Method for representing cuprous oxide particles in fine copper wire

Abstract

The invention relates to the technical field of cuprous oxide particle testing, and discloses a method for characterizing cuprous oxide particles in a fine copper wire, which comprises the following steps: S1, fixing the fine copper wire on a copper sheet by using conductive silver paste, putting the copper sheet into a silica gel square mold, filling a metallographic phase cold inlay, and standing for 30 minutes to obtain a cured sample; s2, putting the cured sample obtained in the step S1 into a cross section cutting sample table of a three-ion-beam cutting instrument, selecting a cross section mode, setting ion gun voltage and ion beam cutting time, and starting a cutting program; and S3, transferring the sample obtained in the step S2 into a scanning electron microscope, selecting an electron channel contrast imaging mode, and setting acceleration voltage, current, working distance and magnification times to obtain a high-resolution scanning electron microscope image of the cross section of the fine copper wire. And key information such as the size, the morphology and the distribution condition of cuprous oxide particles and the interface bonding condition of the cuprous oxide particles and a copper matrix is obtained from the cuprous oxide particles. Therefore, a basis is provided for formulating a reasonable fine copper wire drawing process and a bus continuous casting and rolling process.

Description

Technical Field

[0001] The present invention relates to the technical field of testing copper oxide particles in copper wires, and particularly to a method for characterizing copper oxide particles in fine copper wires. Background Art

[0002] Copper wires with a diameter less than 0.1 mm are generally defined as fine copper wires. Fine copper wires are widely used in packaging wires for the back-end packaging process of integrated circuits, micro-motors, high-frequency ultra-fine coaxial wires connecting LCD (Liquid Crystal Display) and the main board, cables for high-speed broadband transmission, wires for high-speed transmission in computer peripheral systems, and fine wires for biochemical medical use, etc. With the rapid development of the electronic information industry, especially the rapid development of notebook computers, mobile communication products, and terminal signal transmission products, the demand for ultra-fine copper wires will increase day by day.

[0003] At present, fine copper wires are all produced by the drawing method. The drawing method has the characteristics of high production efficiency, high product size accuracy, and simple production equipment. However, due to the small size of ultra-fine copper wire products, the tension they can withstand is very limited, and it is easy to break during the drawing process, especially at the end of the drawing process, due to the too small wire diameter, the probability of breaking is relatively high. Wire breakage is the main obstacle in the production of ultra-fine copper wires and the main factor causing the rejection rate of products. There are many reasons for wire breakage. Among them, the size, morphology, distribution, and interface characteristics with the matrix of copper oxide particles in fine copper wires have a significant impact on the wire breakage rate. However, due to the small diameter of fine copper wires, when using traditional grinding and polishing techniques, the samples are easily deformed or mechanically damaged, thus masking the true structural information inside the samples. Therefore, it is difficult for traditional grinding and polishing techniques to detect the size, morphology, distribution of copper oxide particles in fine copper wires, and the interface bonding situation with the copper matrix. Summary of the Invention

[0004] To solve the problems existing in the prior art, the purpose of the present invention is to provide a method for characterizing copper oxide particles in fine copper wires, which can clearly observe the size, morphology, distribution of copper oxide particles in fine copper wires, and their interface bonding situation with the copper matrix, and provide a theoretical basis for reducing the wire breakage rate during the drawing process of fine copper wires.

[0005] The present invention proposes the following technical solution: A method for characterizing copper oxide particles in fine copper wires, comprising the following steps: S1. Fix a fine copper wire with a diameter of 20 - 100 microns on a copper sheet with conductive silver paste, place it in a silicone square mold, fill it with a metallographic cold inlay material, and after standing for 30 minutes, obtain a solidified sample; S2. Place the solidified sample obtained in S1 in the cross-section cutting sample stage of a triple ion beam cutter, select the cross-section mode, set the ion gun voltage and the ion beam cutting time, and start the cutting program; S3. Transfer the sample obtained in step S2 to a scanning electron microscope, select the electron channel contrast imaging mode, set the acceleration voltage, current, working distance, and magnification, and obtain a high-resolution scanning electron microscope image of the cross-section of the fine copper wire.

[0006] Further, in step S2, the ion gun voltage is 6.5 - 8 kV, and the ion beam cutting time is 2 - 5 hours.

[0007] Further, in step S3, the acceleration voltage is 10 - 15 kV, the current is 13 - 26 nA, and the working distance is 5 - 6 mm.

[0008] Further, the conductive silver paste is preferably the DJ912 type conductive silver paste of the MECHANIC brand, the metallographic cold inlay material is preferably the XYX - 604 type metallographic cold inlay material of the Yongying brand, and the triple ion beam cutting instrument is preferably the Leica EM TIC 3X model triple ion beam cutting instrument.

[0009] Principle of the present invention: When the focused ion beam impacts the fine copper wire fixed and leveled by the metallographic cold inlay material at a specific angle, the molecules of the cold inlay material and the metal atoms of the copper wire will be impacted and removed, thereby obtaining a cross-section of the fine copper wire without stress damage. The metallographic cold inlay material not only plays a role in fixing the fine copper wire but also fills the originally arc-shaped surface of the copper wire into a flat surface, thus significantly improving the cutting effect of the ion beam.

[0010] When the electron beam of the scanning electron microscope irradiates this cross-section, if the electron beam and the crystal orientation on the cross-section satisfy the Bragg diffraction condition, these crystals will appear as darker regions in the image; conversely, if the crystal orientation does not satisfy the Bragg diffraction condition, they will appear as brighter regions. Through this light and dark contrast, we can clearly observe the morphology, size, and internal defects of the copper crystals.

[0011] After identifying the copper crystals, we can further observe the cuprous oxide particles distributed between and inside the copper crystals, as well as the interfacial bonding situation between these particles and the copper crystals.

[0012] The present invention has the following beneficial effects: By using the method of the present invention, a high-resolution scanning electron microscope image of the cross-section of the fine copper wire can be obtained quickly and conveniently. These images will provide key information such as the size, morphology, distribution of the cuprous oxide particles, and the interfacial bonding characteristics with the copper matrix. This information is crucial for optimizing the drawing process of the fine copper wire and the continuous casting and rolling process of the bus bar, and helps to formulate a more reasonable production process flow. Description of the drawings

[0013] Figure 1Optical microscope image of the sample in Embodiment 1 of the present invention after being processed by a triple ion beam cutting instrument; Figure 2 Optical microscope image of the sample in Embodiment 2 of the present invention after being processed by a triple ion beam cutting instrument; Figure 3 High-resolution scanning electron microscope image obtained in Embodiment 3 of the present invention; Figure 4 High-resolution scanning electron microscope image obtained in Embodiment 4 of the present invention; Figure 5 High-resolution scanning electron microscope image obtained in Embodiment 5 of the present invention; Figure 6 High-resolution scanning electron microscope image obtained in Embodiment 6 of the present invention; Wherein, 1 - copper sheet, 2 - metallographic cold inlay material, 3 - fine copper wire, 4 - copper crystal, 5 - cuprous oxide particles. Specific embodiments

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments, but it is not used as a basis for limiting the present invention. Embodiment 1

[0015] Refer to Figure 1 , fix a 20 - 100 micron fine copper wire on the copper sheet with conductive silver paste, place it in a soft silicone square mold, and fill it with metallographic cold inlay material. After standing for 30 minutes, a cured sample is obtained; put the obtained cured sample on the cross-section cutting standard sample stage of a triple ion beam cutting instrument, and select the cross-section mode. The ion beam action direction is parallel to the cross-section of the fine copper wire. Set the ion gun voltage to 6.5 kV and the ion beam cutting time to 5 hours, and start the cutting program. After the cutting is completed, the optical microscope image of the sample is as shown in Figure 1 shown.

[0016] The conductive silver paste specifically uses DJ912 type conductive silver paste of the MECHANIC brand, the metallographic cold inlay material uses XYX - 604 type metallographic cold inlay material of the Yongying brand, and the triple ion beam cutting instrument uses a Leica EM TIC 3X model triple ion beam cutting instrument. Embodiment 2

[0017] Refer to Figure 2 , the difference from Embodiment 1 is that the ion beam action direction is parallel to the longitudinal section of the fine copper wire, the ion gun voltage is 8.0 kV, and the ion beam cutting time is 2 hours. After the cutting is completed, the optical microscope image of the sample is as shown in Figure 2 shown. Embodiment 3

[0018] Refer to Figure 3, the sample obtained in Example 1 was transferred to a scanning electron microscope. The electron channel contrast imaging mode was selected, and the acceleration voltage was set to 10 kV, the current was 26 nA, and the working distance was 5 mm. From the captured image ( Figure 3 ), it can be seen that the cuprous oxide particles in the fine copper wire are nearly spherical, with a size of 0.5 - 2 microns, and are distributed both between and inside the copper grains. Example 4

[0019] Refer to Figure 4 , the sample obtained in Example 2 was transferred to a scanning electron microscope. The electron channel contrast imaging mode was selected, and the acceleration voltage was set to 15 kV, the current was 13 nA, and the working distance was 6 mm. From the captured image ( Figure 4 ), the aggregation situation of the cuprous oxide particles in the fine copper wire can be seen. Example 5

[0020] Refer to Figure 5 , the difference from Example 4 is that the acceleration voltage is 10 kV, the current is 26 nA, and the working distance is 5 mm. From the captured image ( Figure 5 ), it can be seen that there is an obvious gap at the interface between the cuprous oxide particles and the copper matrix. Example 6

[0021] Refer to Figure 6 , the difference from Example 1 is that after fixing the fine copper wire on the copper sheet surface with conductive silver paste, the fine copper wire is not filled and fixed with metallographic cold embedding material. The sample cut by ion beam was transferred to a scanning electron microscope. The electron channel contrast imaging mode was selected, and the acceleration voltage was set to 10 kV, the current was 26 nA, and the working distance was 5 mm. The captured image ( Figure 6 ) has obvious curtain effect and the deficiency that some grains are difficult to distinguish.

[0022] From the image results of Examples 1 - 6, it can be seen that by using the method of the present invention, high - resolution scanning electron microscope images of the cross - section of fine copper wire can be obtained quickly and conveniently. These images will provide key information such as the size, morphology, distribution of cuprous oxide particles, and the interfacial bonding characteristics with the copper matrix.

[0023] The above - mentioned are only the preferred examples of the present invention, and do not impose any formal or substantial limitations on the present invention. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. Any equivalent changes and modifications made to the above examples based on the essential technology of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A method for characterizing cuprous oxide particles in fine copper wires, characterized in that, Including the following steps: S1. Fix the fine copper wire on the copper sheet with conductive silver paste, place it in a silicone square mold, fill it with metallographic cold inlay material, and obtain a cured sample after standing for 30 minutes; S2. Place the cured sample obtained in S1 in the cross-section cutting sample stage of a triple ion beam cutting instrument, select the cross-section mode, set the ion gun voltage and ion beam cutting time, and start the cutting program to perform cutting to obtain a cut sample; S3. Transfer the cut sample obtained in step S2 to a scanning electron microscope, select the electron channel contrast imaging mode, set the acceleration voltage, current, working distance and magnification, and obtain a high-resolution scanning electron microscope image of the cross-section of the fine copper wire.

2. The method for characterizing cuprous oxide particles in fine copper wires according to claim 1, characterized in that: The ion gun voltage in step S2 is 6.5 - 8 kV, and the ion beam cutting time is 2 - 5 hours.

3. A method for characterizing cuprous oxide particles in fine copper wires according to claim 1, wherein: The acceleration voltage in step S3 is 10 - 15 kV, the current is 13 - 26 nA, and the working distance is 5 - 6 mm.

4. A method for characterizing cuprous oxide particles in fine copper wires according to claim 1, characterized in that: The diameter of the fine copper wire is 20 - 100 microns.

5. A method for characterizing cuprous oxide particles in fine copper wires according to claim 1, characterized in that: The conductive silver paste is MECHANIC brand DJ912 type conductive silver paste, the metallographic cold inlay material is Yongying brand XYX-604 type metallographic cold inlay material, and the triple ion beam cutting instrument uses a triple ion beam cutting instrument of Leica EM TIC 3X model.

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