[0025] An embodiment of the present invention provides a method for preparing an adhesive for adhesive tape solder, comprising: according to the weight ratio of each component, 30-70% of epoxy resin, 21-63% of plasticizer and 3 -21% of the toughening agent is placed in a stirrer and stirred at a speed of 30-60r/min for 5-15min to prepare the binder.
[0026] In the present embodiment, epoxy resin is used for bonding solder powder. In some preferred embodiments, the grade of epoxy resin is E44, and it is a bisphenol A type epoxy resin with strong adhesion and a thermal decomposition temperature T d The temperature is 385°C-413°C, and the amount of residual carbon after welding is low. And compared with the polymethyl methacrylate that mostly uses in the prior art, epoxy resin E44 is cheap, has cost advantage, and polymethyl methacrylate is solid under normal temperature, needs heating and complex process in the preparation process , while the epoxy resin E44 is liquid at room temperature and has a certain viscosity. The stirring time required during the mixing process is short, and there is no need for long-term drying after the preparation is completed, which simplifies the process and further reduces energy consumption.
[0027] In this embodiment, the plasticizer is used to increase the plasticity of the adhesive tape solder when rolling. In some preferred embodiments, the plasticizer includes terpene resin and the first diluent, and the plasticizer consists of The terpene resin with a weight ratio of 10-50% and the first diluent with a weight ratio of 50-90% are placed in a stirrer and stirred at a speed of 30-60r/min for 5-15min.
[0028] Terpene resin in the present embodiment, molecular formula is (C 10 h 16 ) n , the material has high cohesion and strong adhesion, which can increase the plasticity of the binder and improve the processing performance. The thermal decomposition temperature T of terpene resin d It is about 160 ℃, and the amount of residual carbon after welding is low.
[0029] In this embodiment, the first diluent swells the plasticizer, making the plasticizer a liquid that is easy to add and mix at room temperature. In some preferred embodiments, the first diluent is selected from N-formazol One or more of pyrrolidone, acetone, ethyl acetate, and dibutyl phthalate.
[0030] In this embodiment, the toughening agent is used to increase the toughness of the adhesive tape solder during rolling. In some preferred embodiments, the toughening agent includes an elastomer and a second diluent, and the toughening agent consists of The elastomer with a weight ratio of 60-95% and the second diluent with a weight ratio of 5-40% are placed in a stirrer and stirred at a speed of 30-60r/min for 5-15min.
[0031] In some preferred embodiments, the elastomer is selected from one or more of ethyl cellulose, styrene-based thermoplastic elastomer, acrylonitrile-butadiene-styrene terpolymer, butadiene rubber .
[0032] In this embodiment, the second diluent swells the toughening agent, making the toughening agent a liquid that is easy to add and mix at room temperature. In some preferred embodiments, the second diluent is selected from ethyl acetate , absolute ethanol, acetone or one or more.
[0033] Therefore, the binder for adhesive tape solder of the present invention is suitable for many kinds of solder, has simple preparation process, no pollution to the environment, and low amount of residual carbon after welding. The prepared adhesive tape solder has good flexibility, can be processed into various shapes, is suitable for vacuum brazing under complex conditions, and has uniform joint structure and excellent performance after welding.
[0034] The embodiment of the present invention also provides a kind of adhesive tape solder, including solder powder and the binder prepared according to the preparation method of the adhesive tape solder binder, and the adhesive tape solder has a weight ratio of 6-14% of the binder and 86-94% of the solder powder are placed in a stirrer, stirred at a speed of 30-60r/min for 20-60min, fully mixed and rolled to a thickness of 0.1-2mm adhesive tape solder.
[0035] Preferably, the solder powder is a high-temperature solder powder, and the solder powder is selected from one of nickel-based solder powder, cobalt-based solder powder or copper-based solder powder, thus meeting various requirements. The preparation of sticky solder has a wide range of applications.
[0036] Preferably, the solder powder includes particles of four different particle sizes, and the weight ratios of the particles of the four different particle sizes are arranged in order of increasing particle size as 5-25%, 20-35%, 25%. -35% and 15-25%. In some specific embodiments, the solder powder includes particles with four diameters of 5 μm, 10 μm, 30 μm, and 50 μm, and the weight ratio of each component is: 5-25% of particles with a diameter of 5 μm, 20-35% of particles with a diameter of 10 μm, 25-35% for 30 μm diameter particles, 15-35% for 50 μm diameter particles. Therefore, in this embodiment, by adjusting the ratio of particles of various sizes, the gaps in the coarse particles are just filled by the medium particles, and the gaps in the medium particles are just filled by the fine particles, so that the material can be packed most densely and the accumulation of the solder powder can be improved. The density improves the welding quality of the sticky solder.
[0037] Therefore, the adhesive tape solder in the embodiment of the present invention has good flexibility, can be processed into various shapes, and is suitable for vacuum brazing under complex conditions. The post-weld joint has uniform structure, excellent performance and low post-weld carbon residue.
[0038] like figure 1 As shown, the embodiment of the present invention also provides a brazing method, comprising the following steps:
[0039] Step S1, pre-welding treatment, smoothing the surface of the workpiece to be welded with 100-2000 mesh sandpaper, ultrasonically cleaning the to-be-welded part of the workpiece to be welded with acetone for 5-10 minutes, and attaching the adhesive tape solder to the parts to be welded;
[0040] Step S2, place the whole workpiece to be welded in a vacuum brazing furnace, close the furnace door and use a vacuum pump to evacuate the furnace into a vacuum state, then raise the temperature to 550-600°C at a heating rate of 8-10°C/min, and keep warm for 5 -10min, at this time the temperature has reached the decomposition temperature of the binder component in the adhesive tape solder, the binder component is fully decomposed, and the decomposition products are discharged by the vacuum pump;
[0041] Step S3, continue to raise the temperature to 700-750°C at a heating rate of 8-10°C/min, keep it warm for 5-10min to ensure the uniformity of the overall temperature of the workpiece to be welded, and then raise the temperature to the first temperature at a heating rate of 5°C/min Preset the temperature and keep it warm for 5-10 minutes. At this time, the solder powder melts and forms a good metallurgical bond with the alloy on both sides. Finally, it cools down to room temperature at a cooling rate of 10°C/min to complete the welding.
[0042] Preferably, the first preset temperature in step S2 is the melting temperature of the adhesive tape solder, so as to ensure that the solder powder melts and forms a good metallurgical bond with the alloys on both sides.
[0043] Compared with the prior art, the brazing method of the present invention has two times of heat preservation before the brazing temperature, which ensures that the binder is fully decomposed, and at the same time improves the uniformity of the overall temperature of the workpiece to be welded, the structure is uniform, and the performance is excellent. After welding, the residual carbon content of the brazed joint is low, only 0.05%-0.5%.
