentage of the raw materials: Ag4.8-5.2%, P6.5-7.0%, the balance is Cu; the Ag2CuP comprises the following components by weight percentage of the raw materials: Ag1.8-2.2%, P6.8-7.2%, the balance is Cu; the CuPSnNi comprises the following components by weight percentage of the raw materials: P6.0-7.0%, Sn6.0-7.0%, Ni4.0-6.0%, the balance is Cu; the CuPSn comprises the following components by weight percentage of the raw materials: P6.0-7.2%, Sn6.0-7.0%, the balance is Cu.

[0054] As a further preferred embodiment, the moisturizing agent is one or more solvent-type alcohols such as ethylene glycol, glycerol, 1,4-butanediol, and n-butanol.

[0055] The components and dosage are analyzed as follows:

[0056] ① Selection and dosage design of alloy solder

[0057] The alloy solders of the present invention have self-brazing properties, that is, they can be directly brazed with the metal surface within an appropriate temperature range without the need to add flux; a small amount of P element in the alloy can significantly reduce the melting point, improve the wettability of the solder, and make it easier to melt and spread on the surface of the base material. The improvement in wettability helps to form a uniform and dense connection, reduce the formation of surface oxides, and improve the adhesion of the solder to the base material; at the same time, they can diffuse with the metal surface at the brazing temperature to achieve connection, making the welding process faster. Active metal phosphides help to enhance the stability and strength of the weld. In summary, the self-brazing alloy solders used in the present invention can simplify the process of preparing gel-like solders, improve the consistency of the finished product, and are economical, efficient, and environmentally friendly.

[0058] ② Selection of moisturizers and gelling agents

[0059] The present invention adopts alcohol moisturizing agents such as propylene glycol, 1,4-butanediol, and n-butanol to mix with gelling promoters, which can more finely control the viscosity of the gel material, ensure that it has suitable rheological properties during the coating or application process, and ensure that the gel material maintains the required fluidity and viscosity; at the same time, the alcohol moisturizing agent is mixed with gelling promoters such as polyacrylamide, which is helpful to form a stable gel structure, form a cross-linked structure or gel network in advance, and provide a stable foundation for subsequent standing and hardening, which can improve the initial adhesion of the solder gel layer, improve fluidity, and make it more firmly attached to the workpiece surface.

[0060] Furthermore, the applicant has found through a large number of experiments that the amount of gelling agent should not be too much, and the most suitable mass ratio of gelling agent to alloy solder is (0.01-0.15):90; too much gelling agent makes the fluidity of the gel material worse and the viscosity increases, thereby affecting the performance and operability of the gel solder and reducing the soldering rate.

[0061] At the same time, the amount of ultrapure water should not be too much or too little. Excessive use will cause the viscosity of the gel to be too thin, affecting its viscosity and controllability. If the amount is too little, the viscosity of the gel increases, making it difficult to operate during coating or application, and may also reduce the fluidity of the gel, making it difficult to evenly cover the surface of the workpiece. This will affect the quality and uniformity of the solder gel layer, and may result in insufficient strength of the welded joint or leakage. In addition, due to the increase in the viscosity of the gel, more moisturizers need to be added to adjust its fluidity to maintain suitable coating performance. In this way, the amount of moisturizer will be increased, which may cause the formula ratio of the gel to be unbalanced, thereby affecting the quality and stability of the welded joint. Therefore, in the present invention, the mass ratio of the ultrapure water to the alloy solder is 1:5 optimal. Under this ratio, the viscosity, fluidity, etc. of the entire formula are more balanced, the amount of moisturizer is more reasonable, and the soldering rate is better.

[0062] In summary, the present invention makes the solder into a gel state and improves the raw material components of the solder so that the prepared solder can be cut into appropriate sizes according to the shapes and sizes of the components to be welded. The solder is more flexible and customizable, and can adapt to various complex welding requirements, reducing the defects of sheet solders that have a certain shape during the preparation process and are difficult to adjust. Furthermore, since the gel-like solder can be accurately cut into a shape and size that matches the welding part, the waste of precious metal materials is reduced, and the welding control is more refined, and the solder can be more accurately positioned in the area where welding is required, greatly improving the welding accuracy. On the other hand, its viscosity and gel properties help prevent the overflow and flow of the solder, especially on vertical or horizontal welding surfaces, which helps to improve the aesthetics of the product and reduce the risk of the solder flowing to unnecessary areas.

[0063] The present invention also provides a method for preparing a gel-type solder for brazing, comprising the following steps:

[0064] S1: sieve the alloy solder in the formula amount to remove the powder of 100 mesh and set aside;

[0065] S2: Add the alloy solder in S1 into a stirring device, and add 1 / 2 of the formula amount of ultrapure water to mix evenly;

[0066] S3: premix the formulated amount of moisturizer with the remaining ultrapure water, and then add it to the mixture in S2 and continue stirring;

[0067] S4: Add a gelling agent to the mixture in S3 and ensure that it is stirred evenly, and let it stand to obtain the solder gel layer.

[0068] As a further preferred embodiment, in S2, the stirring speed is set to 80-100 rpm / min; the stirring time is 4-5 min; in S3, the stirring speed is set to 200-250 rpm / min; the stirring time is 10-15 min.

[0069] As a further preferred embodiment, in S4, after adding the gelling agent, the stirring speed is set to 350-400 rpm / min; the stirring time is 20-25 min; and after stirring evenly, the mixture is allowed to stand for 0-1.5 h.

[0070] The feeding sequence of the solder gel layer of the present invention comprises the following steps: adding a portion of ultrapure water to initially wet the alloy solder, and then premixing the two before adding a humectant and a gel promoter, so as to form a cross-linked structure or a gel network in advance, thereby providing a stable basis for subsequent standing and hardening, improving the initial adhesion of the solder gel layer, improving fluidity, and making it more firmly attached to the workpiece surface; at the same time, the gel promoter can be evenly distributed in the alloy solder and other components, thereby ensuring the overall uniformity of the gel layer, balancing many factors such as wetting performance, soldering rate, production cost, etc., forming an overall stable gel structure, and providing better wettability and wetting performance during welding.

[0071] In S2, the low speed and relatively short time in this stage help to fully wet the alloy solder with ultrapure water to form a preliminary uniform mixture; in S3 and S4, the stirring speed and time are increased to ensure the full mixing of the components. In particular, in S4, the stirring speed is further increased after the gelling agent is added, and high-speed stirring is performed to make the components more evenly distributed, thereby improving the stability and uniformity of the gel solder.

[0072] like Figure 1-4As shown, the present invention also provides an application of a gel-type solder for brazing prepared by the above preparation method in the preparation of a solder paste, wherein the solder further comprises a release layer 2 and a protective layer; the solder gel layer is arranged between the release layer and the protective layer; the preparation of the solder paste comprises the following steps:

[0073] 1) Preparation of release layer

[0074] Clean the release layer and set aside;

[0075] 2) Coating of solder gel layer

[0076] The prepared solder gel layer is coated on the release layer through a perforated mold a by a scraper, a coater or a screen printing method;

[0077] 3) Covering of protective layer

[0078] Covering the upper surface of the solder gel layer in step 2) with a release layer or a PE film as a protective layer to obtain the solder paste;

[0079] 4) Cutting of plaster

[0080] The solder paste is cut into appropriate sizes for welding according to the size of the assembly to be welded.

[0081] As a further illustration of the above scheme, in step 2), the solder gel layer coated on the release layer through the perforated mold a is a continuous gel with holes or side openings.

[0082] The present invention can apply the gel-like solder to the part to be welded at a fixed point and in a quantitative manner through the coating with a perforated die, thereby reducing the waste of solder, effectively saving precious metal materials and reducing production costs; in addition, excessive solder is likely to cause the risk of fusion welding, and the coating with a perforated die can accurately control the coating amount of the solder, which not only effectively prevents the occurrence of climbing, but also reduces the coating amount of the solder, reducing the risk of fusion welding, which is more critical in hard soldering; at the same time, a continuous body with holes is formed to ensure uniform coating of the welding part, which helps to improve the appearance quality of the product and prevent quality defects such as poor size and inability to assemble caused by problems such as climbing; further, the advantage of the perforated die also includes that the gel-like solder is accurately coated on the part to be welded according to the set hole shape, size and layout, thereby ensuring the accuracy and controllability of welding.

[0083] The following are specific embodiments of the present invention. Unless otherwise specified, the raw materials, equipment, etc. used in the following embodiments can be obtained by purchase.

[0084] Examples 1-3 and Comparative Examples 1-4

[0085] Weigh the raw materials according to the ratios in Table 1 below, and prepare the products according to the steps in Examples 1-3. See Table 1 for details:

[0086] Table 1 Raw material ratio table of Examples 1-4 and Comparative Examples 1-3

[0087]

[0088]

[0089] Unless otherwise specified, in order to reflect the comparability of the test results, the raw materials used in the above Examples 1-3 and Comparative Example 1 are the same.

[0090] Preparation method

[0091] The preparation method of the gel-type solder for brazing of Examples 1-3 and Comparative Example 1 comprises the following steps:

[0092] S1: sieve the alloy solder in the formula amount to remove the powder of 100 mesh and set aside;

[0093] S2: Add the alloy solder in S1 into a stirring device, and add 1 / 2 of the formula amount of ultrapure water to mix evenly;

[0094] S3: premix the formulated amount of moisturizer with the remaining ultrapure water, and then add it to the mixture in S2 and continue stirring;

[0095] S4: Add a gelling agent to the mixture in S3 and ensure that it is stirred evenly, and let it stand to obtain the solder gel layer.

[0096] Comparative Example 2

[0097] Taking the component formula of Example 2 as a reference, the alloy solder in the formula of Comparative Example 2 adopts Ag65CuZn, and the formula is consistent with that of Example 2. Compared with the preparation method of Example 2, in step S1.

[0098] The preparation process of using the gel-type solder for brazing prepared by the preparation methods of Examples 1-3 and Comparative Examples 1-2 together with a release layer and a protective layer to prepare a solder paste includes the following steps:

[0099] 1) Preparation of release layer

[0100] Clean the release layer and set aside;

[0101] 2) Coating of solder gel layer

[0102] The prepared solder gel layer is coated on the release layer through a perforated mold by a scraper, a coater or a screen printing method;

[0103] 3) Covering of protective layer

[0104] Covering the upper surface of the solder gel layer in step 2) with a release layer or a PE film as a protective layer to obtain the solder paste;

[0105] 4) Cutting of plaster

[0106] The solder paste is cut into appropriate sizes for welding according to the size of the assembly to be welded.

[0107] Comparative Example 3

[0108] Comparative Example 3 is a soldering iron and soldering flux purchased from a certain manufacturer.

[0109] Comparative Example 4

[0110] Comparative Example 4 is a solder paste purchased from a certain manufacturer using Ag18CuP as the alloy solder.

[0111] Effect evaluation and performance testing

[0112] The gel-type brazing materials for brazing of Examples 1-3 and Comparative Examples 1-4 were subjected to welding tests, and their welding appearance, brazing rate and other properties were tested. The test items and results are shown in Table 2.

[0113] The test method is as follows: (according to SJ / T 3200-2016 standard)

[0114] 1. Welding appearance

[0115] Check the external quality of the weld by visual inspection or a 5-10x magnifying glass to ensure that there is no peeling, blistering, cracking, overburning, etc. on the surface of the brazed assembly; there is no residual flux on the weld joint; the brazing seam surface is uniform, continuous and smoothly transitions to the base material, without defects such as brazing material accumulation, welding leakage, dissolution, slag inclusion, incomplete brazing, partial melting of the base material, etc.

[0116] 2. Ultrasonic inspection

[0117] The specific results are shown in Table 2 below:

[0118] Table 2: Welding performance test results

[0119]

[0120]

[0121] Note: According to the ultrasonic testing result diagram in Table 2 above, the colors in the diagram are arranged according to the welding quality level. The best welding quality is blue, followed by green, yellow, red, and white. Therefore, the closer to white, the larger and more welding holes, and the lower the welding quality. Conversely, the closer to blue, the darker the blue, the better the welding quality.

[0122] According to the contents of Table 2 above, it can be seen that Example 2 is the best example of the present invention, the appearance quality of the welding part is high, the surface is uniform without pores or cracks, and there is no climbing phenomenon; Figure 5 As shown, the oval frame part is the blue area, and the square frame part represents the red or white area; the ultrasonic detection results show that the blue area is dark in color, and there is no red in the dark blue area, there are few welding holes, and the brazing rate is high, reaching more than 85%, and the overall welding quality is better than other embodiments and comparison examples.

[0123] In Example 1, the amount of ultrapure water is reduced, and more moisturizer needs to be added to ensure the fluidity of the gel solder, which not only increases the cost, but also its ultrasonic detection results show that the dark blue area has lower welding uniformity and a slightly lower soldering rate than Example 2.

[0124] The amount of ultrapure water used in Example 3 is equivalent to that in Example 1, and more humectants need to be added to ensure the fluidity of the gel solder. At the same time, the alloy solder uses CuPSnNi. Although the amount is increased compared with Example 1, the overall welding quality and soldering rate are both reduced compared with Examples 1-2.

[0125] Comparative Example 1 uses the component formula of Example 2 as a reference, the difference is that the amount of gelling agent is increased and the amount of alloy solder is reduced. Too much gelling agent makes the fluidity of the gel material worse and the viscosity increases, thereby affecting the performance and operability of the gel solder. From the ultrasonic detection results, it can be seen that the red area increases and the soldering rate is also significantly reduced.

[0126] In Comparative Example 2, Ag45CuZnSn without P was used, and there was no self-welding effect. Figure 6 As shown in the figure, from the ultrasonic testing results, it can be seen that the white area accounts for a large proportion, there are many overall welding holes, the welding quality is low, and the brazing rate is greatly reduced.

[0127] Comparative Example 3 is a commonly purchased solder sheet and flux, the welding appearance quality is poor, and there are light brown, dark brown and other dirt on the contact surface, which affects the welding quality and cannot guarantee the soldering rate.

[0128] Comparative Example 4 is a solder paste purchased using Ag18CuP as the alloy solder. Although the welding appearance quality is slightly better than that of Comparative Example 3, its appearance quality and soldering rate are significantly different from those of Example 2 of the present invention.

[0129] In summary, in terms of component ratio, the alloy solder of the present invention adopts Ag18CuP, and there is no need to add additional additives such as flux to improve the fluidity, wettability and other properties of the solder; the mass ratio of P is 6.0-6.7%, and a small amount of P element in the alloy can significantly improve the wettability of the solder, help reduce the formation of surface oxides, improve the adhesion of the solder to the base material, make it easier to melt and spread on the surface of the base material, help to form a uniform and dense connection, and enhance the bonding between the solder and the base material; in addition, sodium polyacrylate is used as a gelling agent to promote the formation of a gel of the solder, which helps to improve the adhesion and stability of welding, increase the viscosity of the solder, and improve the accuracy and control of welding.

[0130] In combination with the optimization of the preparation method of the present invention, a portion of ultrapure water is first added to preliminarily wet the alloy solder, and then the two are premixed before the humectant and the gel promoter are added, so as to form a cross-linked structure or a gel network in advance, which provides a stable basis for subsequent standing and hardening, and can improve the initial adhesion of the solder gel layer, improve fluidity, and make it more firmly attached to the workpiece surface; at the same time, the gel promoter can be evenly distributed in the alloy solder and other components, so as to ensure the overall uniformity of the gel layer and balance the wetting performance and the soldering rate.

[0131] From the appearance, since the present invention is coated through a perforated mold, the coating amount of the solder can be accurately controlled, which not only effectively prevents the occurrence of climbing, but also reduces the coating amount of the solder, reducing the risk of fusion welding.

[0132] 4. Analysis of silver dot surface composition

[0133] Energy dispersive X-ray fluorescence spectrometer (EDX) was used to analyze the silver spot surface composition of the welding parts of the gel-type solder for brazing in Example 2 and Comparative Example 3, and the elemental composition of the silver spot surface was determined and recorded and analyzed. The specific results are shown in Table 3-4 below:

[0134] Table 3 Surface composition analysis of silver dots in Example 2

[0135]

[0136] After analysis and testing, the main components such as Ag, Sn, Cu on the surface of the silver dots in Example 2 all meet the requirements of relevant standards, there is no P pollutant, the overall welding appearance is good, and the welding quality is high.

[0137] Table 4 Comparative Example 3 Silver Point Surface Composition Analysis

[0138]

[0139] After component analysis, the dirt contained Cu and P in the solder, and the substance was not the original element on the contact surface. It was judged to be caused by the solder climbing. A large amount of overflowed solder could easily cause the contact bridge and the electrode to adhere, causing great damage to the electrode. At the same time, it would easily cause the contact material to be welded when used in the product.

[0140] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A gel-type brazing material for brazing, characterized in that: The invention comprises a solder gel layer; the solder gel layer is composed of the following components in percentage by mass: 80-86% alloy solder, 0.01-1% gelling agent, 0.05-5% moisturizing agent, and 10-20% ultrapure water; the mass ratio of the gelling agent to the alloy solder is (0.01-0.15):90; the sum of the mass percentages of the above components is 100%; The alloy solder is one of Ag18CuP, Ag15CuP, Ag6CuP, Ag5CuP, Ag2CuP, CuPSnNi, and CuPSn.

2. The gel-type brazing material for brazing according to claim 1, wherein: The gelling agent is one or more of methyl cellulose, sodium hydroxymethyl cellulose, polyacrylamide, polyacrylate, sesbania gum, yellow gum, carbomer, and water glass.

3. The gel-type brazing material for brazing according to claim 1, wherein: The mesh number of the alloy solder is minus 100 mesh; the Ag18CuP includes the following components by weight percentage of the raw materials: Ag17.2-18.0%, P6.0-6.7%, and the balance is Cu; the Ag15CuP includes the following components by weight percentage of the raw materials: Ag14.5-15.5%, P4.8-5.2%, and the balance is Cu; the Ag6CuP includes the following components by weight percentage of the raw materials: Ag5.8-6.2%, P7.0-7.5%, and the balance is Cu; the Ag5CuP includes The following components are included: Ag4.8-5.2%, P6.5-7.0%, and the balance is Cu; the Ag2CuP includes the following components by weight percentage of the raw materials: Ag1.8-2.2%, P6.8-7.2%, and the balance is Cu; the CuPSnNi includes the following components by weight percentage of the raw materials: P6.0-7.0%, Sn6.0-7.0%, Ni4.0-6.0%, and the balance is Cu; the CuPSn includes the following components by weight percentage of the raw materials: P6.0-7.2%, Sn6.0-7.0%, and the balance is Cu.

4. The gel-type brazing material for brazing according to claim 1, wherein: The moisturizing agent is one or more of ethylene glycol, propylene glycol, 1,4-butanediol and n-butanol.

5. A method for preparing a gel-type brazing material for brazing as claimed in any one of claims 1 to 4, characterized in that: The steps include: S1: sieve the alloy solder in the formula to remove the powder with particle size of 100 mesh and set aside; S2: Add the alloy solder in S1 into a stirring device, and add 1 / 2 of the formula amount of ultrapure water to mix evenly; S3: premix the formulated amount of moisturizer with the remaining ultrapure water, and then add it to the mixture in S2 and continue stirring; S4: Add a gelling agent to the mixture in S3 and ensure that it is stirred evenly, and let it stand to obtain the solder gel layer.

6. The method for preparing a gel-type solder for brazing according to claim 5, characterized in that: In S2, the stirring speed is set to 80-100 rpm / min; the stirring time is 4-5 minutes; in S3, the stirring speed is set to 200-250 rpm / min; the stirring time is 10-15 minutes.

7. The method for preparing a gel-type solder for brazing according to claim 5, characterized in that: In S4, after adding the gelling agent, set the stirring speed to 350-400 rpm / min; the stirring time is 20-25 min; after stirring evenly, let it stand for 0-1.5 h.

8. Use of a gel-type brazing material for brazing prepared by the preparation method according to any one of claims 5 to 7 in the preparation of a brazing material paste, characterized in that: The solder material further comprises a release layer and a protective layer; the solder material gel layer is arranged between the release layer and the protective layer; the solder material paste production comprises the following steps: 1) Preparation of release layer Clean the release layer and set aside; 2) Coating of solder gel layer The prepared solder gel layer is coated on the release layer through a perforated mold by a scraper, a coater or a screen printing method; 3) Covering of protective layer Covering the upper surface of the solder gel layer in step 2) with a release layer or a PE film as a protective layer to obtain the solder paste; 4) Cutting of the plaster The solder paste is cut into appropriate sizes for welding according to the size of the assembly to be welded.

9. Use of the gel-type solder for brazing as claimed in claim 8 in the preparation of solder paste, characterized in that: In step 2), the solder gel layer coated on the release layer through the perforated mold is a continuous gel with holes or side openings.

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