Wiring board and wiring method

Abstract

To provide a wiring board or a wiring method capable of suppressing noise.SOLUTION: A wiring board 12 has a plurality of wiring layers, and at least some of the wirings 31 formed in the plurality of wiring layers have a meander pattern 33, and the meander patterns 33 are set on the basis of different parameters for the wirings 31 formed in different wiring layers. For example, the meander pattern 33 may be used such that the length of the wirings 31 does not become a specific wiring length.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a wiring board and a wiring method. [Background technology]

[0002] Patent Document 1 discloses a wiring pattern in a vehicle instrument. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-116348 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a wiring board and a wiring method capable of suppressing noise. [Means for solving the problem]

[0005] A wiring board according to one embodiment of the present disclosure is a wiring board having a plurality of wiring layers, at least some of the wiring formed in the plurality of wiring layers have a meander pattern, and the meander patterns of the wiring formed in different wiring layers are set based on different parameters. Effect of the Invention

[0006] The present disclosure can provide a wiring board and a wiring method capable of suppressing noise. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view illustrating a configuration example of an electronic device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a wiring pattern that does not use a meander pattern according to the embodiment. [Diagram 3]FIG. 3 is a diagram showing an example of a wiring pattern that does not use a meander pattern according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a wiring pattern using a meander pattern according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a wiring pattern using a meander pattern according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating a configuration example of a microstrip line on a surface layer according to an embodiment. [Figure 7] FIG. 7 is a diagram illustrating a configuration example of an inner layer strip line according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangement and connection forms, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components that are not described in the independent claims will be described as optional components.

[0009] In addition, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, the same reference numerals are used for substantially the same configurations, and duplicated explanations may be omitted or simplified.

[0010] (Embodiment) [Knowledge that formed the basis of the invention] In in-vehicle devices, the shift to EVs (Electric Vehicles) has led to the advancement of digitalization of electronic devices, resulting in increased noise interference between devices. In addition, as the number of devices installed in vehicles increases, there is a demand for in-vehicle devices to be lighter. One possible method for achieving weight reduction is to use a plastic case instead of a metal case. However, there are concerns that using a plastic case may reduce noise resistance. For these reasons, EMC (Electromagnetic Compatibility) measures for in-vehicle devices have become an issue.

[0011] On the other hand, the external size of the board is determined by the product size that can be placed inside the vehicle. In addition, due to the constraints of the external shape of the board, the distance between each component (i.e., the wiring pattern length) cannot be freely determined in the layout of each component. This causes a problem that the wiring length of the wiring in the board matches the specific wiring length corresponding to a specific frequency band (hereinafter also referred to as the specific band), such as the BDS (Beidou Navigation Satellite System) band and the GLONASS (Global Navigation Satellite System) band, which have the strictest limit values ​​of the EMI (Electromagnetic Interference) standard, and the noise level in the specific band becomes high. Here, the specific wiring length is the wiring length that becomes an antenna pattern for the specific band.

[0012] In contrast, in this embodiment, the wiring length of all the wiring in the board is intentionally made long so as not to reach the specific wiring length. This makes it possible to prevent the wiring from becoming an antenna pattern for a specific band. Therefore, for example, even when a resin case is used, the EMI standard can be met.

[0013] Furthermore, in this embodiment, in addition to controlling the wiring length, the actual effective relative dielectric constant is calculated from the relative dielectric constant based on the board material. Also, the propagation delay characteristics of the high-speed transmission path of digital signals in the surface layer wiring and inner layer wiring are taken into account. As a result, the wiring length of each layer in the board can be precisely controlled.

[0014] [Electronic device configuration] First, a configuration example of an electronic device 10 according to the present embodiment will be described. Fig. 1 is a perspective view of the electronic device 10 according to the present embodiment. Fig. 1 shows the electronic device 10 in an exploded state.

[0015] The electronic device 10 includes a housing 11 and a substrate 12. The housing 11 is made of, for example, resin, and includes an upper chassis 13 and a lower chassis 14.

[0016] Substrate 12 is a wiring board and has multiple wiring layers. The wiring layers include a surface layer and one or more inner layers. The number of wiring layers is not particularly limited, but substrate 12 is, for example, a four-layer substrate or a six-layer substrate. Substrate 12 is disposed inside housing 11.

[0017] In addition, a plurality of elements (electronic components) such as integrated circuits are disposed on the substrate 12. Note that only some of these are shown in Fig. 1, with the rest being omitted.

[0018] The electronic device 10 is, for example, an in-vehicle ECU (Electronic Control Unit). The ECU includes, for example, at least one of an ASC (Active Sound Control) unit and an ANC (Active Noise Control) unit that perform in-vehicle sound-related processing. In other words, the ECU has at least one of the functions of ASC and ANC. The ASC performs processing to add engine sound and the like in an EV or hybrid vehicle. The ANC performs processing to cancel noise inside the vehicle.

[0019] It should be noted that the electronic device 10 is not limited to the above example, and may be an electronic device for in-vehicle use other than the above, or may be an electronic device for use other than in-vehicle use.

[0020] [Wire length adjustment] In this embodiment, the wiring length of all the wiring on the substrate 12 is made long so as not to become a specific wiring length corresponding to a specific band. This makes it possible to prevent the wiring from becoming an antenna pattern in a specific band. In other words, the substrate 12 does not include wiring with a specific wiring length corresponding to a specific band. In other words, the wiring length of all the wiring on the substrate 12 is not the specific wiring length.

[0021] Specifically, a meander pattern (also called a meander type pattern) is used as a method for adjusting the wiring length of the substrate 12. A meander pattern is a wiring pattern in which the wiring length is longer by meandering the wiring, rather than a wiring pattern in which the wiring length is the shortest.

[0022] 2 and 3 are diagrams for comparison, showing examples of wiring patterns that do not use meander patterns, respectively showing wiring 21 and wiring 22 that do not use meander patterns.

[0023] 4 and 5 correspond to Fig. 2 and Fig. 3, respectively, and are diagrams showing examples of wiring patterns using meander patterns. Wiring 31 shown in Fig. 4 includes a meander pattern 33. Wiring 32 shown in Fig. 5 includes a meander pattern 34.

[0024] Here, the meander pattern is generally used for the purpose of matching communication timing by aligning the wiring lengths of multiple wirings, for example, by matching the delay times of signals in multiple wirings such as data lines and clock lines, i.e., for matching propagation delay characteristics. In other words, the meander pattern is used to achieve equal-length wiring for each signal line that must be synchronized. On the other hand, in this embodiment, this meander pattern is used to prevent the wiring length from becoming a specific wiring length.

[0025] [Calculating specific wiring length] Next, a method for calculating the specific wiring length will be described. First, the propagation speed of a wiring in a vacuum will be described. The propagation speed in a vacuum is 300,000 km / sec, which is the same as the speed of light c. Specifically, the propagation speed in a vacuum is defined by the following (Equation 1).

[0026] c=1 / √(ε0×μ0) (Equation 1)

[0027] Here, ε0 is the dielectric constant of a vacuum, ε0=8.85×10 -12 μ0 is the magnetic permeability of a vacuum, μ0=4π×10 -7 Therefore, the propagation speed c = 2.99792458 × 10 8 [m / sec].

[0028] On the other hand, in the case of coaxial cables, the propagation speed decreases mainly due to the influence of the relative dielectric constant εr of the material. This decrease in propagation speed is called wavelength shortening. In this case, the wavelength is expressed by the following (Equation 2).

[0029] λ=λ0×1 / √εr (Formula 2)

[0030] Here, λ0 is the wavelength in a vacuum. For example, if the insulator is polyethylene, εr = 2.2 to 2.4, and the propagation velocity is 2.99792458 / √2.3 = 1.97677293 × 10 8 [m / sec]. In other words, the propagation speed in a coaxial cable is about 66% of that in a vacuum. Therefore, the wavelength shortening factor is 0.66.

[0031] As with the coaxial cable, the propagation speed of a signal in the wiring formed on the board can be calculated.

[0032] Here, this propagation velocity is generally calculated to be about half the speed of light c. If the board material is glass epoxy (FR-4), its relative dielectric constant is 4.3 / 1GHz. Therefore, the propagation velocity is 2.99792458 / √4.3=1.4457276101×10 8 [m / sec].

[0033] However, the propagation velocity obtained by this calculation has an error with respect to the actual propagation velocity, and since the error is particularly large in the GHz band, more strict control is required.

[0034] Here, a microstrip line is used on the surface layer of the substrate, and a strip line is used on the inner layer of the substrate. In this embodiment, different calculations are performed on the surface layer and the inner layer, so that the propagation speeds that differ between the surface layer and the inner layer are precisely calculated.

[0035] Fig. 6 is a diagram showing a configuration example of a microstrip line on the surface layer. As shown in Fig. 6, on the surface layer, the substrate 12 includes a ground conductor 41, an insulating layer 42, and a wiring 43. The ground conductor 41 is an electrically grounded conductor, for example, a metal layer. The insulating layer 42 is an insulator layer disposed between the ground conductor 41 and the wiring 43, and is also called an insulator prepreg. The wiring 43 is a metal wiring pattern and transmits a signal.

[0036] In this embodiment, the effective relative dielectric constant εe is calculated from the relative dielectric constant εr of the insulating layer 42, the thickness (height) h of the insulating layer 42, and the width w of the wiring 43 according to the following (Equation 3).

[0037] εe=((εr+1) / 2)+((εr-1) / 2)×1 / (√(1+(10×h) / w) ··· (Formula 3)

[0038] In addition, the propagation velocity v is calculated from the speed of light c and the effective relative dielectric constant εe of the insulating layer 42 according to the following (Equation 4).

[0039] v=c / √εe ··· (Equation 4)

[0040] Furthermore, the wavelength λ is calculated from the frequency f and propagation speed v of a specific band using the following (Equation 5).

[0041] λ=v / f (Equation 5)

[0042] Fig. 7 is a diagram showing a configuration example of a stripline in an inner layer. As shown in Fig. 7, in the inner layer, the substrate 12 includes ground conductors 51 and 54, an insulating layer 52, and a wiring 53. The ground conductors 51 and 54 are electrically grounded conductors, for example, metal layers. The insulating layer 52 is an insulator layer disposed between the ground conductor 51 and the ground conductor 54. The wiring 53 is a metal wiring pattern disposed in the insulating layer 52, and transmits a signal.

[0043] In this case, the propagation velocity v is calculated from the speed of light c and the relative dielectric constant εr of the insulating layer 42 according to the following (Equation 6).

[0044] v=c / √εr ··· (Equation 6)

[0045] In addition, the wavelength λ is calculated from the propagation velocity v obtained by (Equation 6) using the above (Equation 5). In this way, different propagation velocities v are calculated for the surface layer and the inner layer, and different wavelengths λ are calculated.

[0046] Next, the specific wiring length of the surface layer is calculated based on the wavelength λ of the surface layer, and the specific wiring length of the inner layer is calculated based on the wavelength λ of the inner layer. For example, the specific wiring length is λ / 4.

[0047] Next, all wiring patterns of the surface layer and the inner layer are created so that the wiring length of the wiring of the surface layer is not equal to the calculated specific wiring length of the surface layer, and the wiring length of the wiring of the inner layer is not equal to the calculated specific wiring length of the inner layer. For example, the wiring patterns are created based on a predetermined rule (for example, so that the wiring length is the shortest). Next, from the created wiring patterns, wiring having a wiring length that matches the calculated specific wiring length is extracted, and the extracted wiring is replaced with a wiring having a different wiring length (for example, a wiring having the above-mentioned meander pattern).

[0048] For example, when εr = 3.9, h = 0.2 mm, and w = 0.1 mm, the propagation velocity v of the surface layer is 1.80481941 × 10 8 [m / sec], and the propagation velocity v of the inner layer is 1.51805812×10 8[m / sec]. Therefore, the specific wiring length of the surface layer corresponding to the BDS band (1.56 GHz) is about 28.9 mm, and the specific wiring length of the inner layer is about 24.3 mm. In detail, since the BDS band is a band of 1559.052 MHz to 1563.144 MHz, the specific wiring length of the surface layer corresponding to the BDS band is included in 28.8 mm to 29.0 mm, and the specific wiring length of the inner layer is included in 24.2 mm to 24.4 mm.

[0049] In addition, the specific wiring length of the surface layer corresponding to the GLONASS band (1.60 GHz) is about 28.1 mm to 28.2 mm, and the specific wiring length of the inner layer is about 23.7 to 23.8 mm. In detail, since the GLONASS band is a band of 1594.0625 MHz to 1609.375 MHz, the specific wiring length of the surface layer is included in 28.0 mm to 28.4 mm, and the specific wiring length of the inner layer is included in 23.5 mm to 23.9 mm.

[0050] In the above, the specific wiring length is λ / 4, but the specific wiring length may be λ / 2. In that case, the specific wiring length of the surface layer corresponding to the GLONASS band (1.60 GHz) is about 56.2 mm to 56.4 mm, and the specific wiring length of the inner layer is about 47.4 to 47.6 mm. In detail, since the GLONASS band is a band of 1594.0625 MHz to 1609.375 MHz, the specific wiring length of the surface layer is included in 56.0 mm to 56.8 mm, and the specific wiring length of the inner layer is included in 47.0 mm to 47.8 mm. In addition, both λ / 4 and λ / 2 may be used as the specific wiring length.

[0051] When λ / 2 is used, in the above example, the specific wiring length of the surface layer corresponding to the BDS band (1.56 GHz) is about 57.8 mm, and the specific wiring length of the inner layer is about 48.6 mm. For example, the specific wiring length of the surface layer corresponding to the BDS band is included in 57.6 mm to 58.0 mm, and the specific wiring length of the inner layer is included in 48.4 mm to 48.8 mm.

[0052] In addition, the specific wiring length of the surface layer corresponding to the GLONASS band (1.60 GHz) is about 56.3 mm to 56.5 mm, and the specific wiring length of the inner layer is about 47.3 mm to 47.5 mm. For example, the specific wiring length of the surface layer is included in 56.0 mm to 56.8 mm, and the specific wiring length of the inner layer is included in 47.0 mm to 47.8 mm.

[0053] The numerical ranges shown above are merely examples, and if the part number of the board is different, the dielectric constant εr will change due to the different base material, so control of the line length will be necessary. In addition, to ensure a larger margin, the numerical range of the specific line length may be widened. Conversely, to widen the range of usable line lengths, the numerical range of the specific line length may be narrowed.

[0054] In the above, the BDS band and the GLONASS band are given as examples of the specific band, but the specific band may be another frequency band. Furthermore, the specific band is not limited to the GHz band. For example, the specific band may be the operating frequency of a circuit or the like included in the electronic device 10, or the operating frequency of a device connected to the electronic device 10. Furthermore, the specific band may be a frequency that is n times (n is a natural number) these operating frequencies. For example, the specific band may be a frequency that is an odd-numbered multiple of these operating frequencies.

[0055] In addition, there may be a plurality of specific bands. In this case, the unused wiring length is determined for each specific band, and the wiring pattern is generated so as not to include any of the wiring lengths determined.

[0056] [Effects, etc.] Inventions derived from the disclosure of this specification are, for example, the following inventions. Hereinafter, the inventions derived from the disclosure of this specification will be described together with the effects and the like obtained by the inventions.

[0057] For example, the substrate 12 according to one embodiment of the present disclosure is a substrate 12 having a plurality of wiring layers, in which at least a portion of the wiring 31 (or wiring 32) formed in the plurality of wiring layers has a meander pattern 33 (or meander pattern 34), and the meander patterns of the wiring formed in different wiring layers are set based on different parameters. Here, the substrate 12 is an example of a wiring substrate. Here, the parameters are, for example, a propagation speed v, a wavelength λ, or a wiring length corresponding to a specific band.

[0058] According to this, the meander pattern can be formed for each wiring layer using parameters suitable for that wiring layer, and therefore, for example, noise corresponding to a specific band can be suppressed.

[0059] For example, a meandering pattern may be used so that the length of the wiring does not become a specific wiring length corresponding to a specific frequency band. Here, the specific wiring length is, for example, a wiring length that becomes an antenna pattern for a specific frequency band (specific band).

[0060] According to this, the wiring can be prevented from becoming a specific wiring length corresponding to a specific band, so that noise corresponding to the specific band can be suppressed.

[0061] For example, different specific wiring lengths may be set for different wiring layers. In this way, the length of the wiring corresponding to the specific band can be calculated for each wiring layer using parameters suitable for that wiring layer. Therefore, the noise corresponding to the specific band can be suppressed.

[0062] For example, the different wiring layers may be a surface layer and an inner layer. In this way, the lengths of the wirings corresponding to the specific band can be calculated appropriately for the surface layer and the inner layer. Therefore, the noise corresponding to the specific band can be suppressed.

[0063] For example, the specific wiring length of the surface layer may be determined based on a wavelength λ1 determined based on εe=((εr1+1) / 2)+((εr1-1) / 2)×1 / (√(1+(10×h) / w), v1=c / √εe, and λ1=v1 / f, and the specific wiring length of the inner layer may be determined based on a wavelength λ2 determined based on v2=c / √εr2, λ2=v2 / f, where εe is the effective relative dielectric constant of the first insulating layer included in the surface layer, εr1 is the relative dielectric constant of the first insulating layer, h is the thickness of the first insulating layer, w is the width of the wiring on the surface layer, c is the speed of light, v1 is the propagation velocity in the surface layer, f is a specific frequency band, εr2 is the relative dielectric constant of the second insulating layer included in the inner layer, and v2 is the propagation velocity in the inner layer. This allows noise corresponding to the specific band to be appropriately suppressed in the surface layer and the inner layer.

[0064] For example, the specific frequency band may be a band included in the band from 1559.052 MHz to 1563.144 MHz, or a band included in the band from 1594.0625 MHz to 1609.375 MHz. In other words, the specific frequency band may be the BDS band and the GLONASS band.

[0065] For example, the specific wiring length of the surface layer may be in the range of 28.8 mm to 29.0 mm, and the specific wiring length of the inner layer may be in the range of 24.2 mm to 24.4 mm. This allows noise corresponding to the specific band to be appropriately suppressed in the surface layer and the inner layer.

[0066] For example, the specific wiring length of the surface layer may be in the range of 28.0 mm to 28.4 mm, and the specific wiring length of the inner layer may be in the range of 23.5 mm to 23.9 mm. This allows noise corresponding to the specific band to be appropriately suppressed in the surface layer and the inner layer.

[0067] For example, the specific wiring length may be set based on a specific frequency band, a wiring width, and a thickness of the insulating prepreg. For example, the specific wiring length is calculated using the above (Equation 3) to (Equation 5). This allows the specific wiring length to be calculated with high accuracy by taking into account multiple parameters.

[0068] For example, the wiring board may be for use in a vehicle. For example, the wiring board may be used in an ECU (Electronic Control Unit) including at least one of an ASC (Active Sound Control) unit and an ANC (Active Noise Control) unit.

[0069] For example, a wiring method according to an embodiment of the present disclosure is a wiring method for a substrate 12 having multiple wiring layers, in which at least a part of the wiring 31 (or wiring 32) formed in the multiple wiring layers has a meander pattern 33 (or meander pattern 34), and the wiring method sets meander patterns based on different parameters for the wirings formed in different wiring layers. Here, the parameters are, for example, a propagation speed v, a wavelength λ, or a wiring length corresponding to a specific band.

[0070] According to this, the meander pattern can be formed for each wiring layer using parameters suitable for that wiring layer, and therefore, for example, noise corresponding to a specific band can be suppressed.

[0071] (Other embodiments) Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments.

[0072] For example, the electronic device according to the above embodiment may be mounted on a moving body device other than a vehicle. The moving body device may be, for example, an aircraft or a ship. Furthermore, the present disclosure may be realized as such a moving body device other than a vehicle.

[0073] In addition, the general or specific aspects of the present disclosure may be realized in a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or in any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a computer-readable non-transitory recording medium.

[0074] In addition, the present disclosure also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may conceive, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of the present disclosure. [Industrial Applicability]

[0075] The electronic device of the present disclosure is useful, for example, as an in-vehicle electronic device. [Explanation of symbols]

[0076] 10 Electronic equipment 11. Cabinet 12 Substrate 13 Upper chassis 14 Lower Chassis 21, 22, 31, 32 Wiring 33, 34 Meander pattern 41, 51, 54 Ground conductor 42, 52 Insulation layer 43, 53 Wiring

Claims

1. A wiring board having a plurality of wiring layers, At least some of the wirings formed in the plurality of wiring layers have a meander pattern, The meandering patterns of the wirings formed in different wiring layers are set based on different parameters. Wiring board.

2. The meander pattern is used so that the length of the wiring does not become a specific wiring length corresponding to a specific frequency band. The wiring board according to claim 1.

3. Different specific wiring lengths are set for different wiring layers. The wiring board according to claim 2.

4. The different wiring layers are a surface layer and an inner layer. The wiring board according to claim 3.

5. The specific wiring length of the surface layer is εe=((εr1+1) / 2)+((εr1-1) / 2)×1 / (√(1+(10×h) / w) v1=c / √εe λ1=v1 / f is determined based on a wavelength λ1 determined based on The specific wiring length of the inner layer is v2 = c / √ εr2 λ2=v2 / f is determined based on a wavelength λ2 determined based on where εe is the effective dielectric constant of the first insulating layer included in the surface layer, εr1 is the dielectric constant of the first insulating layer, h is the thickness of the first insulating layer, w is the width of the wiring in the surface layer, c is the speed of light, v1 is the propagation velocity in the surface layer, f is the specific frequency band, εr2 is the dielectric constant of the second insulating layer included in the inner layer, and v2 is the propagation velocity in the inner layer. The wiring board according to claim 4.

6. The specific frequency band is a band included in a band of 1559.052 MHz to 1563.144 MHz, or a band included in a band of 1594.0625 MHz to 1609.375 MHz. The wiring board according to claim 5.

7. The specific wiring length of the surface layer is included in a range of 28.8 mm to 29.0 mm, The specific wiring length of the inner layer is included in the range of 24.2 mm to 24.4 mm. The wiring board according to claim 4.

8. The specific wiring length of the surface layer is included in a range of 28.0 mm to 28.4 mm, The specific wiring length of the inner layer is included in a range of 23.5 mm to 23.9 mm. The wiring board according to claim 4.

9. The specific wiring length is set based on the specific frequency band, the wiring width, and the thickness of the insulating prepreg. The wiring board according to claim 2.

10. The wiring board is for use in a vehicle. The wiring board according to any one of claims 1 to 9.

11. The wiring board is used in an ECU (Electronic Control Unit) including at least one of an ASC (Active Sound Control) unit and an ANC (Active Noise Control) unit. The wiring board according to claim 10.

12. A wiring method for a wiring board having a plurality of wiring layers, comprising the steps of: At least some of the wirings formed in the plurality of wiring layers have a meander pattern, The wiring method includes: The meander pattern is set based on different parameters for wiring formed in different wiring layers. Wiring method.

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