CN1298493C - Copper welding paste for automatic brazing and its preparing method - Google Patents

Abstract

A copper solder paste for automatic brazing and a preparation method thereof, comprising brazing material, brazing flux, and a paste, wherein the brazing material is based on Cu, and alloying elements P, Sn, Ni, B, Ti, In and rare earth are added element, the brazing flux is chemically synthesized intermediate polyboride M, and potassium fluoroborate N and flux Q are added to polyboride M, and the paste is made of polyisobutylene mixtures of different molecular weights and organic solvents Miscible. The present invention has added P, Sn, Ni, B, Ti, In, rare earth elements in the brazing filler metal with Cu as the matrix, especially P, Sn, Ni and B, Ti, In, rare earth elements organic Combined in one body, the solder has good fluidity, wettability and seam filling, and the polyboride synthesized by chemical methods, and then by adding potassium fluoroborate and flux, ensure the appearance and quality of the solder paste. The performance of solder. In addition, because of the additives added in the preparation process of the paste, it is beneficial to the passage of the solder paste, which provides a guarantee for automation and large-scale production.

Description

A kind of copper solder paste for automatic brazing and preparation method thereof

technical field

The invention relates to a copper soldering paste for automatic brazing, in particular to a composition of the copper soldering paste-copper-phosphorous-tin-based solder, copper flux, components for forming a paste and a preparation method thereof.

Background technique

With the advancement of brazing science and technology and the miniaturization, diversification and complexity of the shape of brazing workpieces, the brazing processing industry has gradually replaced backward manual production with highly efficient automated production lines. The brazing operation process is to manually dip the wire-shaped, strip-shaped or sheet-shaped solder with flux, and then fix the solder coated with flux to the part of the workpiece to be brazed, and then heat the workpiece to melt the solder. The welding of the workpiece has extremely low production efficiency, which is extremely disharmonious with the modern high-speed economic development. It will be replaced by a cream brazing material—solder paste. Its biggest feature is that it can be quantitatively applied to the parts to be welded by pneumatic extrusion, which meets the needs of automatic flame brazing machines. Fast and accurate feeding requirements during the welding process, so as to realize the brazing of multiple parts at the same time, for example, the brazing between the copper sleeve electric heating tube and the brass flange of the main components of electric water heaters, electric kettles and electric coffee pots There are often more than 6 parts to be brazed on a workpiece, and the production efficiency of computer-controlled brazing will be dozens of times higher than that of manual operation, which can greatly improve production efficiency and stabilize product quality. . In addition, the realization of brazing production automation greatly reduces the impact of exhaust gas on the health of operators during the brazing process, making production more environmentally friendly and hygienic. Chinese patent CN1029407C discloses a copper-based solder paste and a welding method for copper ornaments. Although the patent CN1029407C and the product of this patent invention are all composed of copper solder, copper-based solder and organic paste, both The copper brazing flux, copper-based brazing filler metal and organic paste are obviously different in composition and preparation process. The brazing flux mentioned in patent CN1029407C is traditional FB102 and FB103, which have moisture absorption; in terms of brazing filler metal, this patent adds Trace elements increase wettability, corrosion resistance, etc.; and in terms of paste formation, the paste formation mentioned in patent CN1029407C has a low boiling point and is easy to dry, so it is not suitable for automatic feeding.

Contents of the invention

The purpose of the present invention is to provide a copper solder paste for automatic brazing and a preparation method thereof for the brazing processing industry, which can meet the automatic application of solder paste on a computer-controlled flame welding machine and can meet the welding quality requirements of products.

The technical solution of the present invention is a kind of brazing paste for automatic brazing, comprising brazing filler metal, brazing flux, forming paste, it is characterized in that above-mentioned brazing filler metal, brazing flux and forming paste are respectively made up of following components by weight percentage:

a. Brazing material: with Cu as the matrix, alloying elements P, Sn, Ni, B and rare earth elements or P, Sn, Ni, Ti and rare earth elements or P, Sn, Ni, In and rare earth elements are added, of which:

Cu: 85%-90%

P: 4%-8%

Sn: 4%-7%

Ni: 0.52%-1%

B: 0.05%-0.9%

Ti: 0.05%-0.5%

In: 0.5%-0.9%

Rare earth elements: 0.05%-0.1%

b. Brazing flux: the intermediate polyboride M synthesized by chemical method, its chemical formula is K _{x By} O _z , wherein the value of x is 1-2, the value of y is 4-6, the value of z is 6-9, and the other Potassium fluoborate N and flux Q are added to polyboride M, wherein the chemical formula of flux is KF·(1-2)HF·2.5H ₂ O, and the mass percentage of M:N:Q is: 18-22: 55-63: 17-23;

c. Paste: miscible with polyisobutylene mixtures of different molecular weights and organic solvents, wherein the mixed polyisobutylene has a molecular weight of 450-800000, accounting for 13.8-17% of the paste by weight; the organic solvent is a mixture of C6-C18, Accounting for 80.2-84.2% of the paste by weight percentage, the above-mentioned paste also includes:

The non-ionic surfactant composed of nonylphenol polyoxyethylene ether and fatty acid glyceride accounts for 0.8-1.6% of the paste.

The additive is benzotriazole, unsaturated fatty acid ester and animal and vegetable oil, and its components account for 0.75-1.25% by weight of the paste.

A kind of preparation method of above-mentioned copper solder paste, at first respectively make solder, brazing flux and paste body, its respective preparation steps are as follows:

a. Brazing material:

(1) According to the composition of the solder;

(2) Smelting under vacuum conditions;

(3) Refining and purification;

(4) Ultrasonic inert airflow pulverizes the molten metal flow into droplets;

(5) The liquid droplets are solidified and cooled under a protective atmosphere;

(6) Powder particle size classification;

(7) vacuum treatment;

(8) Intermediate products;

b. Flux:

Quickly condense the molten flux and grind it at high speed to prepare -160 mesh flux;

c, into a paste:

Select low-, medium- and high-molecular-weight polyisobutylene mixtures, mix them with organic solvents, non-ionic surfactants, and additives, and heat them to 80-150°C to fully stir to make an organic paste;

d. Synthesize the brazing filler metal, brazing flux and paste made respectively, the steps are as follows:

(1) The brazing filler metal and the brazing flux are mixed evenly in a ratio of 12-18: 88-82 by weight;

(2) Add the mixed solder and brazing flux into the organic paste and stir evenly, wherein the weight percentage of the organic paste is 7.60±2.5%.

The present invention has added P, Sn, Ni, B, Ti, In, rare earth elements in the brazing filler metal with Cu as the matrix, especially P, Sn, Ni and B, Ti, In, rare earth elements organic Combined in one body, it not only overcomes the defects of high brittleness and low strength of the solder caused by P in the solder, but also makes the solder have excellent brazing process characteristics such as better fluidity, wettability and seam filling. , and the intermediate polyboride with chemical film removal function firstly synthesized by chemical methods, and then the flux prepared by adding potassium fluoroborate and flux and using a specific process has the ability to not absorb moisture or weakly absorb moisture in the air The characteristics of moisture ensure the appearance of the solder paste and the performance of the solder, and because additives such as benzotriazole, unsaturated fatty acid ester, and animal oil are added in the preparation process of the paste, the solder and organic solder are greatly increased. Part of the surface bonding force is beneficial to the anti-delamination and tube passing of the solder paste, which provides a technological guarantee for automation and mass production.

Detailed ways

The present invention is a kind of copper solder paste for automatic brazing, comprising brazing filler metal, brazing flux, forming paste, it is characterized in that above-mentioned brazing filler metal, brazing flux and forming paste are respectively made up of following components by weight percentage:

a. The brazing material is based on Cu, and alloying elements P, Sn, Ni, B and rare earth elements or P, Sn, Ni, Ti and rare earth elements or P, Sn, Ni, In and rare earth elements are added, among which:

Cu: 85%-90%

P: 4%-8%

Sn: 4%-7%

Ni: 0.52%-1%

B: 0.05%-0.9%

Ti: 0.05%-0.5%

In: 0.5%-0.9%

Rare earth elements: 0.05%-0.1%

b. Brazing flux: the intermediate polyboride M synthesized by chemical method, its chemical formula is K _{x By} O _z , wherein the value of x is 1-2, the value of y is 4-6, the value of z is 6-9, and the other Potassium fluoborate N and flux Q are added to polyboride M, wherein the chemical formula of flux is KF·(1-2)HF·2.5H ₂ O, and the mass percentage of M:N:Q is: 18-22: 55-63: 17-23;

c. Paste: miscible with polyisobutylene mixtures of different molecular weights and organic solvents, wherein the mixed polyisobutylene has a molecular weight of 450-800000, accounting for 13.8-17% of the paste by weight; the organic solvent is C ₆ -C ₁₈ The mixture accounts for 80.2-84.2% of the paste by weight percentage, and the above paste also includes:

The non-ionic surfactant composed of nonylphenol polyoxyethylene ether and fatty acid glyceride accounts for 0.8-1.6% of the paste.

The additive is benzotriazole, unsaturated fatty acid ester and animal and vegetable oil, and its components account for 0.75-1.25% by weight of the paste.

A kind of preparation method of above-mentioned copper solder paste, at first respectively make solder, brazing flux and paste body, its respective preparation steps are as follows:

a. Brazing material:

(1) According to the composition of the solder;

(2) Smelting under vacuum conditions;

(3) Refining and purification;

(4) Ultrasonic inert airflow pulverizes the molten metal flow into droplets;

(5) The liquid droplets are solidified and cooled under a protective atmosphere;

(6) Powder particle size classification;

(7) vacuum treatment;

(8) Intermediate products.

b. Flux:

Quickly condense the molten flux and grind at a high speed to prepare -160 mesh flux.

c, into a paste:

Select low, medium and high molecular weight polyisobutylene mixtures and organic solvents, non-ionic

Surfactant and additives are mixed and heated to 80-150°C and fully stirred to make an organic paste;

d. Synthesize the brazing filler metal, brazing flux and paste made respectively, the steps are as follows:

(1) The brazing filler metal and the brazing flux are mixed evenly in a ratio of 12-18: 88-82 by weight;

(2) Add the mixed solder and brazing flux into the organic paste and stir evenly, wherein the weight percentage of the organic paste is 7.60±2.5%.

The further principle of the present invention and technical scheme and embodiment are as follows:

(1) Solder

Brazing material is the main component of solder paste, which has a key influence on the brazing process and welding strength. The solder involved in the present invention uses Cu as the matrix, adds appropriate amount of alloy elements and adopts an original powder making process, so that the solder powder has the characteristics of fine structure, uniform composition, smooth and spherical surface of powder particles, etc. The defects of brazing filler metal, such as high weld brittleness, low strength, poor air tightness and poor electroplating performance due to the existence of P, are greatly improved, and the mechanical properties and brazing process performance of the brazing filler metal are well improved.

The brazing filler metal used in this solder paste is prepared by vacuum smelting ultrasonic airflow atomization powder making technology. This process has the advantages of rapid solidification, short process flow, high efficiency, smooth powder particle surface, low oxygen content, uniform composition and fine structure. It satisfies the solder paste specification very well. Specific milling method: batching according to composition requirements - smelting under vacuum conditions - refining and purification - ultrasonic inert air flow crushes molten metal into droplets - solidification and cooling of droplets in a protective atmosphere - powder particle size classification - vacuum treatment - intermediate products.

(2) Flux

The chemical synthesis method is used to prepare high-quality powdered copper flux with the characteristics of good soldering performance, no moisture absorption or weak moisture absorption, low corrosion, good coexistence with solder, and less residue after welding. The key technology lies in: flux formula and preparation technology engineering technology, product quality and stable performance control technology.

Synthesize the intermediate polyboride M, which has the function of chemical film removal and does not absorb moisture in the air, by chemical methods. The chemical formula is K _x B _y O _z , where the value of x is 1-2, and the value of y is 4-6 , the value of z is 6-9.

Add potassium fluoroborate N and flux Q (chemical formula KF·(1-2)HF·2.5H ₂ O) to M, let the mixture fully react at 400-500°C, and remove excess water, among which M : N: The mass percentage of Q is 18-22: 55-63: 17-23;

Rapidly condense the molten flux and grind it at high speed to prepare -160 mesh flux. The flux has the characteristics of no moisture absorption (or weak moisture absorption) in the air, thereby ensuring the appearance status of the solder paste and the performance of the solder. At the welding temperature, the flux will decompose into high-efficiency active substances, which can effectively remove the oxide film. The welding slag generated by the flux is easily soluble in water, so that it is easy to clean after welding and does not affect the quality of electroplating.

(3) into a paste

Prepare a paste-solder paste carrier that is oily and delicate, moderate in viscosity, good in delamination resistance, good in coexistence with solder and flux, odorless, non-toxic, and has no residue after soldering.

Select low-, medium- and high-molecular-weight polyisobutylene mixtures to be miscible with organic solvents, and prepare an organic paste by heating (80-150°C); the molecular weight range of mixed polyisobutylene is 450-800000, accounting for 13.8% of the paste. -17%; the organic solvent is a mixture of C ₆ -C ₁₈ , accounting for 80.2-84.2% in the paste.

A non-ionic surfactant is added to the paste to adjust the smoothness of the paste; the surfactants are mainly nonylphenol polyoxyethylene ether and fatty acid glyceride, accounting for 0.8-1.6% in the paste.

Thickeners, antistatic agents, anti-lamination agents and other additives are added to ensure the stability of the organic paste. The main additives are benzotriazoles, unsaturated fatty acid esters, animal and vegetable oils, etc.

(4) Solder paste synthesis

Synthesize the above three intermediate products into the final solder paste product. The key to the technology lies in the ratio of solder, flux, and paste in the mixture and its synthesis process. Adjust the viscosity of the solder paste to suit the climate change and stabilize the comprehensive solder paste. Performance, to ensure the performance of solder paste brazing process and welding quality, to meet various use requirements. The specific process steps can firstly mix the brazing material and flux with a ratio of 12-18:88-82, then add the mixed solder and flux to the organic paste, stir evenly, and the organic paste The proportion of body is 7.60±2.50%

The present invention can produce following beneficial effect owing to having adopted above-mentioned component preparation, in addition reasonable equipment preparation:

(1) The composition of the solder is innovative. Adding trace alloy elements to the solder matrix overcomes the defects of high brittleness and low strength of the solder due to the presence of P in the solder, so that the solder has fluidity, wettability, Excellent brazing process characteristics such as seam filling, and the weld has excellent mechanical properties and corrosion resistance.

(2) Vacuum smelting ultrasonic inert gas flow atomization technology is used to prepare powdered solder. The surface of the prepared solder powder particles is smooth, the sphericity is high (sphericality is not less than 95%), and the oxygen content is low (less than 150ppm). High yield (the yield of -100 mesh powder is above 85%), good controllability of powder particle size and distribution, and good stability, which well meet the requirements of solder paste characteristics and ensure smooth and smooth feeding during the use of solder paste The accuracy of the dosage.

(3) The above-mentioned brazing flux overcomes the disadvantages of traditional brazing fluxes such as easy moisture absorption, poor coexistence with solder, easy delamination of solder paste, and low chemical activity during brazing. Synthesize an intermediate that has the function of chemical film removal and does not absorb moisture in the air by chemical methods, and then prepares the flux by adding fluoroborate and flux with a specific process. The flux has the characteristics of no moisture absorption (or weak moisture absorption) in the air, thereby ensuring the appearance status of the solder paste and the performance of the solder. At the welding temperature, the flux will decompose into high-efficiency active substances, which can effectively remove the oxide film. The welding slag generated by the flux is easily soluble in water, thus meeting the requirements of easy cleaning after welding and not affecting electroplating.

(4) The above-mentioned paste formation and the selection of specific processes to prepare solder paste can meet the needs of automatic welding production: the paste formation in the solder paste is the bridge connecting the flux and the solder, and is the key to whether the solder paste can be automatically fed . The present invention adopts a unique process to prepare a variety of organic mixtures into pastes with moderate viscosity and strong greasy feeling, and controls the performance indicators of different batches of pastes through strict detection means and effective adjustment methods to avoid The influence of different batches, temperature, storage time, etc. All the ingredients in the paste are inert and completely decompose at the welding temperature without carbon deposits or residues.

(5) The solder paste preparation process is one of the keys to whether the solder paste can be mass-produced. Adding surface active additives during the preparation process increases the surface bonding force between the solder and the organic part, which is beneficial to the anti-delamination of the solder paste And through the tube, and effectively suppress the tailing phenomenon of automatic feeding. By selecting the appropriate solder, flux, and paste ratio, the prepared solder paste is uniform, dense, thick and non-sticky, with a long shelf life, good brazing process performance, low cost, and technical performance indicators that meet or exceed imported products. level, the qualification rate of welding workpieces is greater than 95%,

The components in the solder of Example 1 are: P: 5.5%, Sn: 6%, Ni: 0.5%, B and a small amount of rare earth elements, and the balance of Cu. In the flux after melting, B: 13.5%, K: 30.2%, F: 45.6%, O: balance. In the organic paste (accounting for 7.75%), polyisobutylene: 15.6%, C ₆ -C ₁₅ : 82.3%, surfactant: 1.2%, additive: 0.9%. Brazing filler metal: brazing flux = 84.5: 15.5.

The composition of the brazing filler metal in Example 2 is: P: 6.5%, Sn: 6%, Ni: 0.6%, Ti and rare earth elements trace amounts, and the balance Cu. In the molten flux, B: 15.02%, K: 31.23%, F: 46.14%, and the balance of O. The organic paste (accounting for 6.78%) is mixed with polyisobutylene: 14.2%, C ₆ -C ₁₅ : 83.2%, surfactant 1.5%, and additive 1.1%. Brazing filler metal: brazing flux = 83.0: 17.0.

The components in the brazing filler metal of Example 3 are: P: 7%, Sn: 7.5%, Ni: 0.8%, In and rare earth element traces, and the balance Cu. In the molten flux, B: 16.25%, K: 32.10%, F: 44.50%, and the balance of O. In the organic paste (accounting for 8.00%), 16.4% of polyisobutylene, 81.2% of C ₆ -C ₁₅ , 1.3% of surfactant and 1.1% of additives are mixed. Brazing filler metal: flux = 82.4: 17.6.

Claims (2)

1, a kind of automatic brazing brazing cream comprises solder, brazing flux, one-tenth lotion, it is characterized in that above-mentioned solder, brazing flux and becomes lotion to be made up of following component respectively by weight percentage:

A, solder: with Cu is matrix, adds alloying element P, Sn, Ni, B and rare earth element or P, Sn, Ni, Ti and rare earth element or P, Sn, Ni, In and rare earth element, wherein:

Cu：85％-90％

P：4％-8％

Sn：4％-7％

Ni：0.52％-1％

B：0.05％-0.9％

Ti：0.05％-0.5％

In：0.5％-0.9％

Rare earth element: 0.05%-0.1%

B, brazing flux: He Cheng many borides of intermediate M chemically, its chemical formula is K _xB _yO _z, wherein the x value is 1～2, and the y value is 4～6, and the z value is 6～9, adds potassium fluoborate N, flux Q in addition in many borides M, and wherein the chemical formula of flux is KF (1-2) HF2.5H ₂O, the mass percent of M: N: Q is: 18-22: 55-63: 17-23;

C, one-tenth lotion: with the polyisobutene mixture and the immiscible organic solvent of different molecular weight, wherein mixing the polyisobutene molecular weight is 450-800000, accounts for into lotion 13.8-17%; Organic solvent is C ₆-C ₁₈Mixture, account for into lotion 80.2-84.2%, above-mentioned one-tenth lotion also comprises:

The nonionic surface active agent that hydroxybenzene polyoxydivinyl ether, fatty acid glycerine fat are formed, its component accounts for into the 0.8-1.6% of lotion;

Additive, described additive are BTA, unsaturated fatty acid ester or vegetable and animals oils, and its ingredients constitute becomes the 0.75-1.25% of lotion.

2, a kind of preparation method of above-mentioned brazing cream makes solder, brazing flux at first respectively and becomes lotion, and its preparation process separately is as follows:

A, solder:

(1) presses the solder ingredient composition;

(2) melting under the vacuum condition;

(3) refining purifies;

(4) ultrasonic inert gas pulverizing molten metal bath stream becomes drop;

(5) drop solidifies cooling under protective atmosphere;

(6) powder size classification;

(7) application of vacuum;

(8) intermediate products;

B, brazing flux:

With the brazing flux rapid condensation of fusion ,-160 purpose brazing fluxes are prepared in polishing at a high speed.

C, one-tenth lotion:

Choose polyisobutene mixture and organic solvent, nonionic surface active agent, the additive mixing of basic, normal, high molecular weight and be heated to 80-150 ℃ of abundant the stirring and make organic lotion;

D, the solder with making respectively, brazing flux and one-tenth lotion synthesize into soldering paste, and its step is as follows:

(1) with solder and brazing flux being that the ratio of 12-18: 88-82 mixes by weight;

(2) solder and the brazing flux that mixes joined in organic lotion, stir, wherein the percentage by weight of organic lotion is 7.60 ± 2.5%.