Method for preparing silver-copper-indium-tin alloy brazing filler metal by using waste ITO (Indium Tin Oxide)

Abstract

The invention discloses a method for preparing silver-copper-indium-tin alloy brazing filler metal through waste ITO. The method comprises the steps that firstly, the waste ITO is pretreated to obtain waste A; 2, silver is added into the waste A, hydrogen-containing atmosphere is introduced for calcination, and an alloy B is obtained; and thirdly, according to the composition proportion of a target product, metal elementary substances are added into the alloy B for burdening, and then the silver-copper-indium-tin alloy brazing filler metal is obtained through calcination and smelting treatment under vacuum. According to the method, silver with low oxyphilicity is added into the pretreated waste ITO, then the hydrogen-containing atmosphere is introduced for calcination reduction, it is guaranteed that the zero-valence phase of indium and tin is obtained, rapid removal of oxygen is achieved, complete utilization of indium and tin in the waste ITO is achieved, the separation and purification process of indium and tin is omitted, the technological process is short, operation is easy, and the method is suitable for industrial production. The method has the advantages of high indium-tin metal utilization rate, high product added value, low raw material cost and good industrial prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical recycling and preparation, and specifically relates to a method for preparing silver-copper-indium-tin alloy solder by utilizing waste ITO. Background Art

[0002] ITO (Tin-doped Indium Oxide) is an indium tin oxide compound, which is mainly made into a target material for the production of ITO film transparent conductive glass in flat liquid crystal displays. It is widely used in the electronics industry, liquid crystal panels, high-end curtain walls and lighting fixtures. However, the utilization rate of ITO targets in the production of electronic products is low, with a one-time utilization rate of only 30%. Its molding and use process will generate a large amount of waste, scraps and cuttings. Since ITO has a high purity and contains about 74% indium and 7% tin (the rest is oxygen), its recycling value is relatively high.

[0003] The core of existing ITO waste target recycling technology lies in the effective separation of indium and tin. It usually uses waste ITO ball milling, acid / alkali leaching, indium and tin separation in the solution to obtain crude indium, and further purification by electrolysis. There are many steps, and the existing comprehensive recovery rate of waste ITO is only 65%, and the resource utilization rate is low.

[0004] On the other hand, indium-containing alloys are also one of the main areas of indium consumption. Among them, silver-copper-indium-tin alloy solder can meet the high requirements of welding strength for metal materials such as alloy steel, stainless steel, titanium and titanium alloy, and is widely used in semiconductors, industry and other fields. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing silver-copper-indium-tin alloy solder using waste ITO in view of the deficiencies of the above-mentioned prior art. The method ensures that the zero-valent phase of indium tin is obtained by adding silver with low oxygen affinity to the pretreated waste ITO and then introducing a hydrogen-containing atmosphere for calcination reduction, thereby achieving rapid removal of oxygen, achieving full utilization of indium and tin in the waste ITO, and also eliminating the separation and purification process of indium and tin, reducing the cost of raw materials, obtaining high value-added products, and solving the problems of low recovery rate of waste ITO, complex recovery process, long recovery process, and low utilization rate of metal elements.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing silver-copper-indium-tin alloy solder using waste ITO, characterized in that the method comprises the following steps:

[0007] Step 1: pretreating waste ITO to obtain waste A;

[0008] Step 2: adding silver to the waste material A obtained in step 1, placing the waste material A in a graphite crucible and introducing a hydrogen-containing atmosphere for calcining to obtain alloy B;

[0009] Step 3: According to the composition ratio of the target product, silver-copper-indium-tin alloy solder, metal elements are added to the alloy B obtained in step 2 for batching, and then calcined and smelted under vacuum conditions to obtain the silver-copper-indium-tin alloy solder.

[0010] The invention uses waste ITO to prepare silver-copper-indium-tin alloy solder according to the component matching of waste ITO and silver-copper-indium-tin alloy and the applicability of indium in main consumption fields. Firstly, since the waste ITO has a high purity and the pollution only exists on the surface, the present invention pre-treats the waste ITO to remove the surface pollution and obtain a relatively pure ITO raw material, namely, waste A; secondly, the component of ITO is an indium tin oxide composite with a high oxygen content of more than 16%, so it is calcined in a hydrogen-containing atmosphere to be reduced to a metal, but compared with indium and tin, silver has a lower affinity for oxygen. When the waste A and silver are melted at a high temperature, they are transformed into a molten indium tin silver oxide mixture. Due to the presence of silver oxide, the hydrogen-containing atmosphere is very easy to combine with oxygen to reduce silver, thereby realizing rapid removal of oxygen, that is, by adding silver with weaker oxygen affinity to the indium tin oxide composite, rapid removal of oxygen is realized, thereby obtaining a zero-valent phase of indium tin; and then, according to the composition ratio of the silver-copper-indium-tin alloy solder, each metal element is added to the alloy B, namely, the silver-indium-tin alloy, for batching, and calcined and smelted under vacuum to obtain the silver-copper-indium-tin alloy solder.

[0011] The above-mentioned method for preparing silver-copper-indium-tin alloy solder using waste ITO is characterized in that the waste ITO in step one is waste target material and scraps and cuttings in the target material preparation process, and the pretreatment is grinding and pickling.

[0012] The above-mentioned method for preparing silver-copper-indium-tin alloy solder using waste ITO is characterized in that the mass ratio of silver to waste material A in step 2 is 0.5-1.0:1, the calcination temperature is 900°C-1100°C, the holding time is 30min-90min, the hydrogen-containing atmosphere is a hydrogen-argon mixed gas with a hydrogen volume content of 10%, and high-purity argon atmosphere is used for cooling after calcination. By controlling the mass ratio of silver to waste material A, it is ensured that the amount of silver added is sufficient, thereby achieving the purpose of rapid deoxidation, while ensuring the oxygen content in waste material A, so as to achieve deep deoxidation.

[0013] The above-mentioned method for preparing silver-copper-indium-tin alloy solder using waste ITO is characterized in that the temperature of the calcination and smelting treatment in step 3 is 1000°C to 1200°C, and the holding time is 5min to 30min. By controlling the calcination and smelting treatment temperature, it is ensured that all metal materials can be melted quickly, and the holding time is controlled to further ensure the removal of oxygen elements and achieve mixed melting of all elements, and compared with conventional vacuum melting, the processing time is significantly shortened.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention adds silver with low oxygen affinity to the pretreated waste ITO, and then introduces a hydrogen-containing atmosphere for calcination reduction to ensure that the zero-valent phase of indium tin is obtained. Combined with subsequent feeding and calcination, the waste ITO is used to prepare a silver-copper-indium-tin alloy solder. Compared with the traditional recycling of waste ITO, the separation and purification process of indium and tin is omitted. Compared with the traditional preparation of silver-copper-indium-tin, the cost of metal raw materials is reduced, the utilization rate of indium tin metal is improved, and the added value of the product is increased.

[0016] 2. The present invention achieves rapid removal of oxygen by adding silver with weaker oxygen affinity, which not only improves the reduction purity of the product, but also shortens the process flow, simplifies the recycling process, and broadens the utilization of waste ITO.

[0017] 3. The preparation method of the present invention has a short process flow, simple operation, high utilization rate of indium tin metal, high product added value, low cost of main raw materials, and good industrialization prospects.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD spectrum of the silver-copper-indium-tin alloy solder prepared in Example 1 of the present invention.

[0020] Figure 2 The scanning electron microscope and element surface distribution images of the silver-copper-indium-tin alloy solder prepared in Example 1 of the present invention.

[0021] Figure 3 The scanning electron microscope and element surface distribution images of the silver-copper-indium-tin alloy solder prepared in Example 2 of the present invention.

[0022] Figure 4 The scanning electron microscope and element surface distribution images of the silver-copper-indium-tin alloy solder prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] Example 1

[0024] This embodiment includes the following steps:

[0025] Step 1: polish the contaminated areas on the surface of the waste ITO, and pickle it with dilute hydrochloric acid with a concentration of 0.1 mol / L for 20 minutes to obtain waste A; the waste ITO is waste target material and scraps and cuttings in the process of target material preparation;

[0026] Step 2, adding 15g of silver to 30g of the waste A obtained in step 1, and placing it in a graphite crucible and introducing a hydrogen-containing atmosphere for calcination, the calcination temperature is 900°C, the holding time is 90min, the hydrogen-containing atmosphere is a hydrogen-argon mixed gas with a hydrogen volume content of 10%, and after calcination, cooling is performed in a high-purity argon atmosphere to obtain alloy B;

[0027] Step 3: According to the composition ratio of the target product silver-copper-indium-tin alloy solder Ag59Cu23In14Sn4, 69.8g of silver, 37g of copper and 4g of tin are added to the alloy B obtained in step 2 for batching, and then calcined and smelted under vacuum conditions at a temperature of 1000°C and a holding time of 30min to obtain a silver-copper-indium-tin alloy solder.

[0028] Figure 1 The XRD pattern of the silver-copper-indium-tin alloy solder prepared in this example is as follows: Figure 1 It can be seen that the silver-copper-indium-tin alloy solder has a sharp XRD characteristic peak, indicating that it is a crystalline structure, and its characteristic peak does not overlap with those of silver, copper, indium, and tin, proving that it is an alloy structure.

[0029] Figure 2 The scanning electron microscope and element distribution image of the silver-copper-indium-tin alloy solder prepared in this embodiment are shown in FIG. Figure 2 It can be seen that the four elements of silver, copper, indium and tin in the silver-copper-indium-tin alloy solder are evenly distributed on the alloy surface, indicating that they are evenly distributed under the microstructure and present an alloy structure.

[0030] Example 2

[0031] This embodiment includes the following steps:

[0032] Step 1: polish the contaminated areas on the surface of the waste ITO, and pickle it with dilute hydrochloric acid with a concentration of 0.1 mol / L for 20 minutes to obtain waste A; the waste ITO is waste target material and scraps and cuttings in the process of target material preparation;

[0033] Step 2, adding 50g of silver to 50g of the waste A obtained in step 1, and placing it in a graphite crucible and introducing a hydrogen-containing atmosphere for calcination, the calcination temperature is 1100°C, the holding time is 30min, the hydrogen-containing atmosphere is a hydrogen-argon mixed gas with a hydrogen volume content of 10%, and after calcination, cooling is performed in a high-purity argon atmosphere to obtain alloy B;

[0034] Step 3: According to the composition ratio of the target product silver-copper-indium-tin alloy solder Ag43Cu29In24Sn4, 17.3g of silver, 45.4g of copper and 2.2g of tin are added to the alloy B obtained in step 2 for batching, and then calcined and smelted under vacuum conditions. The calcination and smelting temperature is 1200°C and the insulation time is 5min to obtain the silver-copper-indium-tin alloy solder.

[0035] Figure 3 The scanning electron microscope and element distribution image of the silver-copper-indium-tin alloy solder prepared in this embodiment are shown in FIG. Figure 3 It can be seen that the four elements of silver, copper, indium and tin in the silver-copper-indium-tin alloy solder are evenly distributed on the alloy surface, indicating that they are evenly distributed under the microstructure and present an alloy structure.

[0036] Example 3

[0037] This embodiment includes the following steps:

[0038] Step 1: polish the contaminated areas on the surface of the waste ITO, and pickle it with dilute hydrochloric acid with a concentration of 0.1 mol / L for 20 minutes to obtain waste A; the waste ITO is waste target material and scraps and cuttings in the process of target material preparation;

[0039] Step 2, adding 30g of silver to 40g of the waste A obtained in step 1, and placing it in a graphite crucible and introducing a hydrogen-containing atmosphere for calcination, the calcination temperature is 1000°C, the holding time is 45min, the hydrogen-containing atmosphere is a hydrogen-argon mixed gas with a hydrogen volume content of 10%, and after calcination, cooling is performed in a high-purity argon atmosphere to obtain alloy B;

[0040] Step 3: According to the composition ratio of the target product silver-copper-indium-tin alloy solder Ag59Cu27In10Sn4, 147g of silver, 81g of copper and 8.8g of tin are added to the alloy B obtained in step 2 for batching, and then calcined and smelted under vacuum conditions. The calcination and smelting temperature is 1090°C and the insulation time is 15min to obtain the silver-copper-indium-tin alloy solder.

[0041] Figure 4 The scanning electron microscope and element distribution image of the silver-copper-indium-tin alloy solder prepared in this embodiment are shown in FIG. Figure 4 It can be seen that the four elements of silver, copper, indium and tin in the silver-copper-indium-tin alloy solder are evenly distributed on the alloy surface, indicating that they are evenly distributed under the microstructure and present an alloy structure.

[0042] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing silver-copper-indium-tin alloy solder using waste ITO, characterized in that: The method comprises the following steps: Step 1: pre-treating waste ITO to obtain waste A; Step 2: adding silver to the waste material A obtained in step 1, placing the waste material A in a graphite crucible and introducing a hydrogen-containing atmosphere for calcining to obtain alloy B; Step 3: According to the composition ratio of the target product silver-copper-indium-tin alloy solder, metal elements are added to the alloy B obtained in step 2 for batching, and then calcined and smelted under vacuum conditions to obtain the silver-copper-indium-tin alloy solder.

2. The method for preparing silver-copper-indium-tin alloy solder using waste ITO according to claim 1, characterized in that: The waste ITO in step 1 is waste target material and scraps and cuttings in the target material preparation process, and the pretreatment is grinding and pickling.

3. The method for preparing silver-copper-indium-tin alloy solder using waste ITO according to claim 1, characterized in that: In step 2, the mass ratio of silver to scrap A is 0.5 to 1.0:1, the calcination temperature is 900° C. to 1100° C., the holding time is 30 min to 90 min, the hydrogen-containing atmosphere is a hydrogen-argon mixture with a hydrogen volume content of 10%, and high-purity argon atmosphere is used for cooling after calcination.

4. The method for preparing silver-copper-indium-tin alloy solder using waste ITO according to claim 1, characterized in that: The temperature of the calcination and smelting treatment in step 3 is 1000° C. to 1200° C., and the holding time is 5 min to 30 min.

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