A coating rod and application thereof

Abstract

The present application belongs to the technical field of brazing filler metal preparation, and particularly relates to a coating brazing filler metal and application. The coating brazing filler metal comprises an inner core layer and a coloring layer covering the surface of the inner core layer; the inner core layer comprises a brazing filler metal; the coloring layer comprises a coloring agent; the thermal characteristic temperature of the coloring agent is less than or equal to 600 DEG C, and the thermal characteristic temperature comprises one or more of a vaporization temperature, a sublimation temperature or a decomposition temperature. The coloring agent is contained in the coloring layer of the coating brazing filler metal, and the color of the coating brazing filler metal surface can be adjusted by adjusting the color type of the coloring agent, so that the color of the coating brazing filler metal surface is different from that of the metal base material to be welded; during CAB brazing, the coating brazing filler metal and the metal base material to be welded are distinguished by comparing the colors, so that the detection rate of naked eyes and CCD visual detection equipment is improved. The thermal characteristic temperature of the coloring agent is less than or equal to 600 DEG C, the coloring agent sublimates, decomposes or vaporizes during brazing, residues possibly existing are reduced, and the brazing effect is not affected.

Description

Technical Field

[0001] This invention belongs to the field of brazing filler metal preparation technology, and particularly relates to a flux-coated brazing filler metal and its application. Background Technology

[0002] Controlled atmosphere brazing (CAB) is currently the mainstream brazing process for aluminum alloys and is widely used in the production of power battery radiators. Power battery radiators are mostly made of aluminum alloy and typically consist of a radiator body and a water nozzle mounted on it. The radiator body has internal channels for the flow of cooling medium and is the core component responsible for heat exchange. The water nozzle serves as the connection interface between the radiator body and external cooling pipes; one end connects to the flow channel port of the radiator body, and the other end connects to the external pipes, enabling the introduction and export of the cooling medium. The water nozzle is usually fixed to the radiator body by brazing. During the brazing process, a ring-shaped filler metal, or brazing ring, needs to be pre-placed at the interface to be brazed.

[0003] With the development of power batteries, the number of radiators and water taps has increased accordingly, leading to a significant increase in the number of times brazing rings need to be placed. However, brazing rings are mostly in their natural metallic color, such as silver-white, with little color difference from aluminum alloy, resulting in a certain probability of being missed during detection. As the number of water taps increases, the probability of missed detection further increases; if a brazing ring is missed and not detected, it can lead to ineffective welding between the water tap and the radiator body, causing a safety accident. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a flux-cored solder and its application.

[0005] In a first aspect, the present invention provides a flux-coated solder, comprising an inner core layer and a coloring layer covering the surface of the inner core layer; the inner core layer comprises a solder; the coloring layer comprises a colorant; the thermal characteristic temperature of the colorant is less than or equal to 600°C, and the thermal characteristic temperature includes one or more of a vaporization temperature, a sublimation temperature, or a decomposition temperature.

[0006] As an optional implementation, the thermal characteristic temperature of the colorant is 50℃-550℃.

[0007] As an optional implementation, the thickness of the coloring layer is 0.3μm-50μm.

[0008] As an optional implementation, the colorant includes one or more of blue pigments or dyes, red pigments or dyes, and yellow pigments or dyes, as well as intermediates for synthesizing the pigments or dyes.

[0009] As an optional implementation, the mass content of the colorant in the coloring layer is 0.05%-20%.

[0010] As an optional implementation, the colorant includes one or more of ferrocene, solvent red, solvent yellow, phthalocyanine blue, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and perylene pigments.

[0011] As an optional implementation, the coloring layer includes a skeleton material.

[0012] As an optional implementation, the thermal characteristic temperature of the skeleton material is less than or equal to 600°C.

[0013] As an optional implementation, the mass content of the skeleton material in the coloring layer is 75.5%-99.5%.

[0014] As an optional implementation, the skeleton material includes one or more of naphthalene, benzoic acid, polyoxymethylene, pyromellitic dianhydride, and methyl methacrylate-butyl acrylate-methacrylic acid terpolymer.

[0015] As an optional implementation, the coloring layer includes an adhesive.

[0016] As an optional implementation, the adhesive has a decomposition temperature of less than or equal to 600°C.

[0017] As an optional implementation, the adhesive content in the coloring layer is 0-4.5% by mass.

[0018] As an optional implementation, the adhesive includes one or more of ethyl cellulose, polyethylene glycol, and polyvinyl alcohol.

[0019] As an optional implementation, the flux-cored solder further includes a transition layer disposed between the inner core layer and the coloring layer.

[0020] As an optional implementation, the thermal characteristic temperature of the components in the transition layer is less than or equal to 550°C.

[0021] As an optional implementation, the transition layer includes one or both of hydrogenated rosin methyl ester and rosin glycerol ester; and / or, the thickness of the transition layer is less than or equal to 0.005 mm.

[0022] As an optional implementation, the flux coating has a ring-shaped structure.

[0023] As an optional implementation, the surface of the inner core layer is provided with a micron- and / or nano-scale rough structure.

[0024] As an optional implementation, the inner core layer is filamentous or rod-shaped, and the cross-sectional shape of the inner core layer includes circular, elliptical, polygonal, L-shaped, T-shaped, or cross-shaped.

[0025] As an alternative implementation, the inner core layer extends in a spiral shape and forms a ring structure.

[0026] As an optional implementation, the maximum radial dimension of the inner core layer cross-section is 0.5mm-3mm.

[0027] As an optional implementation, the inner core layer has at least two spiral turns.

[0028] As an optional implementation, the difference between the pitch of the inner core layer and the maximum radial dimension of the inner core layer cross-section is 0-1 mm.

[0029] As an optional implementation, the solder includes an aluminum-silicon based solder.

[0030] And / or, the inner core layer further includes a flux comprising potassium fluoroaluminate.

[0031] As an optional implementation, the flux content in the inner core layer is 3%-20% by mass.

[0032] As an optional implementation, the potassium fluoroaluminate comprises KAlF4 and / or K3AlF6.

[0033] Secondly, the present invention provides the application of the above-mentioned flux-coated brazing filler metal in welding the battery radiator body and the water nozzle.

[0034] Thirdly, the present invention provides a mobile device including a battery radiator, wherein the battery radiator body and the water nozzle are connected by brazing using the aforementioned flux-cored brazing filler metal.

[0035] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: 1. This invention provides a flux-coated brazing filler metal, comprising an inner core layer and a coloring layer covering the surface of the inner core layer; the inner core layer comprises a brazing filler metal; the coloring layer comprises a colorant; the thermal characteristic temperature of the colorant is less than or equal to 600°C, and the thermal characteristic temperature includes one or more of vaporization temperature, sublimation temperature, or decomposition temperature. The coloring layer of the flux-coated brazing filler metal of this invention contains a colorant. Adjusting the color of the colorant can make the surface color of the flux-coated brazing filler metal different from the metal substrate to be brazed. During CAB brazing, the flux-coated brazing filler metal and the metal substrate to be brazed are distinguished by color comparison, thereby improving the detection rate of visual inspection equipment and CCD vision inspection, avoiding missed detections, and thus improving the effective welding rate and reducing the occurrence of safety accidents. Simultaneously, by controlling the thermal characteristic temperature of the colorant to be less than or equal to 600°C, the colorant sublimates, decomposes, or vaporizes during the brazing process, reducing possible residues and not affecting the brazing effect. This reduces problems such as porosity and incomplete welds caused by the colorant filling the weld as impurities. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of the flux-cored filler metal of the present invention; Figure 2 This is another structural schematic diagram of the flux coating of the present invention. Detailed Implementation

[0039] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0041] In a first aspect, embodiments of the present invention provide a flux-coated solder, comprising an inner core layer and a coloring layer covering the surface of the inner core layer; the inner core layer comprises a solder; the coloring layer comprises a colorant; the thermal characteristic temperature of the colorant is less than or equal to 600°C, and the thermal characteristic temperature includes one or more of a vaporization temperature, a sublimation temperature, or a decomposition temperature.

[0042] The coloring layer of the flux-coated brazing filler metal of this invention contains a colorant. Adjusting the color of the colorant can make the surface color of the flux-coated filler metal different from the metal substrate to be brazed. During CAB brazing, the flux-coated filler metal and the metal substrate to be brazed are distinguished by color comparison, thereby improving the detection rate of visual inspection equipment and CCD vision inspection, avoiding missed detections, and thus improving the effective welding rate and reducing the occurrence of safety accidents. At the same time, by controlling the thermal characteristic temperature of the colorant to be less than or equal to 600°C, the colorant sublimates, decomposes, or vaporizes during the brazing process, reducing possible residues and not affecting the brazing effect. This also reduces the problem of poor welding such as porosity and incomplete welds caused by the colorant filling the weld as impurities.

[0043] In this invention, the thermal characteristic temperature is defined as the critical temperature at which the colorant vaporizes, sublimates, or thermally decomposes when heated.

[0044] For example, the thermal characteristic temperature of the colorant is 50°C, 80°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or within any two of the above values. As an optional embodiment, the thermal characteristic temperature of the colorant is 50°C-550°C.

[0045] Furthermore, brazing includes at least a drying process and a brazing welding process. The temperature of the drying process is usually 200℃-300℃. When the thermal characteristic temperature of the colorant is less than or equal to 300℃, it will be vaporized, sublimated or decomposed in the drying process. Since the drying process has an independent gas collection and exhaust system, the colorant can be discharged after decomposition, sublimation or vaporization, without affecting the brazing welding process.

[0046] Furthermore, the temperature of the brazing process is usually 580℃-620℃. When the colorant vaporizes, sublimates or decomposes at this temperature, its products cannot destroy the brazing atmosphere and do not affect the brazing effect. Optionally, the oxygen content in the atmosphere of the brazing process is ≤100ppm.

[0047] As an optional implementation, the thickness of the coloring layer is 0.3 μm-50 μm. By controlling the thickness of the coloring layer within this range, the present invention not only distinguishes the flux-coated solder from the metal substrate to be soldered, but also ensures that the flux-coated solder has good induction heating efficiency and reduces the risk of the coloring layer cracking and peeling off. If the thickness of the coloring layer is less than 0.3 μm, the contrast between the surface color of the flux-coated solder and the color of the metal substrate to be soldered is insufficient, affecting the success rate of human eye or CCD recognition; if the thickness of the coloring layer is greater than 50 μm, it will not only affect the induction heating efficiency during soldering, but also increase the risk of the coloring layer cracking and peeling off.

[0048] For example, the thickness of the coloring layer is 0.3μm, 0.8μm, 1μm, 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, or within any two of the above values.

[0049] As an optional implementation, the colorant includes one or more of blue pigments or dyes, red pigments or dyes, and yellow pigments or dyes, as well as intermediates for synthesizing the pigments or dyes. By selecting pigments, dyes, or intermediates of the aforementioned colors, this invention can better distinguish the flux-cored solder from the metal substrate to be soldered, further reducing the probability of missed detections.

[0050] In this invention, the blue family refers to blue and its similar hues, such as blue, bluish-purple, and bluish-green; the red family refers to red and its similar hues, such as red, orange-red, and magenta; and the yellow family refers to yellow and its similar hues, such as yellow, orange-yellow, and yellow-green. These colors can be distinguished from the heat sink body.

[0051] As an optional implementation, the colorant includes one or more of ferrocene, solvent red, solvent yellow, phthalocyanine blue, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and perylene pigments. The colorant selected by this invention, based on the aforementioned specific substances, can better distinguish the flux-coated brazing filler metal from the metal substrate to be brazed. After vaporization, sublimation, or decomposition, the colorant leaves no residue or a very small amount of residue, and its impact on the strength or airtightness of the brazed joint is negligible, i.e., it does not affect the brazing effect.

[0052] Specifically, ferrocene provides an orange-yellow color and begins to sublimate and escape significantly above 100°C. Solvent reds include Solvent Red 27, etc. Taking Solvent Red 27 as an example, its melting point is approximately 120°C. When the temperature rises to the melting point of Solvent Red 27, it begins to decompose and vaporizes in the range of 120°C-300°C. Solvent yellows include Solvent Yellow 43, etc. Taking Solvent Yellow 43 as an example, it provides a fluorescent yellow color and its melting point is approximately 126°C. It decomposes in the range of 150-300°C. Phthalocyanine blue decomposes or sublimates between 550-600°C. 1,4,5,8-Naphthalenetetracarboxylic dianhydride (NTCDA) provides an orange-yellow color and begins to sublimate above 246°C. It can fully sublimate and escape completely at 450-550°C. Perylene pigments decompose or sublimate between 550-600°C. The pigments, dyes or their intermediates mentioned above escape or decompose into gas during the drying or brazing process, which does not affect the brazing.

[0053] As an optional implementation, the colorant content in the coloring layer is 0.05%-20% by mass. By controlling the amount of colorant within the above range, the solder coating of the present invention exhibits a more vibrant color and better differentiation from the metal substrate to be soldered.

[0054] For example, the mass content of the colorant in the coloring layer is 0.05%, 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, or within any two of the above values.

[0055] As an optional implementation, the coloring layer includes a skeleton material.

[0056] As an optional implementation, the thermal characteristic temperature of the skeleton material is less than or equal to 600°C. This invention controls the skeleton material to meet the above requirements, enabling it to sublimate, vaporize, or decompose at high temperatures with little or no residue, thus not affecting the brazing effect. If the thermal characteristic temperature of the skeleton material is higher than the above temperature, a continuous carbonized film will form during the brazing process, affecting the wetting and spreading of the brazing filler metal.

[0057] As an optional implementation, the mass content of the skeleton material in the coloring layer is 75.5%-99.5%.

[0058] As an optional implementation, the skeleton material includes one or more of naphthalene, benzoic acid, polyoxymethylene, pyromellitic dianhydride, and methyl methacrylate-butyl acrylate-methacrylic acid terpolymer. By adding the above substances to the coloring layer, this invention enables the flux-cored solder to possess suitable flexibility, reducing cracking or adhesion during transportation. Furthermore, when the flux-cored solder has a spring-like structure, the inclusion of a skeleton material in the coloring layer can further reduce cracking during winding. Specifically, naphthalene has a melting point of approximately 80°C and a boiling point of approximately 218°C. It exhibits significant volatility at room temperature, readily sublimates, and escapes as gas during the drying process, leaving no residue. Benzoic acid has a melting point of approximately 122°C and sublimates significantly at approximately 100°C. Polyoxymethylene has an initial thermal decomposition temperature of approximately 280°C and rapidly decomposes into formaldehyde gas above 350°C. Pyromellitic dianhydride sublimates and escapes at 320°C-500°C. The methyl methacrylate-butyl acrylate-methacrylic acid terpolymer depolymerizes into monomers at 350℃-450℃ and escapes. These substances escape or decompose into gases during the drying or brazing process, without affecting the brazing process.

[0059] As an optional implementation, the coloring layer includes an adhesive. By incorporating an adhesive into the coloring layer, this invention further improves the adhesion of the coloring layer to the surface of the inner core layer, reducing the likelihood of the coloring layer peeling off.

[0060] As an optional implementation, the decomposition temperature of the binder is less than or equal to 600°C. The present invention regulates the binder to meet the above conditions, enabling it to decompose at high temperatures with little or no residue, thus not affecting the brazing effect. Since binders are mostly organic substances, if the binder's decomposition temperature exceeds the above-mentioned temperature, a continuous carbonized film will form during the brazing process, affecting the wetting and spreading of the brazing filler metal.

[0061] As an optional implementation, the adhesive content in the coloring layer is 0-4.5% by mass.

[0062] As an optional implementation, the adhesive includes one or more of ethyl cellulose, polyethylene glycol, and polyvinyl alcohol. This not only improves the bonding strength between the colored layer and the inner core layer but also decomposes during the brazing process, reducing residue.

[0063] As an optional implementation, the flux-coated solder further includes a transition layer disposed between the inner core layer and the coloring layer, wherein the thermal characteristic temperature of the components in the transition layer is less than or equal to 550°C. The flux-coated solder of the present invention also includes a transition layer, which, on the one hand, has anti-corrosion function, preventing direct contact between the coloring layer and the inner core layer, further reducing the probability of corrosion and rusting of the inner core layer. On the other hand, the transition layer can further enhance the bonding strength between the coloring layer and the inner core layer, reducing the peeling off of the coloring layer.

[0064] As an optional implementation, the transition layer includes one or both of hydrogenated rosin methyl ester and rosin glycerol ester.

[0065] As an optional implementation, the thickness of the transition layer is less than or equal to 0.005 mm.

[0066] As an optional implementation, the structural schematic diagram of the flux-coated filler metal is shown in Figure 1, and the flux-coated filler metal has a ring-shaped structure.

[0067] As an optional implementation, the surface of the inner core layer is provided with a micron- and / or nano-scale rough structure. This invention controls the surface of the inner core layer to have the aforementioned structure, utilizing physical interlocking or anchoring effects to make the coloring layer adhere more firmly to the surface of the inner core layer, thereby improving the bonding strength between the coloring layer and the inner core layer, and further reducing the possibility of the coloring layer falling off during transportation and assembly.

[0068] It should be noted that the rough structure includes multiple pits and / or protrusions distributed on the surface of the inner core layer; each of the pits and / or protrusions is independently micron-sized and / or nano-sized; furthermore, the rough structure is formed by chemical etching or sandblasting.

[0069] As an optional implementation, the inner core layer is filamentous or rod-shaped, and the cross-sectional shape of the inner core layer includes circular, elliptical, polygonal, L-shaped, T-shaped, or cross-shaped. This invention adjusts the cross-sectional shape of the inner core layer, increasing the contact area between the inner core layer and the coloring layer, thereby enhancing the anchoring effect of the inner core layer on the coloring layer and further improving the bonding strength between the inner core layer and the coloring layer. Therefore, during transportation, installation, and automated placement, the shedding of the coloring layer is further reduced, meeting the vibration and friction resistance requirements of the automated placement process.

[0070] As an alternative implementation, another structural schematic diagram of the flux-cored solder is shown in Figure 2, wherein the inner core layer extends in a spiral shape and forms a ring structure.

[0071] As an optional implementation, the inner core layer has at least two spiral turns.

[0072] As an optional implementation, the maximum radial dimension of the inner core layer cross-section is 0.5mm-3mm; wherein, the maximum radial dimension refers to the straight-line distance between the two points furthest apart on the outer contour of the inner core layer cross-section.

[0073] As an optional implementation, the difference between the pitch of the inner core layer and the maximum radial dimension of the inner core layer cross-section is 0-1 mm. This invention regulates the difference between the pitch of the inner core layer and the maximum radial dimension of the inner core layer cross-section, ensuring an appropriate spacing between adjacent inner core layers. This improves the problem of color layer accumulation between adjacent inner core layers due to excessively small spacing and the issue of incomplete color layer application. Consequently, the color layer can adhere uniformly and continuously to the surface of the inner core layer, increasing the bonding strength between the inner core layer and the color layer, and reducing visual recognition defects caused by incomplete application, further lowering the probability of missed detection.

[0074] As an optional implementation, the brazing filler metal includes an aluminum-silicon based brazing filler metal. The inner core layer of the present invention includes this brazing filler metal, which melts during the brazing process and diffuses between the metal substrates to be brazed, forming a stable and reliable metallurgical connection.

[0075] Optionally, the grades of aluminum-silicon solders include AL4045 (the main component of this aluminum-silicon solder is AlSi, in which the mass content of silicon is 9%-11%, and the melting point is 577℃-599℃), AL4047 (the main component of this aluminum-silicon solder is AlSi, in which the mass content of silicon is 11%-13%, and the melting point is 577℃-582℃), and AL4343 (the main component of this aluminum-silicon solder is AlSi, in which the mass content of silicon is 6.8%-8.2%, and the melting point is 577℃-613℃), etc.

[0076] As an optional implementation, the inner core layer also includes flux.

[0077] As an optional implementation, the flux includes potassium fluoroaluminate, which has a melting point of 560℃-580℃. Potassium fluoroaluminate, as a flux, has a better melting point match with aluminum-silicon brazing filler metals, which is beneficial for improving brazing performance.

[0078] As an optional implementation, the flux content in the inner core layer is 3%-20% by mass.

[0079] As an optional implementation, the potassium fluoroaluminate comprises KAlF4 and / or K3AlF6.

[0080] Furthermore, the flux-coated solder is prepared using methods known in the art. As an example, the method for preparing the above-mentioned flux-coated solder includes: (1) Pre-treat the flux-coated solder matrix to form an inner core layer; wherein the pre-treatment includes alkaline washing and / or acid washing; or, the pre-treatment includes sandblasting; (2) Prepare a mixture containing colorant; The inner core layer obtained in step (1) is immersed in a mixture containing colorant; or the mixture containing colorant is sprayed onto the surface of the inner core layer; and dried to form a color layer.

[0081] As an optional implementation, before step (2), the method further includes: preparing a suspension, immersing the inner core layer in the suspension, and drying it to form a transition layer.

[0082] It should be noted that this invention does not impose specific requirements on the preparation method of the flux-cored filler metal, as long as the product that meets the requirements can be obtained.

[0083] As another optional implementation, the coloring layer further includes dibutyl phthalate, wherein the mass content of dibutyl phthalate in the coloring layer is 0.1%-1%.

[0084] As another alternative implementation, the coloring layer includes an inorganic binder; the inorganic binder includes sodium silicate, etc., which can act as a flux during the brazing process and transforms into a glassy state after brazing.

[0085] As an optional implementation, the transition layer includes a passivation film and / or an oxide film, wherein the passivation film is formed during the cleaning process, and the thickness of the oxide film is less than or equal to 0.005 mm; the present invention does not impose any limitations on the thickness, composition, etc. of the passivation film and the oxide film; for example, the composition of the passivation film includes products of the reaction between manganese, titanium or zirconium and the aluminum alloy substrate, and the composition of the oxide film includes aluminum oxide, etc.

[0086] Secondly, embodiments of the present invention provide the application of the above-mentioned flux-coated brazing filler metal in welding the battery radiator body and the water nozzle.

[0087] Optionally, when the colorant and the radiator body belong to the same color family, the color difference between the colorant and the radiator body is greater than or equal to 4.0.

[0088] Thirdly, the present invention provides a mobile device including a battery radiator, wherein the battery radiator body and the water nozzle are connected by brazing using the aforementioned flux-cored brazing filler metal.

[0089] As an alternative implementation, the mobile device is a car.

[0090] As another alternative implementation, the mobile device is a robot.

[0091] Example 1 This embodiment provides a flux-coated solder in the form of a circular solder ring, the structure of which is referenced. Figure 2From the inside out, it includes an inner core layer, a transition layer, and a coloring layer. The inner core layer consists of solder AL4045 and flux K3AlF6, with K3AlF6 comprising 10% by mass. The inner core layer has a circular cross-sectional shape, a wire diameter (maximum radial dimension) of 1.3 mm, extends in a spiral shape forming a ring structure, has 3 spiral turns, a pitch of 2.1 mm, and a difference of 0.8 mm between the pitch and the wire diameter. The surface of the inner core layer has micron- and nano-scale rough structures. The transition layer consists of hydrogenated rosin methyl ester with a thickness of 2 μm. The coloring layer consists of ferrocene and naphthalene as colorants, with ferrocene comprising 12% by mass and a thickness of 0.3 μm.

[0092] This embodiment also provides a method for preparing the above-mentioned flux-cored solder, which specifically includes the following steps: (1) Place the aluminum alloy welding ring in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e. micron-level and / or nano-level rough structures.

[0093] (2) Dissolve hydrogenated rosin methyl ester in anhydrous ethanol to prepare a 2% dilute solution; the aluminum alloy obtained in step (1) is completely immersed in the dilute solution and then pulled out at a uniform speed of 10 mm / s. Dry it in clean air at room temperature for 15 minutes to form a very thin viscous film, i.e., a transition layer.

[0094] (3) Dissolve 88g of refined naphthalene and 12g of ferrocene in 500ml of anhydrous ethanol and stir in a water bath at 45℃ to obtain a mixture. Keep it at 35℃ for later use. Immerse the welding ring obtained in step (2) into the mixture and slowly and uniformly pull it out at a speed of 5mm / s. Drain excess liquid in the air to form a coloring layer.

[0095] Example 2 This embodiment provides a flux-cored solder; from the inside out, it includes an inner core layer and a coloring layer; the parameters of the inner core layer are the same as in Embodiment 1. The coloring layer includes the colorant solvent Red 27 and benzoic acid, the mass content of the colorant in the coloring layer is 1%, and the thickness of the coloring layer is 12 μm.

[0096] The preparation method of the flux coating in this embodiment includes the following steps: (1) Place the aluminum alloy welding ring in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e. micron-level and / or nano-level rough structures.

[0097] (2) Dissolve 99g of benzoic acid and 1g of Solvent Red 27 in 650ml of anhydrous ethanol and stir in a water bath at 55℃ to obtain a mixture. Immerse the welding ring obtained in step (1) into the mixture, slowly and uniformly pull it out at a speed of 6mm / s, dry it, and form a coloring layer.

[0098] Example 3 This embodiment provides a flux-coated solder ring in the form of a circular solder ring. From the inside out, it includes an inner core layer, a transition layer, and a coloring layer. The parameters of the inner core layer are the same as in Embodiment 1. The transition layer includes rosin glycerol ester and has a thickness of 5 μm. The coloring layer includes the colorant Solvent Yellow 43 and polyoxymethylene, with a colorant content of 0.5% by mass and a thickness of 0.3 μm.

[0099] The preparation method of the flux coating in this embodiment includes the following steps: (1) Place the aluminum alloy welding ring in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e. micron-level and / or nano-level rough structures.

[0100] (2) Dissolve rosin glycerol ester in anhydrous ethanol to prepare a 3% solution; the aluminum alloy obtained in step (1) is completely immersed in the solution, and then pulled out at a uniform speed of 12 mm / s. Dry in clean air at room temperature for 12 minutes to form a transition layer.

[0101] (3) Dissolve 99.5g of polyoxymethylene and 0.5g of solvent yellow 43 in hexafluoroisopropanol to obtain a mixture. The total concentration of polyoxymethylene and solvent yellow 43 in the mixture is 6wt%. Immerse the welding ring obtained in step (2) into the mixture and slowly and uniformly pull it out at a speed of 5mm / s. After drying, a colored layer is formed.

[0102] Example 4 This embodiment provides a flux-coated solder ring, which is circular and comprises, from the inside out, an inner core layer, a transition layer, and a coloring layer; the parameters of the inner core layer are the same as in Embodiment 1. The transition layer comprises hydrogenated rosin methyl ester and has a thickness of 2 μm. The coloring layer comprises phthalocyanine blue and polyoxymethylene, with the phthalocyanine blue content in the coloring layer being 0.05% by mass and the thickness of the coloring layer being 15 μm.

[0103] The preparation method of the flux coating in this embodiment includes the following steps: (1) Place the aluminum alloy welding ring in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e. micron-level and / or nano-level rough structures.

[0104] (2) Dissolve hydrogenated rosin methyl ester in anhydrous ethanol to prepare a 2% dilute solution; the aluminum alloy obtained in step (1) is completely immersed in the dilute solution and then pulled out at a uniform speed of 10 mm / s. Dry in clean air at room temperature for 15 minutes to form a transition layer.

[0105] (3) Take 0.5g of phthalocyanine blue and 99.5g of polyoxymethylene, mix them in a high-speed mixer for 10min, and melt-extrude and granulate them at 180-200℃ using a small twin-screw extruder to obtain 0.5% blue POM masterbatch. Dissolve 10g of blue POM masterbatch and 90g of polyoxymethylene resin in hexafluoroisopropanol to prepare a dilute solution with a solid content of 6%, stir to dissolve, and let stand to defoam. Completely immerse the aluminum alloy welding ring obtained in step (2) in the above dilute solution, pull it out at a uniform speed of 5mm / s, and dry it to form a colored layer.

[0106] Example 5 This embodiment provides a flux-coated solder ring, which is circular and includes an inner core layer and a coloring layer from the inside out; the parameters of the inner core layer are the same as in Embodiment 1. The NTCDA content in the coloring layer is 20%, and the thickness of the coloring layer is 20 μm.

[0107] The preparation method of the flux coating in this embodiment includes the following steps: (1) Place the aluminum alloy welding ring in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e. micron-level and / or nano-level rough structures.

[0108] (2) NTCDA and pyromellitic dianhydride (PMDA) were mixed at a mass ratio of 1:4 and wet-milled using zirconia balls with a diameter of 5 mm. Ethanol was used as the milling medium, and the milling time was 4 h. After drying, mixed micro powder with an average particle size of <5 μm was obtained. The micro powder was then dispersed in a solution containing 0.5 wt% ethyl cellulose to prepare a suspension with an NTCDA concentration of 10%. The surfactant Triton X-100 was added to the suspension to improve dispersibility. The content of surfactant Triton X-100 in the suspension was 0.05%. The suspension was then sprayed onto the surface of the weld ring obtained in step (1) by spraying. The spraying parameters included: a distance of 15-20 cm, a nozzle diameter of 0.5 mm, an air pressure of 0.15 MPa, and two spraying times. The mixture was then dried at 120 °C for 15 min to form a colored layer.

[0109] Example 6 This embodiment provides a flux-coated solder, which is in the form of a circular solder ring, and its structure is as follows: Figure 1 As shown, from the inside out, it includes an inner core layer and a coloring layer. The inner core layer consists of solder AL4045 and flux K3AlF6, with the K3AlF6 flux accounting for 16% of the total mass. The inner core layer has a square cross-sectional shape, with a maximum radial dimension (i.e., diagonal) of 2.3 mm. The surface of the inner core layer has micron- and nano-scale rough structures. The coloring layer consists of a perylene red pigment and an MMA-BA-MAA terpolymer, with the perylene red pigment accounting for 2% of the total mass. The thickness of the coloring layer is 10 μm ± 2 μm.

[0110] The preparation method of the flux coating in this embodiment includes the following steps: (1) Place the aluminum alloy welding ring (with an inner diameter of about 30 mm) in a 5% NaOH solution at 50°C and sonicate for 30 seconds; then immerse it in a 30% HNO3 solution and leave it for 60 seconds to make its surface bright; clean it with deionized water and then dry it at 100°C to form pits on the surface of the aluminum alloy welding ring. The pits include micron-level pits and nano-level pits, i.e., micron-level and / or nano-level rough structures.

[0111] (2) Butyl acetate and propylene glycol methyl ether acetate were mixed in a ratio of 7:3 to form a mixed solvent; MMA-BA-MAA terpolymer was added to the mixed solvent to form a mixed solution with a solid content of 15%; Perylene red pigment (Pigment Red 149) was added to the mixed solution, dispersed at 3000 rpm for 30 min, and then ultrasonically dispersed for 5 min to obtain a solution containing colorant, the content of colorant in the solution being 0.3%.

[0112] The welding ring obtained in step (1) is immersed in a solution containing colorant, and slowly and uniformly pulled out at a speed of 3 mm / s. It is then suspended in the air to drain excess liquid, and successively dried at 80°C for 30 min and 150°C for 30 min to form a coloring layer.

[0113] Example 7 This embodiment provides a flux-cored solder, which is basically the same as that in Embodiment 1, except that the thickness of the coloring layer is different. In this embodiment, the thickness of the coloring layer is 0.1 μm.

[0114] Example 8 This embodiment provides a flux-coated solder, which is basically the same as that in Embodiment 1, except that the thickness of the coloring layer is different. In this embodiment, the thickness of the coloring layer is 60 μm.

[0115] Test case This test case provides performance tests of the flux-coated solders provided in each embodiment and comparative example, as detailed below: Test method for false negative rate: The radiator body and water tap are both silver. The radiator body and water tap are assembled and pre-fixed. The flux-coated solder provided in Examples 1-8 is placed outside the welding area of ​​the body and water tap, respectively. A CCD vision inspection system is used to automatically identify whether the flux-coated solder is accurately placed outside the designated welding area. During testing, 100 samples are continuously sampled from each example and inspected one by one. The judgment criteria are: if the system identifies that the flux-coated solder has been placed, it is judged as qualified; if the system identifies that the flux-coated solder has not been placed, it is judged as unqualified, i.e., a false positive. The test results of each example are statistically analyzed, and the false positive rate is calculated as: False positive rate = (Number of false positives / 100) × 100%. The number of false positives refers to the total number of samples judged as unqualified by the system, i.e., the flux-coated solder was actually placed but was mistakenly judged as not placed. A false positive rate ≤ 3% is used as the judgment criterion; meeting this result indicates that the detection error is within an acceptable range.

[0116] Test method for color layer peeling: Take a clean plastic bag and accurately weigh its mass, recorded as m0, accurate to 0.01g; take approximately 100g of the flux-cored filler material provided in each embodiment, put it into the plastic bag and seal it, accurately weigh the total mass, recorded as m1, accurate to 0.01g; drop the sealed plastic bag freely from a height of 1.5m to simulate the mechanical impact during actual transportation and use; after the drop, open the plastic bag, remove the debris generated by the impact, put the remaining intact flux-cored filler material back into the plastic bag, and accurately weigh its total mass again, recorded as m2, accurate to 0.01g. The color layer peeling rate is calculated to characterize the bonding strength between the color layer and the inner core layer. Peeling rate = (m1-m2) / (m1-m0)×100%, peeling rate ≤5%, the lower the peeling rate, the better the bonding strength between the color layer and the inner core layer.

[0117] Table 1 Test Results

[0118] Based on the above tests, when the flux-coated brazing filler metal provided in Examples 1-8 is applied to the brazing of radiators, not only does the flux-coated brazing filler metal form a good color difference with the radiator body, reducing the false detection rate of the CCD vision system, but also the bonding strength between the color layer and the inner core layer is good, reducing the possibility of the color layer falling off during actual transportation and use.

[0119] Furthermore, compared with Examples 7-8, Examples 1-6 adjusted the thickness of the coloring layer to 0.3μm-50μm, which further improved the color contrast between the surface of the solder coating and the heat sink body, and further improved the CCD recognition success rate. At the same time, the thickness of the coloring layer being 0.3μm-50μm can further reduce the peeling rate and further reduce the risk of cracking and falling off of the coloring layer.

[0120] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A type of flux-cored filler metal, characterized in that, It includes an inner core layer and a coloring layer covering the surface of the inner core layer; the inner core layer includes solder; the coloring layer includes a colorant; the thermal characteristic temperature of the colorant is less than or equal to 600°C, and the thermal characteristic temperature includes one or more of the following: vaporization temperature, sublimation temperature, or decomposition temperature.

2. The flux-cored filler metal according to claim 1, characterized in that, The thermal characteristic temperature of the colorant is 50℃-550℃.

3. The flux-cored filler metal according to claim 1 or 2, characterized in that, The thickness of the coloring layer is 0.3μm-50μm.

4. The flux-cored filler metal according to any one of claims 1-3, characterized in that, The colorant includes one or more of blue pigments or dyes, red pigments or dyes, and yellow pigments or dyes, as well as intermediates for synthesizing the pigments or dyes; And / or, the mass content of the colorant in the coloring layer is 0.05%-20%.

5. The flux-cored filler metal according to claim 4, characterized in that, The colorant includes one or more of ferrocene, solvent red, solvent yellow, phthalocyanine blue, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and perylene pigments.

6. The flux-cored filler metal according to any one of claims 1-5, characterized in that, The coloring layer includes a skeleton material; The thermal characteristic temperature of the skeleton material is less than or equal to 600°C; and / or, the mass content of the skeleton material in the coloring layer is 75.5%-99.5%; and / or, the skeleton material includes one or more of naphthalene, benzoic acid, polyoxymethylene, pyromellitic dianhydride, and methyl methacrylate-butyl acrylate-methacrylic acid terpolymer.

7. The flux-cored filler metal according to any one of claims 1-6, characterized in that, The coloring layer includes an adhesive; The adhesive has a decomposition temperature of less than or equal to 600°C; and / or, the mass content of the adhesive in the coloring layer is 0-4.5%; and / or, the adhesive includes one or more of ethyl cellulose, polyethylene glycol, and polyvinyl alcohol.

8. The flux-cored filler metal according to any one of claims 1-7, characterized in that, The flux-cored solder also includes a transition layer, which is disposed between the inner core layer and the coloring layer; The thermal characteristic temperature of the components in the transition layer is less than or equal to 550°C; and / or, the transition layer includes one or both of hydrogenated rosin methyl ester and rosin glycerol ester; and / or, the thickness of the transition layer is less than or equal to 0.005 mm.

9. The flux-cored filler metal according to any one of claims 1-8, characterized in that, The flux coating has a ring-shaped structure.

10. The flux-cored filler metal according to any one of claims 1-9, characterized in that, The surface of the inner core layer is provided with a micron- and / or nano-scale rough structure; And / or, the inner core layer is filamentous or rod-shaped, and the cross-sectional shape of the inner core layer includes circular, elliptical, polygonal, L-shaped, T-shaped or cross-shaped; And / or, the inner core layer extends in a spiral shape and forms a ring structure.

11. The flux-cored filler metal according to claim 10, characterized in that, The maximum radial dimension of the inner core layer cross-section is 0.5mm-3mm; And / or, the number of spiral turns of the inner core layer is greater than or equal to 2 turns; And / or, the difference between the pitch of the inner core layer and the maximum radial dimension of the inner core layer cross section is 0-1 mm.

12. The flux-cored filler metal according to any one of claims 1-11, characterized in that, The brazing filler metal includes aluminum-silicon based brazing filler metal; And / or, the inner core layer further includes a flux comprising potassium fluoroaluminate.

13. The flux-cored filler metal according to claim 12, characterized in that, The flux content in the inner core layer is 3%-20% by mass. And / or, the potassium fluoroaluminate comprises KAlF4 and / or K3AlF6.

14. The application of the flux-coated solder according to any one of claims 1-13 in welding the battery radiator body and the water tap.

15. A mobile device, characterized in that, It includes a battery radiator, wherein the battery radiator body and the water nozzle are connected by brazing using the flux-cored brazing filler metal according to any one of claims 1-13.

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