514 results about "Solder material" patented technology

The invention discloses an intelligent welding forming method and system for a green building steel heating radiator, and the method comprises the following steps: carrying out the surface defect recognition of a steel heating radiator base material based on an AI visual inspection system, recognizing a qualified base material, and automatically matching the type of a welding material from a material database according to the material and thickness parameters of the qualified base material. Welding parameters are intelligently matched through AI visual inspection and a neural network model, a laser and friction stir hybrid welding process is combined, traditional manual operation is replaced, the welding efficiency and precision are improved, and the problems of uneven welding seams and the like are solved; welding data are analyzed in real time through a multi-mode AI model, parameters are dynamically adjusted, intelligent defect recognition and repair welding are achieved in cooperation with 3D visual inspection, and the quality stability is improved through whole-process monitoring; smoke dust is treated through an environment-friendly process, acid pickling is replaced with mechanical rust removal, efficient recycling of materials is achieved through waste recycling, a green manufacturing system is constructed, and the sustainable development requirement of green buildings is met.

A connector configured to connect densely disposed cables to a board. The connector may include two or more rows of terminals held by a housing such that the two or more rows of terminals are at a same height with respect to a board that the connector would be mounted to. Such a configuration enables the connector to fit into a space limited by, for example, another component mounted to the board. The terminals may include first contact portions configured to be mounted onto a surface of the board when pressure is applied to the terminals so as to avoid the use of materials that may cause undesired shorting such as soldering materials. The terminals may include second contact portions configured to receive the cables. The second contact portions of ground terminals of a same row may be connected by a strip configured to contact shields of cables attached to the row.

The invention discloses an austenitic stainless steel welding wire for a liquid hydrogen storage tank and a preparation method and application of the austenitic stainless steel welding wire, and belongs to the technical field of welding materials and preparation of the welding materials. The welding wire solves the problem that the low-temperature performance of a welding seam is poor when the current welding wire for the liquid hydrogen storage tank is used for welding. The welding wire comprises the following chemical components in percentage by mass: less than or equal to 0.02% of C, 0.4-1.5% of Si, 5.0-7.5% of Mn, less than or equal to 0.020% of S, less than or equal to 0.030% of P, 16.0-22.0% of Cr, 15.0-18.0% of Ni, 2.0-5.0% of Mo, 0.05-0.2% of N, less than or equal to 0.01% of O and the balance of Fe and inevitable impurities. According to the welding wire, deposited metal is low in low-temperature embrittlement tendency, high in low-temperature strength and excellent in low-temperature impact and fracture toughness. The welding wire is used for welding the austenitic stainless steel liquid hydrogen storage tank and is wide in application range, and the mechanical property of deposited metal is good.

The invention provides a manufacturing method of an Al-Cu series aluminum alloy bright welding wire. The manufacturing method comprises the steps of burdening, smelting, casting, uniform heating, peeling, hot rolling, primary annealing, primary cold rolling, secondary annealing, secondary cold rolling, third annealing, intermediate drawing, fourth annealing, scraping, finish drawing, cleaning, drying and layer winding. By optimizing the composition and the processing technology of the welding wire, the prepared welding wire is high in strength and good in processing performance, welding and welding joints do not exist in the production process of the welding wire, and the consistency of the structure and overall deformation of the welding wire is ensured. A finished product can be manufactured into a disc-loaded welding wire or a barrel-loaded welding wire with a large weight, and welding materials with higher quality and higher efficiency are provided for automatic welding.

The invention belongs to the technical field of welding materials, and particularly relates to efficient scaling powder and a preparation method thereof. The efficient scaling powder is composed of, by mass, 4%-10% of organic acid activating agents, 1%-2% of thiourea reinforcing agents, 0.15%-0.3% of wetting agents, 0.2%-0.6% of antioxidants, 0.3%-0.5% of surfactants, 0.05%-0.2% of defoaming agents, 3%-5% of film forming agents, 10%-15% of solvents and the balance water. The prepared scaling powder has good spreadability, stability, corrosion resistance and the like.

The invention belongs to the technical field of electronic packaging and welding materials, and relates to lead-free solder powder for reflow soldering and a preparation method of the lead-free solder powder. The lead-free solder powder is based on a Sn-Ag-Cu alloy system, and melt purification, beta-Sn grain refinement and interface IMC stabilization are achieved by compositely adding trace Ce and Ni elements. The Sn-Cu-Ce alloy comprises the following components in percentage by mass: 2.9%-3.1% of Ag, 0.45%-0.55% of Cu, 0.01%-0.10% of Ce, 0.01%-0.05% of Ni and the balance of Sn and impurities. During preparation, a Ce-Ni intermediate alloy is adopted to introduce microalloy elements, and the spherical solder powder is obtained through vacuum melting, inert gas atomization and surface treatment. The obtained solder powder is low in oxygen content, good in wettability, slow in interface IMC growth after backflow, high in welding spot strength and excellent in thermal cycle reliability, and is suitable for the field of high-reliability electronic packaging.

The invention relates to the technical field of welding materials, in particular to a titanium carbide reinforced iron-based wear-resistant corrosion-resistant flux-cored wire for surfacing on the surface of a conveying roller. According to the specific technical scheme, the flux core comprises, by mass, 10%-20% of graphite, 25%-35% of ferrotitanium, 2%-6% of ferrovanadium, 3%-8% of electrolytic manganese metal, 2%-10% of ferromolybdenum, 5%-15% of ferrosilicon, 2% of aluminum-magnesium alloy and the balance Fe powder. According to the flux-cored wire prepared through the flux core, the surfacing alloy obtained through electric arc surfacing is good in surfacing manufacturability, attractive in weld joint forming and small in surface air hole number, and the flux-cored wire has high hardness, high-temperature abrasion resistance and corrosion resistance.

The invention discloses an intelligent distribution system for welding material management and an operation method thereof, and relates to the technical field of welding material pretreatment equipment, and the intelligent distribution system structurally comprises a drying box, a feeding device and a material taking distribution device. A plurality of layers of sliding frames are arranged in the drying box, and material frames are arranged on the sliding frames and can slide out from one side. The feeding device comprises a transferring mechanism and a feeding table, and the transferring mechanism is used for transferring the material frame between the drying box and the feeding table. The material taking and distributing device comprises a mechanical arm and a grabbing mechanism and is used for grabbing and transferring the welding materials in the drying box. The operation method comprises the steps that 1, empty material frames in the drying box are taken out through the transferring mechanism and placed on the workpiece feeding table; 2, a welding material is supplemented into the material frame; 3, taking down the filled material frame through a transferring mechanism, and feeding the material frame into a drying box for drying; and 4, the welding materials are grabbed from the drying box through a material taking and distributing device and put in. By applying the scheme, the technical problems that in the prior art, the working intensity of workers is large, the environment is poor, and whole-process automation is difficult to achieve can be solved.

The invention provides a wind generating set tower tube weld joint optimization method based on hydrodynamics, and relates to the technical field of hydrodynamics, the wind generating set tower tube weld joint optimization method comprises the following steps: obtaining an image of a junction of to-be-welded positions of a wind generating set tower tube, and extracting a junction center line in the image of the junction; according to the extension direction of the boundary center line, a constraint condition for keeping energy continuity of the molten metal at the inflection point of the extension direction is constructed, and the heat flux density formed by the molten metal at the inflection point of the center line is calculated; according to the heat flow density needing to be met in the step S2, the welding heat needing to be absorbed by the to-be-welded material when the welding seam is formed at each inflection point of the tower barrel welding seam is calculated; and a welding parameter-inflection point heat mapping model is constructed, optimal welding parameters are output through a global optimization algorithm, the fatigue strength of a welding seam under the wind load effect is improved, and the service life of a tower drum of the wind generating set is prolonged.

The application belongs to the technical field of welding materials, and discloses a preformed soldering sheet and a preparation method thereof, the preparation method comprising: a flux preparation method, wherein benocyclobutene resin, a thixotropic agent, an active agent, a surfactant, an antioxidant, a corrosion inhibitor and a solvent are weighed, mixed and heated and stirred to mix, and then cooled to obtain the required flux; a processing method of a preformed soldering sheet body soldering strip, wherein lead-free filler metal is melted at high temperature to form a soldering strip; and a preformed soldering sheet preparation method, wherein the soldering strip is uniformly coated with the flux by a coating machine, and the flux is cured and attached to the soldering strip after baking; the preformed soldering sheet is obtained by the above preparation method. The application realizes improved welding quality of the soldering sheet coated with the flux film and solder metal oxidation resistance, and the preformed soldering sheet has high stability, good wettability and good weldability, and can meet the requirements of the market for the use of the preformed soldering sheet with low cavities.

The invention discloses a heat-treatment-free control method for inhibiting hydrogen-induced cracks in ultrahigh-strength steel welding, which belongs to the technical field of welding, and enables weld metal to obtain a low-phase-transition-temperature characteristic and a double-phase structure containing retained austenite under a specific dilution rate window by cooperatively regulating and controlling components of a welding material and welding process parameters. Therefore, preheating-free and post-heat-treatment-free efficient welding of the ultrahigh-strength steel is achieved. According to the method, the volume expansion effect generated by low-temperature martensite phase transformation of weld metal is utilized to actively counteract restrained tensile stress formed by welding cooling shrinkage; on the other hand, the effect of the retained austenite serving as an efficient'hydrogen trap 'is fully played, migration and enrichment of hydrogen to crack sensitive areas such as a heat affected zone or a fusion line are effectively blocked, and finally effective inhibition of hydrogen-induced cracks in ultrahigh-strength steel welding is achieved; the obtained welding joint is free of hydrogen-induced cracks and has the mechanical property level well matched with base metal.

The invention discloses a high-temperature liquid metal circulating pump welding tool, which belongs to the technical field of welding and comprises a fixing frame, a first annular groove is formed in one end of the fixing frame, a first annular block is slidably mounted in the first annular groove, and an electric push rod is fixedly mounted on the first annular block. A welding head is fixedly installed at the end, close to the center part of the first annular block, of the electric push rod, an adjusting assembly is further arranged at the end, close to the welding head, of the first annular block, and a detection assembly used for judging the thickness of a welding material is installed in the shrinkage groove. Therefore, the welding duration is reasonably controlled, insufficient firmness of a welding point caused by too long or insufficient welding time is avoided, and the danger of the high-temperature liquid circulating pump in the using process of a liquid metal coolant with the physical characteristics of high temperature, high flow speed, high density, strong corrosivity and the like is reduced.

Pattern transfer source substrates and printing methods are described, providing multi-layer paste stack elements like conductor lines or bumps, so that each stack element is printed on a receiving substrate in a single illumination step. The paste is filled layer-by-layer, possibly having different materials in different layers, with layer thickness controlled by parameters of the filling elements, e.g., in case of blades, the pressure, angle, velocity and flexibility (material) of the blade. Specifically, a bottom layer of the stack may be configured to interface the receiving substrate while one or more top layers may be configured to optimize the quality of the printed features. For example, bottom layers may be configured to bind to the substrate, to modify the substrate and / or provide a barrier from top layer(s) which may not be compatible with the substrate. In case of bumps, different layers may include adhesive and soldering materials.

The invention provides a method for inhibiting abnormal grain growth of a 7xxx series aluminum alloy friction stir welding joint, which comprises the following steps: step 1), performing wire filling welding treatment on a to-be-welded aluminum alloy part to obtain a welding part; wherein the welding flux is an aluminum alloy containing a scandium element; (2) the welding part is subjected to friction stir welding treatment, and a friction stir welding head is obtained; and (3) post-treatment is conducted on the friction stir welding head. Welding materials used are characterized in that a certain amount of scandium is added, then differential friction stir welding treatment is carried out, the differential friction stir welding treatment is carried out by independently regulating and controlling the rotating speed of a shaft shoulder and the rotating speed of a stirring needle, and on the premise that the rotating speed of the stirring needle is greatly increased to improve material flowing, the welding efficiency is greatly improved. The low shaft shoulder rotating speed is applied to eliminate overheating, defects are avoided, pinning particles are dispersed, and the effect of completely inhibiting growth of abnormal crystal grains is achieved.

The invention relates to the technical field of ferrous metallurgy, in particular to a high-strength extremely-low-temperature welding material wire rod and a manufacturing method and application thereof.The manufacturing method comprises the steps that molten steel smelting is conducted according to chemical components and percentages of the high-strength extremely-low-temperature welding material wire rod, a square billet is manufactured in a forging and rolling mode after die casting, the square billet is heated and subjected to heat preservation for 4.5-6 h, and then the square billet is rolled into a first-diameter wire rod; cooling after rolling, uncoiling a wire rod, reducing the diameter from a first diameter to a second diameter through three times of drawing, annealing, reducing the diameter from the second diameter to a third diameter through three times of drawing after annealing, and finally performing finish drawing to a fourth diameter. The high-manganese steel liquid hydrogen storage tank welding material can be used for producing the high-manganese steel liquid hydrogen storage tank welding material, is matched with high-manganese steel welding and is good in forming, the content of Mn in formed weld metal is 24-28 wt%, the situation that due to large-range diffusion of the manganese element, the structure and performance near a fusion line are greatly different is avoided, and the extremely-low-temperature service mechanical performance of the weld metal is guaranteed.

The invention relates to a preheating-free 690MPa-grade high-strength and high-toughness submerged-arc welding wire, a preparation method thereof and a submerged-arc welding process, and belongs to the technical field of welding materials. The welding wire comprises the following chemical components in percentage by mass: 0.07 to 0.10 percent of C; 0.25% to 0.50% of Si; mn: 1.20% to 1.50%; 0.20% to 0.50% of Cr; 2.10% to 3.30% of Ni; 0.45% to 0.65% of Mo; 0.03% to 0.05% of Ti; s < = 0.005%; p < = 0.005%; and the balance of Fe. By optimizing the content of C and the proportion of Ni and introducing Ti microalloying means and combining low-S and low-P control and hydrogen control processes, preheating-free welding of the 690 MPa-grade low-temperature high-strength steel under the normal-temperature or low-temperature condition is achieved, traditional preheating operation is avoided, energy consumption is reduced, and the process is simplified.

The invention discloses a low-corrosion halogen-free soldering flux for aluminum-based part brazing and a preparation method of the low-corrosion halogen-free soldering flux, and belongs to the technical field of halogen-free welding materials.The low-corrosion halogen-free soldering flux comprises, by mass, 4-6 parts of oxalic acid, 1-2 parts of triethanolamine, 0.8-1.5 parts of Tween-80, 4-6 parts of polyvinylpyrrolidone, 0.3-1 part of compound nano cerium oxide, 0.5-1.5 parts of chitosan oligomer and the balance deionized water. And the welding spot oxidation resistance and the interface self-repairing capability are further improved. Through the synergistic effect of four mechanisms of complexing, oxidation prevention, wetting and film forming, the flux achieves efficient film removal, excellent wetting, no corrosion residue and stable film forming protection, is high in shear strength, low in welding spot porosity and clean in surface after welding, and is suitable for electronic packaging, heat exchanger manufacturing and high-reliability aluminum welding occasions.

The invention belongs to the field of metal material processing, and particularly relates to a multi-element nickel alloy composite welding wire with low thermal crack sensitivity and a preparation method of the multi-element nickel alloy composite welding wire with the low thermal crack sensitivity. The welding wire comprises the following powder raw materials in parts by weight: 0.01 to 0.05 percent of C, 0.10 to 0.20 percent of Si, 28.5 to 30.5 percent of Cr, 7.0 to 11.0 percent of Fe, less than or equal to 1.0 percent of Mn, 1.0 to 2.0 percent of Co, 4.0 to 5.0 percent of Mo, 0.001 to 0.005 percent of B, 0.1 to 0.2 percent of Al + Ti, 0.005 to 0.020 percent of Zr, 1.0 to 2.0 percent of Nb, 0.1 to 0.4 percent of Ta, 0.5 to 1.0 percent of Sn, 0.20 to 0.30 percent of RE, less than 0.005 percent of S, less than 0.005 percent of P and the balance of Ni. And the plating layer comprises a titanium carbide layer and a nickel layer from inside to outside. A welding wire raw material is subjected to smelting, high and low temperature refining, annealing, forging and rolling, multi-pass drawing-annealing, solid solution-aging treatment and acid pickling, coating and plating to obtain the nickel-based alloy welding wire, and the problems that in the prior art, when a nickel-based alloy welding material is used for welding, cracks are prone to being generated, and the strength is low due to hot corrosion can be effectively solved.

The invention relates to an intelligent evaluation and optimization method and system for the welding spot quality of a lithium battery protection board in the technical field of intelligent manufacturing, and the method comprises the steps: constructing a welding spot stereoscopic model through employing a geometric modeling algorithm based on a three-dimensional point cloud data set, and determining a welding spot tin material climbing angle and a contact interface shape feature; on the basis of the bridging defect occurrence probability distribution, a mode recognition algorithm is adopted to distinguish normal welding spots from various defect categories, and a defect classification result is obtained; generating a welding spot quality evaluation report in combination with the defect classification result and the three-dimensional point cloud data set, and determining an overall welding reliability index; if the overall welding reliability index is lower than a preset threshold value range, an alarm mechanism is triggered, and position coordinate information of related welding spots on a production line is obtained; and based on the welding spot position coordinate information, processing subsequent scanning data by adopting a data optimization algorithm, and judging whether the optimized data meet a preset precision standard or not.

A wave soldering station includes a solder pot having a reservoir of solder material, a flow duct positioned in the reservoir of the solder pot, and a wave soldering nozzle assembly coupled to the flow duct. The wave soldering nozzle assembly has a solder distribution baffle configured to create a solder wave, a throttle gate coupled to the flow duct and configured to move from an open position to enable complete flow of solder through the solder distribution baffle and a closed position to inhibit a portion of flow of solder through the solder distribution baffle, and an exit wing coupled to the flow duct and configured to move from a lowered position to enable increased solder flow and a raised position to decrease solder flow. A controller is configured to control the movement of the throttle gate and the exit wing to control the flow of solder.

The invention discloses an ultralow-temperature high-toughness non-magnetic steel flux-cored wire for a controllable nuclear fusion device and a preparation method of the ultralow-temperature high-toughness non-magnetic steel flux-cored wire. A special stainless steel strip is adopted to wrap a metal powder type flux core, and the flux core accounts for 29.6%-30.4% of the total mass of the flux-cored wire; the flux core comprises the following components: 14%-18% of electrolytic manganese, 21%-23% of chromium metal, 0.3%-1.0% of ferrotitanium, 4.4%-5.0% of nitrided ferrochromium, 27.5%-28.5% of nickel powder, 0.5%-1.0% of 52 # ferrosilicon, 8%-9% of molybdenum powder, 0.1%-0.3% of lithium fluoride and the balance of atomized iron powder. The problems that an existing non-magnetic steel welding material is insufficient in toughness and high in magnetic conductivity at the ultralow temperature of-269 DEG C are solved by optimizing flux-cored alloy elements of (nickel-chromium-nitrogen) synergistic stable austenite, matching with a manufacturing process of sealed baking and roller die drawing forming of powder at the temperature of 120-140 DEG C and a welding process protected by argon (Ar) with the purity of 99.999%. The AKV2 of a welded joint is larger than or equal to 34J at the temperature of-269 DEG C, the tensile strength is larger than or equal to 620 MPa, the relative permeability is smaller than or equal to 1.02, the problems that nitrogen of an existing solid welding wire is difficult to control, and hardening is easy can be solved, and the welding wire is completely matched with the extreme working condition of a controllable nuclear fusion device.

An in-process structure including an interposer is provided. The interposer includes first interposer bonding pads. An array of copper pillar structures is bonded to the first interposer bonding pads using interposer-side solder material portions. A packaging substrate is attached to the array of copper pillar structures by bonding the array of copper pillar structures to substrate bonding pads located on the packaging substrate using substrate-side solder material portions.

The present invention discloses a locally homogenized metal layered composite material and a preparation method, which belongs to the field of metal layered composite materials. The area to be welded of the metal layered composite raw material is machined, the non-welding material layer is removed and the remaining side is machined into a slope, the welding substrate layer is retained and a machined surface is constructed thereon, and the area to be composited is composed of the slope and the machined surface; a coating preparation method is used to coat the area to be composited with a layer of metal material that is homogeneous with the metal material of the welding substrate layer, so that a uniform material area in which the area to be welded is entirely made of the metal material of the welding substrate layer is obtained, thereby preparing a locally homogenized metal layered composite blank; the composite blank is post-processed to obtain a locally homogenized metal layered composite material. The present invention is particularly suitable for preparing locally homogenized metal layered composite materials with a relatively thin thickness, and can be directly used for industrial low-cost, high-efficiency, high-quality welding-formed metal layered composite products.

The invention relates to the technical field of semiconductor welding, and particularly discloses vacuum eutectic backflow equipment and a using method thereof.The vacuum eutectic backflow equipment comprises a glove box used for providing an inert gas environment and comprises a closed cavity, an observation window fixed to the closed cavity and operation gloves arranged on the observation window; a first material opening and a second material opening which can be opened and closed are formed in the closed cavity; the vacuum eutectic reflow furnace is arranged in the glove box, comprises a furnace body and a cover body which is arranged on the furnace body and can be opened and closed, and is used for vacuum eutectic reflow soldering of the soldering material; and the vacuum and atmosphere control module comprises a vacuum pump communicated with the furnace body and a plurality of gas circuit pipelines and is used for providing vacuum or different atmosphere environments for the furnace body of the vacuum eutectic reflow furnace. The invention can ensure that the semiconductor welding process meets the requirement of preventing small particle pollution.

A solder supply unit able to be attached to a solder cutting unit and is able to detached is provided. The solder supply unit includes a reel holder rotatably holding a reel of a tape-like solder material; and a guidance member guiding the tape-like solder material wound around the reel when the tape-like solder material is fed out. The guidance member includes an extension portion guiding a lower surface of the tape-like solder material along a feeding direction of the tape-like solider material; and an opening penetrating the extension portion in an up-down direction and extending toward an upstream side in the feeding direction from a downstream end of the guidance member. The opening is formed in the predetermined length in the feeding direction so that a holding member, which holds the tape-like solder material together with another holding member, is able to move in the feeding direction.

A method of bonding two substrates together includes applying a plurality of templating spheres to a first metal layer on a first substrate of the two substrates, applying a metal on the plurality of templating spheres to form a porous metal layer, and bonding a solder layer arranged on a second substrate of the two substrates to the porous metal layer with heat and pressure such that pores of the porous metal layer are filled with solder material and intermetallic compounds, forming a metal inverse opals layer bonding the first and second substrates together.

A thermal module assembling structure includes an aluminum base seat which has a heat absorption side, a heat conduction side and a connection section. The connection section is selectively disposed on the heat absorption side, the heat conduction side or embedded in the aluminum base seat (between the heat absorption side and the heat conduction side). The connection section is correspondingly connected with at least one copper heat pipe. A copper embedding layer is disposed on a portion of the connection section, which portion is in contact and connection with the copper heat pipe. A welding material layer is disposed between the copper embedding layer and the copper heat pipe, whereby the aluminum base seat and the copper heat pipe can be more securely connected with each other. The conventional chemical nickel plating is replaced with the copper embedding layer so as to improve the problem of environmental pollution, etc.

The invention relates to a method for securing a spring washer (05) to a combustion chamber housing (02). The combustion chamber housing (02) has a cylindrical receiving portion (03) at least at the downstream end. The spring washer (05) comprises a cylindrical fastening portion (06) and a plurality of spring tabs (07) distributed over the circumference. First, a solder material is applied to the inner face of the fastening portion (06). Then, the spring washer (05) is joined onto the combustion chamber housing (02) such that the fastening portion (06) is located on the receiving portion (03). A connection of the fastening portion (06) to the receiving portion (03) is achieved by heating the fastening portion (06) and / or the receiving portion (03). According to the invention, the spring tabs (07) are cooled at the same time.

The present application relates to the technical field of welding material, in particular to a Nb-Ti-Zr-V brazing filler metal for Nb alloy honeycomb brazing, a brazing filler metal coating and a preparation method thereof. The Nb-Ti-Zr-V brazing filler metal for Nb alloy honeycomb brazing comprises 10-25% of Nb, 42-52.5% of Ti, 9-11.25% of Zr and 9-11.25% of V in terms of mass percentage. The purpose of the Nb-Ti-Zr-V brazing filler metal for Nb alloy honeycomb brazing, the brazing filler metal coating and the preparation method thereof is to solve the problem of poor welding rate when Ti-Zr-V brazing filler metal is used for honeycomb brazing.

The invention discloses a sandwich solder and a preparation method and application thereof, and relates to the technical field of welding materials. The sandwich solder comprises a middle layer and metal active layers arranged on the two sides of the middle layer. The metal active layer is a tin-based alloy active layer and / or an indium-based alloy active layer; the raw material of the middle layer is selected from one of Ag, Cu and Ni; when the thickness of the sandwich solder is less than or equal to 0.1 mm, the thickness ratio of each metal active layer to the middle layer is (1-2): (6-7); when the thickness of the sandwich solder is larger than 0.1 mm, the thickness of each metal active layer ranges from 15 micrometers to 20 micrometers. The sandwich welding flux is high in welding strength, good in thermal fatigue resistance and high in reliability in a complex environment, can meet the requirements of low-temperature welding and high-temperature service at the same time, and is suitable for various different welding conditions.