A rod-shaped magnetic core and its preparation method, an inductor and its preparation method and its application

Abstract

This invention provides a rod-shaped magnetic core and its preparation method, an inductor and its preparation method, and their applications, belonging to the field of non-destructive testing technology for inductor devices. The invention provides a method for preparing a rod-shaped magnetic core, comprising the following steps: filling a mold hole with nanocrystalline alloy wire along the extension direction of the mold hole; then infiltrating the gaps between the nanocrystalline alloy wire with epoxy resin for curing to obtain the rod-shaped magnetic core; the diameter of the nanocrystalline alloy wire is 0.05–0.2 mm; the diameter of the mold hole is 0.3–0.5 mm. The preparation method of this invention can prepare rod-shaped magnetic cores with a diameter of 0.2 mm or more, and the epoxy resin in this invention enhances the strength of the rod-shaped magnetic core, preventing it from breaking when wound with a coil. Furthermore, the rod-shaped magnetic core of this invention does not have the problems of uneven surface and burn-out layer, and does not reduce the relative permeability of the magnetic core.

Description

Technical Field

[0001] This invention belongs to the field of non-destructive testing technology for inductor devices, specifically relating to a rod-shaped magnetic core and its preparation method, an inductor and its preparation method, and its applications. Background Technology

[0002] When a rod-shaped inductor is inserted into a hole with a metal coating, significant eddy current induction occurs in the metal coating at higher frequencies, leading to a noticeable change in inductance. Therefore, rod-shaped inductors can be used for non-destructive testing of metal coatings, finding wide application in light industry, metallurgy, and electronics. Holes on circuit boards serve as solder joints, thus requiring the hole walls to have a metal coating that connects to the printed circuitry. The smallest hole on a circuit board has a diameter of only 0.9 mm, therefore the diameter of the miniature rod-shaped inductor must not exceed 0.9 mm.

[0003] The rate of change of inductance with and without coating is a key factor limiting detector resolution. To improve resolution, a larger inductance value and a larger inductance change value are required. From the formula (1) for a rod-shaped inductor, it can be seen that increasing the cross-sectional area (A) of the core material... c This helps to increase the inductance value.

[0004]

[0005] In equation (1), L s μ0 is the inductance of the rod-shaped inductor, in H; μ0 is the permeability of free space, in H / m; μ0 is the permeability of free space. r A is the relative permeability of the core material, without dimensions; N is the number of turns of the inductor coil, without dimensions; A c The cross-sectional area of ​​the rod-shaped magnetic core is expressed in meters (m²). 2 l represents the length of the rod-shaped magnetic core, in meters (m).

[0006] Since the total diameter of a rod-shaped inductor cannot exceed 0.9 mm, the maximum diameter of the core material can only be around 0.5 mm. Chinese Patent 202211100714.0 reports a fabrication process for a nanocrystalline alloy rod-shaped magnetic core. This involves first preparing an amorphous alloy strip, then performing winding, annealing, and curing processes to obtain a nanocrystalline alloy block. Finally, a CNC wire cutting process is used to cut rod-shaped magnetic cores with a diameter of approximately 0.5 mm from the cured nanocrystalline alloy block. However, this process suffers from uneven cut surfaces and the presence of a burn-off layer, which significantly reduces the relative permeability of the core when the core diameter is very small.

[0007] Amorphous alloy wires can be prepared using a glass-encapsulated drawing process, followed by amorphous crystallization annealing to produce nanocrystalline alloy wires, resulting in nanocrystalline alloy wire cores with very high relative permeability. However, due to limitations in amorphous formation capabilities, current processes cannot produce single amorphous alloy wires with diameters greater than 0.2 mm, and therefore cannot produce single nanocrystalline alloy wires with diameters greater than 0.2 mm. Furthermore, after amorphous crystallization annealing, the nanocrystalline alloy wires become very brittle, unable to withstand stress during coil winding, and are extremely prone to breakage. Summary of the Invention

[0008] The purpose of this invention is to provide a rod-shaped magnetic core and its preparation method, an inductor and its preparation method, and its application. This invention can prepare rod-shaped magnetic cores with a diameter of 0.2 mm or more and the prepared rod-shaped magnetic cores have high strength.

[0009] This invention provides a method for preparing a rod-shaped magnetic core, comprising the following steps:

[0010] The nanocrystalline alloy wire is filled into the mold hole along the extension direction of the rod-shaped magnetic core mold hole, and then epoxy resin is infiltrated into the gap of the nanocrystalline alloy wire for curing to obtain the rod-shaped magnetic core; the diameter of the nanocrystalline alloy wire is 0.05-0.2 mm; the diameter of the mold hole is 0.3-0.5 mm.

[0011] Preferably, the nanocrystalline alloy wire is composed of an iron-based nanocrystalline soft magnetic alloy.

[0012] Preferably, the viscosity of the epoxy resin is less than 1500 mPa·s.

[0013] Preferably, the length of the nanocrystalline alloy wire is equal to the depth of the mold hole.

[0014] The present invention also provides a rod-shaped magnetic core prepared by the preparation method described above, wherein the rod-shaped magnetic core comprises nanocrystalline alloy wire bundles and epoxy resin filling the gaps between the nanocrystalline alloy wire bundles, and the diameter of the rod-shaped magnetic core is 0.3 to 0.5 mm.

[0015] The present invention also provides an inductor comprising a rod-shaped magnetic core, a coil, epoxy resin, and an outer sheath; the coil is wound around the rod-shaped magnetic core; the epoxy resin is filled between the rod-shaped magnetic core on which the coil is wound and the outer sheath.

[0016] The outer diameter of the outer jacket is 0.8–0.9 mm;

[0017] The rod-shaped magnetic core is the rod-shaped magnetic core described in the above scheme.

[0018] Preferably, the length of the rod-shaped magnetic core is 6-8 mm.

[0019] Preferably, the length of the outer jacket is 8-12 mm; the outer jacket is composed of an iron-based nanocrystalline soft magnetic alloy.

[0020] The present invention also provides a method for preparing the inductor described above, comprising the following steps:

[0021] A coil is wound around a rod-shaped magnetic core to obtain a rod-shaped magnetic core with a wound coil.

[0022] The rod-shaped magnetic core of the wound coil is inserted into the outer casing, and epoxy resin is filled into the gap between the rod-shaped magnetic core and the outer casing. After curing, the inductor is obtained.

[0023] The present invention also provides the application of the inductor described in the above-described scheme or the inductor prepared by the above-described scheme in the copper layer of the probe circuit board.

[0024] This invention provides a method for preparing a rod-shaped magnetic core, comprising the following steps: filling a mold hole with nanocrystalline alloy wire along the extension direction of the mold hole; then infiltrating the gaps between the nanocrystalline alloy wire with epoxy resin and curing it to obtain the rod-shaped magnetic core; the diameter of the nanocrystalline alloy wire is 0.05–0.2 mm; the diameter of the mold hole is 0.3–0.5 mm. The preparation method of this invention can prepare rod-shaped magnetic cores with a diameter of 0.2 mm or more, and the epoxy resin in this invention enhances the strength of the rod-shaped magnetic core, preventing it from breaking when wound with a coil. Furthermore, the rod-shaped magnetic core of this invention does not have the problems of uneven surface and burn-out layer, and does not reduce the relative permeability of the magnetic core.

[0025] The rod-shaped magnetic core prepared by this invention has a diameter of 0.3 to 0.5 mm, which lays the foundation for preparing miniature rod-shaped inductors with high inductance and a diameter not exceeding 0.9 mm.

[0026] This invention provides an inductor that, by using a rod-shaped magnetic core with a diameter of 0.3–0.5 mm, allows the outer diameter of the outer casing to be reduced to 0.8–0.9 mm, not exceeding the minimum hole diameter of 0.9 mm on the circuit board, thus enabling non-destructive testing of the copper layer within the circuit board holes. The testing principle is as follows: when a copper layer is tightly attached to the outside of the outer casing, a significant eddy current effect is generated within the copper layer, inducing a current. The induced magnetic field generated by this current significantly reduces the inductance value of the miniature rod-shaped inductor. The thicker the copper layer, the more pronounced the eddy current effect and the greater the reduction in inductance. Therefore, the thickness of the copper layer within the circuit board holes can be determined based on the magnitude of the inductance change, achieving non-destructive testing.

[0027] Furthermore, when the outer casing is made of an iron-based nanocrystalline soft magnetic alloy, the inductor provided by this invention has a rod-shaped magnetic core made of nanocrystalline alloy inserted inside, and is wrapped with an iron-based nanocrystalline soft magnetic alloy cylindrical outer casing. This further constrains the magnetic field lines of the spiral coil, confining them within the iron-based nanocrystalline alloy. Therefore, under the same size and number of turns, the inductance value is much higher than that of ordinary rod-shaped inductors. The results of the embodiments show that the inductor of this invention has a resolution of 0.25–0.45 μH / μm for metal coatings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an inductor; where 1-rod-shaped magnetic core; 2-coil; 3-epoxy resin; 4-outer casing;

[0029] Figure 2 A flowchart for fabricating an inductor;

[0030] Figure 3 The graph shows the change in inductance with frequency when the inductor of Example 1 is used to test the coating in the holes of a circuit board, with and without coating.

[0031] Figure 4 The graph shows the change in inductance with frequency when the inductor of Example 2 is used to test the coating in the holes of a circuit board, with and without the coating.

[0032] Figure 5 The graph shows the change in inductance with frequency when the inductor of Example 3 is used to test the coating in the holes of a circuit board, with and without the coating.

[0033] Figure 6 The graph shows the change in inductance with frequency when the inductor of Example 4 is used to test the coating in the holes of a circuit board, with and without the coating.

[0034] Figure 7 The graph shows the change in inductance with frequency when the inductor of Example 5 is used to test the coating in the holes of a circuit board, with and without the coating.

[0035] Figure 8 The graph shows the change in inductance with frequency when the inductor of Example 6 is used to test the coating in the holes of a circuit board, with and without the coating. Detailed Implementation

[0036] This invention provides a method for preparing a rod-shaped magnetic core, comprising the following steps:

[0037] The nanocrystalline alloy wire is filled into the mold hole along the extension direction of the rod-shaped magnetic core mold hole, and then epoxy resin is infiltrated into the gap of the nanocrystalline alloy wire for curing to obtain the rod-shaped magnetic core; the diameter of the nanocrystalline alloy wire is 0.05-0.2 mm; the diameter of the mold hole is 0.3-0.5 mm.

[0038] In this invention, the nanocrystalline alloy wire is preferably composed of an iron-based nanocrystalline soft magnetic alloy; the iron-based nanocrystalline soft magnetic alloy preferably includes Fe. 73.5 Si 13.5 B9Nb3Cu1 or Fe 73.5 Si 15.5 B7Nb3Cu1.

[0039] In this invention, before filling the mold hole with nanocrystalline alloy wire along the extending direction of the rod-shaped magnetic core mold hole, it is preferable to spray a release agent onto the mold hole. Spraying the release agent facilitates the demolding of the rod-shaped magnetic core.

[0040] In this invention, the method for preparing the nanocrystalline alloy wire preferably includes the following steps:

[0041] The raw materials corresponding to the composition of the nanocrystalline alloy wire are smelted under the action of a coating agent to obtain the master alloy;

[0042] The master alloy is melted to obtain a melt;

[0043] The melt is drawn into nano-amorphous alloy wires.

[0044] The nanocrystalline alloy wire is obtained by vacuum annealing the nano-amorphous alloy wire.

[0045] In this invention, the purity of the master alloy is preferably 99.9%. This invention does not impose any special limitations on the melting process; any method well-known to those skilled in the art can be used to obtain the target purity. Specifically, in this embodiment, vacuum induction melting is employed. In this invention, the coating agent preferably includes boron trioxide and calcium oxide, with a preferred mass ratio of 3:1. In this invention, the amount of the coating agent is preferably 18-25%. This invention does not impose any special limitations on the melting process; any method well-known to those skilled in the art can be used to obtain the melt. Specifically, in this embodiment, the master alloy is placed in a quartz glass tube with an outer diameter of 18-20 mm and a wall thickness of 1.5-2 mm and melted using an induction melting furnace. This invention does not impose any special limitations on the wire drawing process; any method well-known to those skilled in the art can be used. Specifically, in this embodiment, a glass-encased melt wire drawing method is employed. In this invention, the vacuum annealing preferably includes a first vacuum annealing, heating, and a second vacuum annealing. In this invention, the preferred temperature for the first vacuum annealing is 480°C, and the preferred holding time is 120 min; the preferred temperature for the second vacuum annealing is 550°C, and the preferred holding time is 120 min. The preferred heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature is 1°C / min. After vacuum annealing, the amorphous material in the nanocrystalline alloy wire is transformed into crystals, resulting in a nanocrystalline alloy wire.

[0046] Before vacuum annealing the nano-amorphous alloy wire, the present invention preferably cuts the amorphous alloy wire to the length of the target rod-shaped magnetic core.

[0047] In this invention, the diameter of the amorphous nano-alloy wire is equal to that of the nanocrystalline alloy wire; the diameter of the nanocrystalline alloy wire is 0.05–0.2 mm, preferably 0.08–0.15 mm, more preferably 0.1–0.12 mm; the diameter of the mold hole is 0.3–0.5 mm, more preferably 0.4–0.15 mm. In this invention, the length of the nanocrystalline alloy wire is preferably equal to the depth of the mold hole.

[0048] In this invention, the viscosity of the epoxy resin is preferably <1500 mPa·s, more preferably 100-1200 mPa·s, and even more preferably 500-800 mPa·s. This invention does not have a specific limitation on the amount of epoxy resin used; it is sufficient to fully fill the gaps between the nanocrystalline alloy wires.

[0049] The present invention also provides a rod-shaped magnetic core prepared by the preparation method described above, wherein the rod-shaped magnetic core comprises nanocrystalline alloy wire bundles and epoxy resin filling the gaps between the nanocrystalline alloy wire bundles, and the diameter of the rod-shaped magnetic core is 0.3 to 0.5 mm.

[0050] The preparation method of this invention can produce rod-shaped magnetic cores with a diameter of 0.2 mm or more. Furthermore, the epoxy resin in this invention enhances the strength of the rod-shaped magnetic core, preventing it from breaking when wound with a coil. In addition, the rod-shaped magnetic core of this invention does not have the problems of uneven surface or burn-out layers, and does not reduce the relative permeability of the magnetic core.

[0051] The rod-shaped magnetic core prepared by this invention has a diameter of 0.3 to 0.5 mm, which lays the foundation for preparing miniature rod-shaped inductors with high inductance and a diameter not exceeding 0.9 mm.

[0052] The present invention also provides an inductor comprising, from the inside out, a rod-shaped magnetic core, a coil, epoxy resin, and an outer sheath; the coil is wound around the rod-shaped magnetic core; the epoxy resin fills the space between the rod-shaped magnetic core around which the coil is wound and the outer sheath.

[0053] The outer diameter of the outer jacket is 0.8–0.9 mm;

[0054] The rod-shaped magnetic core is the rod-shaped magnetic core described in the above scheme.

[0055] The structural schematic diagram of the inductor of this invention is shown below. Figure 1 As shown. Wherein, 1-rod-shaped magnetic core; 2-coil; 3-epoxy resin; 4-outer jacket.

[0056] In this invention, the length of the rod-shaped magnetic core is preferably 6-8 mm, more preferably 7-7.5 mm.

[0057] In this invention, the diameter of the coil is preferably 0.04–0.1 mm, more preferably 0.06–0.09 mm, and even more preferably 0.07–0.08 mm. In this invention, the coil is wound around the rod-shaped magnetic core, and the number of turns is preferably 30–60, more preferably 35–55, and even more preferably 40–50. In this invention, the coil is preferably enameled copper wire or enameled silver wire, more preferably enameled copper wire. Enameled copper wire has excellent current transmission performance and low cost.

[0058] In this invention, the outer diameter of the outer sleeve is 0.8–0.9 mm, preferably 0.84–0.86 mm; the wall thickness is preferably 0.05–0.1 mm, more preferably 0.06–0.09 mm, and even more preferably 0.07–0.08 mm; the length is preferably 8–12 mm, more preferably 9–10 mm. The inductor provided by this invention, because it uses a rod-shaped magnetic core with a diameter of 0.3–0.5 mm, allows the outer diameter of the outer sleeve to be reduced to 0.8–0.9 mm, not exceeding the minimum hole diameter of 0.9 mm on the circuit board, thus enabling non-destructive testing of the copper layer in the circuit board holes.

[0059] In this invention, the outer casing is preferably composed of an iron-based nanocrystalline soft magnetic alloy; the iron-based nanocrystalline soft magnetic alloy preferably includes Fe. 73.5 Si 13.5 B9Nb3Cu1 or Fe 73.5 Si 15.5 B7Nb3Cu1.

[0060] In this invention, when the outer casing is composed of an iron-based nanocrystalline soft magnetic alloy, the method for preparing the outer casing preferably includes the following steps:

[0061] Iron-based amorphous alloy strips are wound to obtain amorphous alloy cylinders;

[0062] The amorphous alloy cylinder is immersed in epoxy resin, cured, and cut to obtain an amorphous alloy outer shell.

[0063] The amorphous alloy jacket is obtained by vacuum annealing.

[0064] In this invention, the thickness of the iron-based amorphous alloy strip is preferably 16-18 μm, and the width is preferably 12 mm. This invention does not specifically limit the method for achieving the target thickness and width of the iron-based amorphous alloy strip; any method well-known to those skilled in the art can be used. Specifically, this invention employs a single-roller pressure strip forming process. In this invention, the impregnation time is preferably 5 minutes. In this invention, the curing temperature is preferably 60-150°C, more preferably 80-120°C, and even more preferably 90-100°C; the curing time is preferably 1-2 hours, more preferably 1.5-1.8 hours. In this invention, the length of the amorphous alloy cylinder is preferably 2-10 cm. This invention does not specifically limit the cutting; the outer jacket of the amorphous alloy can be cut to the target length. Specifically, in this embodiment of the invention, an electrical discharge wire cutting machine is used for cutting.

[0065] When the outer casing is made of iron-based nanocrystalline soft magnetic alloy, the inductor provided by this invention has a rod-shaped magnetic core made of nanocrystalline alloy inserted inside, and is wrapped with a cylindrical outer casing of iron-based nanocrystalline soft magnetic alloy. This further constrains the range of magnetic field lines of the spiral coil, so that the magnetic field lines are bound within the iron-based nanocrystalline alloy. Therefore, under the same size and number of turns, the inductance value is much higher than that of ordinary rod-shaped inductors.

[0066] The present invention also provides a method for preparing the inductor described above, comprising the following steps:

[0067] A coil is wound around a rod-shaped magnetic core to obtain a rod-shaped magnetic core with a wound coil.

[0068] The rod-shaped magnetic core of the wound coil is inserted into the outer casing, and epoxy resin is filled into the gap between the rod-shaped magnetic core and the outer casing. After curing, the inductor is obtained.

[0069] In this invention, when the coil is wound, the coil is preferably close to one end of the rod-shaped magnetic core, and the coil's input and output wires are led out from the other end of the rod-shaped magnetic core. The input and output wires of the coil have their insulation layer removed to serve as measuring poles.

[0070] In this invention, the gap between the rod-shaped magnetic core and the outer jacket of the wound coil is preferably filled with epoxy resin such that the end of the rod-shaped magnetic core with the coil is flush with one end of the outer jacket, and the other end of the outer jacket is filled with epoxy resin. In this invention, the curing temperature is preferably 60°C, and the curing time is preferably 1 hour.

[0071] The flowchart for the fabrication of the inductor in this invention is as follows: Figure 2 As shown.

[0072] The present invention also provides the application of the inductor described in the above-described scheme or the inductor prepared by the above-described scheme in the copper layer of the probe circuit board.

[0073] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes the rod-shaped magnetic core and its preparation method, the inductor and its preparation method, and its applications, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0074] Example 1

[0075] Formulated into Fe 73.5 Si 15.5 The B7Cu1Nb3 alloy was obtained by vacuum induction melting to obtain a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass) was used for coating and purification, and the amount of coating agent was 20% of the mass of the master alloy.

[0076] 50 grams of master alloy were placed in a quartz glass tube with an outer diameter of 20 mm and a wall thickness of 1.5 mm. The alloy was remelted using an induction melting furnace. A glass-encased melt wire drawing method was used to obtain nano-amorphous alloy wires with a diameter of 0.1 mm from the melt. The nano-amorphous alloy wires were cut into 7.5 mm long segments, and then subjected to a first vacuum annealing and a second vacuum annealing to obtain nanocrystalline alloy wires. The temperature of the first vacuum annealing was 480℃, and the holding time was 120 min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature was 1℃ / min.

[0077] Prepare a mold with an inner diameter of 0.5 mm. After spraying a release agent, insert 11 small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 500 mPa·s into the hole. Place it in a curing oven and cure at 60°C for 1 hour. After demolding, you will get a miniature rod-shaped magnetic core with a diameter of 0.5 mm and a length of 7.5 mm.

[0078] Application Example 1

[0079] (1) Rod-shaped magnetic core for winding coils

[0080] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 1 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.06 mm, and the number of turns of the coil was 50. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0081] (2) Preparation of the outer coat

[0082] An amorphous alloy strip with a thickness of 16 μm and a width of 10 mm was prepared by a single-roller pressure strip forming process. The amorphous alloy strip was then wound into an amorphous alloy cylinder with an outer diameter of 0.9 mm, a wall thickness of 0.08 mm, and a length of 5 cm.

[0083] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 500 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0084] The amorphous alloy cylinder was cut into 10mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0085] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 500 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0086] Two types of circuit boards were selected: one with vias without a copper coating, and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 11 μm. The fabricated miniature rod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 3 As shown in the figure, the rod-shaped inductor of the present invention exhibits excellent performance. At a test frequency of 300 kHz, the inductance value without coating is 18.0 μH, while the inductance value with an 11 μm coating decreases to 13.5 μH, a decrease of 4.5 μH. The calculated resolution for the metal coating is 0.41 μH / μm.

[0087] Example 2

[0088] Formulated into Fe 73.5 Si 15.5 The B7Cu1Nb3 alloy was obtained by vacuum induction melting to obtain a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass content) was used for coating and purification, and the amount of coating agent was 18% of the mass of the master alloy.

[0089] Take 50 grams of the master alloy and place it in a quartz glass tube with an outer diameter of 20 mm and a wall thickness of 2 mm. Remelt the alloy using an induction melting furnace. Obtain nano-amorphous alloy wires with a diameter of 0.05 mm from the melt using a glass-encased melt drawing method. Cut the nano-amorphous alloy wires into 8 mm long segments, and then obtain nanocrystalline alloy wires through a first vacuum annealing and a second vacuum annealing. The temperature of the first vacuum annealing is 480℃, and the holding time is 120 min. The temperature of the second vacuum annealing is 550℃, and the holding time is 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature is 1℃ / min.

[0090] Prepare a mold with an inner diameter of 0.4 mm. After spraying a release agent, insert 34 small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 800 mPa·s into the hole. Place it in a curing box and cure at 60°C for 1 hour. After demolding, you will get a miniature rod-shaped magnetic core with a diameter of 0.4 mm and a length of 8 mm.

[0091] Application Example 2

[0092] (1) Rod-shaped magnetic core for winding coils

[0093] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 2 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.08 mm, and the number of turns of the coil was 50. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0094] (2) Preparation of the outer coat

[0095] An amorphous alloy strip with a thickness of 18μm and a width of 35mm was prepared by a single-roller pressure strip forming process, and then cut into an amorphous alloy strip with a width of 10mm by a roll shearing machine; the amorphous alloy strip with a width of 10mm was then wound into an amorphous alloy cylinder with an outer diameter of 0.9mm, a wall thickness of 0.1mm, and a length of 8cm.

[0096] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 800 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0097] The amorphous alloy cylinder was cut into 10mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0098] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 800 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0099] Two types of circuit boards were selected: one with vias without a copper coating, and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 11 μm. The fabricated miniature rod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 4 As shown in the figure, the rod-shaped inductor of the present invention exhibits excellent performance. At a test frequency of 300 kHz, the inductance value without coating is 17.1 μH, while the inductance value with an 11 μm coating decreases to 12.9 μH, a decrease of 4.2 μH. The resolution for the metal coating can be calculated to be 0.38 μH / μm.

[0100] Example 3

[0101] Formulated into Fe 73.5 Si 15.5 The B7Cu1Nb3 alloy was obtained by vacuum induction melting to obtain a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass content) was used for coating and purification, and the amount of coating agent was 25% of the mass of the master alloy.

[0102] 50 grams of master alloy were placed in a quartz glass tube with an outer diameter of 18 mm and a wall thickness of 1.5 mm. The alloy was remelted using an induction melting furnace. A glass-encased melt wire drawing method was used to obtain nano-amorphous alloy wires with a diameter of 0.2 mm from the melt. The nano-amorphous alloy wires were cut into 8 mm long segments, and then subjected to a first vacuum annealing and a second vacuum annealing to obtain nanocrystalline alloy wires. The temperature of the first vacuum annealing was 480℃, and the holding time was 120 min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature was 1℃ / min.

[0103] Prepare a mold with an inner diameter of 0.5 mm. After spraying a release agent, insert four small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 600 mPa·s into the hole. Place the mold in a curing oven and cure at 60°C for 1 hour. After demolding, you will get a miniature rod-shaped magnetic core with a diameter of 0.5 mm and a length of 8 mm.

[0104] Application Example 3

[0105] (1) Rod-shaped magnetic core for winding coils

[0106] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 3 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.08 mm, and the number of turns of the coil was 50. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0107] (2) Preparation of the outer coat

[0108] An amorphous alloy strip with a thickness of 16μm and a width of 35mm was prepared by a single-roller pressure strip forming process, and then cut into an amorphous alloy strip with a width of 12mm by a roll shearing machine; the amorphous alloy strip with a width of 12mm was then wound into an amorphous alloy cylinder with an outer diameter of 0.9mm, a wall thickness of 0.08mm, and a length of 8cm.

[0109] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 600 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0110] The amorphous alloy cylinder was cut into 12mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0111] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 600 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0112] Two types of circuit boards were selected: one with vias without a copper coating, and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 11 μm. The fabricated miniature rod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 5 As shown. From Figure 5 It can be seen that the rod-shaped inductor of the present invention has excellent performance. At a test frequency of 300KHz, the inductance value without coating is 18.9μH, and the inductance value with 11μm coating decreases to 14.0μH, a decrease of 4.9μH. The resolution for metal coating can be calculated to be 0.45μH / μm.

[0113] Example 4

[0114] Formulated into Fe 73.5 Si13.5 The B9Nb3Cu1 alloy was obtained by vacuum induction melting to obtain a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass content) was used for coating and purification, and the amount of coating agent was 20% of the mass of the master alloy.

[0115] Take 50 grams of the master alloy and place it in a quartz glass tube with an outer diameter of 20 mm and a wall thickness of 2 mm. Remelt the alloy using an induction melting furnace. Obtain nano-amorphous alloy wires with a diameter of 0.1 mm from the melt using a glass-encased melt drawing method. Cut the nano-amorphous alloy wires into 7 mm long segments, and then obtain nanocrystalline alloy wires through a first vacuum annealing and a second vacuum annealing. The temperature of the first vacuum annealing is 480℃, and the holding time is 120 min. The temperature of the second vacuum annealing is 550℃, and the holding time is 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature is 1℃ / min.

[0116] Prepare a mold with an inner diameter of 0.5 mm. After spraying a release agent, insert 17 small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 700 mPa·s into the hole. Place it in a curing oven and cure at 60°C for 1 hour. After demolding, you will get a miniature rod-shaped magnetic core with a diameter of 0.5 mm and a length of 7 mm.

[0117] Application Example 4

[0118] (1) Rod-shaped magnetic core for winding coils

[0119] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 4 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.06 mm, and the number of turns of the coil was 60. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0120] (2) Preparation of the outer coat

[0121] An amorphous alloy strip with a thickness of 16μm and a width of 35mm was prepared by a single-roller pressure strip forming process, and then cut into an amorphous alloy strip with a width of 12mm by a roll shearing machine; the amorphous alloy strip with a width of 12mm was then wound into an amorphous alloy cylinder with an outer diameter of 0.9mm, a wall thickness of 0.06mm, and a length of 10cm.

[0122] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 700 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0123] The amorphous alloy cylinder was cut into 12mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0124] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 700 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0125] Two types of circuit boards were selected: one with vias without a copper coating and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 15 μm. The fabricated microrod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 6 As shown. From Figure 6 As can be seen, the rod-shaped inductor of the present invention has excellent performance. At a test frequency of 300KHz, the inductance value without coating is 22.5μH, and the inductance value with 15μm coating decreases to 16.9μH, a decrease of 5.6μH. The resolution for metal coating can be calculated to be 0.37μH / μm.

[0126] Example 5

[0127] Formulated into Fe 73.5 Si 13.5 The B9Nb3Cu1 alloy was obtained by vacuum induction melting to produce a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass) was used for coating and purification, with the amount of coating agent being 20% ​​of the mass of the master alloy.

[0128] Take 50 grams of the master alloy and place it in a quartz glass tube with an outer diameter of 20 mm and a wall thickness of 2 mm. Remelt the alloy using an induction melting furnace. Obtain nano-amorphous alloy wires with a diameter of 0.1 mm from the melt using a glass-encased melt drawing method. Cut the nano-amorphous alloy wires into 7 mm long segments, and then obtain nanocrystalline alloy wires through a first vacuum annealing and a second vacuum annealing. The temperature of the first vacuum annealing is 480℃, and the holding time is 120 min. The temperature of the second vacuum annealing is 550℃, and the holding time is 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature is 1℃ / min.

[0129] Prepare a mold with an inner diameter of 0.5 mm. After spraying a release agent, insert 17 small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 700 mPa·s into the hole. Place it in a curing oven and cure at 60°C for 1 hour. After demolding, you will get a miniature rod-shaped magnetic core with a diameter of 0.5 mm and a length of 7 mm.

[0130] Application Example 5

[0131] (1) Rod-shaped magnetic core for winding coils

[0132] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 5 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.06 mm, and the number of turns of the coil was 60. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0133] (2) Preparation of the outer coat

[0134] An amorphous alloy strip with a thickness of 16μm and a width of 35mm was prepared by a single-roller pressure strip forming process, and then cut into an amorphous alloy strip with a width of 12mm by a roll shearing machine; the amorphous alloy strip with a width of 12mm was then wound into an amorphous alloy cylinder with an outer diameter of 0.9mm, a wall thickness of 0.06mm, and a length of 10cm.

[0135] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 600 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0136] The amorphous alloy cylinder was cut into 12mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0137] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 600 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0138] Two types of circuit boards were selected: one with vias without a copper coating and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 15 μm. The fabricated microrod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 7 As shown. From Figure 7As can be seen, the rod-shaped inductor of the present invention has excellent performance. At a test frequency of 300KHz, the inductance value without coating is 15.1μH, and the inductance value with 15μm coating decreases to 11.3μH, a decrease of 3.8μH. The resolution for metal coating can be calculated to be 0.25μH / μm.

[0139] Example 6

[0140] Formulated into Fe 73.5 Si 13.5 The B9Nb3Cu1 alloy was obtained by vacuum induction melting to obtain a master alloy with a purity of 99.9%. During the melting process, a coating agent (composed of 75% boron trioxide and 25% calcium oxide by mass content) was used for coating and purification, and the amount of coating agent was 20% of the mass of the master alloy.

[0141] Take 30 grams of master alloy and place it in a quartz glass tube with an outer diameter of 20 mm and a wall thickness of 2 mm. Remelt the alloy using an induction melting furnace. Obtain nano-amorphous alloy wires with a diameter of 0.1 mm from the melt using a glass-encased melt drawing method. Cut the nano-amorphous alloy wires into 7.5 mm long segments, and then obtain nanocrystalline alloy wires through a first vacuum annealing and a second vacuum annealing. The temperature of the first vacuum annealing is 480℃, and the holding time is 120 min. The temperature of the second vacuum annealing is 550℃, and the holding time is 120 min. The heating rate from the first vacuum annealing temperature to the second vacuum annealing temperature is 1℃ / min.

[0142] Prepare a mold with an inner diameter of 0.4 mm. After spraying a release agent, insert 11 small segments of nanocrystalline alloy wire into the mold. Pour epoxy resin with a viscosity of 600 mPa·s into the hole. Place it in a curing oven and cure at 60°C for 1 hour. After demolding, a miniature rod-shaped magnetic core with a diameter of 0.5 mm and a length of 7.5 mm is obtained.

[0143] Application Example 6

[0144] (1) Rod-shaped magnetic core for winding coils

[0145] A solenoid coil was wound around the rod-shaped magnetic core obtained in Example 6 using enameled copper wire to obtain a rod-shaped magnetic core with a wound coil. The diameter of the copper wire was 0.06 mm, and the number of turns of the coil was 40. The coil was placed near one end of the rod-shaped magnetic core, and the input and output wires were led out from the other end of the rod-shaped magnetic core. The insulation layer was removed from both ends of the enameled copper wire to serve as measuring poles.

[0146] (2) Preparation of the outer coat

[0147] An amorphous alloy strip with a thickness of 16μm and a width of 35mm was prepared by a single-roller pressure strip forming process, and then cut into an amorphous alloy strip with a width of 10mm by a roll shearing machine; the amorphous alloy strip with a width of 10mm was then wound into an amorphous alloy cylinder with an outer diameter of 0.8mm, a wall thickness of 0.08mm, and a length of 5cm.

[0148] The amorphous alloy cylinder was impregnated in epoxy resin with a viscosity of 800 mPa·s for 5 min, dried, and then placed in a curing oven at 60°C for 1 h to obtain the amorphous alloy cylinder.

[0149] The amorphous alloy cylinder was cut into 10mm long segments using an electrical discharge wire cutting machine, and then subjected to a first vacuum annealing and a second vacuum annealing. Vacuum crystallization annealing yielded a nanocrystalline alloy jacket. The temperature of the first vacuum annealing was 480℃, and the holding time was 120min. The temperature of the second vacuum annealing was 550℃, and the holding time was 120min.

[0150] Insert the rod-shaped magnetic core with the coil wound in (1) into the outer jacket in (2), keeping the end of the rod-shaped magnetic core with the coil flush with one end of the outer jacket. Drip epoxy resin with a viscosity of 800 mPa·s onto the other end of the outer jacket, and place it in a curing box to cure at 60°C for 1 hour to obtain a miniature rod-shaped inductor.

[0151] Two types of circuit boards were selected: one with vias without a copper coating and the other with vias coated with a copper coating. The diameter of the vias was 0.9 mm, and the thickness of the copper coating was 15 μm. The fabricated microrod-shaped inductors were inserted into both types of vias, and the inductance versus frequency curves were obtained for both cases with and without the coating, as shown in the figure. Figure 8 As shown. From Figure 8 As can be seen, the rod-shaped inductor of the present invention has excellent performance. At a test frequency of 300KHz, the inductance value without coating is 15.3μH, and the inductance value with 15μm coating decreases to 11.5μH, a decrease of 3.8μH. The resolution for metal coating can be calculated to be 0.25μH / μm.

[0152] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a rod-shaped magnetic core, characterized in that, Includes the following steps: The nanocrystalline alloy wires are filled into the mold holes along the extension direction of the rod-shaped magnetic core, and then epoxy resin is infiltrated into the gaps between the nanocrystalline alloy wires for curing to obtain the rod-shaped magnetic core; the diameter of the nanocrystalline alloy wires is 0.05~0.2mm; the diameter of the mold holes is 0.3~0.5mm; The length of the nanocrystalline alloy wire is equal to the depth of the mold hole.

2. The preparation method according to claim 1, characterized in that, The nanocrystalline alloy wire is composed of an iron-based nanocrystalline soft magnetic alloy.

3. The preparation method according to claim 1, characterized in that, The viscosity of the epoxy resin is less than 1500 mPa·s.

4. The rod-shaped magnetic core prepared by the preparation method according to any one of claims 1 to 3, characterized in that, The rod-shaped magnetic core comprises nanocrystalline alloy wire bundles and epoxy resin filling the gaps between the nanocrystalline alloy wire bundles, and the diameter of the rod-shaped magnetic core is 0.3~0.5mm.

5. An inductor, characterized in that, It includes a rod-shaped magnetic core, a coil, epoxy resin, and an outer sheath; the coil is wound around the rod-shaped magnetic core; the epoxy resin fills the space between the rod-shaped magnetic core around which the coil is wound and the outer sheath; The outer diameter of the outer jacket is 0.8~0.9mm; The rod-shaped magnetic core is the rod-shaped magnetic core as described in claim 4.

6. The inductor according to claim 5, characterized in that, The length of the rod-shaped magnetic core is 6~8mm.

7. The inductor according to claim 5, characterized in that, The length of the outer jacket is 8~12mm; the outer jacket is composed of an iron-based nanocrystalline soft magnetic alloy.

8. The method for preparing the inductor according to any one of claims 5 to 7, characterized in that, Includes the following steps: A coil is wound around a rod-shaped magnetic core to obtain a rod-shaped magnetic core with a wound coil. The rod-shaped magnetic core of the wound coil is inserted into the outer casing, and epoxy resin is filled into the gap between the rod-shaped magnetic core and the outer casing. After curing, the inductor is obtained.

9. The application of the inductor according to any one of claims 5 to 7 or the inductor prepared by the preparation method according to claim 8 in the copper layer of a probe circuit board.

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