Quantitative method for zinc plating amount on surface of copper foil, composite film and circuit board

Abstract

The invention relates to the technical field of copper foil surface galvanization, in particular to a method for quantifying the galvanization amount of a copper foil surface, a composite film and a circuit board. The invention provides a method for quantifying the zinc plating amount on the surface of a copper foil. The zinc plating amount on the surface of the copper foil meets the following formula (1): # imgabs0 #, wherein W represents the zinc plating amount on the surface of the copper foil, the unit is mg / m < 2 >, W0 represents the initial zinc plating amount, the unit is mg / m < 2 >, W0 is larger than 0, k represents a constant, I represents the electroplating current density, the unit is A / m < 2 >, pH represents the real-time pH value in the zinc plating process, pH 0 represents the preset control value, and calculation is dimensionless. According to the quantitative method for the zinc plating amount on the surface of the copper foil, the zinc plating amount on the surface of the copper foil can be theoretically calculated according to the parameters of the production equipment and the process conditions, the zinc plating amount on the surface of the copper foil can be more conveniently regulated and controlled from the process, and the process control and processing efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of copper foil surface zinc plating, and in particular to a method for quantifying the amount of zinc plating on the copper foil surface, a composite film and a circuit board. Background Art

[0002] In circuit boards or electronic components, copper foil, as the primary conductive material, can provide a low-resistance current path. However, due to the problems of copper foil being susceptible to oxidation corrosion and having poor wear resistance, most of the current methods are currently to protect the copper foil by zinc plating on its surface. At the same time, zinc-plated copper foil can also improve the welding performance of the copper foil and enhance process adaptability. Existing technologies generally galvanize copper foil by electrogalvanizing, hot-dip galvanizing, or vacuum galvanizing. The amount of zinc plating is generally measured by specific instruments, such as X-ray fluorescence spectrometers and inductively coupled plasma emission spectrometers. However, on the one hand, the method of measuring the amount of zinc plating cannot accurately control the amount of zinc plating on the copper foil, which not only leads to waste of resources, but also causes insufficient or excessive plating of the galvanized copper foil after processing. Insufficient plating can lead to poor electroplating adhesion, while excessive plating can affect surface flatness and circuit accuracy. On the other hand, during the processing process, each zinc content test by instrument requires a lot of time to process samples, which increases personnel and time costs. At the same time, when the number of samples is large, the instrument measurement test speed is slow, which is not conducive to the control of the copper foil production process and low efficiency. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the above-mentioned defects, thereby providing a method for quantifying the amount of zinc plating on the surface of copper foil, a composite film and a circuit board.

[0004] After extensive research, the inventors found that, under the conditions that factors such as electroplating time, electroplating area, and zinc ion concentration of the zinc plating solution are constant, the amount of zinc plating on the copper foil surface is proportional to the electroplating current; when the pH value of the zinc plating solution fluctuates, it has a certain impact on the electroplating efficiency, and thus affects the amount of zinc plating. The research found that the effect of pH on the electroplating efficiency is close to an exponential relationship; and the amount of zinc plating must be a positive real number. The proportional relationship between the zinc plating current and the amount of zinc plating requires that the current has a certain intensity to achieve a stable electroplating effect. Therefore, it is proportional within a certain range of positive real numbers, rather than proportional starting from 0, which means that the amount of zinc plating must be greater than a certain initial value.

[0005] Based on this, the present invention provides a method for quantifying the amount of zinc plating on the surface of a copper foil, wherein the amount of zinc plating on the surface of the copper foil satisfies the following formula (1): (1); Where W represents the zinc coating amount on the copper foil surface, in mg / m 2 , W0 represents the initial galvanizing amount, the unit is mg / m 2, and W0>0, k represents a constant, I represents the electroplating current density, the unit is A / m 2 , pH represents the real-time pH value during the galvanizing process, pH0 represents the preset control value, and the calculation is dimensionless. In formula (1), e represents the natural exponential function.

[0006] Formula (1) shows that under the conditions of stable equipment parameters, constant zinc ion concentration, and constant flow rate, the amount of zinc plating on the copper foil surface is mainly affected by the current and the pH of the plating solution. In a certain positive real number interval, the amount of zinc plating is proportional to the current and exponentially related to the pH of the plating solution. According to the relationship in formula (1), the theoretical zinc plating content on the copper foil surface can be calculated based on the parameters and process conditions of the production equipment. By inputting information such as equipment parameters, zinc ion concentration of the plating solution, and pH of the plating solution, the amount of zinc plating can be theoretically calculated, thereby saving instrument testing time and making it easier to timely control the amount of zinc plating on the copper foil surface from a process perspective, thereby improving process control capabilities and processing efficiency.

[0007] For example, the initial zinc coating amount W0 is 1 mg / m 2 , 1.5mg / m 2 , 3mg / m 2 , 5mg / m 2 , 8mg / m 2 , 11mg / m 2 , 15mg / m 2 , 20mg / m 2 , 50mg / m 2 Or any interval consisting of two values.

[0008] In some embodiments, 0<pH0<14, illustratively, pH0 is 1, 2, 5, 7, 7.5, 8.2, 10.5, 10.6, 11, 12, 14 or an interval consisting of any two values.

[0009] The amount of zinc plating on the surface of the copper foil is related to the electroplating current, electroplating area, electroplating efficiency, zinc ion concentration in the electroplating solution, and pH of the electroplating solution. The embodiment of the present invention determines the amount of zinc plating on the surface of the copper foil by determining the influence of the above-mentioned influencing factors on the amount of zinc plating and establishing a corresponding functional relationship. In the production process of copper foil galvanizing, for the same equipment, parameters such as electroplating time and electroplating area are all controlled by the equipment, and the zinc ion concentration in the zinc plating solution and the flow rate of the zinc plating solution are controlled by the dosing circulation system and fluctuate within a very small range. Therefore, the parameters such as electroplating time and electroplating area controlled by the equipment and the parameters such as zinc ion concentration in the zinc plating solution and the flow rate of the zinc plating solution controlled by the dosing system are constants. The constant k in formula (1) satisfies the following formula (2): k = t × v × c / S (2); wherein t represents the electroplating time, the unit is s, and v represents the flow rate of the zinc plating solution, the unit is m 3 / h, v represents the zinc ion concentration in the zinc plating solution, the unit is g / L, S represents the electroplating area, the unit is dm 2 The calculation formula in this embodiment is dimensionless. Preferably, the plating time t is 20-60s. For example, the plating time can be 20s, 25s, 30s, 40s, 42s, 50s, 55s, 60s or an interval consisting of any two values. Preferably, the plating solution flow rate is 0.5-20m 3 / h, for example, the plating solution flow rate is 0.5m 3 / h、1.5m 3 / h、5m 3 / h、10m 3 / h、15m 3 / h、20m 3 / h or an interval consisting of any two values; preferably, the zinc ion concentration of the zinc plating solution is 5-25g / L, and exemplary, the zinc ion concentration of the zinc plating solution is 5g / L, 8g / L, 10g / L, 13g / L, 15g / L, 20g / L, 24g / L, 25g / L or an interval consisting of any two values; preferably, the electroplating area is 2-200dm 2 , for example, the plating area is 2dm 2 5dm 2 , 15dm 2 50dm 2 、60dm 2 、80dm 2 , 100dm 2 、150dm 2 , 200dm 2 Or any interval consisting of two values.

[0010] The electroplating efficiency is determined by the conductive efficiency of the equipment, and the conductive efficiency is generally constant due to the influence of the equipment. In order to obtain a more accurate zinc plating amount, the embodiment of the present invention classifies the electroplating efficiency into the range of a constant k. Specifically, the k satisfies the following formula (3): k=η×t×v×c / S(3); wherein η represents the electroplating efficiency and is dimensionless.

[0011] Preferably, the electroplating efficiency η satisfies 0.9≤η≤0.99. Exemplarily, the electroplating efficiency is 0.9, 0.92, 0.93, 0.95, 0.98, 0.99 or an interval consisting of any two values.

[0012] It should be noted that when switching equipment, only the constant k needs to be corrected. After re-entering the electroplating time t, electroplating area S, equipment electroplating efficiency η, zinc ion concentration c of the zinc plating solution, and plating solution flow rate v, the above formula still applies.

[0013] In some embodiments, the constant k is in the range of 0.1 to 8.5. For example, the constant k is 0.1, 1.0, 2.0, 3.0, 4.5, 5.0, 6.2, 7.5, 8.0, 8.5, or an interval consisting of any two values.

[0014] In some embodiments, the electroplating current density I is in the range of 5 to 50 A / dm 2 For example, the electroplating current density I is 5A / dm 2 , 8A / dm 2 、10A / dm 2 、15A / dm 2 , 25A / dm 2 、30A / dm 2 、35A / dm 2 、40A / dm 2 、50A / dm 2 Or any interval consisting of two values.

[0015] On the other hand, the present invention also provides a copper foil, which is galvanized using the above-mentioned method for quantifying the amount of zinc plated on the surface of the copper foil.

[0016] The present invention also provides a composite film comprising the above copper foil.

[0017] Optionally, the composite film may be a metal-clad laminate, an electromagnetic shielding film, an absorbing film, an RCC film, a peelable metal foil with a carrier, an embedded barrier metal foil, an embedded capacitance metal foil, a PET composite metal foil or other composite film materials.

[0018] The present invention also provides a circuit board, comprising the above-mentioned copper foil and / or the above-mentioned composite film. DETAILED DESCRIPTION

[0019] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0020] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0021] Example 1

[0022] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are as follows:

[0023] (1) According to the electroplating time t, electroplating area S, zinc ion concentration c of the zinc plating solution, and zinc plating flow rate v of the production equipment, the constant k = 0.75 is determined, where the electroplating time t is 20s and the electroplating area S is 133dm 2 , zinc ion concentration c of galvanizing solution is 10g / L, galvanizing flow rate v is 0.5m 3 / h.

[0024] (2) Calculate the zinc coating amount W on the copper foil surface according to formula (1), where the electroplating current density I is 24A / m 2 During the galvanizing process, the real-time pH value is 10.6, and the preset control pH value pH0 is 10.5. W = 11 + 0.75 × 24 × e (10.6-10.5) =30.8931mg / m 2 .

[0025] (3) galvanizing the copper foil using the production equipment provided in step (1); after the galvanizing is completed, the amount of galvanized copper foil surface is measured by atomic absorption spectrometry (AAS).

[0026] The specific steps for determining the zinc content on the surface of copper foil by atomic absorption spectrometry are as follows:

[0027] Cut a certain area of copper foil sample and accurately record its area or mass.

[0028] Place the copper foil sample in an appropriate amount of acid (such as dilute nitric acid) and dissolve the zinc on the surface of the copper foil under appropriate conditions (such as heating and stirring) to form a solution containing zinc ions. During the dissolution process, care should be taken to avoid splashing and volatilization of the solution.

[0029] Transfer the dissolved solution to a volumetric flask, dilute to a certain volume with deionized water, and shake well for later use. Meanwhile, prepare a blank solution, which is the same as the sample solution preparation except that the copper foil sample is not added.

[0030] Accurately weigh a certain amount of zinc standard substance (such as benchmark zinc oxide), dissolve it with an appropriate amount of acid, and transfer it to a volumetric flask to prepare a zinc standard stock solution, the concentration of which is usually 1000 μg / mL or higher.

[0031] Appropriate amounts of zinc standard stock solution were taken separately and diluted with deionized water to prepare a series of standard working solutions of different concentrations, such as 0.1 μg / mL, 0.5 μg / mL, 1.0 μg / mL, 2.0 μg / mL, 5.0 μg / mL, etc. The specific concentration range can be adjusted according to the estimated zinc content in the sample.

[0032] Aspirate the prepared sample solution into the atomic absorption spectrometer, perform spray measurement, and record the absorbance value of the sample solution.

[0033] Each sample solution should be measured at least three times, and the average value should be taken as the measurement result to reduce the measurement error.

[0034] According to the absorbance value of the sample solution, the corresponding zinc concentration is found from the standard curve. Then, according to the dilution factor of the sample solution and the area or mass of the copper foil sample, the zinc content on the copper foil surface is calculated. The calculation formula is as follows:

[0035]

[0036] Where ω(Zn) is the zinc content on the copper foil surface (mg / cm 2 or mg / g);

[0037] ρ is the concentration of zinc in the sample solution obtained from the standard curve (μg / mL);

[0038] V is the volume of the sample solution (mL);

[0039] n is the dilution factor of the sample solution;

[0040] m is the mass of the copper foil sample (g);

[0041] S is the area of the copper foil sample (cm 2 ).

[0042] The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0043] Example 2

[0044] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are the same as those in Example 1, except that the electroplating current I is 28 A / m 2 After calculation, the zinc coating amount W on the copper foil surface is 34.2086 mg / m 2 ; The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0045] Example 3

[0046] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are the same as those in Example 1, except that the electroplating current I is 32 A / m 2 After calculation, the zinc coating amount W on the copper foil surface is 3.5241 mg / m 2 ; The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0047] Example 4

[0048] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are the same as those in Example 1, except that the electroplating current I is 32 A / m 2The real-time pH value during the galvanizing process is 10.4. The calculated zinc coating amount W on the copper foil surface is 32.7161 mg / m 2 ; The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0049] Example 5

[0050] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are the same as those in Example 1, except that the electroplating current I is 28 A / m 2 The real-time pH value during the galvanizing process is 10.4. The calculated zinc coating amount W on the copper foil surface is 30.0016 mg / m 2 ; The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0051] Example 6

[0052] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are as follows:

[0053] (1) According to the electroplating time t, electroplating area S, zinc ion concentration c of the zinc plating solution, zinc plating flow rate v, and electroplating efficiency η of the production equipment, the constant k = 0.71 is determined, where the electroplating time t is 20s and the electroplating area S is 133dm 2 , zinc ion concentration c of galvanizing solution is 10g / L, galvanizing flow rate v is 0.5m 3 / h, and the electroplating efficiency η is 0.95.

[0054] (2) Calculate the zinc coating amount W on the copper foil surface according to formula (1), where the electroplating current density I is 24A / m 2 During the galvanizing process, the real-time pH value is 10.6, and the preset control pH value pH0 is 10.5. W = 11 + 0.71 × 24 × e (10.6-10.5) =29.8321mg / m 2 .

[0055] (3) The copper foil is galvanized using the production equipment provided in step (1). After the galvanizing is completed, the amount of galvanized copper foil surface is measured. The measured amount of galvanized copper foil surface is shown in Table 1.

[0056] Example 7

[0057] This embodiment provides a method for quantifying the amount of zinc plating on the surface of copper foil. The specific steps and parameters are the same as those in Example 6. The difference is that the electroplating efficiency η is 0.98, and the amount of zinc plating on the surface of the copper foil W is calculated to be 30.6278 mg / m 2 ; The measured zinc coating amount on the copper foil surface is shown in Table 1.

[0058] Example 8

[0059] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are as follows:

[0060] (1) According to the electroplating time t, electroplating area S, zinc ion concentration c of the zinc plating solution, and zinc plating flow rate v of the production equipment, the constant k = 3 is determined, where the electroplating time t is 20s and the electroplating area S is 200dm 2 , zinc ion concentration c of galvanizing solution is 5g / L, galvanizing flow rate v is 5m 3 / h.

[0061] (2) Calculate the zinc coating amount W on the copper foil surface according to formula (1), where the electroplating current density I is 24A / m 2 During the galvanizing process, the real-time pH value is 10.6, and the preset control pH value pH0 is 10.5. W = 11 + 3 × 24 × e (10.6-10.5) =90.5723mg / m 2 .

[0062] (3) The copper foil is galvanized using the production equipment provided in step (1). After the galvanizing is completed, the amount of galvanized copper foil surface is measured. The measured amount of galvanized copper foil surface is shown in Table 1.

[0063] Example 9

[0064] This embodiment provides a method for quantifying the amount of zinc plating on a copper foil surface. The specific steps and parameters are as follows:

[0065] (1) According to the electroplating time t, electroplating area S, zinc ion concentration c of the zinc plating solution, and zinc plating flow rate v of the production equipment, the constant k = 8 is determined, where the electroplating time t is 30s and the electroplating area S is 150dm 2 , zinc ion concentration c of galvanizing solution is 10g / L, galvanizing flow rate v is 4m 3 / h.

[0066] (2) Calculate the zinc coating amount W on the copper foil surface according to formula (1), where the electroplating current density I is 24A / m 2 During the galvanizing process, the real-time pH value is 10.6, and the preset control pH value pH0 is 10.5. W = 11 + 8 × 24 × e (10.6-10.5) =223.1928mg / m 2 .

[0067] (3) The copper foil is galvanized using the production equipment provided in step (1). After the galvanizing is completed, the amount of galvanized copper foil surface is measured. The measured amount of galvanized copper foil surface is shown in Table 1.

[0068] The constant k of Examples 1-9 and the zinc coating amount W on the copper foil surface are expressed in mg / m 2 , represents the initial galvanizing amount W0, the unit is mg / m 2, electroplating current density I, unit is A / m 2 The real-time pH value pH during the galvanizing process, the preset control pH value pH0, and the measured zinc coating amount on the surface of the copper foil are summarized, and the theoretical zinc coating amount on the surface of the copper foil is calculated at the same time. The zinc coating amount on the surface of the copper foil and the error value between the theoretical value and the measured value are measured according to the specific steps for determining the zinc content on the surface of the copper foil provided in Example 1. The error value (%) = | measured zinc coating amount on the surface of the copper foil - theoretical zinc coating amount on the surface of the copper foil | / measured zinc coating amount on the surface of the copper foil × 100%, see Table 1.

[0069] Table 1: Copper foil surface galvanizing amount

[0070]

[0071] As shown in Table 1, the error between the theoretical zinc coating amount on the copper foil surface calculated according to the formula and the actual measured value of the instrument does not exceed 5%, which proves that the quantitative method provided by the present invention has high accuracy and can meet the needs of process control of the production process.

[0072] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for quantifying the amount of zinc plating on a copper foil surface, characterized in that: The zinc plating amount on the copper foil surface satisfies the following formula (1): Where W represents the amount of zinc plating on the copper foil surface, in mg / m 2 , W0 represents the initial galvanizing amount, the unit is mg / m 2 , and W0>0, k represents a constant, I represents the electroplating current density, the unit is A / m 2 , pH represents the real-time pH value during the galvanizing process, pH0 represents the preset control pH value, and the calculation is dimensionless.

2. The method for quantifying the amount of zinc plating on a copper foil according to claim 1, wherein: 0<pH0<14.

3. The method for quantifying the amount of zinc plating on a copper foil according to claim 1, wherein: The k satisfies the following formula (2): k=t×v×c / S(2); Where t represents the electroplating time in seconds, and v represents the flow rate of the zinc plating solution in meters. 3 / h, v represents the zinc ion concentration in the zinc plating solution, the unit is g / L, S represents the electroplating area, the unit is dm 2 .

4. The method for quantifying the amount of zinc plating on a copper foil according to claim 3, wherein: The k satisfies the following formula (3): k=η×t×v×c / S(3); Here, η represents the electroplating efficiency and is dimensionless.

5. The method for quantifying the amount of zinc plating on a copper foil according to claim 4, wherein: 0.9≤η≤0.

99.

6. The method for quantifying the amount of zinc plating on a copper foil according to any one of claims 1 to 5, wherein: The value range of the constant k is 0.1 to 8.

5.

7. The method for quantifying the amount of zinc plating on a copper foil according to claim 1, wherein: The electroplating current density I ranges from 5 to 50 A / dm 2 .

8. A copper foil, characterized in that The copper foil is galvanized using the method for quantifying the amount of zinc plating on the surface of the copper foil according to any one of claims 1 to 7.

9. A composite membrane, characterized in that The invention comprises the copper foil according to claim 8.

10. A circuit board, characterized in that: It comprises the copper foil according to claim 8 and / or the composite film according to claim 9.

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