WO2023060951A1 - Planar transformer and power supply module - Google Patents

Abstract

The present application provides a planar transformer and a power supply module. A first dielectric assembly and a second dielectric assembly having different relative magnetic permeability are stacked, so that the leakage flux of a primary coil is reduced, the degree of coupling between the primary coil and a secondary coil is improved, and then the leakage inductance of the transformer is reduced. The planar transformer provided in the present application comprises a coil assembly as well as the first dielectric assembly and the second dielectric assembly which are stacked. The coil assembly comprises the primary coil and the secondary coil, the primary coil and the secondary coil are both arranged on the first dielectric assembly, and the relative magnetic permeability of the second dielectric assembly can be greater than the relative magnetic permeability of the first dielectric assembly.

Description

Planar Transformers and Power Modules

This application claims the priority of a Chinese patent application with application number 202111190502.1 and application title "Planar Transformer and Power Module" filed with the China Patent Office on October 13, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the field of energy technology, and more specifically, to a planar transformer and a power module in the field of energy technology.

Background technique

As the core component of switching power supply, high-frequency transformer often has a decisive influence on key indicators such as efficiency and power density of switching power supply. Therefore, it is necessary to conduct in-depth research on high-frequency transformer.

According to the structure type, high-frequency transformers can be divided into wire-wound transformers and planar transformers. Among them, the wire-wound transformer has the advantages of low cost and small DC resistance of the winding, etc., but the wire-wound transformer also has disadvantages such as low processing efficiency, poor performance consistency, and relatively large size. Compared with wire-wound transformers, planar transformers have the advantages of low height, small size, mass and rapid production, and good performance consistency. However, the planar transformers in the related art also have the disadvantage of large leakage inductance.

Therefore, there is an urgent need for a planar transformer with less leakage inductance.

Contents of the invention

The present application provides a planar transformer and a power module, which have small leakage inductance and volume, and low processing complexity.

In a first aspect, the present application provides a planar transformer, which may include a first dielectric component, a second dielectric component, and a coil component, and the first dielectric component and the second dielectric component may be stacked.

Wherein, the coil assembly may include at least one (that is, one or more) first coils and at least one (that is, one or more) second coils. Both at least one first coil and at least one second coil may be disposed on the first dielectric component.

Optionally, the relative magnetic permeability of the second dielectric component may be greater than that of the first dielectric component.

It should be explained that the relative permeability refers to the ratio of the permeability of the medium (a physical quantity used to characterize the magnetic properties of the medium) to the vacuum permeability. Thus, the relative magnetic permeability of the second dielectric component may refer to the ratio of the magnetic permeability of the second dielectric component to the vacuum magnetic permeability, and the relative magnetic permeability of the first dielectric component may refer to the magnetic permeability of the first dielectric component and vacuum permeability ratio.

Therefore, relative to the first dielectric component, the second dielectric component can be called a high permeability (ie, relatively high permeability) medium component, so the first medium component can be called a low permeability (ie, relatively high permeability) medium component. Relatively low permeability) media components.

The planar transformer provided by the present application reduces the magnetic flux that is not coupled by the second coil in the total magnetic flux generated by the first coil through the first dielectric component with relatively low permeability (that is, reduces the leakage flux of the first coil ), which increases the degree of coupling between the first coil and the second coil, thereby reducing the leakage inductance of the planar transformer.

In a possible implementation manner, the first dielectric component may include a first dielectric layer. Then, one or more first coils and one or more second coils are arranged on the first dielectric layer.

In another possible implementation manner, the first dielectric component may include multiple first dielectric layers, and each layer of the first dielectric layer may be stacked, that is, each layer of the first dielectric layer and the second dielectric component Cascading settings are possible. One or more first coils can be arranged on one or more first dielectric layers in the multi-layer first dielectric layer, similarly, one or more second coils can also be arranged in the multi-layer first dielectric layer layer or layers on the first dielectric layer.

In a possible implementation manner, the single-side width (that is, the single-side width) of at least one first coil may be greater than 1.5 times the thickness of the first dielectric component (that is, the total thickness of all first dielectric layers in the first dielectric component). times. The single side width of at least one second coil may also be greater than 1.5 times the thickness of the first dielectric component.

Further, the above-mentioned second dielectric component may include at least one second dielectric layer. At least one second dielectric layer can be stacked.

Optionally, if there is only one second dielectric layer, the second dielectric layer is stacked with one or more first dielectric layers. If the second dielectric layer has multiple layers, then the multi-layer second dielectric layer is stacked, and the multi-layer second dielectric layer and one or more first dielectric layers are also stacked (that is, the first dielectric component and the second dielectric layer Component cascading settings).

In a possible implementation, the planar transformer provided in the present application may further include a third dielectric component. The third medium component can be stacked with the first medium component and the second medium component, and the third medium component and the second medium component are respectively arranged on two sides of the first medium component.

Optionally, the relative magnetic permeability of the third medium component may be greater than that of the first medium component. Therefore, relative to the first dielectric component, the third dielectric component may also be called a high permeability (ie, relatively high permeability) dielectric component.

Further, the relative magnetic permeability of the third dielectric component may be equal to the relative magnetic permeability of the second dielectric component.

Similar to the second dielectric component, the third dielectric component may also include at least one third dielectric layer.

Optionally, if there is only one third dielectric layer, the third dielectric layer is stacked with one or more first dielectric layers. If the third dielectric layer has multiple layers, then the multi-layer third dielectric layer is stacked, and the multi-layer third dielectric layer and one or more first dielectric layers are also stacked (that is, the third dielectric component and the dielectric component first dielectric layer) one stack setting).

In a possible implementation manner, at least one second dielectric layer in the second dielectric component and at least one third dielectric layer in the third dielectric component can use nickel-zinc ferrite respectively. Of course, at least one second dielectric layer and at least one third dielectric layer may also use other magnetic media such as manganese zinc ferrite as main components, which is not limited in this application.

Further, the second dielectric layer (one or more layers) may be provided with conductor lines (such as pads, etc.). Similarly, the third dielectric layer (one or more layers) may also be provided with conductive lines such as pads. For example, pads may be provided on the outer surface of the second dielectric component and/or the third dielectric component. That is to say, only the outer surface of the second dielectric component may be provided with pads, and only the outer surface of the third dielectric component may be provided with pads, or the outer surface of the second dielectric component and the outer surface of the third dielectric component are respectively Pads are provided.

In a possible implementation manner, the planar transformer provided in the present application may be made by a low-temperature co-fired ceramic process or a high-temperature co-fired ceramic process. Of course, other sintering processes can also be used, which is not limited in this application.

The planar transformer provided by the present application can realize the processing of the planar transformer through the pressing process and the sintering process, and the processing complexity is small. In addition, the integration of the first dielectric component, the second dielectric component, the third dielectric component and the coil component is high, and the whole planar transformer is an integrated design with low height and small volume.

In a second aspect, the present application provides a power module, which may include the planar transformer provided in the first aspect and any possible implementation manner thereof.

In one example, the power module may include a planar transformer and semiconductor devices.

Wherein, the planar transformer is used as a substrate carrier, and pads are provided on the planar transformer, and semiconductor devices can be soldered on the pads.

Optionally, the semiconductor device may be a chip, a resistor, or a capacitor, which is not limited in this application.

It should be noted that, in addition to the planar transformer and the semiconductor device, the power module may also include other functional units, which is not limited in this application.

In another example, the power module may include a planar transformer, a semiconductor device, and a functional unit (such as a filter circuit that functions as a filter, etc.).

Wherein, the functional unit is used as a substrate carrier, the planar transformer is used as an independent component, the planar transformer and the semiconductor device are respectively arranged on the functional unit, and the planar transformer and the semiconductor device have a connection relationship.

Similarly, the semiconductor device may also be a chip, a resistor, or a capacitor, etc., which is not limited in this embodiment of the present application.

It should also be noted that, in addition to functional units such as planar transformers, semiconductor devices, and filter circuits, the power module may also include other functional units, which is not limited in this embodiment of the present application.

It should be understood that the technical solution of the second aspect of the present application is consistent with the technical solution of the first aspect of the present application, and the beneficial effects obtained by the various aspects and the corresponding possible implementation manners are similar, so details are not repeated here.

Description of drawings

FIG. 1 is a schematic structural diagram of a planar transformer in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a planar transformer in an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a planar transformer in an embodiment of the present application;

Fig. 4 is the schematic diagram of the magnetic circuit model of planar transformer in the embodiment of the present application;

FIG. 5 is a schematic structural diagram of a power module in an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a planar transformer in an embodiment of the present application.

Detailed ways

The technical solution in this application will be described below with reference to the accompanying drawings.

In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in this application. Obviously, the described embodiments are part of the embodiments of this application , but not all examples. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

The terms "first" and "second" in the description, embodiments, claims and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be interpreted as indicating or implying relative importance, nor can they be interpreted as indicating or imply order. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, of a sequence of steps or elements. A method, system, product or device is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to the process, method, product or device.

It should be understood that in this application, "at least one (item)" means one or more, and "multiple" means two or more. "And/or" is used to describe the association relationship of associated objects, indicating that there can be three types of relationships, for example, "A and/or B" can mean: only A exists, only B exists, and A and B exist at the same time , where A and B can be singular or plural. The character "/" generally indicates that the contextual objects are an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one item (piece) of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c ", where a, b, c can be single or multiple.

The operating frequency of high-frequency transformers often exceeds the intermediate frequency (such as 10kHz), and can be used in switching power supplies with high switching frequencies to reduce the ripple of the output voltage of switching power supplies. As the core component of switching power supply, high-frequency transformer often has a decisive impact on key indicators such as efficiency and power density of switching power supply. Therefore, it is necessary to conduct in-depth research on high-frequency transformers.

According to the structure type, high-frequency transformers can be divided into wire-wound transformers and planar transformers. The following introduces the wire-wound transformer and the planar transformer respectively:

(1) A wound transformer includes a skeleton, a coil and a magnetic core. The coil is wound on the skeleton, and the coil and the magnetic core can be assembled together. The wire-wound transformer has the advantages of low cost and small DC resistance of the winding, but the wire-wound transformer also has disadvantages such as low processing efficiency, poor performance consistency, and relatively large size.

(2) Planar transformers can be divided into printed circuit board (PCB) planar transformers (which can be called PCB planar transformers) and co-fired magnetic ceramic planar transformers.

Wherein, the PCB planar transformer may include a printed circuit board (with a primary coil and a secondary coil) and a magnetic core (which may adopt an E-type structure or an RM-type structure, etc.) assembled as a whole. PCB planar transformers have the advantages of low height, small size, mass and rapid production, and good performance consistency.

Among them, co-fired magnetic ceramic planar transformers generally include low temperature co-fired ceramics planar transformers (which can be called LTCC planar transformers) and high temperature co-fired ceramics planar transformers (high temperature co-fired ceramics) planar transformers (It can be called HTCC planar transformer).

The following is an example of an LTCC planar transformer. LTCC planar transformers usually include a multilayer magnetic ceramic substrate printed with primary and secondary coils. The multilayer ceramic substrate can be laminated and sintered at a temperature lower than 950°C. Since the magnetic ceramic substrate itself has a certain relative permeability, the LTCC planar transformer does not need to assemble an additional magnetic core, and the laminated and sintered ceramic substrate has the function of a high-frequency transformer. Therefore, compared to PCB planar transformers, LTCC planar transformers are lower in height and smaller in size.

At the same time, since the magnetic ceramic substrate between the primary coil and the secondary coil in the LTCC planar transformer has a certain relative permeability, the magnetic flux generated by the primary coil will pass between the primary winding and the secondary winding when the transformer is working. The magnetic ceramic substrate between them causes the magnetic flux generated by the primary coil not to be coupled by the secondary coil, and the magnetic flux leakage of the primary coil is large. Therefore, the LTCC planar transformer has a problem of large leakage inductance.

In order to overcome the problem of large leakage inductance in the LTCC planar transformer or the HTCC planar transformer, an embodiment of the present invention provides a planar transformer.

As shown in Figure 1, the planar transformer 1 can include a dielectric component 11 (i.e. a first dielectric component), a dielectric component 12 (ie a second dielectric component) and a coil component 13, and the first dielectric component 11 and the second dielectric component 12 can be stacked set up.

Optionally, the coil assembly 13 may include at least one (that is, one or more) coil C (coil) 1 (that is, the first coil, which can be used as the primary coil of the planar transformer 1) and at least one (that is, one or more) The coil C2 (that is, the second coil, which can be used as the secondary coil of the planar transformer 1 ), and the coil C1 and the coil C2 are coupled by magnetic flux (that is, the coil C1 and the coil C2 have a magnetic flux coupling relationship). At least one coil C1 and at least one coil C2 are both disposed (eg, disposed by printing) on the first dielectric component 11 .

Optionally, the relative magnetic permeability of the dielectric component 12 (which can be represented by μ _r2 ) can be greater than the relative magnetic permeability of the dielectric component 11 (which can be represented by μ _r1 ), that is, μ _r2 is greater than μ _r1 .

Therefore, relative to the dielectric component 11, the dielectric component 12 can be called a high-permeability (ie relatively high permeability) medium component, so the medium component 11 can be called a low-permeability (ie relative permeability) low rate) media components.

As mentioned above, the relative magnetic permeability refers to the ratio of the magnetic permeability of the medium (a physical quantity used to characterize the magnetic properties of the medium) and the vacuum permeability (which can be expressed by μ ₀ ).

Therefore, the relative magnetic permeability μ _r2 of the dielectric component 12 can be the ratio of the magnetic permeability of the dielectric component 12 (which can be represented by μ ₂ ) to the vacuum magnetic permeability μ ₀ , ie μ _r2 =μ ₂ /μ ₀ .

Similarly, the relative permeability μ _r1 of the dielectric component 11 can be the ratio of the permeability of the dielectric component 11 (which can be represented by μ ₁ ) to the vacuum permeability μ ₀ , ie μ _r1 =μ ₁ /μ ₀ .

The planar transformer provided in the embodiment of the present application reduces the magnetic flux that is not coupled by the coil C2 in the total magnetic flux generated by the coil C1 through the dielectric component 11 with a relatively low magnetic permeability (that is, reduces the leakage flux of the coil C1), The degree of coupling between the coil C1 and the coil C2 is improved, thereby reducing the leakage inductance of the planar transformer.

In a possible implementation manner, the dielectric component 11 may include a dielectric layer A (that is, the dielectric component 11 only includes a first dielectric layer). Then, one or more coils C1 and one or more coils C2 are arranged on the dielectric layer A.

In another possible implementation manner, the dielectric component 11 may include multiple dielectric layers A (that is, the number of layers of the dielectric layer A is multiple layers), and each layer of the dielectric layer A may be stacked, that is to say, each layer The dielectric layer A and the dielectric component 12 can be stacked. One or more coils C1 can be arranged on one or more layers of dielectric layer A in the multilayer dielectric layer A, similarly, one or more coils C2 can also be arranged on one or more layers of dielectric layer A in the multilayer dielectric layer A layer A.

Optionally, one or more coils C1 and one or more coils C2 may be arranged on the dielectric assembly 11 in the following manner:

Mode 1: one or more coils C1 are arranged on the dielectric layer A with an odd number (it can be all the dielectric layers A with an odd number), and the dielectric layer A with the serial number as coupling (it can be all the dielectric layers A with an even number) ) is provided with one or more coils C2.

That is to say, one or more coils C1 are respectively arranged on the dielectric layer A with an odd number, and one or more coils C2 are not arranged on any of them. One or more coils C2 are respectively arranged on the even-numbered dielectric layer A, and one or more coils C1 are not arranged.

Method 2: Assume that the dielectric layer A has an even number of layers (can be represented by N), and one or more coils C1 are respectively set on the dielectric layer A with the serial number N/2 and the dielectric layer A before the serial number N/2, and the serial number is N One or more coils C2 are respectively arranged on the dielectric layer A after /2.

That is to say, one or more coils C1 are respectively arranged on the dielectric layer A with the serial number N/2 and the dielectric layer A before the serial number N/2, and one or more coils C2 are not provided. One or more coils C2 are respectively arranged on the dielectric layer A after the serial number N/2, and one or more coils C1 are not arranged.

Mode 3: One or more coils C1 and one or more coils C2 are respectively arranged on each dielectric layer A.

It should be noted that the embodiment of the present application only provides several possible arrangements of the coil C1 and the coil C2. Of course, the coil C1 and the coil C2 can also be arranged in other ways than the several methods provided by the embodiment of the present application. The setting (that is, the coil C1 and the coil C2 are not limited to the setting provided in the embodiment of the present application), is not limited in the embodiment of the present application.

In an example, as shown in FIG. 2 , the dielectric component 11 may be provided with four dielectric layers A.

Wherein, the first dielectric layer A and the fourth dielectric layer A are respectively provided with one-turn coil C2, and the one-turn coil C2 provided on the first dielectric layer A and the one-turn coil C2 provided on the fourth dielectric layer A can be Connect between layers through through holes (such as end-to-end connection, that is, the one-turn coil C2 set on the first dielectric layer A is connected in series with the one-turn coil C2 set on the fourth dielectric layer A), and a 2-turn coil can be formed. Coil C2 (that is, the secondary coil is 2 turns).

Wherein, the second dielectric layer A and the third dielectric layer A are respectively provided with 3-turn coil C1, and the one-turn coil C1 provided on the second dielectric layer A and the one-turn coil C1 provided on the third dielectric layer A can be Connect between layers through through holes (such as end-to-end connection, that is, the one-turn coil C1 set on the second dielectric layer A is connected in series with the one-turn coil C1 set on the third dielectric layer A), and a 6-turn coil can be formed. Coil C1 (that is, the primary coil has 6 turns).

Further, continuing to refer to FIG. 2, since the coil C1 has 6 turns and the coil C2 has 2 turns, the single-side width of the coil C1 (that is, the width of the unilateral 3-turn coil C1 in the 6-turn coil C1) or the single-side width of the coil C2 The side width (that is, the width of the one-turn coil C2 on one side of the two-turn coil C2) can be greater than 1.5 times the thickness of the entire dielectric component 11 (that is, the total thickness of the four dielectric layers A, represented by a), that is, b>1.5 a.

It should be noted that if the second layer of dielectric layer A and the third layer of dielectric layer A are respectively provided with one-turn coil C1 and one-turn coil C2, there is only one turn respectively, since the coil C1 and the coil C2 are in the shape of a ring (in the length direction There are two unilaterals), then the single-sided width of the one-turn coil C1 or the one-turn coil C2 can also be greater than the thickness of the entire dielectric assembly 11 (that is, the total thickness of the four dielectric layers A).

In a possible implementation manner, the dielectric component 12 may include at least one dielectric layer B (that is, the dielectric component 12 may include one or more dielectric layers B).

Optionally, if there is only one dielectric layer B, then the dielectric layer B is stacked with one or more dielectric layers A. If the dielectric layer B has multiple layers, then multiple dielectric layers B are stacked, and multiple dielectric layers B and one or more dielectric layers A are also stacked (that is, the dielectric component 12 and the dielectric component 11 are stacked).

The planar transformer 1 provided in the embodiment of the present application may further include a dielectric component 14 (that is, a third dielectric component), as shown in FIG. 2 and FIG. 3 . The medium component 14 can be stacked with the medium component 11 and the medium component 12 , and the medium component 14 and the medium component 12 are arranged on both sides of the medium component 11 respectively.

Optionally, the relative magnetic permeability of the dielectric component 14 (may be represented by μ _r3 ) may be greater than the relative magnetic permeability μ _r1 of the dielectric component 11 , that is, μ _r3 is greater than μ _r1 .

Therefore, relative to the dielectric component 11 , the dielectric component 14 can also be called a high-permeability (ie, relatively high-permeability) medium component.

In an example, the relative magnetic permeability μ _r3 of the dielectric component 14 may be equal to the relative magnetic permeability μ _r2 of the dielectric component 12 , that is, μ _r3 =μ _r2 .

It should be noted that the relative permeability of the dielectric layer A in the dielectric component 11, the dielectric layer B in the dielectric component 12, and the dielectric layer D in the dielectric component 14 can be adjusted according to the application scenario of the planar transformer. The adjustment method is not limited.

Exemplarily, the relative magnetic permeability μ _r1 of the dielectric component 11 can be 10, the relative magnetic permeability μ _r2 of the dielectric component 12 and the relative magnetic permeability μ _r3 of the dielectric component 14 can be 500. It can be seen that μ _r2 and μ _r3 are much larger than μ _r1 .

Similar to the dielectric component 12, the dielectric component 14 may also include at least one dielectric layer D (ie, the dielectric component 14 may include one or more dielectric layers D).

Optionally, if there is only one dielectric layer D, then the dielectric layer D is stacked with one or more dielectric layers A. If the dielectric layer D has multiple layers, then multiple dielectric layers D are stacked, and multiple dielectric layers D and one or more dielectric layers A are also stacked (that is, the dielectric component 14 and the dielectric component 11 are stacked).

In a possible implementation, the dielectric layer B (one or more layers) can be a magnetic medium with main components such as nickel-zinc ferrite, manganese-zinc (MnZn) ferrite, or metal magnetic powder, and the dielectric layer D (a layer or multiple layers) can also use nickel-zinc ferrite, manganese-zinc ferrite or metal magnetic powder as the main component of the magnetic medium. Certainly, the dielectric layer B and the dielectric layer D may also use other materials with higher relative magnetic permeability than the dielectric layer A, which is not limited in this embodiment of the present application.

Further, the dielectric layer B (one or more layers) may be provided with conductor lines (such as pads, etc.). Similarly, the dielectric layer D (one or more layers) may also be provided with conductive lines such as pads. For example, pads may be provided on the outer surface of dielectric component 12 and/or dielectric component 14 .

For example, only the outer surface of the dielectric component 12 may be provided with pads.

If only one layer of dielectric layer B is included in the dielectric component 12 , the pads can be arranged on the outer surface of the dielectric layer B. If the dielectric component 12 includes multiple dielectric layers B, the pads may be disposed on the outer surface of the outermost dielectric layer B in the dielectric component 12 .

For another example, only the outer surface of the dielectric component 14 may be provided with pads.

If only one dielectric layer D is included in the dielectric component 14 , the pads can be disposed on the outer surface of the dielectric layer D. If the dielectric component 14 includes multiple dielectric layers D, the pads may be disposed on the outer surface of the outermost dielectric layer D in the dielectric component 14 .

Also for example, the outer surfaces of the dielectric component 12 and the dielectric component 14 are respectively provided with pads.

If the dielectric component 12 includes only one layer of dielectric layer B, and the dielectric component 14 includes only one layer of dielectric layer D, then pads are provided on the outer surface of the dielectric layer B and the outer surface of the dielectric layer D respectively. If multiple dielectric layers B are included in the dielectric assembly 12, and multiple dielectric layers D are included in the dielectric assembly 14, then the outer surface of the outermost dielectric layer B in the dielectric assembly 12 (i.e. the outer surface of the dielectric assembly 12) and Welding pads are provided on the outer surface of the outermost dielectric layer D in the dielectric component 14 (that is, the outer surface of the dielectric component 14 ).

Of course, pads or other types of conductor lines can be flexibly set according to the application scenarios of the planar transformer.

In a possible implementation manner, the multi-layer dielectric layers A in the dielectric component 11 can be stacked in the vertical direction, and the multi-layer dielectric layers B in the dielectric component 12 and the multi-layer dielectric layers in the dielectric component 14 D is stacked with multiple dielectric layers A respectively, and then all dielectric layers (including all dielectric layers A, all dielectric layers B, and all dielectric layers D) are laminated using a pressing process, and the application can be obtained by using a sintering process The planar transformer provided by the embodiment.

The planar transformer provided in the embodiment of the present application can realize the processing of the planar transformer through the pressing process and the sintering process, and the processing complexity is small. In addition, the three dielectric components (namely, the dielectric component 11 , the dielectric component 12 and the dielectric component 14 ) and the coil component 13 have a high degree of integration, and the entire planar transformer is an integrated design with a low height and a small volume.

Further, the planar transformer provided in the embodiment of the present application can adopt low temperature co-fired ceramics (low temperature co-fired ceramics, LTCC) process (ie LTCC process) or high temperature co-fired ceramics (high temperature co-fired ceramics, HTCC) process ( That is, HTCC process) and other sintering processes. Of course, other sintering processes can also be used, which is not limited in this embodiment of the present application.

The embodiment of the present application is described by taking the low temperature co-fired ceramic technology as an example, therefore, the planar transformer provided in the embodiment of the present application may be called an LTCC planar transformer. At the same time, the dielectric layer B and dielectric layer D in the embodiment of the present application take nickel-zinc ferrite as an example, so the planar transformer provided in the embodiment of the present application can also be called low temperature co-fired ceramic ferrite (low temperature co-fired ceramic ferrite) ceramics ferrite, LTCF) planar transformer (ie LTCF planar transformer).

In a possible implementation manner, the transformer shown in FIG. 3 may be equivalent to the magnetic circuit model shown in FIG. 4 . In FIG. 4 , F represents the magnetomotive force generated by one or more coils C1, and satisfies F=NI, wherein, N represents the total number of turns of the coil C1, and I is the current flowing through the coil C1.

Indicates the total magnetic flux generated by coil C1,

represents the magnetic flux coupled by coil C2, and

R1 represents the magnetic flux

Through the reluctance of the magnetic circuit,

Indicates the magnetic flux that is not coupled by coil C2 (i.e. the leakage flux of coil C1), and

R2 represents the magnetic flux

Reluctance through the magnetic circuit. R is the total magnetic flux

The total reluctance, and R = R1//R2.

Optionally, the proportion K of the leakage flux can be expressed as:

Since the relative permeability μ _r3 of the medium component 14 can be equal to the relative permeability μ _r2 of the medium component 12, μ _r3 =μ _r2 =μ _r can be set. Therefore, according to the relative permeability μ _r1 of the dielectric component 11, the relative permeability μ _r of the dielectric component 12 and the dielectric component 14, and the vacuum permeability μ ₀ , combined with the unilateral width b of the coil C1 or coil C2 and the medium Thickness a of component 11, magnetic flux

The reluctance R1 passing through the magnetic circuit can be expressed as:

R1＝2b/(μ ₀ ·μ _r1 ·Ae _b )+2a(μ ₀ ·μ _r ·Ae _a ) (2)

Similarly, magnetic flux

The reluctance R2 passing through the magnetic circuit can be expressed as:

R2＝2b/(μ ₀ ·μ _r1 ·Ae _c ) (3)

In formula (2) and formula (3), Ae _a can represent the magnetic flux

The equivalent cross-sectional area in the magnetic circuit of all dielectric layers A. Ae _b can represent magnetic flux

The equivalent cross-sectional area in the magnetic circuit of dielectric layer B and dielectric layer D. Ae _c can represent magnetic flux

The equivalent cross-sectional area in the magnetic circuit of all dielectric layers A.

It should be noted that, in order to simplify the analysis process and intuitively illustrate that the leakage inductance of the planar transformer provided by the embodiment of the present invention is small, Ae _a =Ae _b =Ae _c may be set.

In one example, combining formula (1), formula (2) and formula (3), that is, substituting formula (2) and formula (3) into formula (1), can get:

It can be seen from the above formula (4) that the proportion of leakage flux K and

proportional relationship. So, when

The smaller the value, the smaller the proportion of leakage flux K will be, and the magnetic flux

will be smaller, and then the leakage inductance of the planar transformer will be smaller.

In another example, combining formula (1), formula (2) and formula (3), can also get:

It can be seen from the above formula (5) that the proportion of leakage flux K and

proportional relationship. So, when

The smaller the value, the smaller the proportion of leakage flux K will be, and the magnetic flux

will be smaller, and then the leakage inductance of the planar transformer will be smaller.

In yet another example, electromagnetic simulation can be performed on the planar transformer provided by the related art, and it can be obtained that the exciting inductance of the planar transformer provided by the related art is 64.7uH, the leakage inductance is 20.2uH, and the ratio of the leakage inductance to the exciting inductance (ie leakage Sensitivity) was 31.2%. On the basis that the relative permeability μ _r1 of the medium assembly 11 is 10, the relative permeability μ _r2 of the medium assembly 12 is 500, the relative permeability μ _r3 of the medium assembly 14 is 500 and b=1.5a, Electromagnetic simulation is performed on the planar transformer provided in the embodiment of the present application, and it can be obtained that the excitation inductance of the planar transformer provided in the embodiment of the application is 7.5uH, the leakage inductance is 0.5uH, and the ratio of the leakage inductance to the excitation inductance (that is, the leakage inductance rate) is 6.7 %, as shown in Table 1:

Table 1

the	Magnetizing inductance	Leakage inductance	The ratio of leakage inductance to magnetizing inductance
related technology	64.7	20.2	31.2%
Example of this application	7.5	0.5	6.7%

It can be seen from Table 1 that compared with the related art, the planar transformer provided by the embodiment of the present application has greatly reduced the leakage inductance without increasing the volume, and the leakage inductance rate has also been reduced from 31.2% in the related art to 6.7% of the application examples.

An embodiment of the present application provides a power module, as shown in FIG. 5 . A power supply module (PSM) 1 may include a planar transformer 1 and a semiconductor device 2 .

Wherein, the planar transformer 1 is used as a substrate carrier, and a bonding pad (bonding pad, BP) is provided on the planar transformer 1, and the semiconductor device 2 can be soldered on the bonding pad.

In a possible implementation manner, the semiconductor device 2 may be a chip, a resistor, or a capacitor, which is not limited in this embodiment of the present application.

It should be noted that the power module SPM1 shown in FIG. 5 may include other functional units besides the planar transformer 1 and the semiconductor device 2 , which is not limited in the embodiment of the present application.

The embodiment of the present application also provides another power module, as shown in FIG. 6 . The power module PSM2 may include a planar transformer 1, a semiconductor device 2, and a functional unit 3 (such as a filter circuit that functions as a filter, etc.).

The functional unit 3 serves as a substrate carrier, the planar transformer 1 serves as an independent component, the planar transformer 1 and the semiconductor device 2 are respectively arranged on the functional unit 3, and the planar transformer 1 and the semiconductor device 2 have a connection relationship.

Similarly, the semiconductor device 2 in FIG. 6 may also be a chip, a resistor, or a capacitor, which is not limited in this embodiment of the present application.

It should also be noted that the power module SPM2 shown in FIG. 6 may include other functional units besides the planar transformer 1, the semiconductor device 2 and the filter circuit and other functional units, which is not limited in the embodiment of the present application.

The above is only a specific implementation of the application, but the scope of protection of the application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the application. Should be covered within the protection scope of this application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (13)

1. A planar transformer, characterized by comprising a first dielectric component, a second dielectric component and a coil component;

   The first dielectric component and the second dielectric component are stacked;

   The coil assembly includes at least one first coil and at least one second coil, the at least one first coil and the at least one second coil are both arranged on the first dielectric assembly;

   The relative magnetic permeability of the second dielectric component is greater than the relative magnetic permeability of the first dielectric component.
2. The planar transformer according to claim 1, characterized in that, the single side width of the at least one first coil or the single side width of the at least one second coil is greater than 1.5 times the thickness of the first dielectric component.
3. The planar transformer according to claim 1 or 2, wherein the first dielectric component comprises a first dielectric layer;

   The at least one first coil and the at least one second coil are disposed on the first dielectric layer.
4. The planar transformer according to claim 1 or 2, wherein the first dielectric component comprises multiple first dielectric layers, and each first dielectric layer in the multiple first dielectric layers is stacked;

   The at least one first coil is disposed on at least one first dielectric layer of the multiple first dielectric layers, and the at least one second coil is disposed on at least one first dielectric layer of the multiple first dielectric layers superior.
5. The planar transformer according to any one of claims 1 to 4, wherein the second dielectric component comprises at least one second dielectric layer;

   The at least one second dielectric layer is stacked.
6. The planar transformer according to any one of claims 1 to 5, wherein the planar transformer further comprises a third dielectric component;

   The third dielectric component is stacked with the first dielectric component, and the third dielectric component and the second dielectric component are respectively disposed on both sides of the first dielectric component.
7. The planar transformer according to claim 6, wherein the relative magnetic permeability of the third dielectric component is greater than the relative magnetic permeability of the first dielectric component.
8. The planar transformer according to claim 6 or 7, wherein the relative magnetic permeability of the third dielectric component is equal to the relative magnetic permeability of the second dielectric component.
9. The planar transformer according to any one of claims 6 to 8, wherein the third dielectric component comprises at least one third dielectric layer;

   The at least one third dielectric layer is stacked.
10. The planar transformer according to any one of claims 5 to 8, characterized in that at least one second dielectric layer in the second dielectric component and at least one third dielectric layer in the third dielectric component Nickel-zinc ferrite is used respectively.
11. The planar transformer according to any one of claims 6 to 10, wherein the second dielectric component and/or the third dielectric component are provided with conductor lines.
12. The planar transformer according to any one of claims 1 to 11, characterized in that, the planar transformer is made by low temperature co-fired ceramic technology or high temperature co-fired ceramic technology.
13. A power module, characterized by comprising the planar transformer according to any one of claims 1 to 12.

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