Filter capacitor, electronic circuit and automobile

Abstract

The utility model discloses a filter capacitor, an electronic circuit and an automobile, and relates to the technical field of semiconductors, and the distance L between the positive electrode and the negative electrode of the filter capacitor meets the condition: L = W + 2Z, where W = 4X + 2Y. According to the scheme, the film width W of the filter capacitor is reduced in a manner that the difference value between the value of Y and Ymin is not greater than a first preset value, so that the film width of the filter capacitor is reduced, and the film width of the filter capacitor is reduced. And the distance L between the positive electrode and the negative electrode of the filter capacitor can be effectively reduced, the length of a current path in the filter capacitor can be reduced and the width of the current path can be increased because the distance between the positive electrode and the negative electrode is shortened, the ESL of the filter capacitor body is finally reduced, and the high-frequency performance of the filter capacitor can be improved after the local ESL of the filter capacitor is reduced.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more particularly to a filter capacitor, electronic circuit, and automobile. Background Technology

[0002] The high-frequency performance of filter capacitors is mainly reflected in their ability to effectively filter out high-frequency noise and ripple in power supplies or signals, making the output signal smoother and more stable. High-frequency filter capacitors typically have a small equivalent series resistance (ESR) and a high self-resonant frequency, which allows them to maintain low impedance in the high-frequency range, thereby effectively absorbing and attenuating high-frequency interference components.

[0003] Analysis revealed a strong correlation between the high-frequency performance of filter capacitors and their equivalent series inductance (ESL). Currently, the ESL of filter capacitors in the industry is generally in the range of 40-50nH. The specific value of ESL depends on the capacitor size and mechanical structure design; in some products, the ESL of the filter capacitors may exceed 50nH. A higher ESL causes the capacitor to enter its inductive characteristic range earlier, thus reducing the high-frequency performance of the filter. Utility Model Content

[0004] In view of the above problems, this application provides a filter capacitor, electronic circuit, and automobile to reduce the ESL of the filter capacitor and thus improve the high-frequency performance of the filter. The specific solution is as follows:

[0005] A filter capacitor, comprising:

[0006] The distance L between the positive and negative terminals of the filter capacitor satisfies the condition: L = W + 2Z;

[0007] Where W = 4X + 2Y;

[0008] W is the film width of the filter capacitor;

[0009] X is the creepage safety distance of the filter capacitor;

[0010] Y is the effective metallization film width of the filter capacitor;

[0011] Z represents the thickness of the metallization layer of the filter capacitor.

[0012] The value of Y and Y min The difference between them is not greater than a first preset value, wherein Y min This is the minimum effective metallization film width of the filter capacitor, determined based on the capacitance value.

[0013] Optionally, in the above-mentioned filter capacitor, X is the minimum creepage safety distance determined based on the withstand voltage requirement of the filter capacitor.

[0014] Optionally, the filter capacitor mentioned above is a thin-film capacitor.

[0015] Optionally, in the above-mentioned filter capacitor, the thin-film capacitor includes:

[0016] First insulating film;

[0017] A first metal layer disposed on the first insulating film;

[0018] A second insulating film is disposed on the side of the first metal layer away from the first insulating film;

[0019] A first electrode and a second electrode are disposed on the side of the second insulating film away from the first metal layer, and the first electrode and the second electrode are symmetrically distributed on the second insulating film;

[0020] A first metallization layer and a second metallization layer, wherein a first insulating film, a first metal layer, a second insulating film, a first electrode, and a second electrode are disposed between the first metallization layer and the second metallization layer, and the surfaces of the first insulating film, the first metal layer, the second insulating film, the first electrode, and the second electrode are perpendicular to the surfaces of the first metallization layer and the second metallization layer;

[0021] The distance between the first metallization layer and the second metallization layer is the film width of the filter capacitor;

[0022] The distance between the first metal layer and the first metallization layer and the second metallization layer is equal, and the distance between the first metal layer and the first metallization layer is the creepage safety distance X;

[0023] The distance between the first electrode and the second electrode is twice the creepage safety distance X of the filter capacitor;

[0024] The length of the overlap between the first metal layer and the first electrode or the second electrode in a first direction is the effective metallization film width, and the first direction is the direction perpendicular to the surface of the first metallization layer.

[0025] Optionally, the above-mentioned filter capacitors include:

[0026] The first preset value is not greater than Y min 67%.

[0027] Optionally, in the above-mentioned filter capacitor, the values ​​of X, Y, and Z correspond to the capacitance value and withstand voltage value of the filter capacitor.

[0028] Optionally, in the above-mentioned filter capacitor, when the capacitance value of the filter capacitor is 0.033uF and the withstand voltage is 400V, the value of X is not greater than 1mm, the value of Y is not greater than 2.5mm, and the value of Z is not greater than 0.5mm.

[0029] Optionally, the filter capacitor mentioned above can be a filter capacitor with leads or a filter capacitor without leads.

[0030] An electronic circuit that uses the filter capacitor described in any one of the above-mentioned methods.

[0031] Optionally, the electronic circuit is a filter circuit.

[0032] An automobile that uses any of the electronic circuits described above.

[0033] Using the above technical solution, the distance L between the positive and negative terminals of the filter capacitor provided in this application satisfies the condition: L = W + 2Z, where W = 4X + 2Y. This solution modifies the value of Y with Y min The difference between the two is configured to be no greater than the first preset value. This reduces the film width W of the filter capacitor and can also effectively reduce the distance L between the positive and negative electrodes of the filter capacitor. As the distance between the positive and negative electrodes is shortened, the current path length in the filter capacitor will be reduced and the current path width will be increased, which will ultimately reduce the ESL of the filter capacitor body. When the local ESL of the filter capacitor is reduced, its high-frequency performance will also be improved. Attached Figure Description

[0034] The above and other features, advantages, and aspects of the embodiments disclosed in this application will become more apparent when taken in conjunction with the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0035] Figure 1 This is a graph showing the relationship between the ESL of the filter capacitor and the noise index in high-frequency performance.

[0036] Figure 2 A schematic diagram of the structure of a filter capacitor provided in this application;

[0037] Figure 3 This is a list of parameters for a filter capacitor with a withstand voltage of 400V in the prior art;

[0038] Figure 4 for Figure 3 A diagram illustrating the meaning of each parameter of the filter capacitor in the list. Detailed Implementation

[0039] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0040] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0041] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a product or device comprising a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to such products or devices.

[0042] Taking the CLC filter topology (capacitor-input π-type filter topology) as an example, the relationship between the ESL of the filter capacitor and the noise index in high-frequency performance is as follows: Figure 1 As shown, Figure 1 The horizontal axis represents frequency, and the vertical axis represents noise level. Figure 1 As can be seen, the noise level of a capacitor with an ESL of 10nH is 22.2dB at a high frequency of 80MHz, the noise level of a capacitor with an ESL of 20nH is 31.8dB at a high frequency of 80MHz, the noise level of a capacitor with an ESL of 30nH is 37dB at a high frequency of 80MHz, and the noise level of a capacitor with an ESL of 40nH is 40.4dB at a high frequency of 80MHz. It is evident that the lower the ESL of a capacitor, the lower its noise level at high frequencies.

[0043] Since the capacitance value of a capacitor is proportional to the area of ​​the effective metallization film, and the area of ​​the effective metallization film is proportional to the volume of the capacitor, the ESL of the filter capacitor in the system can be optimized by reducing the width of the effective metallization film and increasing its length, while keeping the total capacitance value (capacitor volume) constant. This effectively reduces the spacing of the capacitor's output leads.

[0044] Based on the above design concept, this application discloses a filter capacitor. By adjusting the effective metallization film width of the filter capacitor while keeping the capacitance value constant, the effective metallization film width is reduced, while the effective metallization film length is increased, thereby optimizing the capacitor's ESL. See also Figure 2The filter capacitor in this application is designed as follows:

[0045] The distance L between the positive and negative terminals of the filter capacitor satisfies the condition: L = W + 2Z. The distance between the positive and negative terminals refers to the distance between the outermost edges of the two metallization layers connected to the positive and negative electrodes of the filter capacitor. The outermost edge is the side of the metallization layer facing the outside of the filter capacitor. Of course, when the filter capacitor is a capacitor with capacitor leads, the distance L between the positive and negative terminals can also refer to the width between the two capacitor leads.

[0046] Where W = 4X + 2Y;

[0047] W is the film width of the filter capacitor;

[0048] X is the creepage safety distance of the filter capacitor;

[0049] Y is the effective metallization film width of the filter capacitor;

[0050] Z represents the thickness of the metallization layer of the filter capacitor. The metallization layer can also be called a gold sputtering layer, electrode layer, metal spraying layer, conductive layer, or metal deposition layer. It is the part of the thin-film capacitor used to connect capacitor leads or external objects.

[0051] The value of Y and Y min The difference between them is not greater than a first preset value, wherein Y min The minimum value of Y for the filter capacitor is determined based on the capacitance value of the filter capacitor.

[0052] In the design and manufacturing of capacitors, the effective metallization film width is one of the key factors affecting the capacitance value. As the capacitor's plates, the effective area of ​​the metallization film is directly proportional to the capacitance value. Therefore, when other conditions (such as dielectric constant, film thickness, electrode spacing, etc.) remain constant, increasing the width of the effective metallization film, while keeping the length constant, will directly increase the capacitor's capacitance value. However, if the effective metallization film's width is increased while its length is decreased, or vice versa, the capacitance value will remain unchanged. Therefore, it is evident that in the practical design of filter capacitors, the effective metallization film width is selectable within a certain range, the minimum of which is denoted as Y. min This application sets the effective metallization film width Y of the filter capacitor to be the same as the value of Y. minThe difference between them is not greater than the first preset value. This ensures that the filter capacitor has a smaller effective metallization film width Y while meeting the design requirements. Since the distance between the positive and negative electrodes of the filter capacitor is L = W + 2Z, reducing the effective metallization film width Y can also effectively reduce the distance between the positive and negative electrodes of the filter capacitor. As the distance between the positive and negative electrodes is shortened, the current path length and the current path width within the filter capacitor will be reduced, ultimately reducing the ESL of the filter capacitor body. When the local ESL of the filter capacitor is reduced, its high-frequency performance will also be improved.

[0053] In this embodiment, as can be seen from the formula W = 4X + 2Y, the width W of the filter capacitor is related not only to the effective metallization film width Y of the filter capacitor, but also to the creepage safety distance X of the filter capacitor. The size of the creepage safety distance varies with the withstand voltage requirement of the filter capacitor. In order to further reduce the width W of the filter capacitor, the creepage safety distance X of the filter capacitor also needs to be selected as a small value. Specifically, in this embodiment, X is the minimum creepage safety distance determined based on the withstand voltage requirement of the filter capacitor.

[0054] In this embodiment, as can be seen from the formula L = W + 2Z, the distance L between the positive and negative terminals of the filter capacitor is related not only to the film width W of the filter capacitor, but also to the thickness Z of the metallization layer of the filter capacitor. The thicker the metallization layer, the thicker the distance L between the positive and negative terminals of the filter capacitor. In order to further reduce the distance L between the positive and negative terminals of the filter capacitor, the thickness Z of the metallization layer of the filter capacitor can be set to the minimum value in the allowable range of metallization layer thicknesses.

[0055] In this embodiment, the magnitude of the first preset value can be set according to design requirements. In this application, the magnitude of the first preset value can be set based on a comprehensive consideration of the reliability of the filter capacitor and the ESL of the filter capacitor. For example, in this embodiment, the first preset value can be set to be no greater than Y. min Of course, the first preset value can also be set to other values.

[0056] The filter capacitor described in this embodiment can be a film capacitor, ceramic capacitor, electrolytic capacitor, tantalum capacitor, polyester capacitor, or other types of capacitor. These filter capacitors can be leaded or leadless. The following embodiment uses a film capacitor as an example to describe the structure of the film capacitor. See [link to documentation]. Figure 2 The thin-film capacitor includes

[0057] First insulating film 01;

[0058] A first metal layer 02 disposed on the first insulating film 01;

[0059] A second insulating film 03 is disposed on the side of the first metal layer 02 away from the first insulating film 01;

[0060] A first electrode 04 and a second electrode 05 are disposed on the side of the second insulating film 03 away from the first metal layer 02, and the first electrode 04 and the second electrode 05 are symmetrically distributed on the second insulating film 03.

[0061] A first metallization layer 06 and a second metallization layer 07, a first insulating film 01, a first metal layer 02, a second insulating film 03, a first electrode 04, and a second electrode 05 are disposed between the first metallization layer 06 and the second metallization layer 07, and the surfaces of the first insulating film 01, the first metal layer 02, the second insulating film 03, the first electrode 04, and the second electrode 05 are perpendicular to the surfaces of the first metallization layer 06 and the second metallization layer 07;

[0062] The distance between the first metallization layer 06 and the second metallization layer 07 is the film width W of the filter capacitor;

[0063] The distance between the first metal layer 02 and the first metallization layer 06 and the second metallization layer 07 is equal, and the distance between the first metal layer 02 and the first metallization layer 06 is the creepage safety distance X;

[0064] The distance between the first electrode 04 and the second electrode 05 is 2X;

[0065] The length of the overlapping portion between the first metal layer 02 and the first electrode 04 or the second electrode 05 in a first direction is the effective metallization film width Y, and the first direction is the direction perpendicular to the surface of the first metallization layer 06.

[0066] In the technical solution disclosed in this embodiment, the values ​​of X, Y, and Z in the filter capacitor need to correspond to the capacitance value and withstand voltage value of the filter capacitor. Different capacitance values ​​and withstand voltage values ​​of the filter capacitor result in different values ​​of X, Y, and Z. For example, when the capacitance value of the filter capacitor is 0.033uF and the withstand voltage is 400V, the value of X is no greater than 1mm, the value of Y is no greater than 2.5mm, and the value of Z is no greater than 0.5mm.

[0067] Furthermore, in order to verify the effect of the filter capacitor designed using this scheme, this application also conducted a series of comparative experiments, and a set of specific experimental data is provided below.

[0068] Figure 3 This is a parameter list for a 400V filter capacitor from a certain film capacitor supplier's existing technology, where CR (μF) is the capacitance value. Figure 3The references to other parameters are as follows: Figure 4 As shown, Figure 3 The P-equivalent level in the above embodiments of this application refers to the distance L between the positive and negative electrodes, which is determined by... Figure 3 As can be seen, when the withstand voltage is 400V, the distance between the positive and negative terminals of the capacitor with a capacitance of 0.033uF is 22.5mm.

[0069] Under ideal conditions, with a withstand voltage of 400V and a capacitance of 0.033uF, the minimum creepage safety distance X of the film capacitor is 1mm, the minimum effective metallization film width Y is 1.5mm, the minimum film width W is 7mm (4×1+2×1.5), and the minimum distance between the positive and negative electrodes is 8mm (7+2×0.5, where the thickness of the metallization layer is chosen to be 0.5mm). To improve the high-frequency performance of the film capacitor, this application sets the effective metallization film width Y to 2.5mm, the creepage safety distance X to 1mm, and the metallization layer thickness to 0.5mm. In this case, the film width is 9mm, and the distance between the positive and negative electrodes is 10mm. Then, the ESL of the film capacitor designed based on this method is compared with that of a film capacitor with a positive-to-negative electrode distance of 22.5mm in the existing scheme.

[0070] During the comparison process, the inductance of the capacitor body is calculated first using finite element simulation. The specific analytical formula for this process is as follows:

[0071]

[0072] Where l0 is the metal side length of the film capacitor, r is the equivalent conductor cross-sectional area radius of the film capacitor, and μ0 is the free permeability. By substituting the relevant parameters of the film capacitor designed using this scheme and the film capacitor of the existing scheme into Formula 1 above, the inductance of the film capacitor body of the film capacitor designed using this scheme and the film capacitor of the existing scheme can be calculated.

[0073] Next, calculate the lead inductance of the film capacitor. The formula for calculating lead inductance is:

[0074]

[0075] Where l1 is the lead length of the film capacitor, W1 is the width of the film capacitor lead (i.e., the distance between two leads), and H is the thickness of the capacitor lead. By substituting the relevant parameters of the film capacitor designed using this scheme and the film capacitor of the existing scheme into Formula 2 above, the lead inductance of the film capacitor designed using this scheme and the film capacitor of the existing scheme can be calculated.

[0076] The calculation results during the actual test are shown in Table 1:

[0077]

[0078] Table 1

[0079] As shown in Table 1, compared with existing film capacitors, the film capacitor designed using the design scheme disclosed in this application has a 4nH reduction in body inductance, a 7nH reduction in lead inductance, and an 11nH reduction in overall inductance. Therefore, since the overall inductance of the capacitor generates additional inductance effects in high-frequency circuits, limiting the capacitor's response speed to high-frequency signals and increasing losses, reducing the overall inductance can reduce this effect, making the capacitor behave closer to an ideal capacitor at high frequencies, thus achieving faster response speed and lower losses, thereby improving high-frequency performance.

[0080] Furthermore, this application also discloses an electronic circuit that can utilize the filter capacitor described in any of the above-mentioned embodiments. The electronic circuit is a filter circuit.

[0081] Furthermore, this application also discloses an automobile that can utilize the electronic circuits described in any of the above-mentioned embodiments.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A filter capacitor, characterized in that, include: The filter capacitor is a thin-film capacitor, which includes: First insulating film; A first metal layer disposed on the first insulating film; A second insulating film is disposed on the side of the first metal layer away from the first insulating film; A first electrode and a second electrode are disposed on the side of the second insulating film away from the first metal layer, and the first electrode and the second electrode are symmetrically distributed on the second insulating film; A first metallization layer and a second metallization layer, wherein a first insulating film, a first metal layer, a second insulating film, a first electrode, and a second electrode are disposed between the first metallization layer and the second metallization layer, and the surfaces of the first insulating film, the first metal layer, the second insulating film, the first electrode, and the second electrode are perpendicular to the surfaces of the first metallization layer and the second metallization layer; The distance L between the positive and negative terminals of the filter capacitor satisfies the condition: L = W + 2Z; Where W = 4X + 2Y; W is the film width of the filter capacitor; X is the creepage safety distance of the filter capacitor; Y is the effective metallization film width of the filter capacitor; Z represents the thickness of the metallization layer of the filter capacitor. The value of Y and Y min The difference between them is not greater than a first preset value, wherein Y min This is the minimum effective metallization film width of the filter capacitor, determined based on the capacitance value.

2. The filter capacitor according to claim 1, characterized in that, X is the minimum creepage safety distance determined based on the withstand voltage requirement of the filter capacitor.

3. The filter capacitor according to claim 1, characterized in that, The distance between the first metallization layer and the second metallization layer is the film width of the filter capacitor; The distance between the first metal layer and the first metallization layer and the second metallization layer is equal, and the distance between the first metal layer and the first metallization layer is the creepage safety distance X; The distance between the first electrode and the second electrode is twice the creepage safety distance X of the filter capacitor; The length of the overlap between the first metal layer and the first electrode or the second electrode in a first direction is the effective metallization film width, and the first direction is the direction perpendicular to the surface of the first metallization layer.

4. The filter capacitor according to claim 1 or 2, characterized in that, include: The first preset value is not greater than Y min 67%.

5. The filter capacitor according to claim 1 or 2, characterized in that, The values ​​of X, Y, and Z correspond to the capacitance and voltage rating of the filter capacitor.

6. The filter capacitor according to claim 5, characterized in that, When the capacitance of the filter capacitor is 0.033uF and the withstand voltage is 400V, the value of X is no greater than 1mm, the value of Y is no greater than 2.5mm, and the value of Z is no greater than 0.5mm.

7. The filter capacitor according to claim 1 or 2, characterized in that, The filter capacitor can be a leaded filter capacitor or a leadless filter capacitor.

8. An electronic circuit, characterized in that, The application uses the filter capacitor as described in any one of claims 1-7.

9. A car, characterized in that, The application uses the electronic circuit described in claim 8.

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