Method for detecting content of zn element in surface treatment layer of calendered copper foil

Abstract

The application discloses a kind of detection methods of Zn element content in calendered copper foil surface treatment layer, and the non-detection face of calendered copper foil is pressed with prepreg, and the face to be detected is reserved to prepare detection sample, detection sample is placed in nitric acid, ethanol mixed solvent, after plating layer is dissolved, it is taken out, and the content of zinc element in solvent after ICP method determination dissolved plating layer is determined.The application can protect the surface of calendered copper foil from being damaged by pressing prepreg with the non-detection face of calendered copper foil, and reduce the interference of zinc or copper element in matrix on detection result;The mixed solvent for dissolving zinc layer is slow in reaction speed compared with plating layer, which is convenient for operator to observe the dissolution degree of plating layer, and the extraction work of plating layer is completed simply and quickly;The detection method of Zn element content in calendered copper foil surface treatment layer is simple, fast, safe and pollution-free in sample preparation and testing process.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy quality analysis technology, specifically relating to a method for detecting the Zn element content in the surface treatment layer of rolled copper foil. Background Technology

[0002] Rolled copper foil products possess excellent ductility, flexural strength, low roughness, and high folding endurance, making them a fundamental material for flexible printed circuit boards (PCBs), primarily used in flexible and high-frequency circuit boards. To meet the requirements of PCBs for copper foil's oxidation resistance, heat resistance, corrosion resistance, and solderability, the surface of rolled copper foil typically undergoes anti-oxidation treatment, blackening treatment, and reddening treatment. The heat resistance and corrosion resistance of the copper foil after surface treatment are mainly determined by the Zn content in the plating. Reducing the zinc content often leads to decreased high-temperature oxidation resistance and increased corrosion resistance, while increasing the zinc content increases heat resistance but decreases corrosion resistance. Therefore, in the development of new rolled copper foil products and process optimization, personnel need to accurately test the Zn content in the plating to control the balance between corrosion resistance and high-temperature oxidation resistance, providing a basis for new product development and process optimization.

[0003] The coating thickness of electrodeposited copper foil is typically 0.1~0.2µm. Alloying occurs between the coating and the copper foil substrate, and the copper foil and coating cannot be mechanically peeled off. Traditional testing methods require dissolving both the copper foil and the coating completely before performing spectral analysis on each element. However, this method has the following problems: First, if the copper foil substrate contains Zn, the analytical results will be inaccurate and biased. Second, the copper foil substrate is pure copper with a content of 99.95% or higher. The curing and roughening processes of the copper foil surface treatment involve depositing a dense and porous Cu layer on the copper foil surface. Since Cu and Zn exhibit strong spectral interference during testing, this will affect the Zn element test results. Furthermore, the traditional standard curve method involves cumbersome sample preparation, requires numerous reagents, and can introduce significant errors during testing.

[0004] In conclusion, developing a method for detecting the zinc content on the surface of rolled copper foil, improving the accuracy and sensitivity of the test, and reducing the complexity of the test, is of great significance for the development of new rolled copper foil products and process optimization. Summary of the Invention

[0005] To address the problems of low accuracy, numerous interfering factors, and complex testing processes in existing technologies for testing zinc content on the surface of rolled copper foil, this invention provides a method for detecting the Zn content in the surface treatment layer of rolled copper foil. After effectively bonding a prepreg to the copper foil, a solvent of a certain proportion is prepared to dissolve the coating on the copper foil surface, while retaining the substrate foil. The standard addition method is used to accurately analyze and measure the Zn content in the coating using the dissolved solution.

[0006] This invention is achieved through the following technical solution:

[0007] A method for detecting the Zn content in the surface treatment layer of rolled copper foil, comprising the following steps:

[0008] (1) Press the non-test side of the rolled copper foil with the prepreg, leaving the test side intact, to prepare the test sample;

[0009] (2) Place the test sample prepared in step (1) in a mixed solvent of nitric acid and ethanol, and take it out after the coating has dissolved;

[0010] (3) The zinc content in the solvent after dissolving the coating in step (2) was determined by ICP method.

[0011] Furthermore, the thickness of the rolled copper foil is 12~35µm.

[0012] Further, in step (2), the volume ratio of nitric acid to ethanol in the mixed solvent is 1:1, and the concentration of nitric acid is 10wt%.

[0013] Furthermore, the ICP method described herein employs the standard addition method.

[0014] Beneficial effects

[0015] This invention protects the surface of the rolled copper foil from damage by pressing the prepreg onto the non-detection side of the rolled copper foil, and reduces the interference of zinc or copper elements in the substrate on the detection results.

[0016] The mixed solvent used in this invention to dissolve the zinc plating layer reacts with the coating layer at a relatively slow rate, making it easier for operators to observe the degree of coating dissolution and allowing for simple and quick extraction of the coating layer.

[0017] This invention employs a standard addition method, which can eliminate the spectral interference of copper on zinc during the use of plasma emission spectrometers. Compared with the standard curve method in the national standard method, it does not require electrolytic copper removal or the addition of hazardous chemicals such as lead nitrate and manganese nitrate; it only requires the addition of elemental standard solutions. The entire method is simple, fast, safe, and pollution-free in sample preparation and testing. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0019] Example 1

[0020] (1) Press the non-testing side of the rolled copper foil with the prepreg (heat the prepreg to 140±5℃ and press it with the non-testing side of the copper foil with a hot press when it reaches the flow state), retain the side to be tested, and prepare a test sample;

[0021] (2) Place the test sample prepared in step (1) in a mixed solvent of nitric acid and ethanol. The volume ratio of 10% nitric acid to anhydrous ethanol is 1:1. After the coating is dissolved and the color of the copper foil itself is revealed, take it out.

[0022] (3) The ICP method uses the standard addition method to determine the zinc content in the solvent after dissolving the coating in step (2); the solution dissolved in step (2) is diluted to 100 ml, and 0, 10, 20, 30 and 40 ml are transferred to 50 ml volumetric flasks and 0, 1, 2, 3 and 4 ppm of elemental elements are added in sequence to form a series of standard solutions. The zinc content in each standard solution is measured by ICP, and a working curve is plotted. The curve is extrapolated and intersected with the concentration axis. The intercept on the concentration axis is the concentration of the sample solution.

[0023] The zinc content in known samples was determined using the above method (the standard sample was rolled black foil, with a copper foil thickness of 12 μm and a zinc plating layer thickness of 5 nm). The results are shown in Table 1 below:

[0024] Table 1 Test results of standard samples

[0025]

[0026] Example 2

[0027] Recovery rate experiment

[0028] Spiked recovery experiments were conducted on two samples to determine the recovery amount of each element and then calculate the recovery rate. The results are shown in Table 2 below. As can be seen from Table 2, the recovery rate of zinc element tested by the method of the present invention is between 86% and 112%. The recovery rate results show that it meets the test requirements.

[0029] Table 2 Results of Spiked Recovery Experiment

[0030] .

[0031] Example 3

[0032] Precision analysis

[0033] The precision experiment was performed on the sample, and the results are shown in Table 3 below. The precision of the measured elements is less than 1%, which meets the test requirements.

[0034] Table 3 Precision Experiment Results

[0035] .

Claims

1. A method for detecting the content of Zn element in a surface treatment layer of a rolled copper foil, characterized by, Includes the following steps: (1) When the prepreg is heated to 140±5℃ and reaches the flow state, the non-test side of the rolled copper foil is pressed together with the prepreg using a hot press, while the test side is retained, and the test sample is prepared. (2) Place the test sample prepared in step (1) in a nitric acid and ethanol mixed solvent with a volume ratio of 1:1, and take it out after the coating has dissolved; the concentration of nitric acid is 10 wt%. (3) The zinc content in the solvent after dissolving the coating in step (2) was determined by ICP method.

2. The method for detecting the Zn element content in the surface treatment layer of rolled copper foil according to claim 1, characterized in that, The thickness of the rolled copper foil is 12~35µm.

3. The method for detecting the Zn element content in the surface treatment layer of rolled copper foil according to claim 1, characterized in that, The ICP method described uses the standard addition method.

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