Composite circuit board material and preparation method thereof

Abstract

The invention relates to a composite circuit board material and a preparation method thereof. The composite circuit board material comprises an electromagnetic shielding layer, a magnetic dielectric layer, a conductive layer and an insulating protection layer, and the magnetic medium layer is prepared from a magnetic medium glue solution and a supporting body. The material has an excellent electromagnetic shielding effect and good magnetic conduction and electric conduction capabilities, the electromagnetic compatibility of a product can be effectively improved, the product is safer to use, and the material can be used as a basic material of a power receiving coil of a wireless charging module, so that the overall thickness of the material can be reduced, and an electronic finished product is lighter and thinner.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic materials, and particularly relates to a composite circuit board material and a preparation method thereof. Background Art

[0002] A wireless charger is a charger that does not use a traditional charging power cord to connect to a terminal device that needs to be charged. Currently, wireless charging has been widely used in the field of personal mobile electronic devices, mainly using electromagnetic induction technology. The wireless charging module is basically divided into the following modules: a current converter, a frequency converter, a power output coil, a power receiving coil, a rectifying circuit, and a battery. Among them, the power receiving coil is a core component in mobile electronic devices, and it mainly consists of the following parts: an induction coil, a shielding layer, and a magnetic conductor. Among them, the induction coil is usually processed from a flexible printed circuit board (FPC), and the magnetic conductor is generally a nanocrystalline panel or a ferrite magnetic plate, and the shielding layer is a metal composite material. After these three are processed separately and then assembled together, the manufacturing process is relatively cumbersome, the cost is relatively high, and it is not conducive to the thinning of the product. Therefore, developing a composite material that simultaneously has good electrical conductivity, magnetic conductivity, and electromagnetic shielding effect is of great significance for reducing production costs and accelerating product miniaturization. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a composite circuit board material and a preparation method thereof. The composite circuit board material has excellent electromagnetic shielding effect and good magnetic conductivity and electrical conductivity. It can not only effectively improve the electromagnetic compatibility of the product, making the product safer to use, but also, as the basic material of the power receiving coil of the wireless charging module, can reduce the overall thickness of the material, making the electronic product thinner and lighter.

[0004] The present invention provides a composite circuit board material, including an electromagnetic shielding layer, a magnetic dielectric layer, a conductive layer, and an insulating protective layer; the magnetic dielectric layer is prepared from a magnetic dielectric colloidal solution and a carrier; the powder used in the magnetic dielectric colloidal solution has a D 50 satisfying 0.3 μm < D 50 < 0.5 μm, and D 90 satisfying 0.6 μm < D 90 < 1.0 μm.

[0005] Preferably, the material used for the electromagnetic shielding layer (also called electromagnetic shielding material) is a metal material, a metal composite material, or a metalized polymer material. The metalized polymer materials include metalized polyester (PET), polyimide (PI), polypropylene (PP), high-density polyethylene (HDPE), polyphenylene sulfide (PPS), or polyamide (PA). The thickness of the electromagnetic shielding layer is 5 - 50 μm, and the area is larger than the areas of the magnetic dielectric layer and the conductive layer.

[0006] Preferably, the magnetic conductive material used for the magnetic medium layer includes one or more of zinc ferrite, nickel ferrite, manganese zinc ferrite, nickel zinc ferrite, copper zinc ferrite, and metal magnetic powder materials. The magnetic permeability of the magnetic medium layer is 100 - 2000 H / m; the thickness of the magnetic medium layer is 30 - 50 μm.

[0007] Preferably, the material of the conductive layer is copper, and the conductive layer is fixed on the side of the magnetic medium layer away from the electromagnetic shielding layer; the thickness of the conductive layer is 35 - 105 μm.

[0008] Preferably, the material of the insulating protective layer is PET, PI or PP.

[0009] Preferably, the carrier is a polymer film subjected to plasma surface activation treatment. The polymer film is PI or PET, and the plasma treatment medium can be oxygen, argon or nitrogen.

[0010] The present invention also provides a preparation method of a composite circuit board material, comprising the following steps:

[0011] (1) Prepare magnetic medium powder; then perform surface modification on the magnetic medium powder, using an organic alcohol solution as a solvent and a surfactant as a modifier; wash the surface-modified magnetic medium powder with water and perform multi-stage filtration;

[0012] (2) Add a dispersant to a solvent and mix and stir, then add the magnetic medium powder obtained in step (1) and mix and stir evenly, and finally add a binder to obtain a magnetic medium glue;

[0013] (3) Uniformly spray the magnetic medium glue obtained in step (2) on both sides of the carrier, and then bake; then hot-press a protective film on the outer surfaces of the magnetic medium glue on both sides, and finally sputter metallic copper on the outer surface of the protective film to obtain a magnetic medium layer; (4) Electroplate a metallic copper layer on one side of the magnetic medium layer obtained in step (3) as a conductive layer, and electroplate an electromagnetic shielding material on the other side; bond an insulating protective film on the outer surface of the conductive layer and perform a curing treatment to obtain an insulating protective layer, thus obtaining the composite circuit board material.

[0014] Preferably, the preparation method of the magnetic medium powder in step (1) includes one or more of high-energy ball milling method, hydrolysis precipitation method, solvothermal method, hydrothermal method, and sol-gel method. If the preparation method is high-energy ball milling method, hydrolysis precipitation method or sol-gel method, annealing treatment must be combined subsequently, the annealing temperature is 300 - 600 °C, and the annealing time is 2 - 5 h.

[0015] Preferably, the organic alcohol in the step (1) includes one or more of ethanol, ethylene glycol, diethylene glycol, glycerol, pentaerythritol, neopentyl glycol, and 1,4-butanediol. The mass ratio of alcohol to water in the organic alcohol solution is less than 1 and greater than 0.5.

[0016] Preferably, the surfactant in the step (1) includes one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium pyrophosphate, and sodium polyacrylate.

[0017] Preferably, the dosage of the magnetic medium powder in the step (1) is 20 - 50 g / L, and the dosage of the surfactant is 0.01 - 0.5 g / L.

[0018] Preferably, the surface modification duration in the step (1) is 15 - 60 min; air is continuously introduced during the surface modification process, and continuous stirring is carried out.

[0019] Preferably, the solvent in the step (2) is pure water.

[0020] Preferably, the dispersant in the step (2) includes one or more of carboxymethyl cellulose, gum ghatti, and sodium tripolyphosphate. The mass ratio of the dispersant to the binder is 1:2 - 1:8, and the dispersant accounts for 1% - 5% of the total mass of the magnetic medium colloidal solution.

[0021] Preferably, the binder in the step (2) includes one or more of styrene-butadiene rubber latex, polyvinyl alcohol, polymethyl methacrylate emulsion, thermoplastic polypropylene emulsion, and polyvinyl acetate emulsion.

[0022] Preferably, the stirring speed for adding the solvent in the step (2) is 200 - 1000 rpm, and the duration is 10 - 30 min. The stirring speed for adding the magnetic medium powder is 30 - 1000 rpm, and the duration is 20 - 60 min. The stirring speed for adding the binder is 1000 - 2000 rpm, and the duration is 10 - 20 min.

[0023] Preferably, the viscosity of the magnetic medium colloidal solution in the step (2) is 2000 - 3000 mPa·s, the solid content is 35 - 65%, and the vacuum sieving is ≤200 mesh.

[0024] Preferably, the magnetic medium colloidal solution in the step (3) is uniformly sprayed with a single-sided density of 30 - 50 mg / cm 2 .

[0025] Preferably, the baking temperature in the step (3) is 80 - 100 °C, and the baking time is 15 - 40 min.

[0026] Preferably, the protective film in step (3) is preferably PI, the pressure of thermal lamination is 200 - 400 psi, and the temperature of thermal lamination is 130 - 200 °C.

[0027] Preferably, a glue layer is further provided between the protective film and the magnetic medium adhesive liquid in step (3). The glue layer is a TPI glue layer to increase the adhesion of the protective film.

[0028] Preferably, the copper thickness of the metallic copper in step (3) is 10 - 40 nm.

[0029] Preferably, the process parameters of the electroplated metallic copper layer in step (4) are: the direct current density is 10 - 60 A / dm 2 , the copper ion content in the electrolyte is 50 - 90 g / L, and the acid concentration is 90 - 130 g / L.

[0030] Preferably, the adhesive used for the bonded insulating protective film in step (4) is one or more of epoxy adhesives, polyester adhesives, acrylic adhesives, and polyurethane adhesives.

[0031] Beneficial effects

[0032] (1) The present invention has excellent electromagnetic shielding effect and good magnetic conductivity and electrical conductivity. It can not only effectively improve the electromagnetic compatibility of the product, making the product safer to use, but also, as the basic material of the power receiving coil of the wireless charging module, can reduce the overall thickness of the material, making the electronic product thinner and lighter.

[0033] (2) The present invention strictly controls the particle size distribution of the magnetic medium powder to obtain magnetic medium powder with excellent paramagnetism; uses a polymer film as a carrier, and through modification, makes the magnetic medium powder evenly dispersed in the adhesive liquid, and evenly coats the adhesive liquid on both of its side surfaces, and finally combines with the conductive layer to obtain a composite circuit board material integrating electromagnetic shielding, magnetic conductivity, and electrical conductivity functions. Among them, the magnetic medium layer, as an excellent magnetic conductive medium, can not only confine the magnetic force lines passing through the coil, making the magnetic force lines more concentrated, but also the magnetic medium layer can cooperate with the electromagnetic shielding layer to enhance the suppression effect on electromagnetic interference. The conductive layer uses copper as the conductive medium, which can be used as the conductive material of the flexible circuit board, and when processed into an induction coil winding, it can not only save costs but also reduce the volume of the wireless charging module. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of the composite circuit board material of the present invention;

[0035] Among them, 1 - electromagnetic shielding layer, 2 - magnetic medium layer, 21 - magnetic medium, 22 - carrier, 3 - conductive layer, 4 - insulating protective layer. Detailed Embodiments

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0037] Embodiment 1

[0038] S1: Preparation of magnetic medium powder

[0039] ① Using ferric nitrate and zinc sulfate as raw materials and urea as a precipitant, a colloidal zinc ferrite precursor is obtained by hydrolysis precipitation method; ② The obtained colloidal precursor is annealed in a muffle furnace under an air atmosphere at a temperature of 450 °C for 3.5 h to obtain porous zinc ferrite, and finally ground to obtain zinc ferrite powder;

[0040] ③ Add the above-obtained zinc ferrite powder to an ethanol aqueous solution, where the mass ratio of ethanol to water is 0.8, and the dosage of zinc ferrite is 35 g / L. Ultrasonic stirring is used to disperse it fully, and then 0.1 g / L of sodium dodecyl sulfate is added as a surface modifier; continuous stirring is carried out for 30 min;

[0041] ④ Wash and filter the surface-modified zinc ferrite powder to obtain powder D 50 = 0.36 μm, D 90 = 0.68 μm.

[0042] S2: Preparation of magnetic medium colloid

[0043] First, carboxymethyl cellulose is added to pure water, and the mass of carboxymethyl cellulose accounts for 2% of the total mass of the colloid. Continuous stirring is carried out at a speed of 600 rpm for 15 min; then the zinc ferrite powder obtained in step S1 is added, and continuous stirring is carried out at a speed of 300 rpm for 30 min; finally, a styrene-butadiene rubber emulsion accounting for 8% of the total mass of the colloid is added, and continuous stirring is carried out at a speed of 1500 rpm for 15 min; the finally obtained magnetic medium colloid has a viscosity of 2500 mPa·s, a solid content of 50%, and is vacuum filtered through a sieve with a mesh size of ≤200 mesh.

[0044] S3: Preparation of magnetic medium layer

[0045] ① Select a PI film with a thickness of 12.5 μm as the supporting layer and perform plasma treatment on it using oxygen as the medium; ② Uniformly spray the magnetic medium colloid obtained in step S2 on both sides of the support, and the single-sided density is 40 mg / cm 2 ; Bake the sprayed colloid, the baking temperature is 90 °C, and the baking time is 30 min;

[0046] ③Hot press a PI protective film on the outer surfaces of the adhesive liquids on both sides above. The pressing pressure is 300 psi, and the pressing temperature is 150 °C. The total thickness of the adhesive liquid layer and the supporting layer is 45 μm in the end.

[0047] ④Sputter a layer of metallic copper on the outer surfaces of the protective films on both sides above to obtain a metallized protective film, where the thickness of the copper is 20 nm. S4: Electroplate to obtain an electromagnetic shielding layer and a conductive layer

[0048] ①Electroplate a metallic copper layer on the outer surface of the metallized protective film on one side of the above-mentioned support as a conductive layer. The electroplating process parameters are as follows: the direct current density is 40 A / dm 2 , the copper ion content in the electrolyte is 80 g / L, and the acid concentration is 100 g / L. Obtain a copper layer with a thickness of 75 μm as the conductive layer;

[0049] ②Electroplate single metallic copper on the outer surface of the metallized protective film on the other side of the above-mentioned support to obtain an electromagnetic shielding layer with a copper thickness of 6 μm.

[0050] S5: Bond a PI insulating protective film on the outer surface of the above-mentioned conductive layer. Select an epoxy adhesive as the adhesive and conduct a curing treatment to obtain an insulating protective layer.

[0051] Example 2

[0052] S1: Prepare magnetic medium powder

[0053] ①Use ferric nitrate, zinc sulfate, and nickel sulfate as raw materials and urea as a precipitant to obtain a nickel-zinc ferrite precursor by hydrolysis precipitation method;

[0054] ②Place the obtained precursor in a muffle furnace for annealing treatment. The air atmosphere, the temperature is 600 °C, and the time is 4 h. Finally, grind to obtain nickel-zinc ferrite powder;

[0055] ③Add the nickel-zinc ferrite powder obtained above to an ethylene glycol aqueous solution, where the mass ratio of ethylene glycol to water is 0.6, and the dosage of nickel-zinc ferrite is 50 g / L. Ultrasonically stir to disperse it fully, and then add 0.5 g / L of sodium polyacrylate as a surface modifier; continuously stir for 60 min;

[0056] ④Wash and filter the surface-modified nickel-zinc ferrite powder to obtain powder with D 50 = 0.41 μm and D 90 = 0.78 μm.

[0057] S2: Prepare magnetic medium adhesive liquid

[0058] First, sodium tripolyphosphate is added to pure water. The mass of sodium tripolyphosphate accounts for 5% of the total mass of the adhesive solution, and it is continuously stirred at a speed of 500 rpm for 30 min. Then, the nickel zinc ferrite powder obtained in step S1 is added, and it is continuously stirred at a speed of 700 rpm for 50 min. Finally, polymethyl methacrylate emulsion accounting for 10% of the total mass of the adhesive solution is added, and it is continuously stirred at a speed of 1000 rpm for 20 min. The finally obtained magnetic medium adhesive solution has a viscosity of 3000 mPa·s, a solid content of 60%, and is vacuum filtered through a sieve with a mesh size of ≤200 meshes.

[0059] S3: Preparation of the magnetic medium layer

[0060] ① Select a PET film with a thickness of 12 μm as the support layer, and use argon as the medium to perform plasma treatment on it; ② Uniformly spray the magnetic medium adhesive solution obtained in step S2 on both sides of the support body, with a single-sided density of 50 mg / cm 2 ; Bake the sprayed adhesive solution at a baking temperature of 100 °C for 40 min;

[0061] ③ Thermally press a PI protective film on the outer surfaces of the adhesive solutions on both sides above. The pressing pressure is 350 psi, and the pressing temperature is 200 °C; The total thickness of the adhesive solution layer and the support layer is finally 50 μm;

[0062] ④ Sputter a layer of metallic copper on the outer surfaces of the protective films on both sides above to obtain a metallized protective film, where the copper thickness is 40 nm. S4: Electroplating to obtain the electromagnetic shielding layer and the conductive layer

[0063] ① Electroplate a metallic copper layer on the outer surface of the metallized protective film on one side of the above support body as the conductive layer. The electroplating process parameters are: the direct current density is 60 A / dm 2 , the copper ion content in the electrolyte is 90 g / L, and the acid concentration is 130 g / L. A copper layer with a thickness of 105 μm is obtained as the conductive layer;

[0064] ② Electroplate single metallic copper on the outer surface of the metallized protective film on the other side of the above support body to obtain an electromagnetic shielding layer with a thickness of 12 μm;

[0065] S5: Bond a PET insulating protective film on the outer surface of the above conductive layer. The adhesive is selected as a polyester-based adhesive, and curing treatment is performed to obtain an insulating protective layer.

[0066] Comparative Example 1

[0067] Different from Example 1, in this example, there is no electromagnetic shielding layer.

[0068] Comparative Example 2

[0069] Different from Example 1, in this example, the thickness of the magnetic medium layer is 20 μm.

[0070] Comparative Example 3

[0071] Different from Example 1, in this example, the thickness of the conductive layer is 30 μm.

[0072] Comparative Example 4

[0073] Different from Example 1, in this example, in step S1, the magnetic medium powder is not surface-modified.

[0074] Comparative Example 5

[0075] Different from Example 1, in this example, in step S1, the D of the finally obtained magnetic medium powder 50 = 0.28 μm, D 90 = 0.57 μm.

[0076] Comparative Example 6

[0077] Different from Example 1, in this example, in step S3, the magnetic medium colloidal solution is evenly sprayed on both sides of the carrier, and the single-sided density is 20 mg / cm 2 .

[0078] Comparative Example 7

[0079] Different from Example 1, in this example, in step S3, the carrier is not surface-activated.

[0080] To more clearly highlight the beneficial effects of the present invention, the following provides a detailed description of the examples and comparative examples.

[0081] Comparing Comparative Example 1 with Example 1: The composite circuit board material in Comparative Example 1 does not have an electromagnetic shielding layer. If it is processed into a wireless charging module component, electromagnetic interference cannot be completely eliminated.

[0082] Comparing Comparative Example 2 with Example 1: The thickness of the magnetic medium layer in Comparative Example 2 is too small to provide sufficient magnetic force for the induction coil, and thus cannot provide a stronger induced current.

[0083] Comparing Comparative Example 3 with Example 1: The thickness of the conductive layer is too small to carry a larger current, resulting in circuit burnout.

[0084] Comparing Comparative Example 4 with Example 1: The magnetic medium powder cannot be evenly dispersed in the colloidal solution, resulting in uneven magnetic force received by the induction coil and affecting the stability of the circuit.

[0085] Comparing Comparative Example 5 with Example 1: The particle size of the magnetic medium powder is too small, resulting in a smaller magnetic domain, unable to provide sufficient magnetic force, and the magnetic field lines are not concentrated, which will cause magnetic leakage in the induction coil circuit.

[0086] Comparative Example 6 is compared with Example 1: If the coated areal density is too small, sufficient magnetic force cannot be provided either.

[0087] Comparative Example 7 is compared with Example 1: If the surface of the carrier is not activated, the bonding strength between the adhesive liquid and the carrier is insufficient, and finally poor glue overflow may occur.

Claims

1. A composite circuit board material, characterized in that: It includes an electromagnetic shielding layer, a magnetic medium layer, a conductive layer and an insulating protective layer; the magnetic medium layer is prepared from a magnetic medium colloidal solution and a carrier; the powder used in the magnetic medium colloidal solution has a D 50 satisfying 0.3μm < D 50 < 0.5μm, and D 90 satisfies 0.6μm < D 90 < 1.0μm.

2. The composite circuit board material according to claim 1, characterized in that: The material used for the electromagnetic shielding layer is a metallic material, a metal composite material or a metallized polymer material; the thickness of the electromagnetic shielding layer is 5 - 50 μm, and the area is larger than the areas of the magnetic medium layer and the conductive layer.

3. The composite circuit board material according to claim 1, wherein: The magnetic conductive materials used for the magnetic medium layer include one or more of zinc ferrite, nickel ferrite, manganese zinc ferrite, nickel zinc ferrite, copper zinc ferrite, and metal magnetic powder materials; the magnetic permeability of the magnetic medium layer is 100 - 2000 H / m; the thickness of the magnetic medium layer is 30 - 50 μm.

4. The composite circuit board material according to claim 1, characterized in that: The material of the conductive layer is copper, and the conductive layer is fixed on the side of the magnetic medium layer away from the electromagnetic shielding layer; the thickness of the conductive layer is 35 - 105 μm.

5. The composite circuit board material according to claim 1, wherein: The material of the insulating protective layer is PET, PI or PP.

6. The composite circuit board material according to claim 1, characterized in that: The carrier is a polymer film subjected to plasma surface activation treatment.

7. A method for preparing a composite circuit board material as described in claim 1, comprising the following steps: (1) Prepare magnetic medium powder; then perform surface modification on the magnetic medium powder, using an organic alcohol solution as a solvent and a surfactant as a modifier; wash the surface-modified magnetic medium powder with water and perform multi-stage filtration. (2) Add a dispersant to the solvent and mix and stir, then add the magnetic medium powder obtained in step (1) and mix and stir evenly, and finally add a binder to obtain a magnetic medium glue solution. (3) Evenly spray the magnetic medium glue solution obtained in step (2) on both sides of the carrier, and then perform baking; then hot-press a protective film on the outer surfaces of the magnetic medium glue solution on both sides, and finally sputter metallic copper on the outer surface of the protective film to obtain a magnetic medium layer. (4) Electroplate a metallic copper layer on one side of the magnetic medium layer obtained in step (3) as the conductive layer, and electroplate an electromagnetic shielding material on the other side; bond an insulating protective film on the outer surface of the conductive layer and perform a curing treatment to obtain an insulating protective layer, thus obtaining the composite circuit board material.

8. The preparation method according to claim 7, characterized in that: The organic alcohols in step (1) include one or more of ethanol, ethylene glycol, diethylene glycol, glycerol, pentaerythritol, neopentyl glycol, and 1,4-butanediol; the surfactants include one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium pyrophosphate, and sodium polyacrylate.

9. The preparation method according to claim 7, characterized in that: The solvent in step (2) is pure water; the dispersants include one or more of carboxymethyl cellulose, guar gum, and sodium tripolyphosphate; the binders include one or more of styrene-butadiene rubber latex, polyvinyl alcohol, polymethyl methacrylate latex, thermoplastic polypropylene latex, and polyvinyl acetate latex.

10. The preparation method according to claim 7, characterized in that: A glue layer is further provided between the protective film and the magnetic medium glue solution in step (3).

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