CN110035603A - A kind of preparation method of printed circuit potting inductance - Google Patents

Abstract

The invention relates to a preparation method of an embedded inductor of a printed circuit, belonging to the technical field of inductor preparation. In the present invention, a metal seed layer and a patterned resist layer are sequentially formed on the surface of the medium, a metal conductor structure is formed on the metal seed layer not covered by the resist layer, and the patterned resist layer and the metal seed layer covered thereunder are used as The sacrificial layer is removed, and then a magnetic film is deposited on the metal conductor structure, so as to realize the fabrication of the embedded inductor of the printed circuit. The invention can realize the fabrication of embedded inductors on any base material, which makes the application of embedded inductor elements more convenient and flexible; the inductance value of the obtained product is significantly improved, and at the same time, the inductance performance caused by making through holes on the magnetic conductive material is avoided. Uncontrollable problems; the preparation process is compatible with the printed circuit board production line, no additional process needs to be added, and the investment in equipment and technology is reduced, which is conducive to reducing costs and realizing industrialized production.

Description

A kind of preparation method of printed circuit embedded inductor

technical field

The invention belongs to the technical field of inductance preparation, and particularly relates to a preparation method of a printed circuit embedded inductance.

Background technique

With the development of electronic equipment in the direction of miniaturization, functionalization and high integration, it is bound to put forward higher requirements for various electronic components. As an important magnetic component, inductance components play an important role in signal transmission and processing in high frequency and microwave frequency bands. inside the circuit board. This kind of inductance embedded in the printed circuit board can not only meet the development trend of high integration of electronic systems, but also can realize the minimum distance transmission of electrical signals and improve the integrity of signal transmission. Printed circuit embedded inductor technology has become a current research hotspot.

In "Research on the Microstructure and Properties of Co and CoTaZr Thin Films by Magnetron Sputtering", Yue Wang disclosed a method for preparing thin film inductors by magnetron sputtering magnetic materials on monocrystalline silicon to form inductance circuits. The magnetic material is formed, and the cost of making an embedded inductor with the same inductance value is higher. At the same time, in the actual circuit, the mutual inductance between the coils of the inductor is strong, and the inductance performance is low. In the document "Thick-copper-buried inductors using anodizedaluminum package substrates", Kim et al. introduced a method for realizing the inductor coil with groove metallization. The inductance value of the embedded inductance can only be improved by increasing the number of coils, which is not conducive to the development of miniaturization of inductance components. In order to increase the magnetic induction intensity of the electromagnet, a magnetically conductive material is introduced into the magnetic circuit of the inductance coil. The existence of the magnetically conductive material can enhance the magnetic flux density (magnetic flux) of the magnetic circuit of the electromagnetic coil, reduce the inductance loss, and then increase the electromagnetic induction intensity. It is beneficial to realize the miniaturization of the inductor structure. The technology of constructing magnetic conductive substances in embedded inductors of printed circuits has achieved great development under the efforts of researchers. The Chinese invention patent "An Inductor Structure with Embedded Technology of Printed Circuit Board and Its Manufacturing Method" (application number CN201610791943.X) discloses a method of first etching the conductive coil on the copper foil of the double-sided copper clad substrate, and then etched The invention discloses a method for making a printed circuit embedded inductor by solidifying a magnetic composite material on the surface of a conductive coil to form a magnetic conductive substance. However, the method is complicated in process, and the base material for making the embedded inductor is limited, so that the embedded inductor cannot be fabricated on any medium. With the widespread application of surface mount technology (SMT) in electronic products, reliability problems may be caused by material mismatches when components are further integrated to construct a complete machine. The Chinese invention patent "Method for Making Magnetic Thin-Film Pressed Blind Hole Electromagnetic Induction Multilayer Printed Circuit Board" (application number CN201410285999.9) discloses a method of first using a lamination method to make a magnetically permeable material, and then applying the magnetically permeable material to the The method of making blind holes to form printed circuit embedded inductances is easy to destroy the connection between the magnetic conductive material and the substrate, causing the magnetic conductive material to separate from the substrate, which in turn leads to uncontrollable inductance performance. Chen Jian et al. in the document "An Inductance Core Embedded PCB Technology in the Assembly Process", the magnetic conductive material is embedded in the printed circuit board as a whole, and the energized coil is constructed through metallized vias. Combining magnetic conductive substances to obtain printed circuit embedded inductance with high inductance value, the process is complex, the cost is high, and additional processes are required in the production of the printed circuit board assembly line, and the compatibility with the PCB process is poor. The Chinese invention patent "Preparation Method of Embedded Magnetic Core Inductor for Printed Circuit Board" introduces a method of directly chemically plating a layer of non-metal alloy magnetic material on the inductance coil to prepare the magnetic conductive material embedded in the printed circuit board. method. The method is simple in process, low in production cost, and has obvious effect on the improvement of inductance value, but the non-metallic alloy obtained by this method is not only used as a conductor for electrical signal transmission, but also as a magnetic conductive substance, and the non-metallic alloy with larger resistance value is easy to This results in a low quality factor of the inductor. Sugawa et al. in the document "Carbonyl-iron/epoxy composite magnetic core for planar power inductor used in package-level power grid", and Fan Yuenong et al. in the document "Design and performance research of Ni-Cu-Zn ferrite films for inductors". A method of increasing the inductance value by covering the magnetic composite material obtained by mixing ferrite and resin on the surface of the inductor coil by screen printing is introduced. However, with the screen printing method, due to the thickness error of the process itself, the inductance value obtained under the same process has a large error, and the inductance performance cannot be controlled.

SUMMARY OF THE INVENTION

Aiming at the problems in the prior art, such as limited base material for manufacturing embedded inductors, poor compatibility with PCB process, uncontrollable inductance performance, etc., the present invention provides a manufacturing method for embedded inductors in printed circuits. The seed layer and the patterned resist layer are formed on the metal seed layer without the resist layer to form a metal conductor structure, and the patterned resist layer and the metal seed layer covered under it are removed as a sacrificial layer, and then the metal conductor structure is removed. A magnetic core film is deposited on the top to realize the fabrication of printed circuit embedded inductors. In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows:

A preparation method of an embedded inductor of a printed circuit, characterized in that it comprises the following steps:

Step: 1: forming a metal seed layer on the surface of the dielectric layer;

Step 2: cover the patterned resist layer on the metal seed layer obtained in step 1 by pattern transfer technology;

Step 3: growing a metal conductor layer on the metal seed layer not covered by the resist layer;

Step 4: removing the resist layer and the metal seed layer covered by the resist layer to prepare a conductor structure with embedded inductors;

Step 5: forming a magnetic thin film on the surface of the conductor structure prepared in step 4.

Further, before step 5, a browning treatment step is also included, so that a metal organic thin film layer is formed on the surface of the conductor structure of the embedded inductor.

Further, in the step 1, the metal seed layer is formed by a sputtering process or an electroless plating process.

Further, the electroless plating process includes steps of cleaning, micro-etching, pre-dipping, activation and electroless plating.

Specifically, in the step 1, the metal seed layer may be formed by sputtering titanium copper, electroless copper plating, electroless tin plating or electroless nickel plating.

Further, in the step 2, the patterned resist layer is designed according to the conductor structure of the embedded inductor, and the two are complementary on the plane.

Further, in the step 5, the magnetic thin film is preferably a pure cobalt thin film or a non-metallic cobalt composite material.

Further, the method for forming the magnetic thin film in the step 5 is magnetron sputtering, electroplating or inkjet printing.

As a specific embodiment, the specific operation of electroplating the cobalt film in the step 5 is as follows: the conductor structure obtained in step 4 is placed in the electroplating solution to prepare a pure cobalt film; the electroplating conditions are as follows: the pH of the electroplating solution is 3-6, The electroplating temperature is 20～40℃, the current density is 0.5～4A/dm ² , and the electroplating time is 5～90min; the composition of the electroplating solution includes cobalt salt with a concentration of 20～300g/L, and a concentration of 1～2000mg/L The first complexing agent, the second complexing agent with a concentration of 1-200 mg/L, the buffering agent with a concentration of 10-50 g/L, a pH adjusting agent and deionized water, wherein the first complexing agent includes A mixture of any one or more of glycine, alanine, valine, leucine, isoleucine, aspartic acid, glutamic acid, lysine and arginine, the second complex The mixture includes any one or a mixture of sodium polydisulfide dipropane sulfonate and sodium 3-mercapto-1-propane sulfonate, and the cobalt salt is cobalt chloride, cobalt sulfate, cobalt acetate, cobalt nitrate and sulfamic acid The composition of any one or more of cobalt acid, the pH adjusting agent is the acid corresponding to the anion in the cobalt salt and/or sodium hydroxide, and the buffer is preferably boric acid.

As a specific embodiment, the specific operation of the magnetron sputtering cobalt film in the step 5 is as follows: the cobalt film is completely covered on the surface of the printed circuit board obtained by the step 4 through the magnetron sputtering equipment, and then the conductor The surface of the structure is covered with resist, and then the cobalt film without resist protection is removed by etching, and finally the resist is removed to realize the fabrication of the magnetic thin film. The thickness of the magnetic cobalt film obtained by magnetron sputtering is preferably 0.1-1 μm.

As a specific embodiment, the specific operation of inkjet printing the cobalt film in the step 5 is as follows: the surface of the conductor structure or the surface of the conductor structure coated with the metal organic thin film layer is directly printed on the surface of the conductor structure obtained by the inkjet printing method in step 4. Film composite material; the raw materials used in inkjet printing include thermoplastic resin and cobalt particles, wherein the thermoplastic resin is any one of polylactic acid, polyethylene, polypropylene, and polybutadiene, and the mass fraction of cobalt particles is 60% to 90% %.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) The present invention innovates the means of burying the inductor structure (conductive coil) in the substrate, and further decorates the magnetic film on the surface of the inductor structure to realize the embedding of the inductor forming the magnetic film in the printed circuit board. Compared with the conductive coil produced by the existing subtractive method, the present invention can realize the production of embedded inductance on any substrate, thereby avoiding the adverse effects caused by material mismatch when the SMT technology realizes the integration of components, and makes the application of embedded inductance components possible. More convenient and flexible.

(2) The present invention provides a method for preparing an embedded inductor of a printed circuit. Compared with the existing lamination method, holes can be punched before the conductor structure is formed, and through holes (ie, through holes) can be realized while the metal seed layer is formed. hole metallization), thus avoiding the problem of uncontrollable inductance performance caused by making through holes on the magnetic core.

(3) The present invention provides a method for preparing printed circuit embedded inductance, the process is simple and controllable, compatible with the printed circuit board production line, without adding additional processes, reducing equipment and technology investment, and helping to reduce cost to realize industrial production.

(4) The present invention provides a method for preparing an embedded inductor of a printed circuit. By conducting browning treatment on the conductor structure of the embedded inductor, a metal-organic film is formed on the surface of the conductor structure, and then a magnetic film is deposited. The film has a large resistance value, so that the organic metal film acts as a barrier layer between the copper conductor of the embedded inductor and the magnetic film to ensure the effective performance of the magnetic properties of the magnetic film, which is beneficial to the improvement of the inductance value of the embedded inductor.

(5) The present invention provides a method for preparing a printed circuit embedded inductance, which adopts inkjet printing, electroplating and magnetron sputtering to deposit a magnetic film, which can overcome the large inductance error of the traditional screen printing process under the same process. Defects are beneficial to obtain inductive components with stable performance, improve the performance stability of products, and then achieve mass production.

Description of drawings

FIG. 1 is a schematic diagram of a manufacturing process of a printed circuit embedded inductor based on a magnetron sputtering method to form a magnetic thin film according to Embodiment 1 of the present invention, and a cross-sectional diagram is used in the figure.

FIG. 2 is a schematic diagram of a manufacturing process of a printed circuit embedded inductor based on an inkjet printing method to form a magnetic thin film according to Embodiment 2 of the present invention, and a cross-sectional diagram is used in the figure.

FIG. 3 is a schematic diagram of a manufacturing process for forming a magnetic thin film based on an electroplating method for an embedded inductor of a printed circuit provided in Embodiment 3 of the present invention, and a cross-sectional diagram is used in the figure.

4 is a cross-sectional metallographic diagram of the product obtained in Example 1 of the present invention.

5 is a cross-sectional metallographic diagram of the product obtained in Example 2 of the present invention.

6 is a cross-sectional metallographic diagram of the product obtained in Example 3 of the present invention.

FIG. 7 is a microscopic topography diagram of the plating surface of the printed circuit embedded inductors provided in Example 3 of the present invention and Comparative Examples 1 and 2. FIG.

Figure 8 shows the inductance values of printed circuit embedded inductances provided by different electroplating systems.

Detailed ways

In order to make the solution and principle of the present invention clearer to those skilled in the art, the following detailed description will be given in conjunction with the accompanying drawings and specific embodiments. It should be clear to those skilled in the art that the present invention is not limited to the printed circuit embedded inductor with surface modified magnetic cobalt film, and the method is applicable to the fabrication of any magnetic film modified printed circuit embedded inductor.

Example 1:

A method for forming an embedded inductor of a printed circuit and a magnetic film on its surface, the implementation process is shown in Figure 1, and the specific implementation steps are:

(1) Forming a metal seed layer

a. Cleaning: prepare an acid degreasing solution consisting of sulfuric acid with a concentration of 5% by volume, OP emulsion with a concentration of 5% by volume and deionized water; acid removal of a 4cm×5cm epoxy resin substrate at 50°C Soak in oil for 3 minutes and ultrasonically treat for 1 minute to remove oil stains on the surface. After degreasing treatment, rinse the epoxy resin substrate with deionized water to remove the degreasing liquid attached to the surface;

b. Micro-etching: prepare a micro-etching solution consisting of sulfuric acid with a concentration of 5% by volume, 50 g/L sodium persulfate and deionized water; the epoxy resin substrate obtained after step a is treated in a micro-etching solution at 25°C Medium ultrasonic treatment for 2min, to make the surface into a rough structure with unevenness, to ensure that the coating is closely combined with the surface, after the micro-etching treatment, rinse the epoxy resin substrate with deionized water to remove the micro-etching liquid attached to the surface;

c. Pre-dip: prepare a pre-dip solution consisting of sulfuric acid and deionized water with a concentration of 5% by volume; soak the epoxy resin substrate obtained after step b in the pre-dip solution at 25°C for 1 min to adjust the epoxy resin The acid-base properties of the solution attached to the surface of the substrate maintain the acidity of the activation tank;

d. Activation: the metal is prepared with an activation solution consisting of 60 mg/L palladium chloride, sulfuric acid with a concentration of 5% by volume and deionized water; the epoxy resin substrate obtained after the treatment in step c is soaked in a pre-dip solution at 25° C. 5min, deposit the required catalytic seeds on the surface of the epoxy resin substrate;

e. Making metal seed layer: the preparation consists of 25g/L copper chloride, 20g/L copper sulfate, 4g/L formaldehyde, 20g/L EDTA disodium salt, 10g/L potassium sodium tartrate, 15g/L hydrogen A copper plating solution composed of sodium oxide and deionized water; the epoxy resin substrate obtained after the treatment in step d is immersed in a copper plating solution at 35° C. for 5 minutes to complete the electroless copper plating process to form a metal seed layer;

(2) Forming a patterned resist layer

The surface of the metal seed layer obtained by electroless copper plating is covered with the resist of the negative image inductor coil pattern;

(3) Filler metal

Prepare a copper plating solution consisting of 75g/L copper sulfate, 220g/L concentrated sulfuric acid, 60mg/L chloride ion and deionized water; electroplating the epoxy resin substrate obtained after step (2) in the plating solution at 25°C for 60min , the current density is 2A/dm2, and the metal seed layer without resist is partially filled to form a metal conductor layer;

(4) Etching the metal seed layer and the resist layer

Prepare an etching solution consisting of 100g/L copper chloride, 100g/L ammonia chloride, 600g/L ammonia water and deionized water; remove the resist covering the surface of the printed circuit board, and etch the printed circuit board Immerse in the liquid for 30s to etch away the metal seed layer area outside the embedded inductor coil protected by the resist to form the embedded inductor coil;

(5) Browning treatment

Prepared by 95g/L sulfuric acid, 4g/L water-soluble methoxylated polyethylene glycol, 25mg/L sodium chloride, 150mg/L copper sulfate, 8g/L benzotriazole, 20g/L hydrogen peroxide and deionized water Browning liquid composed of water; soak the formed embedded inductor in the browning liquid at 35℃ for 60s to form a metal-organic film on the surface of the conductor structure;

(6) Forming the magnetic cobalt film on the surface of the embedded inductor

a. Using a metal Co target with a purity of 99.95% to magnetron sputter a layer of magnetic cobalt film on the surface of the embedded inductor obtained in step (5), the sputtering power is 200W, the sputtering time is 5min, and the working pressure is 0.4 Pa;

b. Cover the surface of the embedded inductor coil with resist, then soak the printed circuit board in the etching solution prepared in step (4) for 10s, etch away the cobalt film without resist protection, and finally remove the resist to obtain Printed circuit embedded inductor with magnetic cobalt film deposited on the surface.

The cross-sectional metallographic diagram of the electroplated cobalt film on the surface of the embedded inductor coil obtained in this embodiment is shown in FIG. 4 . Compared with the embedded inductor before the magnetic film is not deposited, the inductance value is increased by 15%.

Example 2:

A method for forming an embedded inductor in a printed circuit and a magnetic film on its surface, the implementation process is shown in Figure 2, and the specific implementation steps are:

(1) Forming a metal seed layer

a. Cleaning: prepare an acid degreasing solution consisting of sulfuric acid with a concentration of 5% by volume, OP emulsion with a concentration of 5% by volume and deionized water; acid removal of a 4cm×5cm epoxy resin substrate at 50°C Soak in oil for 3 minutes and ultrasonically treat for 1 minute to remove oil stains on the surface. After degreasing treatment, rinse the epoxy resin substrate with deionized water to remove the degreasing liquid attached to the surface;

b. Micro-etching: prepare a micro-etching solution consisting of sulfuric acid with a concentration of 5% by volume, 50 g/L sodium persulfate and deionized water; the epoxy resin substrate obtained after step a is treated in a micro-etching solution at 25°C Medium ultrasonic treatment for 2min, to make the surface into a rough structure with unevenness, to ensure that the coating is closely combined with the surface, after the micro-etching treatment, rinse the epoxy resin substrate with deionized water to remove the micro-etching liquid attached to the surface;

c. Pre-dip: prepare a pre-dip solution consisting of sulfuric acid and deionized water with a concentration of 5% by volume; soak the epoxy resin substrate obtained after step b in the pre-dip solution at 25°C for 1 min to adjust the epoxy resin The acid-base properties of the solution attached to the surface of the substrate maintain the acidity of the activation tank;

d. Activation: the metal is prepared with an activation solution consisting of 60 mg/L palladium chloride, sulfuric acid with a concentration of 5% by volume and deionized water; the epoxy resin substrate obtained after the treatment in step c is soaked in a pre-dip solution at 25° C. 5min, deposit the required catalytic seeds on the surface of the epoxy resin substrate;

e. Making metal seed layer: the preparation consists of 25g/L copper chloride, 20g/L copper sulfate, 4g/L formaldehyde, 20g/L EDTA disodium salt, 10g/L potassium sodium tartrate, 15g/L hydrogen A copper plating solution composed of sodium oxide and deionized water; the epoxy resin substrate obtained after the treatment in step d is immersed in a copper plating solution at 35° C. for 5 minutes to complete the electroless copper plating process to form a metal seed layer;

(2) Forming a patterned resist layer

The surface of the metal seed layer obtained by electroless copper plating is covered with the resist of the negative image inductor coil pattern;

(3) Filler metal

Prepare a copper plating solution consisting of 75g/L copper sulfate, 220g/L concentrated sulfuric acid, 60mg/L chloride ion and deionized water; electroplating the epoxy resin substrate obtained after step (2) in the plating solution at 25°C for 60min , the current density is 2A/dm2, and the metal seed layer without resist is partially filled to form a metal conductor layer;

(4) Etching the metal seed layer and the resist layer

Prepare an etching solution consisting of 100g/L copper chloride, 100g/L ammonia chloride, 600g/L ammonia water and deionized water; remove the resist covering the surface of the printed circuit board, and etch the printed circuit board Immerse in the liquid for 30s to etch away the metal seed layer area outside the embedded inductor coil protected by the resist to form the embedded inductor coil;

(5) Browning treatment

Prepared by 95g/L sulfuric acid, 4g/L water-soluble methoxylated polyethylene glycol, 25mg/L sodium chloride, 150mg/L copper sulfate, 8g/L benzotriazole, 20g/L hydrogen peroxide and deionized water Browning liquid composed of water; soak the formed embedded inductor in the browning liquid at 35℃ for 60s to form a metal-organic film on the surface of the conductor structure;

(6) Forming the magnetic cobalt film on the surface of the embedded inductor

a. After drying the polylactic acid in an oven at 50 °C for 12 hours, mix it with cobalt particles with a mass fraction of 90%, and then use a torque rheometer to blend the mixed materials to obtain a magnetic composite wire that can be used for inkjet printing;

b. Using an inkjet printer to form a magnetic cobalt film on the surface of the embedded inductor with the magnetic composite wire in step a to obtain a printed circuit embedded inductor with a magnetic cobalt film deposited on the surface.

The cross-sectional metallographic diagram of the electroplated cobalt film on the surface of the embedded inductor coil obtained in this embodiment is shown in FIG. 5 . Compared with the embedded inductor before depositing the magnetic film, the inductance value is increased by 10% to 20%.

Example 3:

A method for forming an embedded inductor in a printed circuit and a magnetic film on its surface, the implementation process is shown in Figure 3, and the specific implementation steps are:

(1) Forming a metal seed layer

a. Cleaning: prepare an acid degreasing solution consisting of sulfuric acid with a concentration of 5% by volume, OP emulsion with a concentration of 5% by volume and deionized water; acid removal of a 4cm×5cm epoxy resin substrate at 50°C Soak in oil for 3 minutes and ultrasonically treat for 1 minute to remove oil stains on the surface. After degreasing treatment, rinse the epoxy resin substrate with deionized water to remove the degreasing liquid attached to the surface;

b. Micro-etching: prepare a micro-etching solution consisting of sulfuric acid with a concentration of 5% by volume, 50 g/L sodium persulfate and deionized water; the epoxy resin substrate obtained after step a is treated in a micro-etching solution at 25°C Medium ultrasonic treatment for 2min, to make the surface into a rough structure with unevenness, to ensure that the coating is closely combined with the surface, after the micro-etching treatment, rinse the epoxy resin substrate with deionized water to remove the micro-etching liquid attached to the surface;

c. Pre-dip: prepare a pre-dip solution consisting of sulfuric acid and deionized water with a concentration of 5% by volume; soak the epoxy resin substrate obtained after step b in the pre-dip solution at 25°C for 1 min to adjust the epoxy resin The acid-base properties of the solution attached to the surface of the substrate maintain the acidity of the activation tank;

d. Activation: the metal is prepared with an activation solution consisting of 60 mg/L palladium chloride, sulfuric acid with a concentration of 5% by volume and deionized water; the epoxy resin substrate obtained after the treatment in step c is soaked in a pre-dip solution at 25° C. 5min, deposit the required catalytic seeds on the surface of the epoxy resin substrate;

e. Making metal seed layer: the preparation consists of 25g/L copper chloride, 20g/L copper sulfate, 4g/L formaldehyde, 20g/L EDTA disodium salt, 10g/L potassium sodium tartrate, 15g/L hydrogen A copper plating solution composed of sodium oxide and deionized water; the epoxy resin substrate obtained after the treatment in step d is immersed in a copper plating solution at 35° C. for 5 minutes to complete the electroless copper plating process to form a metal seed layer;

(2) Forming a patterned resist layer

The surface of the metal seed layer obtained by electroless copper plating is covered with the resist of the negative image inductor coil pattern;

(3) Filler metal

Prepare a copper plating solution consisting of 75g/L copper sulfate, 220g/L concentrated sulfuric acid, 60mg/L chloride ion and deionized water; electroplating the epoxy resin substrate obtained after step (2) in the plating solution at 25°C for 60min , the current density is 2A/dm2, and the metal seed layer without resist is partially filled to form a metal conductor layer;

(4) Etching the metal seed layer and the resist layer

Prepare an etching solution consisting of 100g/L copper chloride, 100g/L ammonia chloride, 600g/L ammonia water and deionized water; remove the resist covering the surface of the printed circuit board, and etch the printed circuit board Immerse in the liquid for 30s to etch away the metal seed layer area outside the embedded inductor coil protected by the resist to form the embedded inductor coil;

(5) Browning treatment

Prepared by 95g/L sulfuric acid, 4g/L water-soluble methoxylated polyethylene glycol, 25mg/L sodium chloride, 150mg/L copper sulfate, 8g/L benzotriazole, 20g/L hydrogen peroxide and deionized water Browning liquid composed of water; soak the formed embedded inductor in the browning liquid at 35℃ for 60s to form a metal-organic film on the surface of the conductor structure;

(6) Forming the magnetic cobalt film on the surface of the embedded inductor

a. Prepare a solution consisting of 28g/L cobalt sulfate heptahydrate, 30g/L boric acid, 30mg/L glycine, 20mg/L sodium 3-mercapto-1-propane sulfonate and deionized water, and adjust with dilute sulfuric acid and sodium hydroxide The pH value is 4.0, and the electroplating solution is obtained; the embedded inductor obtained in step (5) is used as the cathode, and the metal titanium mesh is used as the anode, and electroplating is carried out in the electroplating solution at 25 ° C for 30min, the current density is 2A/dm2, and the air flow rate of air stirring is 1L /min;

b. The embedded inductor obtained after the treatment in step a is quickly taken out from the electroplating solution after electroplating, rinsed with deionized water for 1-3 minutes, then rinsed with absolute ethanol for 0.5-2 minutes, and finally dried with cold air to obtain the surface deposited magnetic Cobalt film printed circuit embedded inductors.

The cross-sectional metallographic diagram of the electroplated cobalt film on the surface of the embedded inductor coil obtained in this example is shown in FIG. 6 , and the microscopic topography of the coating is shown in FIG. 7c . Compared with the embedded inductance before depositing the magnetic film, the inductance value is improved by 11%.

Comparative Example 1:

A preparation method of a printed circuit embedded inductor, the specific implementation steps are:

(1) Forming a metal seed layer

a. Cleaning: prepare an acid degreasing solution consisting of sulfuric acid with a concentration of 5% by volume, OP emulsion with a concentration of 5% by volume and deionized water; acid removal of a 4cm×5cm epoxy resin substrate at 50°C Soak in oil for 3 minutes and ultrasonically treat for 1 minute to remove oil stains on the surface. After degreasing treatment, rinse the epoxy resin substrate with deionized water to remove the degreasing liquid attached to the surface;

b. Micro-etching: prepare a micro-etching solution consisting of sulfuric acid with a concentration of 5% by volume, 50 g/L sodium persulfate and deionized water; the epoxy resin substrate obtained after step a is treated in a micro-etching solution at 25°C Medium ultrasonic treatment for 2min, to make the surface into a rough structure with unevenness, to ensure that the coating is closely combined with the surface, after the micro-etching treatment, rinse the epoxy resin substrate with deionized water to remove the micro-etching liquid attached to the surface;

c. Pre-dip: prepare a pre-dip solution consisting of sulfuric acid and deionized water with a concentration of 5% by volume; soak the epoxy resin substrate obtained after step b in the pre-dip solution at 25°C for 1 min to adjust the epoxy resin The acid-base properties of the solution attached to the surface of the substrate maintain the acidity of the activation tank;

d. Activation: the metal is prepared with an activation solution consisting of 60 mg/L palladium chloride, sulfuric acid with a concentration of 5% by volume and deionized water; the epoxy resin substrate obtained after the treatment in step c is soaked in a pre-dip solution at 25° C. 5min, deposit the required catalytic seeds on the surface of the epoxy resin substrate;

e. Making metal seed layer: the preparation consists of 25g/L copper chloride, 20g/L copper sulfate, 4g/L formaldehyde, 20g/L EDTA disodium salt, 10g/L potassium sodium tartrate, 15g/L hydrogen A copper plating solution composed of sodium oxide and deionized water; the epoxy resin substrate obtained after the treatment in step d is immersed in a copper plating solution at 35° C. for 5 minutes to complete the electroless copper plating process to form a metal seed layer;

(2) Forming a patterned resist layer

The surface of the metal seed layer obtained by electroless copper plating is covered with the resist of the negative image inductor coil pattern;

(3) Filler metal

Prepare a copper plating solution consisting of 75g/L copper sulfate, 220g/L concentrated sulfuric acid, 60mg/L chloride ions and deionized water; electroplating the epoxy resin substrate obtained after step f in the electroplating solution at 25°C for 60min, the current The density is 2A/dm ² , and the metal seed layer that is not covered by the resist is partially filled to form a metal conductor layer;

(4) Etching the metal seed layer and the resist layer

Prepare an etching solution consisting of 100g/L copper chloride, 100g/L ammonia chloride, 600g/L ammonia water and deionized water; remove the resist covering the surface of the printed circuit board, and etch the printed circuit board Immerse in the liquid for 30s to etch away the metal seed layer area outside the embedded inductor coil protected by the resist to form the embedded inductor coil;

(5) Forming the magnetic cobalt film on the surface of the embedded inductor

a. prepare a solution consisting of 28g/L cobalt sulfate heptahydrate, 30g/L boric acid and deionized water, and adjust the pH value to 4.0 with dilute sulfuric acid and sodium hydroxide to obtain an electroplating solution; the embedding obtained in step (2) The inductor is used as the cathode, the metal titanium mesh is used as the anode, and the electroplating is carried out in the electroplating solution at 25°C for 30min, the current density is 2A/dm ² , and the air flow rate of air stirring is 1L/min;

b. The embedded inductor obtained after the treatment in step a is quickly taken out from the electroplating solution after the electroplating is completed, rinsed with deionized water for 1 to 3 minutes, then rinsed with absolute ethanol for 0.5 to 2 minutes, and finally dried with cold air to obtain the surface modified magnetic Cobalt film printed circuit embedded inductors.

The microscopic topography of the plating layer of the embedded inductor obtained in this embodiment is shown in FIG. 7a. Compared with the embedded inductor (1.373μH@1MHz) without cobalt film modification, the inductance value is improved by 4.7%.

Comparative Example 2:

A preparation method of a printed circuit embedded inductor, the specific implementation steps are:

(1) Forming a metal seed layer

a. Cleaning: prepare an acid degreasing solution consisting of sulfuric acid with a concentration of 5% by volume, OP emulsion with a concentration of 5% by volume and deionized water; acid removal of a 4cm×5cm epoxy resin substrate at 50°C Soak in oil for 3 minutes and ultrasonically treat for 1 minute to remove oil stains on the surface. After degreasing treatment, rinse the epoxy resin substrate with deionized water to remove the degreasing liquid attached to the surface;

b. Micro-etching: prepare a micro-etching solution consisting of sulfuric acid with a concentration of 5% by volume, 50 g/L sodium persulfate and deionized water; the epoxy resin substrate obtained after step a is treated in a micro-etching solution at 25°C Medium ultrasonic treatment for 2min, to make the surface into a rough structure with unevenness, to ensure that the coating is closely combined with the surface, after the micro-etching treatment, rinse the epoxy resin substrate with deionized water to remove the micro-etching liquid attached to the surface;

c. Pre-dip: prepare a pre-dip solution consisting of sulfuric acid and deionized water with a concentration of 5% by volume; soak the epoxy resin substrate obtained after step b in the pre-dip solution at 25°C for 1 min to adjust the epoxy resin The acid-base properties of the solution attached to the surface of the substrate maintain the acidity of the activation tank;

d. Activation: the metal is prepared with an activation solution consisting of 60 mg/L palladium chloride, sulfuric acid with a concentration of 5% by volume and deionized water; the epoxy resin substrate obtained after the treatment in step c is soaked in a pre-dip solution at 25° C. 5min, deposit the required catalytic seeds on the surface of the epoxy resin substrate;

e. Making metal seed layer: the preparation consists of 25g/L copper chloride, 20g/L copper sulfate, 4g/L formaldehyde, 20g/L EDTA disodium salt, 10g/L potassium sodium tartrate, 15g/L hydrogen A copper plating solution composed of sodium oxide and deionized water; the epoxy resin substrate obtained after the treatment in step d is immersed in a copper plating solution at 35° C. for 5 minutes to complete the electroless copper plating process to form a metal seed layer;

(2) Forming a patterned resist layer

The surface of the metal seed layer obtained by electroless copper plating is covered with the resist of the negative image inductor coil pattern;

(3) Filler metal

Prepare a copper plating solution consisting of 75g/L copper sulfate, 220g/L concentrated sulfuric acid, 60mg/L chloride ions and deionized water; electroplating the epoxy resin substrate obtained after step f in the electroplating solution at 25°C for 60min, the current The density is 2A/dm ² , and the metal seed layer that is not covered by the resist is partially filled to form a metal conductor layer;

(4) Etching the metal seed layer and the resist layer

Prepare an etching solution consisting of 100g/L copper chloride, 100g/L ammonia chloride, 600g/L ammonia water and deionized water; remove the resist covering the surface of the printed circuit board, and etch the printed circuit board Immerse in the liquid for 30s to etch away the metal seed layer area outside the embedded inductor coil protected by the resist to form the embedded inductor coil;

(5) Forming the magnetic cobalt film on the surface of the embedded inductor

A. prepare a solution consisting of 28g/L cobalt sulfate heptahydrate, 30g/L boric acid, 30mg/L glycine and deionized water, and adjust the pH value to 4.0 with dilute sulfuric acid and sodium hydroxide to obtain electroplating solution; step (2) ) The obtained embedded inductor is used as the cathode, and the metal titanium mesh is used as the anode, and electroplating in the electroplating solution at 25° C. for 30min, the current density is 2A/dm ² , and the air flow rate of air stirring is 1L/min;

b. The embedded inductor obtained after the treatment in step a is quickly taken out from the electroplating solution after the electroplating is completed, rinsed with deionized water for 1 to 3 minutes, then rinsed with absolute ethanol for 0.5 to 2 minutes, and finally dried with cold air to obtain the surface modified magnetic Cobalt film printed circuit embedded inductors.

The microscopic topography of the plating layer of the embedded inductor obtained in this embodiment is shown in Figure 7b. Compared with the embedded inductance (1.373μH@1MHz) without cobalt film modification, the inductance value is improved by 6.8%.

The addition of glycine in Example 2 significantly reduces the grain size of the coating, and the coercivity decreases with the reduction of the grain size (the coercivity of the coating is 150 Oe when the glycine is not added, and the coercivity of the coating is reduced to 150 Oe after adding the glycine. 71Oe), the magnetic properties of the coating are improved. For inductors, materials with high saturation magnetic induction and low coercivity are more suitable as magnetic media, so the inductance value of the inductor is improved. Combining with Comparative Examples 1 and 2 and Example 3, it can be seen that the addition of glycine significantly reduces the grain size of the coating. While glycine reduces the coercive force of the coating, because sodium 3-mercapto-1-propanesulfonate is in the process of crystal growth. It has the effect of inhibiting the growth of the crystal plane in the characteristic crystal plane, and it can be seen that both substances have an effect on the grain growth of the coating. Further research found that the optimal concentration of the first complexing agent was 30 mg/L, and on the basis of maintaining the optimal concentration of the first complexing agent, the balance between the second complexing agent and the first complexing agent was within a certain range. It is beneficial to improve the inductance value, as shown in Figure 8. Since the magnetic properties of the cobalt coating have an important influence on the specific crystal plane of the crystal, the magnetic saturation intensity of the coating increases (the magnetic saturation intensity of the coating is 19 emu/g without the addition of glycine and sodium 3-mercapto-1-propane sulfonate, and the addition of glycine and 3-mercapto-1-propane sulfonate, the magnetic saturation intensity of the coating increases to 31 emu/g), it can be seen that the inductance value of the coating obtained based on the electroplating cobalt system of the present invention and applied to the embedded inductor is higher than that of the traditional electroplating system.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative rather than restrictive. Under the inspiration of the present invention, many modifications can be made without departing from the spirit of the present invention and the protection scope of the claims, which all belong to the protection of the present invention.

Claims (9)

1. a preparation method of printed circuit embedded inductance, is characterized in that, comprises the steps: Step: 1: forming a metal seed layer on the surface of the dielectric layer; Step 2: cover the patterned resist layer on the metal seed layer obtained in step 1 by pattern transfer technology; Step 3: growing a metal conductor layer on the metal seed layer not covered by the resist layer; Step 4: removing the resist layer and the metal seed layer covered by the resist layer to prepare a conductor structure with embedded inductors; Step 5: forming a magnetic thin film on the surface of the conductor structure prepared in step 4. 2 . The method for preparing an embedded inductor of a printed circuit according to claim 1 , wherein the metal seed layer is formed in the step 1 by a sputtering process or an electroless plating process. 3 . 3 . The method for preparing an embedded inductor in a printed circuit according to claim 1 , wherein the step of browning treatment is further included before step 5 , so that a metal organic thin film layer is formed on the surface of the conductor structure of the embedded inductor. 4 . 4 . The method for preparing an embedded inductor in a printed circuit according to claim 1 or 3 , wherein the method for forming the magnetic thin film in the step 5 is magnetron sputtering, electroplating or inkjet printing. 5 . 5. The preparation method of the printed circuit embedded inductor according to claim 4, characterized in that, in the step 5, the magnetic film is a pure cobalt film, and the pure cobalt film is prepared by an electroplating method, and the specific operations are as follows: In step 4, the prepared conductor structure or the conductor structure with the metal-organic thin film layer is placed in an electroplating solution, and electroplating is performed under the action of an electrode; the composition of the electroplating solution includes a cobalt salt, a first complexing agent, a second complexing agent, Buffering agent, pH adjusting agent and deionized water, wherein: the first complexing agent comprises glycine, alanine, valine, leucine, isoleucine, aspartic acid, glutamic acid, lysine A mixture of any one or more of amino acid and arginine, and the second complexing agent includes any one or two of sodium polydithiodipropane sulfonate and sodium 3-mercapto-1-propane sulfonate mixture. 6 . The method for preparing an embedded inductor of a printed circuit according to claim 5 , wherein the concentration of the cobalt salt in the electroplating solution is 20-300 g/L, and the concentration of the first complexing agent is 1-2000 mg/L. 7 . L, the concentration of the second complexing agent is 1～200mg/L, and the concentration of the buffer is 10～50g/L; The electroplating conditions are as follows: the pH of the electroplating solution is 3～6, the electroplating temperature is 20～40 ℃, the current The density is 0.5～4A/dm ² , and the electroplating time is 5～90min. 7. The method for preparing a printed circuit embedded inductor according to claim 4, wherein the magnetic film in the step 5 is a pure cobalt film, and the pure cobalt film is prepared by a magnetron sputtering method, and the specific operations are as follows : Cover the surface of the printed circuit board processed in step 4 with the cobalt film by magnetron sputtering equipment, then cover the surface of the conductor structure or the surface of the metal-organic film layer with resist, and then etch to remove the non-resist protection. Cobalt film, and finally remove the resist to realize the production of magnetic thin film. 8. The preparation method of the printed circuit embedded inductor according to claim 3 or 6, characterized in that, in the step 5, the magnetic film is a cobalt composite material, and the cobalt composite material is prepared by an inkjet printing method. As follows: the cobalt film composite material is directly printed on the surface of the conductor structure or the surface of the metal organic thin film layer by processing in step 4 by the inkjet printing method. 9. The preparation method of printed circuit embedded inductors according to claim 8, wherein the raw materials used in inkjet printing comprise thermoplastic resin and cobalt particles, wherein the thermoplastic resin is polylactic acid, polyethylene, polypropylene, polyamide For any one of butadiene, the mass fraction of cobalt particles is 60% to 90%.