Balun structure and preparation method thereof

Abstract

The invention provides a balun structure and a preparation method thereof. The balun structure comprises a base body with an input end, a first output end, a second output end and a grounding end arranged on the outer surface, and a first inductance coil with the two ends connected with the input end and the first output end respectively. The two ends of the second inductance coil are connected with the second output end and the grounding end respectively, the two ends of the third inductance coil are connected with the grounding end and the first output end respectively, and the base body comprises a laminated body, two magnetic chips and three magnetic core columns, wherein the two magnetic chips are arranged on the two opposite sides of the laminated body in a laminated mode respectively, and the three magnetic core columns penetrate through the laminated body to be connected with the two magnetic chips. The first inductance coil and the second inductance coil are arranged on the laminated body and are spirally wound among the three magnetic core columns; the third inductance coil is arranged on any magnetic chip, and every two of the first inductance coil, the second inductance coil and the third inductance coil are mutually coupled. The problem that an existing balun cannot be expanded to a low-frequency band and cannot keep excellent amplitude balance characteristics while miniaturization is achieved is solved.

Description

Technical Field

[0001] This application relates to the field of microwave communication technology, and in particular to a balun structure and its preparation method. Background Technology

[0002] Electronic technology is developing towards multifunctionality, miniaturization, and high reliability, and Low-Temperature Co-fired Ceramics (LTCC) technology is receiving increasing attention. Baluns, as balanced-to-unbalanced converters, are widely used in microwave systems, such as antennas, mixers, and frequency multipliers, and are an important component in microwave systems. A laminated balun is a balun structure made using ceramic diaphragms through LTCC.

[0003] Traditional LTCC baluns have difficulty extending their application frequency band to below 200MHz, resulting in a limited range of applications. On the other hand, wire-wound baluns, which can achieve low-frequency applications below 200MHz, are difficult to miniaturize during manufacturing, and due to the use of wire-wound coils, they suffer from amplitude imbalance. Summary of the Invention

[0004] This application provides a balun structure and its fabrication method, which solves the problem that existing baluns cannot simultaneously achieve miniaturization while extending to lower frequency bands and maintaining excellent amplitude balance characteristics.

[0005] This application is implemented as follows: a balun structure includes a substrate, a first inductor coil, a second inductor coil, and a third inductor coil. The substrate includes a laminate and a magnetic core structure. The magnetic core structure includes two magnetic chips and three spaced-apart magnetic core pillars. The two magnetic chips are respectively stacked on opposite sides of the laminate, and the magnetic core pillars penetrate the laminate to connect with the two magnetic chips. The first inductor coil is disposed on the laminate and is spirally wound between the three magnetic core pillars. The second inductor coil is disposed on the laminate, and the third inductor coil... Two inductors are spirally wound between the three magnetic core pillars; a third inductor is disposed on any one of the magnetic chips, and the first, second, and third inductors are coupled to each other in pairs; the outer surface of the substrate is provided with an input terminal, a first output terminal, a second output terminal, and a ground terminal, the two ends of the first inductor are respectively connected to the input terminal and the first output terminal, the two ends of the second inductor are respectively connected to the second output terminal and the ground terminal, and the two ends of the third inductor are respectively connected to the ground terminal and the first output terminal.

[0006] In one embodiment, the sum of the inductance of the first inductor and the inductance of the second inductor is the first inductance, and the inductance of the third inductor is the second inductance. The difference between the second inductance and the first inductance is in the range of -130nH to 200nH.

[0007] In one embodiment, the magnetic chip includes a plurality of magnetic films stacked sequentially;

[0008] The third inductor coil includes a third conductive pattern, which is printed on any of the magnetic films of the magnetic chip except for the magnetic films located on opposite sides.

[0009] In one embodiment, the magnetic chip includes a plurality of magnetic films stacked sequentially;

[0010] The third inductor coil includes multiple third conductive patterns, which are printed on different magnetic films of the magnetic chip, excluding the magnetic films located on opposite sides, and the multiple third conductive patterns are connected in sequence.

[0011] In one embodiment, the three magnetic core pillars are arranged along a first direction, the three magnetic core pillars including two first magnetic core pillars and a common magnetic core pillar located between the two first magnetic core pillars, the first direction being perpendicular to the thickness direction of the laminate;

[0012] Both the first inductor and the second inductor are spirally wound around the common magnetic core pillar. Along the thickness direction of the laminate, the orthogonal projections of the first inductor and the second inductor on the magnetic chip are staggered.

[0013] In one embodiment, the laminate includes a plurality of dielectric films;

[0014] The first inductor coil includes a plurality of first conductive patterns and a first connecting conductor. The plurality of first conductive patterns are printed on a plurality of dielectric films. The first connecting conductor passes through the dielectric film and is used to connect two adjacent first conductive patterns.

[0015] The second inductor coil includes a plurality of second conductive patterns and a second connecting conductor. The plurality of second conductive patterns are printed on a plurality of dielectric films. The second connecting conductor passes through the dielectric film and is used to connect two adjacent second conductive patterns.

[0016] Along the thickness direction of the laminate, the dielectric film printed with the first conductive pattern and the dielectric film printed with the second conductive pattern are alternately stacked.

[0017] In one embodiment, the first inductor and the second inductor have the same wire diameter, which is 40μm to 80μm.

[0018] The distance between the orthogonal projections of the first inductor and the second inductor on the magnetic chip is equal to the wire diameter.

[0019] In one embodiment, the number of the first conductive patterns is the same as the number of the second conductive patterns.

[0020] In one embodiment, the laminate is made of a ceramic material with a dielectric constant of 3-10.

[0021] Both the magnetic chip and the magnetic core post are made of ferrite material, and the magnetic permeability of the ferrite material is 300-1000.

[0022] The beneficial effects of the balun structure provided in this application are as follows: Compared with the prior art, this application includes a laminate, two magnetic chips, and three magnetic core pillars. The two magnetic chips are respectively laminated on opposite sides of the laminate, and the three magnetic core pillars penetrate the laminate and are connected to the two magnetic chips. A first inductor and a second inductor are provided on the laminate, and a third inductor is provided on any one of the magnetic chips. Under the action of the magnetic field generated by the magnetic chips and magnetic core pillars, the first, second, and third inductors are coupled in pairs, which can improve the coupling coefficient between the inductors, reduce leakage flux, and increase the inductance of the balun, so that the application range of the balun can be extended to lower frequency bands, thereby expanding the application frequency range. The entire balun structure adopts a laminated structure, which can reduce the volume of the balun structure. In addition, the third inductor is connected to the first and second inductors respectively. Since the third inductor can filter low-frequency waves, it can keep the amplitudes of the first and second inductors balanced, which is beneficial for the balun structure to maintain excellent amplitude balance characteristics and phase balance characteristics.

[0023] This application also provides a method for preparing a balun structure, used to prepare a balun structure as described in the above embodiments, comprising:

[0024] Two magnetic chips and multiple dielectric films are prepared, wherein a third inductor coil is provided in one of the magnetic chips;

[0025] A magnetic core hole is formed on each of the dielectric films, and a first through hole or a second through hole is formed on some of the dielectric films;

[0026] The first conductive pattern or the second conductive pattern is printed on each of the dielectric films;

[0027] The dielectric film printed with the first conductive pattern and the dielectric film printed with the second conductive pattern are alternately stacked on the magnetic chip with the third inductor coil. After each dielectric film is stacked, a first connecting conductor is filled into the first through hole or a second connecting conductor is filled into the second through hole until the first inductor coil and the second inductor coil are formed. Then, a magnetic core film is filled into the magnetic core hole to form the magnetic core column.

[0028] Another magnetic chip is stacked on the last of the stacked dielectric films to form a balun structure.

[0029] In one embodiment, each of the dielectric films has the same thickness;

[0030] The thickness of the magnetic core diaphragm filling the magnetic core hole of each of the dielectric diaphragms is equal to the thickness of the dielectric diaphragm.

[0031] In one embodiment, after fabricating two magnetic chips and multiple dielectric films, the process further includes:

[0032] A first alignment hole is formed on the magnetic chip;

[0033] A second alignment hole is formed on the dielectric film, and an alignment background material is printed around the second alignment hole. The alignment background material is made of the same material as the magnetic chip.

[0034] In one embodiment, after fabricating two magnetic chips and multiple dielectric films, the process further includes:

[0035] A first alignment hole is formed on the magnetic chip, and an alignment background material is printed around the first alignment hole. The alignment background material is made of the same material as the dielectric film.

[0036] A second alignment hole is formed on the dielectric membrane.

[0037] In one embodiment, the fabrication of a magnetic chip equipped with a third inductor coil includes:

[0038] Multiple magnetic films were prepared;

[0039] A third conductive pattern is printed on a portion of the magnetic film;

[0040] A third through hole is formed on the magnetic film in the portion where the third conductive pattern is printed, and a third connecting conductor is filled in the third through hole;

[0041] The magnetic film with a portion of the third conductive pattern not printed, the magnetic film with the third conductive pattern printed, and the remaining magnetic film with the third conductive pattern not printed are stacked to obtain a magnetic chip with a third inductor coil.

[0042] Since the method for preparing the balun structure can also prepare the balun structure of the above embodiments, the effect achieved by the method for preparing the balun structure is the same as that achieved by the balun structure described above, and will not be repeated here. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the external structure of the balun structure provided in the embodiments of this application;

[0045] Figure 2 This is a partial structural schematic diagram of the balun structure provided in the embodiments of this application;

[0046] Figure 3 This is a schematic diagram of the internal structure of the balun structure provided in the embodiments of this application;

[0047] Figure 4 This is an equivalent circuit diagram of the balun structure provided in the embodiments of this application;

[0048] Figure 5-1 This is an amplitude simulation diagram of a balun structure without a third inductor coil;

[0049] Figure 5-2 This is a simulation diagram of the amplitude consistency of a balun structure without a third inductor coil.

[0050] Figure 5-3 This is an amplitude simulation diagram of a balun structure with a third inductor coil.

[0051] Figure 5-4 This is a simulation diagram of the amplitude consistency of a balun structure without a third inductor coil.

[0052] Figure 6 This is a schematic diagram of the third inductor coil of the balun structure provided in the embodiments of this application;

[0053] Figure 7 This is an exploded view of the first and second inductor coils of the balun structure provided in the embodiments of this application;

[0054] Figure 8 This is a schematic flowchart of the preparation method of the balun structure provided in the embodiments of this application;

[0055] Figure 9 This is another schematic flowchart of the preparation method of the balun structure provided in the embodiments of this application;

[0056] Figure 9-1 A schematic diagram showing the printing of alignment background material at the four corners of a dielectric film;

[0057] Figure 10 This is another schematic flowchart of the preparation method of the balun structure provided in the embodiments of this application;

[0058] Figure 11 This is a simulation diagram of the phase coherence of the balun structure provided in the embodiments of this application;

[0059] Figure 12 This is a simulation diagram of the insertion loss of the balun structure provided in the embodiments of this application;

[0060] Figure 13 This is a simulation diagram of the return loss of the balun structure provided in the embodiments of this application.

[0061] Reference numerals: 10, substrate; 101, input terminal; 102, first output terminal; 103, second output terminal; 104, ground terminal; 11, dielectric diaphragm; 12, magnetic core structure; 121, magnetic chip; 1210, magnetic diaphragm; 122, common magnetic core post; 123, first magnetic core post;

[0062] 20. First inductor coil; 21. First conductive pattern; 22. First connecting conductor;

[0063] 30. Second inductor coil; 31. Second conductive pattern; 32. Second connecting conductor;

[0064] 40. Third inductor coil; 41. Third conductive pattern; 42. Third connecting conductor;

[0065] 50. Magnetic core hole; 60. Alignment background material. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0067] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0068] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0070] It should also be noted that in the embodiments of this application, the same reference numerals are used to represent the same component or part. For the same part in the embodiments of this application, the reference numerals may only be used to mark one part or component as an example. It should be understood that the reference numerals are also applicable to other identical parts or components.

[0071] This application provides a balun structure and its fabrication method, which solves the problem that existing baluns cannot simultaneously achieve miniaturization while extending to lower frequency bands and maintaining excellent amplitude balance characteristics.

[0072] Electronic technology is developing towards multifunctionality, miniaturization, and high reliability, and Low-Temperature Co-fired Ceramics (LTCC) technology is receiving increasing attention. Baluns, as balanced-to-unbalanced converters, are widely used in microwave systems such as antennas, mixers, and frequency multipliers, and are an important component in microwave systems. A laminated balun is a balun structure made using ceramic diaphragms through LTCC. The LTCC process involves forming a precisely thick and dense green ceramic tape from low-temperature sintered ceramic powder, which serves as the circuit board material. The desired patterned conductors are then created on the green ceramic tape using processes such as laser drilling, micro-hole injection, and precision conductor paste printing. Multiple passive components are embedded within these conductors, and then the tapes are stacked together and sintered at approximately 900°C to create a three-dimensional circuit network of passive integrated components. This process can also create three-dimensional circuit boards with built-in passive components, on which ICs and active devices can be mounted to create passive / active integrated functional modules.

[0073] The balun structure in related technologies is typically a stacked, sheet-like structure. For example, a balun structure with a length of 2mm and a width of 1.2mm (referring to the package size of the balun structure) has advantages such as small size, high reliability, and simple manufacturing process, meeting the requirements of miniaturization, high reliability, high performance, and low cost for downstream electronic devices. However, the lower limit of the frequency band achievable by this balun structure is usually greater than 200 MHz, making it difficult to achieve the goal of extending to frequency bands below 200 MHz while simultaneously meeting miniaturization requirements. Currently, there is another type of balun structure on the market that can meet the requirement of extending to frequency bands below 200 MHz. However, because this balun structure has two sets of coils, it is prone to amplitude imbalance during use, affecting the amplitude balance and phase balance characteristics of the balun structure.

[0074] In order to enable the balun structure in related technologies to be miniaturized while extending to the frequency band below 200 MHz and maintaining excellent amplitude balance characteristics, this application provides a balun structure.

[0075] refer to Figure 1-Figure 4The balun structure provided in this application embodiment includes a substrate 10, a first inductor coil 20, a second inductor coil 30, and a third inductor coil 40. The substrate 10 includes a laminate and a magnetic core structure 12. The magnetic core structure 12 includes two magnetic chips 121 and three magnetic core pillars spaced apart from each other. The two magnetic chips 121 are respectively stacked on opposite sides of the laminate, and the magnetic core pillars penetrate the laminate to connect with the two magnetic chips 121. The first inductor coil 20 is disposed on the laminate and is spirally wound between the three magnetic core pillars. The second inductor coil 30 is disposed on the laminate and is spirally wound between the three magnetic core pillars. The magnetic core pillars are spirally wound together; the third inductor coil 40 is disposed on any one of the magnetic chips 121, and the first inductor coil 20, the second inductor coil 30 and the third inductor coil 40 are coupled to each other in pairs; the outer surface of the substrate 10 is provided with an input terminal 101, a first output terminal 102, a second output terminal 103 and a ground terminal 104, the two ends of the first inductor coil 20 are respectively connected to the input terminal 101 and the first output terminal 102, the two ends of the second inductor coil 30 are respectively connected to the second output terminal 103 and the ground terminal 104, and the two ends of the third inductor coil 40 are respectively connected to the ground terminal 104 and the first output terminal 102.

[0076] In this embodiment, the balun structure includes a laminate, two magnetic chips 121, and three magnetic core pillars. The two magnetic chips 121 are respectively stacked on opposite sides of the laminate. The three magnetic core pillars penetrate the laminate and are connected to the two magnetic chips 121. A first inductor coil 20 and a second inductor coil 30 are provided on the laminate. A third inductor coil 40 is provided on any one of the magnetic chips 121. Under the action of the magnetic field generated by the magnetic chips 121 and the magnetic core pillars, the first inductor coil 20, the second inductor coil 30, and the third inductor coil 40 are coupled in pairs, which can improve the inductance of the coil. The coupling coefficient between them is reduced, leakage flux is decreased, and the inductance of the balun is increased, so that the application range of the balun can be extended to lower frequency bands, thereby expanding the application frequency range. The entire balun structure adopts a stacked structure, which can reduce the volume of the balun structure. In addition, the third inductor 40 is connected to the first inductor 20 and the second inductor 30 respectively. Since the third inductor 40 can filter low-frequency waves, it can keep the amplitude of the first inductor 20 and the second inductor 30 balanced, which is conducive to the balun structure maintaining excellent amplitude balance characteristics and phase balance characteristics.

[0077] It should be noted that the aforementioned laminated structure can typically be made of dielectric ceramic material, while the magnetic chip 121 and the magnetic core pillar are made of magnetic insulating material, such as ferrite. The first inductor coil 20 and the second inductor coil 30 are made of conductive paste. The aforementioned balun structure is manufactured using a heterogeneous multilayer co-firing process. Heterogeneous multilayer co-firing is based on the low-temperature co-firing ceramic technology (LTCC), which uses two or more materials co-fired with conductive paste to achieve multifunctionality and high integration of the product. Compared to the balun structure in related technologies with a length of 2mm and a width of 1.2mm, the balun structure in this embodiment uses dielectric ceramic material, magnetic insulating material, and conductive paste co-fired, thereby enabling the balun structure to extend to frequencies below 100 MHz or even lower.

[0078] Specifically, refer to Figure 4 If an all-ceramic material is used to fabricate the balun using the low-temperature co-fired ceramic (LTCC) process, the high magnetic reluctance of ceramic materials will make it difficult to extend the frequency range below 100MHz. In other words, to achieve this extension, high inductance is required. Ferrite materials have the characteristics of higher permeability, lower magnetic reluctance, and higher inductance. Therefore, this application incorporates high-permeability ferrite material into the balun structure, namely the magnetic chip 121 and the core pillar. (Reference) Figure 2 By setting three magnetic core pillars, and connecting each of the three magnetic core pillars to two magnetic chips 121, two closed magnetic circuits can be formed, thereby improving the coupling coefficient of the first inductor coil 20 and the second inductor coil 30, reducing leakage flux, lowering magnetic resistance, and increasing inductance.

[0079] In any one of the magnetic chips 121 in this application embodiment, a third inductor coil 40 is provided, as referenced. Figure 4 The third inductor 40 is connected to both the first inductor 20 and the second inductor 30, and serves to balance the amplitudes of the first inductor 20 and the second inductor 30. Specifically, the third inductor 40 acts as a high-pass filter, filtering out low-frequency bands passing through the first inductor 20 and the second inductor 30, thus maintaining the amplitude balance between the two inductors.

[0080] For example, you can refer to it. Figures 5-1 to 5-4 , Figure 5-1 This is an amplitude simulation diagram of a balun structure without a third inductor coil 40. Figure 5-2 This is a simulation diagram of the amplitude consistency of a balun structure without a third inductor coil 40. Figure 5-3 This is a simulation diagram of the amplitude of the balun structure with the third inductor coil 40. Figure 5-4 This is a simulation diagram of the amplitude consistency of a balun structure without a third inductor coil 40. (Comparison) Figure 5-1 and Figure 5-3 It can be seen that without the third inductor 40, the amplitudes of the first inductor 20 and the second inductor 30 differ significantly, resulting in poor balance. With the third inductor 40, the amplitudes of the first inductor 20 and the second inductor 30 are less different, maintaining a near-balance. (Comparison) Figure 5-2 and Figure 5-4 It can also be seen that without the third inductor 40, the amplitude difference between the first inductor 20 and the second inductor 30 is at most 20. After the third inductor 40 is set, the amplitude difference between the first inductor 20 and the second inductor 30 is at most 0.3. It can be seen that after setting the third inductor 40, the amplitude difference between the first inductor 20 and the second inductor 30 can be made smaller and basically balanced, which is conducive to the balun structure to achieve excellent amplitude balance characteristics.

[0081] In some embodiments, the input terminal 101, the first output terminal 102, the second output terminal 103, and the ground terminal 104 each include three plating layers, which are silver plating, nickel plating, and tin plating from the inside out. This three-layer plating structure ensures the solderability of the product.

[0082] The silver paste in the above coating is sintered at a temperature of about 880℃, contains 85% silver, has a thickness of 10μm, and a width of 60μm.

[0083] For example, the dimensions of the substrate 10 in this application are 2.0mm * 1.2mm * 0.8mm (length * width * height).

[0084] It should be noted that since the third inductor 40 is set to maintain the amplitude balance of the first inductor 20 and the second inductor 30, the inductance of the third inductor 40 needs to be set according to the inductance of the first inductor 20 and the second inductor 30 in order to adjust the amplitude of the first inductor 20 and the second inductor 30 and maintain amplitude balance.

[0085] In some embodiments, the sum of the inductance of the first inductor 20 and the inductance of the second inductor 30 is the first inductance, and the inductance of the third inductor 40 is the second inductance. The difference between the second inductance and the first inductance ranges from -130nH to 200nH. This allows the amplitudes of the first inductor 20 and the second inductor 30 to remain balanced under the influence of the third inductor 40, improving the amplitude balance of the balun structure.

[0086] It should be noted that the first inductance can be represented as H1, and the second inductance as H2. The difference between the second inductance and the first inductance refers to the difference between the second inductance and the first inductance, that is, the value of H2-H1 is -130nH-200nH.

[0087] In some embodiments, reference Figure 6 The magnetic chip 121 includes a plurality of magnetic films 1210 stacked sequentially; the third inductor coil 40 includes a third conductive pattern 41, which is printed on any magnetic film 1210 of the magnetic chip 121 except for the magnetic films 1210 located on opposite sides.

[0088] There are multiple magnetic films 1210, which are stacked. Along the stacking direction, the first magnetic film 1210 and the last magnetic film 1210 are the magnetic films 1210 on opposite sides of the magnetic chip 121. The magnetic films 1210 other than those on opposite sides are the middle magnetic films 1210. In this application, the third conductive pattern 41 is printed on any one of the middle magnetic films 1210. In order to connect the third inductor coil 40, the first inductor coil 20 and the second inductor coil 30, a third through hole can be opened on some of the magnetic films 1210 to fill the third connecting conductor 42.

[0089] It should be noted that the third inductor coil 40 of this application is formed by a third conductive pattern 41, and the number of third conductive patterns 41 can be selected according to the sum of the inductance of the first inductor coil 20 and the inductance of the second inductor coil 30. As long as the inductance of the third inductor coil 40 is within the range of -130nH to 200nH compared with the sum of the inductance of the first inductor coil 20 and the inductance of the second inductor coil 30, that is, the difference between the second inductance and the first inductance is within the range of -130nH to 200nH, the third inductor coil 40 can include only one third conductive pattern 41. The third conductive pattern 41 can be printed on any magnetic film 1210 of the magnetic chip 121 except for the magnetic films 1210 located on opposite sides to complete the setting of the third inductor coil 40.

[0090] Of course, in some embodiments, if the sum of the inductance of the first inductor coil 20 and the inductance of the second inductor coil 30 is relatively large, the third inductor coil 40 can also be configured to include a plurality of third conductive patterns 41. The plurality of third conductive patterns 41 are printed on different magnetic films 1210 of the magnetic chip 121 other than the magnetic chips located on opposite sides, and the plurality of third conductive patterns 41 are connected in sequence.

[0091] In this embodiment of the application, while expanding to frequencies below 100 MHz or even lower, it is also necessary to expand to higher frequencies in order to broaden the application frequency range.

[0092] In some embodiments, reference Figure 2 and Figure 3 Three magnetic core pillars are arranged along a first direction, including two first magnetic core pillars 123 and a common magnetic core pillar 122 located between the two first magnetic core pillars 123. The first direction is perpendicular to the thickness direction of the laminate. The first inductor coil 20 and the second inductor coil 30 are both spirally wound around the common magnetic core pillar 122. Along the thickness direction of the laminate, the orthographic projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 are staggered.

[0093] The above settings not only help reduce the parasitic capacitance between the coupling lines of the first inductor coil 20 and the second inductor coil 30, thus broadening the application range of the high-frequency band, but also help ensure excellent amplitude-frequency and phase characteristics of the upper band pass limit.

[0094] In some embodiments, reference Figure 2 The cross-sectional area of ​​the common magnetic core post 122 is larger than the cross-sectional area of ​​each first magnetic core post 123, wherein the cross-section is a section perpendicular to the thickness direction of the laminate.

[0095] By increasing the cross-sectional area of ​​the common magnetic core column 122, the magnetic field strength of the common magnetic circuit is enhanced, which helps to reduce the parasitic capacitance between the coupling lines of the first inductor coil 20 and the second inductor coil 30.

[0096] In some embodiments, in order to broaden the application frequency of the balun structure and realize low-frequency applications, a magnetic chip 121 and a magnetic core pillar can be introduced into the balun structure. The magnetic chip 121 and the magnetic core pillar are both made of ferrite material, and the ferrite material is a high permeability ferrite material, specifically a permeability of 300-1000. This makes the inductance of the magnetic chip 121 and the magnetic core pillar larger, which is conducive to expanding the application frequency of the balun structure to below 100 MHz or even lower frequency bands.

[0097] In some embodiments, the laminate is made of ceramic material. In order to broaden the application frequency of the balun structure and realize high frequency band applications, a low dielectric constant ceramic material can be used as the laminate. Specifically, the dielectric constant of the ceramic material is 3-10.

[0098] In some embodiments, reference Figure 3 and Figure 7The laminate includes multiple dielectric films 11; the first inductor coil 20 includes multiple first conductive patterns 21 and a first connecting conductor 22, the multiple first conductive patterns 21 are printed on the multiple dielectric films 11, and the first connecting conductor 22 passes through the dielectric film 11 to connect two adjacent first conductive patterns 21; the second inductor coil 30 includes multiple second conductive patterns 31 and a second connecting conductor 32, the multiple second conductive patterns 31 are printed on the multiple dielectric films 11, and the second connecting conductor 32 passes through the dielectric film 11 to connect two adjacent second conductive patterns 31; along the thickness direction of the laminate, the dielectric films 11 with the first conductive patterns 21 and the dielectric films 11 with the second conductive patterns 31 are alternately laminated.

[0099] The above settings further reduce the parasitic capacitance between the coupling lines of the first inductor coil 20 and the second inductor coil 30, effectively ensuring excellent amplitude-frequency and phase characteristics in the high-frequency band (upper limit of the band).

[0100] For example, refer to Figure 7 The number of dielectric films 11 is six, wherein the first conductive pattern 21 includes 21a, 21b and 21c, and the first connecting conductor 22 includes 22a and 22b. Figure 7 (Not shown), the second conductive pattern 31 includes 31a, 31b and 31c, and the second connecting conductor 32 includes 32a and 32b. Figure 7 (Not shown), the first conductive patterns 21a, 21b, and 21c, and the second conductive patterns 31a, 31b, and 31c are staggered and stacked. That is, 21a, 22a, 32a, 21b, 22b, 32b, and 21c are connected sequentially to form the first inductor coil 20, and 31a, 32a, 22a, 31b, 32b, 22b, and 31c are connected sequentially to form the second inductor coil 30. This facilitates the three-dimensional spiral winding of the first inductor coil 20 and the second inductor coil 30 around the common magnetic core pillar 122 along the thickness direction of the laminate. Furthermore, along the thickness direction of the laminate, some patterns in the first conductive patterns 21 and the second conductive patterns 31 can be designed to include planar spiral structures, such as 21a, 21b, 31a, and 31b. This not only helps to ensure that the number of turns of the first inductor coil 20 and the second inductor coil 30 is the same, but also helps to reduce parasitic capacitance.

[0101] Of course, the number of dielectric membranes 11 can also be any number other than six, and no specific limitation is made here.

[0102] In some embodiments, a first through hole is formed at intervals on a portion of the dielectric film 11 on which the second conductive pattern 31 is printed, and a second through hole is formed at intervals on a portion of the dielectric film 11 on which the first conductive pattern 21 is printed. Both the first and second through holes are used to fill conductive material to form a first connecting conductor 22 and a second connecting conductor 32, respectively.

[0103] The above settings further reduce the parasitic capacitance between the coupling lines of the first inductor coil 20 and the second inductor coil 30.

[0104] It should be noted that the conductive materials used to form the first connecting conductor 22 and the second connecting conductor 32 are the same as those used for the first conductive pattern 21 and the second conductive pattern 31. This not only saves material costs, but also makes it easier for the first conductive pattern 21 to be connected to form the first inductor coil 20 through the first connecting conductor 22 and the second connecting conductor 32, without affecting the conductivity of the first inductor coil 20. At the same time, it also makes it easier for the second conductive pattern 31 to be connected to form the second inductor coil 30 through the first connecting conductor 22 and the second connecting conductor 32, without affecting the conductivity of the second inductor coil 30.

[0105] In some embodiments, the first inductor coil 20 and the second inductor coil 30 have the same wire diameter, which is 40μm to 80μm; the distance between the orthogonal projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 is equal to the wire diameter.

[0106] It should be noted that if the wire diameter of the first inductor coil 20 and the second inductor coil 30 is too large, the size of the balun structure will be too large. If the wire diameter is too small, the first inductor coil 20 and the second inductor coil 30 will be difficult to process. Setting the wire diameter of the first inductor coil 20 and the second inductor coil 30 to 40μm to 80μm is not only conducive to the miniaturization of the balun structure, but also reduces the parasitic capacitance between the first inductor coil 20 and the second inductor coil 30.

[0107] For example, the wire diameter of the first inductor coil 20 and the second inductor wire 30 can be 60 μm. The thickness of the first inductor coil 20 and the second inductor coil 30 along the thickness direction of the laminate is 10 μm.

[0108] In this application, the spacing between the orthographic projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 is set to be equal to the wire diameter. This is because if the spacing between the orthographic projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 is too small compared to the wire diameter, it will produce a large parasitic capacitance. On the other hand, if the spacing between the orthographic projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 is too large compared to the wire diameter, it will result in a large size of the balun structure. Through the above setting, it is beneficial to achieve the miniaturization design and reduce parasitic capacitance of the balun structure. That is, the balun structure can be miniaturized while ensuring excellent amplitude-frequency characteristics and phase characteristics in the high-frequency band.

[0109] For example, the distance between the orthographic projections of the first inductor coil 20 and the second inductor coil 30 on the magnetic chip 121 can be 60 μm.

[0110] In some embodiments, reference Figure 7 The number of first conductive patterns 21 is the same as the number of second conductive patterns 31. This makes it easier to make the structures of the first inductor coil 20 and the second inductor coil 30 the same or similar, thereby helping to reduce the parasitic capacitance between the coupling lines of the first inductor coil 20 and the second inductor coil 30.

[0111] In some embodiments, the three magnetic core pillars and the two magnetic chips 121 are integrated into one structure.

[0112] The above configuration ensures a reliable connection between the three magnetic core pillars and the two magnetic chips 121, thereby enhancing the magnetic field formed by the magnetic core structure 12 and facilitating the expansion of the balun structure to lower frequency bands.

[0113] refer to Figure 8 This application also provides a method for preparing a balun structure, which includes the following steps:

[0114] S101. Prepare two magnetic chips 121 and multiple dielectric films 11, wherein a third inductor coil 40 is provided in one of the magnetic chips 121.

[0115] It should be noted that the preparation of the magnetic chip 121 with the third inductor coil 40 may specifically include the following steps: preparing a plurality of magnetic films 1210; printing a third conductive pattern 41 on a portion of the magnetic films 1210; opening a third through hole on the portion of the magnetic films 1210 with the third conductive pattern 41 printed, and filling the third through hole with a third connecting conductor 42; stacking a portion of the magnetic films 1210 without the third conductive pattern 41 printed, a portion of the magnetic films 1210 with the third conductive pattern 41 printed, and the remaining portion of the magnetic films 1210 without the third conductive pattern 41 printed, to obtain the magnetic chip 121 with the third inductor coil 40.

[0116] It is understood that, referring to the above method for preparing a magnetic chip 121 with a third inductor coil 40, preparing a magnetic chip 121 without a third inductor coil 40 may specifically include the following steps: preparing a plurality of magnetic films 1210; and stacking the plurality of magnetic films 1210 in sequence to obtain a magnetic chip 121 without a third inductor coil 40.

[0117] The magnetic chip 121 is made of a high-permeability ferrite material with a permeability of 300-1000, while the dielectric diaphragm 11 is made of a low-dielectric-constant ceramic material with a dielectric constant of 3-10. This design enhances the inductance, extending the balun structure to frequencies below 100MHz, and reduces parasitic capacitance between the inductor coils, allowing the balun structure to extend to higher frequencies, thus broadening the application frequency range of the balun structure.

[0118] S102. A magnetic core hole 50 is formed on each dielectric diaphragm 11, and a first through hole or a second through hole is formed on some of the dielectric diaphragms 11.

[0119] It should be noted that there are three magnetic core holes 50 on each dielectric film 11, and the positions of the magnetic core holes 50 on each dielectric film 11 are corresponding to each other. The purpose of making a first through hole or a second through hole on some dielectric films 11 is to place conductive material in the first through hole or the second through hole. The first through hole and the second through hole have the same shape and size, which makes it easier to make the first through hole or the second through hole and improves the manufacturing efficiency.

[0120] There are several ways to open the magnetic core hole 50, the first through hole, or the second through hole on the dielectric film 11, such as laser drilling. Using laser drilling can improve both the accuracy and efficiency of drilling.

[0121] S103. Print a corresponding first conductive pattern 21 or second conductive pattern 31 on each dielectric film 11.

[0122] It should be noted that the conductor paste used to print the first conductive pattern 21 or the second conductive pattern 31 can be silver paste, gold paste, etc., and this application embodiment does not make specific limitations.

[0123] In this embodiment, the first conductive pattern 21 or the second conductive pattern 31 is printed on the dielectric film 11 before the lamination process. This can effectively control the printing level and position of the first conductive pattern 21 or the second conductive pattern 31, ensuring that the conductivity of the first conductive pattern 21 or the second conductive pattern 31 is not affected. The printing position is more accurate, which is beneficial to reducing the coupling capacitance between the first inductor coil 20 and the second inductor coil 30.

[0124] S104. A dielectric film 11 printed with a first conductive pattern 21 and a dielectric film 11 printed with a second conductive pattern 31 are alternately stacked on a magnetic chip 121 with a third inductor coil 40. After each dielectric film 11 is stacked, a first connecting conductor 22 is filled into a first through hole or a second connecting conductor 32 is filled into a second through hole until a first inductor coil 20 and a second inductor coil 30 are formed. A magnetic core film is then filled into a magnetic core hole 50 to form a magnetic core column.

[0125] It should be noted that the magnetic core diaphragm is directly filled into the magnetic core hole 50. This magnetic core diaphragm is obtained by cutting it from the magnetic diaphragm 1210 using laser technology.

[0126] In some embodiments, each dielectric diaphragm 11 has the same thickness; the thickness of the magnetic core diaphragm filling the magnetic core hole 50 of each dielectric diaphragm 11 is equal to the thickness of the dielectric diaphragm 11.

[0127] It should be noted that, since the magnetic core diaphragm and the magnetic diaphragm 1210 are made of the same material, an adhesive is generally added to the material during the fabrication of the magnetic diaphragm 1210. Therefore, the thickness of the magnetic core diaphragm is set to be equal to the thickness of the dielectric diaphragm 11. In this way, when the magnetic core diaphragm is filled into the magnetic core hole 50, the magnetic core diaphragm will contact and adhere to the magnetic core diaphragm below it or the magnetic core diaphragm below it, thereby ensuring that the magnetic core diaphragm in the magnetic core hole 50 is fully filled. Compared with the prior art of filling the magnetic core hole 50 with magnetic slurry to form a magnetic core column, the process is cumbersome and air bubbles are easy to appear in the slurry, affecting the density of the magnetic core column. The embodiment of this application can not only improve the manufacturing efficiency of the magnetic core column, but also improve the density of the magnetic core column, maximizing the role of the magnetic core column.

[0128] S105. Another magnetic chip 121 is stacked on the last dielectric film 11 to form a balun structure.

[0129] The embodiments of this application are used to prepare the balun structure in the above embodiments. Therefore, the beneficial effects that the above balun structure can achieve can also be achieved by the balun structure preparation method of this application, so they will not be described again here.

[0130] To more clearly illustrate the preparation process of the balun structure preparation method of this application, a specific embodiment is described below. The example uses four dielectric films 11.

[0131] First, four dielectric films 11 are prepared using ceramic material, and multiple magnetic films 1210 are prepared using ferrite material. The multiple magnetic films 1210 are directly stacked to obtain a magnetic sheet. Then, a third conductive pattern 41 is printed on some of the magnetic films 1210. The multiple magnetic films 1210 and the magnetic films 1210 with the third conductive pattern 41 are stacked to obtain a magnetic sheet with a third inductor coil 40. Corresponding first conductive patterns 21 are printed on two dielectric films 11, and first through holes and magnetic core holes 50 are opened. Corresponding second conductive patterns 31 are printed on the other two dielectric films 11, and second through holes and magnetic core holes 50 are opened.

[0132] The lamination process is as follows: A first dielectric film 11 printed with a first conductive pattern 21 is laminated onto a magnetic chip 121 equipped with a third inductor coil 40. Then, a first connecting conductor 22 is filled into the first through-hole of the dielectric film 11, and a magnetic core film is filled into the core hole 50. Next, a first dielectric film 11 printed with a second conductive pattern 31 is laminated, and a second connecting conductor 32 is filled into the second through-hole of the dielectric film 11, and a magnetic core film is filled into the core hole 50. This process is repeated. A second dielectric film 11 with a first conductive pattern 21 is overlaid, and a first connecting conductor 22 is filled into the first through hole of the dielectric film 11 and a magnetic core film is filled into the magnetic core hole 50. Then, a second dielectric film 11 with a second conductive pattern 31 is overlaid, and a second connecting conductor 32 is filled into the second through hole of the dielectric film 11 and a magnetic core film is filled into the magnetic core hole 50. Finally, a magnetic chip 121 without a third inductor coil 40 is overlaid to obtain a balun structure.

[0133] Furthermore, in the above-mentioned method for preparing the balun structure, in order to ensure that each dielectric film 11 and each magnetic chip 121 can be accurately aligned during the stacking process, alignment holes can be provided on each dielectric film 11 and each magnetic film 1210 included in the fabrication of the magnetic chip 121.

[0134] refer to Figure 9 This application also provides another method for preparing a balun structure, including the following steps:

[0135] S201. Prepare two magnetic chips 121 and multiple dielectric films 11, wherein one of the magnetic chips 121 is provided with a third inductor coil 40.

[0136] S202, A first alignment hole is made on the magnetic chip 121.

[0137] It should be noted that the first alignment hole on the magnetic chip 121 can be formed by forming an alignment hole on each magnetic diaphragm 1210, or by stacking multiple magnetic diaphragms 1210 to form the magnetic chip 121 and then directly forming the first alignment hole on the magnetic chip 121.

[0138] S203. A second alignment hole is formed on the dielectric film 11, and alignment background material 60 is printed around the second alignment hole. The alignment background material 60 is made of the same material as the magnetic chip 121.

[0139] It should be noted that the second alignment hole on the dielectric film 11 corresponds to the first alignment hole. This ensures that each dielectric film 11 is accurately aligned and that the dielectric film 11 is accurately aligned with the magnetic chip 121 when the dielectric films 11 are stacked. This facilitates the accurate connection between the first conductive patterns 21 to form the first inductor coil 20, and the accurate connection between the second conductive patterns 31 to form the second inductor coil 30.

[0140] Because the magnetic chip 121 and the dielectric film 11 are made of different materials, their colors are different. In this embodiment, an alignment background material 60 is printed around the second alignment hole. The alignment background material 60 is made of the same material as the magnetic chip 121. In this way, when the dielectric film 11 and the magnetic chip 121 are stacked, the alignment background can be kept consistent, allowing films of different colors to be aligned using the same image, thus avoiding alignment deviations caused by different types of films.

[0141] In this embodiment, the second alignment hole on the dielectric film 11 and the first alignment hole on the magnetic chip 121 have the same shape and size. The positions of the first alignment hole on the magnetic chip 121 and the second alignment hole on the dielectric film 11 must be matched with each other. Specifically, since the first alignment hole and the second alignment hole are directly opposite each other, it is necessary to ensure that the first alignment hole will not damage the third inductor coil 40 disposed in the magnetic chip 121, and also to ensure that the second alignment hole will not damage the first inductor coil 20 and the second inductor coil 30.

[0142] For example, first alignment holes can be set at the four corners of the magnetic chip 121, and second alignment holes can be set at the four corners of the dielectric film 11. This allows for control over the alignment accuracy of the dielectric film 11 and the magnetic chip 121 during the stacking process, making the alignment of the dielectric film 11 and the magnetic chip 121 more precise. Moreover, the first and second alignment holes are located in the edge area, which will not damage the inductor coil or affect the normal printing of the conductive pattern.

[0143] Figure 9-1 A schematic diagram showing the printing of the alignment background material 60 at the four corners of the dielectric film 11.

[0144] S204. A magnetic core hole 50 is formed on each dielectric diaphragm 11, and a first through hole or a second through hole is formed on some of the dielectric diaphragms 11.

[0145] S205. Print a corresponding first conductive pattern 21 or second conductive pattern 31 on each dielectric film 11.

[0146] S206. A dielectric film 11 printed with a first conductive pattern 21 and a dielectric film 11 printed with a second conductive pattern 31 are alternately stacked on a magnetic chip 121 with a third inductor coil 40. After each dielectric film 11 is stacked, a first connecting conductor 22 is filled into a first through hole or a second connecting conductor 32 is filled into a second through hole until a first inductor coil 20 and a second inductor coil 30 are formed. A magnetic core film is then filled into a magnetic core hole 50 to form a magnetic core column.

[0147] S207. Another magnetic chip 121 is stacked on the last dielectric film 11 to form a balun structure.

[0148] refer to Figure 8 This application also provides another method for preparing a balun structure, comprising the following steps:

[0149] S301. Prepare two magnetic chips 121 and multiple dielectric films 11, wherein one of the magnetic chips 121 is provided with a third inductor coil 40.

[0150] S302. A second alignment hole is made on the dielectric membrane 11.

[0151] S303. A first alignment hole is opened on the magnetic chip 121, and an alignment background material 60 is printed around the first alignment hole. The alignment background material 60 is made of the same material as the dielectric film 11.

[0152] It should be noted that the first alignment hole on the magnetic chip 121 can be formed by forming an alignment hole on each magnetic diaphragm 1210, or by stacking multiple magnetic diaphragms 1210 to form the magnetic chip 121 and then directly forming the first alignment hole on the magnetic chip 121.

[0153] It is understandable that, since the magnetic chip 121 includes multiple magnetic films 1210, printing the alignment background material 60 around the first alignment hole means printing the alignment background material 60 around the first alignment hole of the outermost magnetic film 1210 of the multiple stacked magnetic films 1210 included in the magnetic chip 121. This can avoid the waste of material caused by printing the alignment background material 60 on each magnetic film 1210.

[0154] The first alignment hole and the second alignment hole on the magnetic chip 121 correspond to each other, so that when the dielectric film 11 and the magnetic chip 121 are stacked, the alignment of each dielectric film 11 and the magnetic chip 121 can be accurate. This is beneficial for the accurate connection between the first conductive patterns 21 to form the first inductor coil 20, and the accurate connection between the second conductive patterns 31 to form the second inductor coil 30.

[0155] Because the magnetic chip 121 and the dielectric film 11 are made of different materials, their colors are different. In this embodiment, an alignment background material 60 is printed around the first alignment hole. The alignment background material 60 is made of the same material as the dielectric film 11. In this way, when the dielectric film 11 and the magnetic chip 121 are stacked, the alignment background can be kept consistent, allowing films of different colors to be aligned using the same image, thus avoiding alignment deviations caused by different types of films.

[0156] In this embodiment, the second alignment hole on the dielectric film 11 and the first alignment hole on the magnetic chip 121 have the same shape and size. The positions of the first alignment hole on the magnetic chip 121 and the second alignment hole on the dielectric film 11 must be matched with each other. Specifically, since the first alignment hole and the second alignment hole are directly opposite each other, it is necessary to ensure that the first alignment hole will not damage the third inductor coil 40 disposed in the magnetic chip 121, and also to ensure that the second alignment hole will not damage the first inductor coil 20 and the second inductor coil 30.

[0157] For example, first alignment holes can be set at the four corners of the magnetic chip 121, and second alignment holes can be set at the four corners of the dielectric film 11. This allows for control over the alignment accuracy of the dielectric film 11 and the magnetic chip 121 during the stacking process, making the alignment of the dielectric film 11 and the magnetic chip 121 more precise. Moreover, the first and second alignment holes are located in the edge area, which will not damage the inductor coil or affect the normal printing of the conductive pattern.

[0158] A schematic diagram of printing the alignment background material 60 on the magnetic chip 121 can be found here. Figure 9-1 .

[0159] S304. A magnetic core hole 50 is formed on each dielectric diaphragm 11, and a first through hole or a second through hole is formed on some of the dielectric diaphragms 11.

[0160] S305. Print a corresponding first conductive pattern 21 or second conductive pattern 31 on each dielectric film 11.

[0161] S306. A dielectric film 11 printed with a first conductive pattern 21 and a dielectric film 11 printed with a second conductive pattern 31 are alternately stacked on a magnetic chip 121 with a third inductor coil 40. After each dielectric film 11 is stacked, a first connecting conductor 22 is filled into a first through hole or a second connecting conductor 32 is filled into a second through hole until a first inductor coil 20 and a second inductor coil 30 are formed. A magnetic core film is then filled into the magnetic core hole 50 to form a magnetic core column.

[0162] S307. Another magnetic chip 121 is stacked on the last dielectric film 11 to form a balun structure.

[0163] The preparation method of the balun structure and the prepared balun structure are illustrated below through a specific example.

[0164] The example balun structure includes a first inductor 20 comprising three connected first conductive patterns 21N11, N12, and N13; a second inductor 30 comprising three connected second conductive patterns 31N21, N22, and N23; and a third inductor 40 comprising two connected third conductive patterns 41L11 and L12. N11, N12, N13, N21, N22, and N23 are all designed as planar spiral inductor coupling lines, distributed on different planes.

[0165] Before stacking to form the balun structure, six dielectric films 11, multiple magnetic films 1210, and eighteen magnetic core films are first fabricated. Three magnetic core holes 50 and at least one through hole are opened on each dielectric film 11. First conductive patterns 21N11, N12, and N13 are printed on three dielectric films 11 respectively, and second conductive patterns 31N21, N22, and N23 are printed on the other three dielectric films 11 respectively. Third conductive patterns 41L11 and L12 are printed on two magnetic films 1210 respectively. Other magnetic films 1210 without the third conductive pattern 41 can be called blank magnetic films 1210.

[0166] The lamination process is as follows: Using a blank magnetic film 1210 as a base, multiple blank magnetic films 1210, two magnetic films 1210 with printed third conductive patterns 41L11 and L12, and multiple blank magnetic films 1210 are sequentially laminated. Then, a dielectric film 11 with printed first conductive pattern 21N11 is laminated. Conductive material is then filled into the through-holes of the dielectric film 11, and magnetic core films of corresponding sizes are filled into the three magnetic core holes 50. Finally, a dielectric film 11 with printed second conductive pattern 31N21 is laminated. The dielectric film 11 is then filled with conductive material into the through holes of the dielectric film 11, and magnetic core films of corresponding sizes are filled into the three magnetic core holes 50 respectively. The remaining four dielectric films 11 are stacked alternately in the above-mentioned stacking manner, so that the conductive pattern is arranged in the order of N11, N21, N12, N22, N13, and N23 along the thickness direction of the dielectric film 11. Finally, multiple blank magnetic films 1210 are stacked on the dielectric film 11, and then the product is formed by isostatic pressing.

[0167] Typically, to facilitate differentiation between the input terminal 101, ground terminal 104, first output terminal 102, and second output terminal 103 of the molded product, a marking pattern is printed on the surface of the magnetic chip 121 away from the laminate. This marking pattern is used to mark the position of the input terminal 101. Since the balun structure is rectangular in shape after packaging, the positions of the ground terminal 104, first output terminal 102, and second output terminal 103 can be determined based on the shape of the balun structure after marking the position of the input terminal 101, which facilitates the application of the balun structure.

[0168] The dimensions of the balun structure package fabricated in the above embodiment are 2.0mm*1.2mm*0.8mm (length*width*height).

[0169] The dielectric diaphragm 11 is made of ceramic material with a dielectric constant of 5 and a dielectric loss (tan) ≤ 0.01. The magnetic diaphragm 1210 and the magnetic core diaphragm are both made of ferrite material with a magnetic permeability of 600. After the stacking is completed, the balun structure can be formed and fixed by sintering at a temperature of 880℃.

[0170] The conductive paste used to print the first conductive pattern 21, the second conductive pattern 31 and the third conductive pattern 41 is made of silver paste. The silver paste is sintered at 875℃, contains 85% silver, has a silver layer thickness of 10μm and a silver layer width of 60μm.

[0171] Simulations show that the passband of the balun structure in the above embodiment is 20MHz-1500MHz, and the amplitude imbalance is ≤1dB. Figure 5-4 As shown; phase imbalance ≤ 10°, reference Figure 11 Insertion loss within the passband ≤3dB, reference Figure 12 Return loss ≥10dB, reference Figure 13 .

[0172] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A balun structure, characterized in that, include: The substrate (10) includes a laminate and a magnetic core structure (12). The magnetic core structure (12) includes two magnetic chips (121) and three magnetic core pillars spaced apart from each other. The two magnetic chips (121) are respectively stacked on opposite sides of the laminate. The magnetic core pillars penetrate the laminate to connect with the two magnetic chips (121). A first inductor coil (20) is disposed on the laminate, and the first inductor coil (20) is spirally wound between the three magnetic core pillars; The second inductor coil (30) is disposed on the laminate and is spirally wound between the three magnetic core pillars; The third inductor (40) is disposed on any one of the magnetic chips (121), and the first inductor (20), the second inductor (30) and the third inductor (40) are coupled to each other in pairs; The outer surface of the substrate (10) is provided with an input terminal (101), a first output terminal (102), a second output terminal (103) and a ground terminal (104). The two ends of the first inductor (20) are respectively connected to the input terminal (101) and the first output terminal (102). The two ends of the second inductor (30) are respectively connected to the second output terminal (103) and the ground terminal (104). The two ends of the third inductor (40) are respectively connected to the ground terminal (104) and the first output terminal (102).

2. The balun structure according to claim 1, characterized in that, The sum of the inductance of the first inductor (20) and the inductance of the second inductor (30) is the first inductance, and the inductance of the third inductor (40) is the second inductance. The difference between the second inductance and the first inductance is in the range of -130nH to 200nH.

3. The balun structure according to claim 2, characterized in that, The magnetic chip (121) includes a plurality of magnetic films (1210) stacked sequentially; The third inductor coil (40) includes a third conductive pattern (41) which is printed on any of the magnetic films (1210) of the magnetic chip (121) except for the magnetic films (1210) located on opposite sides. Alternatively, the third inductor coil (40) includes a plurality of third conductive patterns (41), which are printed on different magnetic films (1210) of the magnetic chip (121) except for the magnetic films (1210) located on opposite sides, and the plurality of third conductive patterns (41) are connected in sequence.

4. The balun structure according to any one of claims 1-3, characterized in that, The three magnetic core pillars are arranged along a first direction, the three magnetic core pillars including two first magnetic core pillars (123) and a common magnetic core pillar (122) located between the two first magnetic core pillars (123), the first direction being perpendicular to the thickness direction of the laminate; The first inductor coil (20) and the second inductor coil (30) are both spirally wound around the common magnetic core column (122). Along the thickness direction of the laminate, the orthographic projections of the first inductor coil (20) and the second inductor coil (30) on the magnetic chip (121) are staggered.

5. The balun structure according to claim 4, characterized in that, The laminate includes a plurality of dielectric films (11); The first inductor coil (20) includes a plurality of first conductive patterns (21) and a first connecting conductor (22). The plurality of first conductive patterns (21) are printed on a plurality of dielectric films (11). The first connecting conductor (22) passes through the dielectric film (11) and is used to connect two adjacent first conductive patterns (21). The second inductor coil (30) includes a plurality of second conductive patterns (31) and a second connecting conductor (32). The plurality of second conductive patterns (31) are printed on a plurality of dielectric films (11). The second connecting conductor (32) passes through the dielectric film (11) and is used to connect two adjacent second conductive patterns (31). Along the thickness direction of the laminate, the dielectric film (11) printed with the first conductive pattern (21) and the dielectric film (11) printed with the second conductive pattern (31) are alternately stacked.

6. The balun structure according to claim 5, characterized in that, The first inductor coil (20) and the second inductor coil (30) have the same wire diameter, which is 40μm to 80μm; The distance between the orthographic projections of the first inductor coil (20) and the second inductor coil (30) onto the magnetic chip (121) is equal to the wire diameter; Alternatively, the laminate is made of ceramic material, and the dielectric constant of the ceramic material is 3-10; The magnetic chip (121) and the magnetic core post are both made of ferrite material, and the magnetic permeability of the ferrite material is 300-1000.

7. A method for preparing a balun structure, used to prepare the balun structure as described in claim 5, characterized in that, include: Two magnetic chips (121) and multiple dielectric films (11) are prepared, wherein a third inductor coil (40) is provided in one of the magnetic chips (121); A magnetic core hole (50) is formed on each of the dielectric films (11), and a first through hole or a second through hole is formed on some of the dielectric films (11); The first conductive pattern (21) or the second conductive pattern (31) is printed on each of the dielectric films (11); The dielectric film (11) printed with the first conductive pattern (21) and the dielectric film (11) printed with the second conductive pattern (31) are alternately stacked on the magnetic chip (121) provided with the third inductor coil (40). After each dielectric film (11) is stacked, a first connecting conductor (22) is filled into the first through hole or a second connecting conductor (32) is filled into the second through hole until the first inductor coil (20) and the second inductor coil (30) are formed. Then, a magnetic core film is filled into the magnetic core hole (50) to form the magnetic core column. Another magnetic chip (121) is stacked on the last of the stacked dielectric films (11) to form a balun structure.

8. The preparation method according to claim 7, characterized in that, Each of the dielectric films (11) has the same thickness; The thickness of the magnetic core diaphragm filling the magnetic core hole (50) of each of the dielectric diaphragms (11) is equal to the thickness of the dielectric diaphragm (11).

9. The preparation method according to claim 7 or 8, characterized in that, After fabricating two magnetic chips (121) and multiple dielectric films (11), the process further includes: A first alignment hole is formed on the magnetic chip (121); A second alignment hole is formed on the dielectric film (11), and an alignment background material (60) is printed around the second alignment hole. The alignment background material (60) is made of the same material as the magnetic chip (121). Alternatively, a first alignment hole may be formed on the magnetic chip (121), and an alignment background material (60) may be printed around the first alignment hole, wherein the alignment background material (60) is made of the same material as the dielectric film (11). A second alignment hole is formed on the dielectric membrane (11).

10. The preparation method according to claim 7 or 8, characterized in that, Fabricating a magnetic chip (121) with a third inductor coil (40) includes: Multiple magnetic films (1210) were prepared; A third conductive pattern (41) is printed on a portion of the magnetic film (1210); A third through hole is formed on the magnetic film (1210) on the part of the third conductive pattern (41) being printed, and a third connecting conductor (42) is filled in the third through hole; The magnetic film (1210) with a portion of the third conductive pattern (41) not printed, the magnetic film (1210) with the third conductive pattern (41) printed, and the remaining magnetic film (1210) with the third conductive pattern (41) not printed are stacked to obtain a magnetic chip (121) with a third inductor coil (40).

Images