A gamma irradiation-induced nanocrystalline oxide layer on the surface of Sn-based solder and its preparation method

Abstract

The present invention relates to a gamma-irradiation-induced nanocrystalline oxide layer on the surface of a Sn-based solder and a preparation method thereof, belonging to the technical field of nanomaterial preparation. The nanocrystalline oxide layer on the surface of a Sn-based solder is prepared using a gamma-irradiation-induced nanocrystalline oxidation method. The nanocrystalline oxide layer has an average grain diameter of 10-20 nm and a thickness of 50 nm to 1 μm. This significantly shortens the growth cycle of the oxide on the solder surface, increases the upper limit of the oxide thickness, and improves the corrosion resistance of the material.

Description

Technical Field

[0001] The invention relates to radiation-induced solder nanocrystal oxidation and a preparation method thereof, belonging to the technical field of nano material preparation. Background Art

[0002] With the development of the electronics industry and materials science, solders play a vital role in electronic packaging and connection technologies. Sn-based solders are widely used in the interconnection of electronic devices due to their excellent wettability, low melting point, and good mechanical properties. However, with the miniaturization and higher performance of integrated circuits and electronic devices, higher performance requirements are being placed on solders, especially for their corrosion resistance and mechanical stability.

[0003] In existing technologies, Sn-based solders tend to form an oxide layer on their surface during use. While this phenomenon can prevent further oxidation to a certain extent, the traditional oxide layer grows slowly and unevenly, affecting the overall performance of the solder. To improve the corrosion resistance of the solder surface, researchers have attempted to modify it through various methods, such as electroplating, chemical vapor deposition, and physical vapor deposition. However, these methods typically require complex equipment and processes, are costly, and are prone to introducing impurities during processing, affecting the purity and performance of the final product.

[0004] As an emerging material modification method, gamma irradiation technology offers advantages such as uniform treatment, strong penetration, and environmental friendliness, and has shown broad application prospects in the field of material modification. Gamma ray irradiation can effectively induce physical and chemical changes on the material surface under normal temperature and pressure conditions, generating a uniform and dense nanocrystalline oxide layer, thereby improving the material's corrosion resistance. However, research on gamma irradiation modification of Sn-based solders is still in its infancy, lacking systematic research methods and process parameter optimization.

[0005] Therefore, it is urgent to propose a γ-irradiation-induced nanocrystalline oxide layer on the surface of Sn-based solder and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0006] To address the above-mentioned issues, a gamma-irradiation-induced nanocrystalline oxide layer on the surface of a Sn-based solder and a method for preparing the same are provided. A brief overview of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive overview of the invention. It is not intended to identify key or important aspects of the invention, nor is it intended to limit the scope of the invention.

[0007] The technical solution of the present invention:

[0008] A gamma irradiation-induced nanocrystalline oxide layer on the surface of a Sn-based solder is prepared by a gamma irradiation-induced nanocrystalline oxidation preparation method. The nanocrystalline oxide layer on the surface of the Sn-based solder has an average grain diameter of 10-20 nm and a thickness of 50 nm-1 μm.

[0009] A method for preparing Sn-based solder surface nanocrystals by gamma irradiation-induced oxidation comprises the following steps:

[0010] Step 1: Surface pretreatment of solder;

[0011] Step 2: Electron irradiation of the solder.

[0012] Preferably: in step 1, the solder surface is sanded and polished and then dried to remove surface impurities, the sandpaper polishing is sequentially 80 mesh, 240 mesh, 800 mesh, 1500 mesh, 2000 mesh and 3000 mesh, and the polishing is sequentially 0.5 μm diamond polishing agent and water polishing.

[0013] Preferably, step 2 comprises the following steps:

[0014] Step 2.1: Place the Sn-based solder sample in a γ-irradiation device equipped with a potassium silver dichromate dose meter, and measure the γ-irradiation dose rate in the irradiation chamber;

[0015] Step 2.2: Use 60 The brazing material sample was gamma irradiated by gamma rays emitted by Co source;

[0016] Step 2.3: Obtain a solder having a nanocrystalline oxide layer on the surface.

[0017] Preferably: in step 2.1, the solder sample is fixed on the platform surface.

[0018] Preferably, in step 2.2, the irradiation dose rate is 0.05 gy (Si) / s to 0.5 gy (Si) / s, the irradiation time is 300 h to 5000 h, and the total irradiation dose is 5.4 × 10 4 gy~9×10 6 gy.

[0019] Preferably: a method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by γ irradiation is applied to the oxidation of the Sn-based solder.

[0020] Preferably: the Sn-based solder (solder) includes Sn a1 Bi b1 and / or Sn a1 Zn b1Alloy, wherein a1 and a2 correspond to the mass percentage content of each element atom, 50%≤a1≤100%, 5,0%≤b1≤50%, a1+b1=100%.

[0021] Preferably, the platform diameter is 10 cm, in step 2.2, the temperature is 40° C. to 70° C., and the platform rotation speed is 10 rpm to 60 rpm.

[0022] Preferably, the Sn-based solder is in the form of flakes, filaments, spheres, blocks, powders, columns, foils or pastes, or a combination thereof.

[0023] The present invention has the following beneficial effects:

[0024] The present invention provides a method for preparing a nanocrystalline oxide layer on the surface of Sn-based solder induced by γ irradiation. 60 Irradiating the surface of Sn-based solder with Co source γ-rays can obtain uniform nanocrystalline oxide grains on the solder surface, significantly shorten the growth cycle of the oxide on the solder surface, increase the upper limit of the oxide thickness, and improve the corrosion resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 For those who have not passed 60 Low- and high-magnification SEM images of SnBi eutectic solder joints irradiated with Co source γ-rays and placed at room temperature and pressure for 2000 hours;

[0026] Figure 2 After 200h, the dose rate is 0.1gy(Si) / s 60 Low-magnification and high-magnification SEM images of SnBi eutectic solder joints after Co source γ-ray irradiation;

[0027] Figure 3 For those who have not passed 60 Co source γ-ray irradiation of SnBi eutectic solder balls placed at room temperature and pressure for 2000 hours and irradiated for 200 hours at a dose rate of 0.1gy(Si) / s 60 Shear force-displacement curves of SnBi eutectic solder balls after Co source γ-ray irradiation;

[0028] Figure 4 For the unirradiated and 1000h irradiated conditions, the dose rate is 0.3gy(Si) / s 60 TEM bright field image and HRTEM image of SnZn eutectic solder joint after Co source γ-ray irradiation;

[0029] Figure 5 For those who have not passed 60Co source γ-ray irradiation of SnZn eutectic solder balls placed at room temperature and pressure for 2000 hours and irradiated for 1000 hours at a dose rate of 0.3gy(Si) / s 60 Shear force-displacement curves of SnZn eutectic solder balls after Co source γ-ray irradiation;

[0030] Figure 6 For the unirradiated and 1000h, 0.2gy(Si) / s dose rate 60 TEM bright field image and HRTEM image of Sn96.5Ag3Cu0.5 solder joint after Co source γ-ray irradiation;

[0031] Figure 7 Schematic diagram of the irradiation device structure.

[0032] In the figure: 1- connecting rod structure, 2- irradiation chamber shell, 3- irradiation source, 4- platform, 5- one-way valve, 6- bottom plate, 7- solder. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0034] Specific implementation method 1: Combination Figure 1-6 The present embodiment is described. A gamma irradiation-induced nanocrystalline oxide layer on the surface of a Sn-based solder is prepared by a gamma irradiation-induced nanocrystalline oxidation preparation method for the nanocrystalline oxide layer on the surface of the Sn-based solder. The average grain diameter of the Sn-based solder surface oxide nanocrystals in the nanocrystalline oxide layer on the surface of the Sn-based solder is 10-20 nm, and the thickness of the oxide layer is 50 nm-1 μm. The present invention solves the problems of slow growth, uneven oxide grain size, and thin oxide layer thickness of the naturally generated Sn-based solder surface oxide layer under existing room temperature conditions. By optimizing the process method and process parameters, the corrosion resistance and production efficiency of the nanocrystalline oxide layer on the surface of the Sn-based solder are improved.

[0035] Specific implementation method 2: Combination Figure 1-7 This embodiment describes a method for preparing Sn-based solder surface nanocrystals by gamma irradiation-induced oxidation, comprising the following steps:

[0036] Step 1: Surface pretreatment of solder;

[0037] Step 2: Electron irradiation of the solder;

[0038] The present invention proposes a method for preparing a nanocrystalline oxide layer on the surface of Sn-based solder induced by γ irradiation, by using 60 The gamma rays emitted by the Co source are used to irradiate the Sn-based solder, forming uniform nanocrystalline oxide grains on the solder surface. This method can not only significantly shorten the oxide growth cycle, increase the upper limit of oxide thickness, and the oxidation quality of the deep oxide layer, but also significantly improve the corrosion resistance of the Sn-based solder. It has important application value and broad market prospects.

[0039] Specific implementation method three: Combination Figure 1-7 The present embodiment is described. This embodiment provides a method for preparing Sn-based solder surface nanocrystals by γ-irradiation-induced oxidation. In step 1, an appropriate Sn-based solder sample is selected, and its surface is pre-treated by grinding and polishing and then placed in a vacuum drying oven to remove surface impurities and oxide layers. The sandpaper grinding is sequentially 80 mesh, 240 mesh, 800 mesh, 1500 mesh, 2000 mesh and 3000 mesh, and the polishing is sequentially performed with 0.5 μm diamond polishing agent and water polishing.

[0040] Specific implementation method four: Combination Figure 1-7 This embodiment describes a method for preparing Sn-based solder surface nanocrystals by gamma irradiation-induced oxidation, wherein step 2 includes the following steps:

[0041] Step 2.1: Place the potassium silver dichromate dosage 60 In the Co source γ irradiation device chamber, the sample needs to be fixed during rotation, and can be fixed or not fixed under lifting conditions to measure the γ irradiation dose rate;

[0042] Step 2.2: Use 60 Gamma rays emitted by a Co source are used to gamma-irradiate solder samples. As an emerging material modification method, gamma irradiation technology has shown broad application prospects in the field of material modification due to its advantages such as uniform treatment, strong penetration, and environmental friendliness. Gamma ray irradiation can effectively induce physical and chemical changes on the material surface under normal temperature and pressure conditions, generating a uniform and dense nanocrystalline oxide layer, thereby significantly improving the material's corrosion resistance. However, research on gamma irradiation modification of Sn-based solders is still in its infancy, lacking systematic research methods and process parameter optimization.

[0043] Step 2.3: Obtain a solder with a nanocrystalline oxide layer on the surface; this can be used under normal temperature and pressure conditions. 60 Irradiating Sn-based solder with gamma rays emitted by a Co source can obtain uniform nanocrystalline oxide grains on the solder surface, significantly shorten the growth cycle of oxides on the solder surface, and increase the upper limit of oxide thickness; significantly improving the corrosion resistance of Sn-based solder.

[0044] Specific implementation method five: Combination Figure 1-7 This embodiment describes a method for preparing Sn-based solder surface nanocrystals by gamma irradiation-induced oxidation. In step 2.1, the solder sample is fixed on the platform surface, and the fixed sample and the rotating heating platform are placed in a gamma irradiation device. The irradiation device includes an irradiation chamber shell 2, an irradiation source 3 ( 60 Co-γ irradiation source), platform 4, two one-way valves 5 and bottom plate 6. The top of the irradiation chamber shell 2 is provided with an irradiation source 3, and the inlet and outlet pipes on the left and right sides of the upper part of the irradiation chamber shell 2 are provided with one-way valves 5. The side wall of the irradiation chamber shell 2 is provided with an openable and closable door for taking and placing the solder 7. The platform 4 is provided in the room of the irradiation chamber shell 2. The platform 4 is used to place the solder 7. A heating device is provided on the platform 4 for adjusting the temperature of the sample to improve the efficiency. The irradiation chamber shell 2 is fixedly provided on the bottom plate 6. The bottom plate 6 is connected to the platform 4 for rotation or lifting; a chassis is placed on the bottom plate 6, and a motor is connected to the top of the chassis with bolts. The output end of the motor is connected to the rotating shaft through a gearbox, and the rotating shaft is connected to the middle of the platform 4 with a key, so that the platform can be stably placed in the irradiation room. The experimental conditions are normal pressure air conditions. Start the irradiation source and rotate the platform to drive the sample on the horizontal platform to rotate; when the bottom plate 6 is connected to the platform 4 for lifting, the irradiation device also includes a connecting rod structure 1, which is more than two groups. The connecting rod structure 1 includes two hinged connecting rods. The two ends of the connecting rod structure 1 are hinged to the platform 4 and the bottom plate 6 respectively. The edge of the platform 4 is slidably connected to the inner wall of the irradiation chamber shell 2 through a sealed linear bearing. The inner wall of the irradiation chamber shell 2 is provided with a block to limit the lowest point position of the platform 4. The lower space of the platform 4 is connected to the atmosphere. After the solder is placed and the irradiation chamber shell door and valve are closed, the solder is placed in the closed irradiation chamber, the inlet one-way valve is opened to introduce oxygen, and the irradiation chamber is purged. The purged gas is discharged through the outlet one-way valve to fill the irradiation chamber with oxygen. After the oxygen is consumed by the solder, the inlet one-way valve is closed, and the air is extracted through the outlet pipe. The distance between the platform and the irradiation source is adjusted to adjust the vertical position of the solder. After the adjustment is completed, the irradiation source is started. During the process of oxygen consumption by the solder, the gas in the irradiation chamber on the upper side of the platform decreases and the pressure decreases. Without consuming additional energy, the platform 4 rises as the oxygen is consumed, so that the solder is irradiated evenly in the vertical direction. At the same time, as the space decreases, the unit oxygen content remains basically the same, which is suitable for deep oxidation, not only improving the irradiation efficiency, but also improving the irradiation quality.

[0045] Specific implementation method six: combination Figure 1-7The present embodiment is described as a method for preparing Sn-based solder surface nanocrystals by γ-irradiation-induced oxidation. In step 2.2, the Sn-based solder sample is irradiated with any combination of a dose rate and an irradiation time in the range of 300h to 5000h at an irradiation dose rate of 0.05gy(Si) / s to 0.5gy(Si) / s.

[0046] Specific implementation method seven: combination Figure 1-7 This embodiment is described. This embodiment provides a method for preparing nanocrystalline oxidation on the surface of Sn-based solder induced by γ irradiation. A method for preparing nanocrystalline oxide layer on the surface of Sn-based solder induced by γ irradiation is applied to the oxidation of Sn-based solder.

[0047] Specific implementation method eight: combination Figure 1-7 This embodiment describes a method for preparing Sn-based solder surface nanocrystals by gamma irradiation-induced oxidation. The Sn-based solder includes Sn a1 Bi b1 and / or Sn a1 Zn b1 Alloy, wherein a1 and a2 correspond to the mass percentage content of each element atom, 50%≤a1≤100%, 5,0%≤b1≤50%, a1+b1=100%.

[0048] Specific implementation method nine: Combination Figure 1-7 The present embodiment is described. This embodiment provides a method for preparing nanocrystalline oxidation on the surface of Sn-based solder by γ-irradiation-induced oxidation. The platform diameter is 10 cm. In step 2.2, during the irradiation process, the irradiation chamber temperature is 40°C to 70°C, and the platform rotation speed is 10rpm to 60rpm, thereby achieving controllable preparation of nanocrystalline oxide layers on the surface of Sn-based solder with an average grain diameter of 10-20nm and an oxide layer thickness of 50nm-1μm.

[0049] Specific implementation method ten: Combination Figure 1-7 The present embodiment is described as a method for preparing surface nanocrystals of Sn-based solder by γ-irradiation-induced oxidation. The Sn-based solder is in the form of one or more of flakes, filaments, spheres, blocks, powders, columns, foils or pastes.

[0050] Example 1:

[0051] A method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation, comprising the following steps:

[0052] S1. A SnBi eutectic solder ball with a diameter of 400 μm was polished with 80-mesh, 240-mesh, 800-mesh, 1500-mesh, 2000-mesh, and 3000-mesh sandpaper in sequence, and then polished with 0.5 μm diamond polishing agent and water polished. The polished solder joint was placed in a vacuum drying oven;

[0053] S2. Place the potassium silver dichromate dosage agent into 60 In the Co source gamma irradiation device room (irradiation room), mark the position where the irradiation dose rate is 0.2gy(Si) / s;

[0054] The pretreated SnBi eutectic solder ball sample was placed on the surface of the rotating heating platform (platform 2), and the rotating heating platform temperature was selected to be 50°C and the rotation speed was 60 rpm;

[0055] The polished SnBi eutectic alloy solder balls were irradiated at a dose rate of 0.1gy(Si) / s for 200h. 60 Co source γ irradiation.

[0056] See also Figure 1 As shown, it is not 60 Low-magnification and high-magnification SEM images of the surface of the SnBi eutectic solder joint that was irradiated with Co source γ and placed in a room temperature and pressure environment for 200 hours; it can be found that the solder joint surface is smooth and no oxide is generated. Figure 2 As shown, the irradiation time is 200h at a dose rate of 0.1gy(Si) / s under normal temperature and pressure environment. 60 Low-magnification and high-magnification SEM images of the SnBi eutectic solder joint surface after Co source γ-irradiation; it can be found that a dense Sn oxide layer has grown on the solder joint surface; see Figure 3 As shown in Figure 1, Figure (a) is the force-displacement curve of the solder ball without γ irradiation, and Figure (b) is the force-displacement curve of the solder ball after irradiation for 200h and a dose rate of 0.1gy(Si) / s. 60 Force-displacement curve of SnBi eutectic solder ball after Co source γ irradiation. After irradiation time of 200h and dose rate of 0.1gy(Si) / s 60 The shear force of the SnBi eutectic solder ball after Co source γ irradiation increased from 544.17g to 589.88g, and the shear force increased by 8.40%.

[0057] Example 2:

[0058] A method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation, comprising the following steps:

[0059] S1. A SnZn eutectic solder ball with a diameter of 400 μm was polished with 80-mesh, 240-mesh, 800-mesh, 1500-mesh, 2000-mesh and 3000-mesh sandpaper in sequence, then polished with 0.5 μm diamond polishing agent and water polished, and the polished solder joint was placed in a vacuum drying oven;

[0060] S2. Place the potassium silver dichromate dosage agent into 60 In the Co source gamma irradiation device room, mark the position where the irradiation dose rate is 0.2gy(Si) / s;

[0061] The pretreated SnZn eutectic solder ball sample was placed on the surface of a rotating heating platform, and the temperature of the rotating heating platform was selected to be 50°C and the rotation speed was 60 rpm;

[0062] The polished SnZn eutectic solder balls were subjected to a 0.3gy(Si) / s dose rate for 1000h. 60 Co source gamma irradiation; see Figure 5 As shown, Figure (a) is a bright field phase image of the SnZn eutectic TEM sample without γ irradiation; it can be found that there is no oxide in the Sn crystal; Figure (b) is a bright field phase image of the SnZn eutectic TEM sample after irradiation at a dose rate of 0.3gy(Si) / s for 1000h; it can be found that a large number of Sn oxide nanocrystals appear in the Sn crystal; Figure (c) is an HRTEM image of the SnZn eutectic TEM sample after irradiation at a dose rate of 0.3gy(Si) / s for 1000h; it can be found that a large number of SnO2 nanocrystals corresponding to the SnO2 lattice structure appear in the Sn crystal; see Figure 6 As shown in Figure 1, Figure (a) is the force-displacement curve of the solder ball without γ irradiation, and Figure (b) is the force-displacement curve of the solder ball after irradiation for 1000h and a dose rate of 0.3gy(Si) / s. 60 Force-displacement curve of SnZn eutectic solder ball after Co source γ irradiation. After irradiation time of 1000h and dose rate of 0.3gy(Si) / s 60 The shear force of the SnZn eutectic solder ball after Co source γ irradiation increased from 488.68g to 563.95g, and the shear force increased by 15.40%.

[0063] Example 3:

[0064] A method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation, comprising the following steps:

[0065] S1. A Sn96.5Ag3Cu0.5 solder ball with a diameter of 400 μm was polished with 80-mesh, 240-mesh, 800-mesh, 1500-mesh, 2000-mesh, and 3000-mesh sandpaper in sequence, then polished with 0.5 μm diamond polishing agent and water polished. The polished solder joint was placed in a vacuum drying oven.

[0066] S2. Place the potassium silver dichromate dosage agent into 60 In the Co source gamma irradiation device room, mark the position where the irradiation dose rate is 0.2gy(Si) / s;

[0067] The polished Sn96.5Ag3Cu0.5 solder ball was subjected to a 250h treatment at a dose rate of 0.2gy(Si) / s. 60 Co source gamma irradiation. Figure 6 As shown, Figure (a) is the bright field phase image of the Sn96.5Ag3Cu0.5 TEM sample that has not been γ-irradiated; it can be found that there is no oxide in the Sn crystal; Figure (b) is the bright field phase image of the Sn96.5Ag3Cu0.5 TEM sample that has been irradiated at a dose rate of 1gy(Si) / s for 200h; it can be found that a large number of Sn oxide nanocrystals appear in the Sn crystal; Figure (c) is the HRTEM image of the Sn96.5Ag3Cu0.5 TEM sample that has been irradiated at a dose rate of 1gy(Si) / s for 200h; it can be found that a large number of SnO2 nanocrystals corresponding to the SnO2 lattice structure appear in the Sn crystal.

[0068] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0069] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation, characterized in that: The following steps are involved: Step 1: Surface pretreatment of solder; Step 2: Electron irradiation of the solder; Step 2 includes the following steps: Step 2.1: Place the Sn-based solder sample into the γ-irradiation device; Step 2.2: gamma irradiation treatment of the solder sample; In step 2.2, the irradiation dose rate is 0.05gy(Si) / s~0.5gy(Si) / s, the irradiation time is 300h~5000h, and the total irradiation dose is 5.4×10 4 gy~9×10 6 gy; In step 2.2, the temperature is 40°C to 70°C, and the platform speed is 10 rpm to 60 rpm; Step 2.3: Obtaining a solder having a nanocrystalline oxide layer on the surface; The average grain diameter of the nanocrystalline oxide on the surface of the Sn-based solder is 10-20 nm, and the thickness of the oxide layer is 50 nm-1 μm.

2. The method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation according to claim 1, characterized in that: In step 1, the solder surface is sanded and polished and then dried to remove surface impurities. The sandpaper polishing is sequentially 80 mesh, 240 mesh, 800 mesh, 1500 mesh, 2000 mesh and 3000 mesh. The polishing is sequentially performed using 0.5 μm diamond polishing agent and water polishing.

3. The method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation according to claim 1, characterized in that: In step 2.1, fix the solder sample on the platform surface.

4. The method for preparing a nanocrystalline oxide layer on the surface of a Sn-based solder induced by gamma irradiation according to claim 1, characterized in that: Sn-based solders include Sn a1 Bi b1 and / or Sn a1 Zn b1 Alloy, where a1 and b1 correspond to the mass percentage of atoms of each element, 50%≤a1≤100%, 0%≤b1≤50%.

5. The method for preparing a nanocrystalline oxide layer on the surface of Sn-based solder induced by gamma irradiation according to claim 1, characterized in that: The Sn-based solder is in the form of one or more of flakes, filaments, balls, blocks, powders, columns, foils or pastes.

Images