Multi-layer composite copper foil capable of being used for GMI sensor and preparation method of multi-layer composite copper foil

Abstract

The invention relates to a multi-layer composite copper foil for a GMI sensor and a preparation method, a copper foil is used as a middle core layer, and barrier layers and soft magnetic layers are sequentially arranged on the upper surface and the lower surface to form a planar laminated structure. The barrier layer is arranged between the copper foil and the soft magnetic layer to prevent the copper foil from being in direct contact with the soft magnetic layer, when the material is used for a GMI sensor probe under high-frequency current excitation, the skin effect is enhanced, however, due to the fact that the barrier layer is poor in conductivity and isolates the copper foil from the soft magnetic layer, the isolation can prevent the copper foil from being in direct electric contact with the soft magnetic layer, and the skin effect is improved. The interference of electromagnetic coupling is reduced, so that the measurement sensitivity of the sensor is improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, and specifically relates to a multilayer composite copper foil that can be used in GMI sensors and its preparation method. Background Technology

[0002] Magnetic sensors are key components in electronic measurement and advanced control systems, widely used in aerospace, automated measurement, magnetic storage, biomedicine, and other industries. With the rapid development of information technology, higher demands are being placed on the size, sensitivity, and power consumption of sensors.

[0003] Giant magnetoimpedance (GMI) refers to the effect where the AC impedance of a magnetic material changes significantly with the change of an applied DC magnetic field. Its core principle is that the permeability of a magnetic material changes dramatically with the change of the external magnetic field, thus causing a change in the material's AC impedance. As a novel magnetic sensing technology, it has advantages such as good stability, miniaturization, and fast response.

[0004] Currently, GMI sensors are mainly classified by structure into amorphous filament structures (e.g., CN106273680A), planar thin-film structures (e.g., CN112813407A), and planar stacked structures (e.g., CN1694275A). Amorphous filament structures offer high measurement sensitivity but are prone to magnetic saturation, resulting in a narrow measurement range. Conversely, planar thin-film structures offer a wide measurement range but suffer from low effective permeability, leading to low measurement sensitivity. Ordinary sandwich planar stacked structures can achieve high measurement sensitivity at lower excitation current frequencies, but this sensitivity decreases as the excitation current frequency increases. This is because when the metal layer and soft magnetic layer are in direct contact, the skin effect is insignificant at lower excitation current frequencies, with magnetic induction playing a dominant role. However, as the excitation current frequency increases, the skin effect becomes increasingly pronounced, generating electromagnetic coupling between the metal layer and the soft magnetic layer. This causes uneven rotation of the magnetic moment in the soft magnetic layer, resulting in low measurement sensitivity. Summary of the Invention

[0005] This invention addresses the problem of low measurement sensitivity of existing planar stacked GMI sensors under high-frequency current excitation by proposing a multilayer composite copper foil and its preparation method that can be used in GMI sensors.

[0006] This invention provides a multilayer composite copper foil that can be used in GMI sensors. The copper foil is used as the middle core layer, and a barrier layer and a soft magnetic layer are sequentially arranged on the upper and lower surfaces to form a planar stacked structure.

[0007] This invention also provides a method for preparing a multilayer composite copper foil that can be used in GMI sensors, comprising the following steps: Using copper foil as the intermediate core layer, the copper foil is subjected to pickling pretreatment, water washing, barrier layer coating, soft magnetic layer electroplating, water washing and baking in sequence to obtain a multilayer composite copper foil that can be used in GMI sensors.

[0008] Furthermore, the copper foil has a purity of 4N, a thickness of 3-15μm, preferably 5-12μm, and a surface roughness Rz of 0.4-1.0μm, preferably 0.6-0.8μm.

[0009] Furthermore, the pickling pretreatment adopts immersion pickling, and the pickling solution is a dilute sulfuric acid solution with a concentration of 8-35 g / L, preferably 10-25 g / L.

[0010] Furthermore, the water washing adopts a spray-type water washing method, with a deionized water flow rate of 1-6 m³ / h. 3 / h, preferably 2-4m 3 / h.

[0011] Furthermore, the barrier layer coating is performed by spraying followed by rolling, and the barrier layer solution is a mixture of one of carboxybenzotriazole and mercaptobenzothiazole with one of γ-aminopropyltrimethyloxysilane and vinyltrimethoxysilane.

[0012] Furthermore, the mass ratio of the two components in the mixture is 2:1-3. When preparing the solution, the mixture is first dissolved in a small amount of anhydrous ethanol, and then deionized water is added for complete dissolution.

[0013] Furthermore, the concentration of the barrier layer solution is 500-1500 ppm, preferably 800-1200 ppm.

[0014] Furthermore, the soft magnetic layer is electroplated using an immersion tank method, and the thickness of the soft magnetic layer is 2-8 μm, preferably 3-6 μm. The metal components in the soft magnetic layer include one or more of cobalt, nickel, iron, and chromium.

[0015] Furthermore, the electroplating solution used for the soft magnetic layer electroplating has the following formula: metal ion concentration of 1-10 g / L, boric acid concentration of 10-50 g / L, reducing agent concentration of 1-10 g / L, complexing agent concentration of 0-5 g / L, pH value of 3-5, and temperature of 20-40℃.

[0016] Furthermore, the reducing agent is one or more of ascorbic acid and sodium hypophosphite.

[0017] Furthermore, the complexing agent is one or more of o-sulfonylbenzylimine and sodium allyl sulfonate.

[0018] Furthermore, the baking process employs vacuum halogen tube heating, with a set temperature of 100-200℃.

[0019] Beneficial effects (1) The present invention sets a barrier layer between the copper foil and the soft magnetic layer to prevent the copper foil from directly contacting the soft magnetic layer. When this material is used in the GMI sensor probe under high frequency current excitation, the skin effect is enhanced. However, due to the poor conductivity of the barrier layer and its isolation of the copper foil from the soft magnetic layer, this isolation can prevent the copper foil from directly contacting the soft magnetic layer, reduce electromagnetic coupling interference, and thus improve the measurement sensitivity of the sensor.

[0020] (2) By introducing a barrier layer between the copper foil and the soft magnetic layer, the present invention can suppress the movement of the magnetic domain walls between the copper foil and the soft magnetic layer, reduce the interference caused by the hysteresis effect, and thus further improve the measurement sensitivity of the sensor.

[0021] (3) This invention uses copper foil as the baseband, and when the GMI sensor using this material is applied to a printed circuit board (PCB), it will have good compatibility. Because PCB manufacturing relies on copper-clad laminate manufacturing technology, in PCB manufacturing, electronic devices are made by pressing copper-clad laminate onto a substrate and then soldering patterns and pads on copper foil. The baseband of the structure of this invention is copper foil, and its manufacturing process is compatible with the PCB manufacturing process, resulting in high installation reliability.

[0022] (4) The present invention can be manufactured by using the surface lines of the multi-groove roller system. Compared with the conventional sputtering method, its cost can be greatly reduced and its production efficiency can be greatly improved. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the multilayer composite copper foil of the present invention.

[0024] Figure 2 This is a schematic diagram of the preparation process of the multilayer composite copper foil of the present invention. Detailed Implementation

[0025] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0026] Example 1 like Figure 2As shown, copper foil with a purity of 4N, a surface roughness Rz of 0.6μm, and a thickness of 5μm is sequentially fed through a roller system into an acid pickling pretreatment zone, a water washing zone, a barrier layer coating zone, a soft magnetic layer electroplating zone, a water washing zone, and a baking zone, ultimately forming a copper foil with a purity of 4N, a surface roughness Rz of 0.6μm, and a thickness of 5μm. Figure 1 The structure shown, wherein: Pickling is carried out by immersion pickling. The pickling solution in the pickling pretreatment area is a dilute sulfuric acid solution with a concentration of 10 g / L.

[0027] The washing area uses a spray washing method, and the deionized water flow rate in the washing area is 2m³ / h. 3 / h.

[0028] The barrier layer coating process involves spraying followed by rolling. Spraying and rolling ensure the barrier layer solution is uniformly coated onto the copper foil surface. The formulation for the barrier layer coating area is: carboxybenzotriazole and vinyltrimethoxysilane in a mass ratio of 2:3. After dissolving in a small amount of anhydrous ethanol, the solution is prepared at 800 ppm using deionized water. After stirring for 6 hours, the preparation of the barrier layer coating area solution is complete.

[0029] The soft magnetic layer electroplating is performed using an immersion tank method. A soft magnetic layer is electroplated onto the surface of copper foil that has undergone previous processing. The metallic component of the soft magnetic layer is nickel, and the electroplating solution formula is as follows: nickel ion concentration 4.5 g / L, boric acid concentration 30 g / L, sodium hypophosphite concentration 1 g / L, pH value 3.8 ± 0.2, and temperature 20℃. The thickness of the soft magnetic layer is 3 μm.

[0030] Baking is performed using vacuum halogen tube heating, with the temperature set at 200℃.

[0031] Example 2 The difference from Example 1 is that the metal components in the soft magnetic layer are cobalt and nickel, the thickness is 3 μm, and the electroplating solution formula is as follows: cobalt ion concentration of 10 g / L, nickel ion concentration of 3 g / L, boric acid concentration of 35 g / L, sodium hypophosphite concentration of 2 g / L, o-sulfobenzylimine concentration of 0.5 g / L, sodium allyl sulfonate concentration of 0.2 g / L, pH value of 3.0 ± 0.2, temperature of 25 °C, and all other conditions are the same.

[0032] Example 3 Copper foil with a purity of 4N, a surface roughness Rz of 1.0μm, and a thickness of 12μm is sequentially fed through a roller system into an acid pickling pretreatment zone, a water washing zone, a barrier layer coating zone, a soft magnetic layer electroplating zone, a water washing zone, and a baking zone, ultimately forming a... Figure 1 The structure shown, wherein: Pickling is carried out by immersion pickling. The pickling solution in the pickling pretreatment area is a dilute sulfuric acid solution with a concentration of 25 g / L.

[0033] The washing area uses a spray washing method, and the deionized water flow rate in the washing area is 4m³ / h. 3 / h.

[0034] The barrier layer coating process involves spraying followed by rolling. Spraying and rolling ensure the barrier layer solution is uniformly coated onto the copper foil surface. The formulation for the barrier layer coating area is: mercaptobenzothiazole and γ-aminopropyltrimethyloxysilane in a mass ratio of 2:3. After dissolving in a small amount of anhydrous ethanol, the solution is prepared at 1200 ppm using deionized water. After stirring for 8 hours, the preparation of the barrier layer coating area solution is complete.

[0035] The soft magnetic layer electroplating uses an immersion tank method, where a soft magnetic layer is electroplated onto the surface of copper foil that has undergone previous processing. The metallic components of the soft magnetic layer are cobalt, nickel, and iron. The electroplating solution formula is as follows: cobalt ion concentration 5 g / L, nickel ion concentration 3 g / L, ferrous ion concentration 1 g / L, ascorbic acid concentration 5 g / L, boric acid concentration 35 g / L, sodium hypophosphite concentration 2 g / L, o-sulfobenzylimine concentration 0.5 g / L, sodium allyl sulfonate concentration 0.2 g / L, pH value 3.0 ± 0.2, and temperature 25℃. The thickness of the soft magnetic layer is 3 μm.

[0036] Baking is performed using vacuum halogen tube heating, with the temperature set at 200℃.

[0037] Example 4 The difference from Example 3 is that the metal composition of the soft magnetic layer is nickel, iron, and chromium, and the thickness of the soft magnetic layer is 6 μm. The electroplating solution formula is as follows: nickel ion concentration 5 g / L, ferrous ion concentration 2 g / L, potassium chromium sulfate concentration 1 g / L, ascorbic acid concentration 5 g / L, boric acid concentration 35 g / L, sodium hypophosphite concentration 2 g / L, o-sulfobenzylimine 0.5 g / L, sodium allyl sulfonate 0.2 g / L, pH value 3.0 ± 0.2, temperature 25 °C, and all other parameters are the same.

[0038] Comparative Example 1 Unlike Example 1, it does not have a soft magnetic layer. The soft magnetic layer electroplating area is only sprayed with deionized water for roller system transition, and the rest is the same.

[0039] Comparative Example 2: Unlike Example 3, it does not have a soft magnetic layer. The soft magnetic layer electroplating area is only sprayed with deionized water for roller system transition, and the rest is the same.

[0040] The above embodiments and comparative examples were tested respectively, including the following steps: As can be seen from the above embodiments and test results, the present invention provides a multilayer composite copper foil and its preparation method that can be used in GMI sensors. GMI sensors made using the multilayer composite copper foil material prepared by the present invention can effectively improve the measurement sensitivity of planar stacked GMI sensors under high-frequency current excitation. Furthermore, the preparation process is simple, the equipment requirements are minimal, and mass production can be achieved in a short time.

Claims

1. A multilayer composite copper foil that can be used in GMI sensors, characterized in that: A planar laminated structure is formed by using copper foil as the intermediate core layer and setting a barrier layer and a soft magnetic layer on the upper and lower surfaces in sequence.

2. A method for preparing a multilayer composite copper foil that can be used in GMI sensors, characterized in that, Includes the following steps: Using copper foil as the intermediate core layer, the copper foil is subjected to pickling pretreatment, water washing, barrier layer coating, soft magnetic layer electroplating, water washing and baking in sequence to obtain a multilayer composite copper foil that can be used in GMI sensors.

3. The preparation method according to claim 2, characterized in that: The copper foil has a purity of 4N, a thickness of 3-15μm, and a surface roughness Rz of 0.4-1.0μm on both the upper and lower surfaces.

4. The preparation method according to claim 2, characterized in that: The pickling pretreatment adopts immersion pickling, and the pickling solution is a dilute sulfuric acid solution with a concentration of 8-35 g / L.

5. The preparation method according to claim 2, characterized in that: The water washing is a spray-type water washing, with a deionized water flow rate of 1-6 m³ / h. 3 / h.

6. The preparation method according to claim 2, characterized in that: The barrier layer coating is performed by spraying followed by rolling. The barrier layer solution is a mixture of one of carboxybenzotriazole and mercaptobenzothiazole with one of γ-aminopropyltrimethyloxysilane and vinyltrimethoxysilane.

7. The preparation method according to claim 6, characterized in that: The concentration of the barrier layer solution is 500-1500 ppm.

8. The preparation method according to claim 2, characterized in that: The soft magnetic layer is electroplated using an immersion tank method. The thickness of the soft magnetic layer is 2-8 μm, and the metal components in the soft magnetic layer include one or more of cobalt, nickel, iron, and chromium.

9. The preparation method according to claim 2, characterized in that: The electroplating solution used for the soft magnetic layer electroplating has the following formula: metal ion concentration of 1-10 g / L, boric acid concentration of 10-50 g / L, reducing agent concentration of 1-10 g / L, complexing agent concentration of 0-5 g / L, pH value of 3-5, and temperature of 20-40℃.

10. The preparation method according to claim 2, characterized in that: The baking process uses vacuum halogen tube heating, with a set temperature of 100-200℃.

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