Wiring board and wiring procedure

Abstract

A wiring board (12) is a wiring board (12) comprising a plurality of wiring layers. At least a portion of the wiring (31) arranged in the plurality of wiring layers comprises a meandering pattern (33), and the meandering pattern (33) is designed based on different parameters for wiring (31) arranged in different wiring layers of the plurality of wiring layers. For example, the meandering pattern (33) may be included to give the wiring (31) a length that is not a specific wiring length corresponding to a specific frequency band. For example, different specific wiring lengths may be designed for the different wiring layers.

Description

[Technical field] The present disclosure relates to a wiring board and a wiring method. [State of the art] Patent Literature (PTL) 1 discloses a wiring pattern and so forth for vehicle instruments. [Citation list] [Patent literature] [PTL 1] Japanese Disclosure Document No. 2017-116348 [Summary of the invention] [Technical task] The present disclosure provides a wiring board and a wiring method that are capable of suppressing noise. [Solution to the task] A wiring board according to one aspect of the present disclosure is a wiring board comprising a plurality of wiring layers. At least a portion of the wiring arranged in the plurality of wiring layers comprises a meandering pattern. The meandering pattern is designed based on different parameters for wiring arranged in different wiring layers of the plurality of wiring layers. [Advantageous effects of the invention] The present disclosure can provide a wiring board and a wiring method that are capable of suppressing noise. [Brief description of the drawings] [Fig. 1] Fig. 1 is a perspective view showing an embodiment of an electronic device according to one embodiment. [Fig. 2] Fig. 2 is a diagram showing an example of a wiring pattern that does not use a meandering pattern according to the embodiment. [Fig. 3] Fig. 3 is a diagram showing an example of a wiring pattern that does not use a meandering pattern according to the embodiment. [Fig. 4] Fig. 4 is a diagram showing an example of a wiring pattern that uses the meandering pattern according to the embodiment. [Fig. 5] Fig. 5 is a diagram showing an example of a wiring pattern that uses the meandering pattern according to the embodiment. [Fig. 6] Fig. 6 is a diagram showing an embodiment of a microstrip line of a surface layer according to the embodiment. [Fig. 7] Fig.7 is a diagram that illustrates an embodiment of a strip line of an inner layer according to the embodiment. [Description of embodiments] In the following, embodiments are specifically described with reference to the drawings. Furthermore, each of the embodiments described below illustrates a generic or specific example. The numerical values, shapes, materials, structural elements, the arrangement and connection of the structural elements, steps, the processing sequence of the steps, etc., shown in the following exemplary embodiments are merely examples and are therefore not intended to limit the present disclosure. Furthermore, among the structural elements in the following embodiments, structural elements not listed in the independent claims are described as optional structural elements. Furthermore, the figures are schematic diagrams and not necessarily precise representations. It should be noted that elements that are essentially the same in each figure are labeled with the same reference symbols, and overlapping descriptions may be omitted or simplified. [Version] [Underlying knowledge base of the invention] In vehicle electronics, the increasing digitization of electronic devices due to the shift to electric vehicles (EVs) has led to a rise in noise interference between devices. Furthermore, with the increasing number of devices deployed in vehicles, there is a need for these devices to be lightweight. One method considered to achieve weight reduction is the use of a resin housing instead of a metal one. However, there are concerns that using a resin housing will reduce noise immunity. Because of these factors, electromagnetic compatibility (EMC) measures for in-vehicle electronics have become a critical issue. On the other hand, the external size of a circuit board is determined by the product size that can be placed within the vehicle cabin. Furthermore, due to the constraints of the circuit board's external shape, the spacing between each component (i.e., the length of the wiring pattern) cannot be freely determined in the design of each component. This means that the wiring length on the circuit board must correspond to the specific wiring length associated with a particular frequency band (hereinafter also referred to as the specific band), such as the Beidou Navigation Satellite System (BDS) band and the Global Navigation Satellite System (GLONASS) band, which have the strictest limits in the standard for electromagnetic interference (EMI), leading to a problem of high noise levels in the specific band.Here, the specific wiring length is a wiring length that causes the wiring to function as an antenna pattern for the specific band. In contrast, in the present embodiment, the wiring length of all wiring within the circuit board is intentionally designed to be long, so that it does not become a specific wiring length. This prevents the wiring from becoming an antenna pattern for a specific band. Therefore, for example, the EMI standard can be met even when a resin enclosure is used. In addition, the present embodiment not only controls the wiring length, but also calculates the actual effective relative permittivity from a relative permittivity based on the circuit board material. Furthermore, propagation delay characteristics of digital signals in high-speed transmission paths are taken into account in both surface layer and sublayer wiring. This allows the wiring length to be precisely controlled for each layer on the circuit board. [Design of an electronic device] First, an embodiment of an electronic device 10 according to the present embodiment is described. Fig. 1 is a perspective view of an electronic device 10 according to the present embodiment. Fig. 1 shows an exploded view of an electronic device 10. The electronic device 10 comprises a housing 11 and a circuit board 12. The housing 11 is made of resin, for example, and comprises an upper chassis 13 and a lower chassis 14. The circuit board 12 is a wiring board and comprises a number of wiring layers. These wiring layers include a surface layer and one or more internal layers. It should be noted that, although the number of wiring layers is not particularly limited, circuit board 12 could, for example, be a 4-layer board or a 6-layer board. The circuit board 12 is located within the housing 11. Furthermore, a large number of elements (electronic components), such as integrated circuits, are arranged on the circuit board 12. It should be noted that only some of these elements are shown in Fig. 1, with the rest omitted. The electronic device 10, for example, is an electronic control unit (ECU) for use in a vehicle. The ECU includes, for example, an active sound control unit (ASC) and / or an active noise control unit (ANC) that performs sound-related processing in a vehicle. In other words, the ECU has the function of at least one ASC or ANC. The ASC unit performs processing to add engine noise, etc., in an EV or hybrid vehicle. The ANC unit performs processing to suppress noise within the vehicle. It should be noted that the electronic device 10 is not limited to the example above. The electronic device 10 may be a different electronic device for use in a vehicle than the one above, or it may be a different electronic device for use in a vehicle altogether. [Adjusting the wiring length] In the present embodiment, the total wiring length of the circuit board 12 is designed to be long, so that it does not become a specific wiring length corresponding to a specific band. This prevents the wiring from becoming an antenna pattern in a specific band. In particular, the circuit board 12 does not include any wiring with a specific wiring length corresponding to a specific band. In other words, the total wiring length of the circuit board 12 is not the specific wiring length. In particular, a meandering pattern (also called a meandering pattern) is used as a method for adjusting the wiring length of board 12. A meandering pattern is not a wiring pattern where the wiring length is shortest, but rather a wiring pattern where the wiring length is increased by making the wiring meander. Figures 2 and 3 are diagrams for comparison and show examples of wiring patterns that do not use meandering patterns. Figures 2 and 3 each depict a wiring configuration 21 and a wiring configuration 22, respectively, that do not use meandering patterns. Figures 4 and 5 correspond to Figures 2 and 3, respectively, and are diagrams illustrating examples of wiring patterns that employ meandering patterns. The wiring 31 shown in Figure 4 comprises a meandering pattern 33. The wiring 32 shown in Figure 5 comprises a meandering pattern 34. Here, meandering patterns are generally used to standardize the wiring lengths of multiple wires, to align the delay times of signals on multiple wires, for example, data lines and clock lines, to synchronize communication times, that is, to ensure consistent propagation delay characteristics. In other words, the meandering pattern is used to implement wiring of the same length for each signal line that needs to be synchronized. In contrast, in the present embodiment, the meandering pattern is used to prevent the wiring length from becoming a specific, fixed length. [Calculation of the specific wiring length] Next, a method for calculating the specific wiring length is described. First, the propagation speed of a wire in a vacuum is described. The propagation speed in a vacuum is 300,000 km / s, which is equal to the speed of light c. In particular, the propagation speed in a vacuum is defined by (Equation 1) below. Here, ε0 is the permittivity of a vacuum and ε0 = 8.85 × 10⁻¹². µ0 is the magnetic permeability of a vacuum and µ0 = 4π × 10⁻⁷. Therefore, the propagation speed c = 2.99792458 × 10⁸ [m / s]. On the other hand, in the case of coaxial cables, the propagation speed decreases mainly due to the influence of the material's relative permittivity εr. This decrease in propagation speed is called wavelength reduction. The wavelength in this case is represented by (Equation 2) below. Here, λ0 is the wavelength in a vacuum. If, for example, the insulator is polyethylene, εr = 2.2 to 2.4, and the propagation speed is calculated as 2.99792458 / √2.3 = 1.97677293 × 10⁸ [m / s]. In other words, the propagation speed in a coaxial cable is approximately 66% of that in a vacuum. Therefore, the wavelength reduction rate is 0.66. As with coaxial cables, the propagation speed of a signal in a wiring configuration formed on the circuit board can be calculated. Here, this propagation speed is generally calculated as approximately half the speed of light, c. If the circuit board material is glass epoxy (FR-4), its relative permittivity is 4.3 / 1 GHz. Therefore, the propagation speed is 2.99792458 / √4.3 = 1.4457276101 × 10⁸ [m / s]. However, the propagation speed obtained through this calculation contains an error compared to the actual propagation speed. Since there is a particularly large error in the GHz band, stricter control is required. Here, microstrip lines are used on the surface layer of the circuit board, and strip lines are used on the inner layer of the circuit board. In the present embodiment, different propagation speeds for the surface layer and the inner layer are precisely calculated by performing separate calculations for the surface layer and the inner layer. Fig. 6 is a diagram illustrating an embodiment of a surface layer microstrip line. As shown in Fig. 6, the circuit board 12 in the surface layer comprises a grounding conductor 41, an insulating layer 42, and wiring 43. The grounding conductor 41 is an electrically grounded conductor and is, for example, a metal layer. The insulating layer 42 is an insulating layer located between the grounding 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. In the present embodiment, the effective relative dielectric constant εe is calculated from (equation 3) below using 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. Furthermore, the propagation speed v is calculated from (equation 4) below using the speed of light c and the effective relative permittivity εe of the insulating layer 42. Additionally, the wavelength λ is calculated from the frequency f of the specific band and the propagation speed v using (equation 5) below. Fig. 7 is a diagram illustrating an embodiment of a stripline in an inner layer. As shown in Fig. 7, the circuit board 12 in the inner layer comprises grounding conductors 51 and 54, an insulating layer 52, and wiring 53. The grounding conductors 51 and 54 are electrically grounded conductors and are, for example, metal layers. The insulating layer 52 is an insulating layer arranged between the grounding conductor 51 and the grounding conductor 54. The wiring 53 is a metal wiring pattern arranged within the insulating layer 52 and carries a signal. Furthermore, the propagation speed v is calculated from (equation 6) below using the speed of light c and the relative permittivity εr of the insulating layer 42. Furthermore, the wavelength λ is calculated from the propagation speed v, obtained from (Equation 6), using (Equation 5) above. In this way, different propagation speeds v and different wavelengths λ are calculated for the surface layer and the inner layer. Next, the specific wiring length for the surface layer is calculated based on the wavelength λ of the surface layer, and the specific wiring length for the inner layer is calculated based on the wavelength λ of the inner layer. For example, the specific wiring length is λ / 4. Next, all wiring patterns for the surface layer and the inner layer are generated such that the wiring length in the surface layer is not the calculated specific wiring length for the surface layer, and so that the wiring length in the inner layer is not the calculated specific wiring length for the inner layer. For example, the wiring patterns are generated based on a predetermined rule (for example, so that the wiring length is shortest). Next, a wiring pattern with a length matching the calculated specific wiring length is extracted from the generated wiring patterns, and the extracted wiring pattern is replaced with a wiring pattern with a different length (for example, a wiring pattern with the meandering pattern described above). For example, if εr = 3.9, h = 0.2 mm, and w = 0.1 mm, the propagation speed v of the surface layer is 1.80481941 × 10⁸ [m / s], and the propagation speed v of the inner layer is 1.51805812 × 10⁸ [m / s]. Therefore, the specific wiring length for the surface layer corresponding to the BDS band (1.56 GHz) is approximately 28.9 mm, and the specific wiring length for the inner layer is approximately 24.3 mm. Since the BDS band is a band from 1559.052 MHz to 1563.144 MHz, in particular the specific wiring length for the surface layer corresponding to the BDS band is contained in the range of 28.8 mm to 29.0 mm, and the specific wiring length for the inner layer is contained in the range of 24.2 mm to 24.4 mm. Furthermore, the specific wiring length for the surface layer, corresponding to the GLONASS band (1.60 GHz), is approximately 28.1 mm to 28.2 mm, and the specific wiring length for the inner layer is approximately 23.7 mm to 23.8 mm. Since the GLONASS band is a band from 1594.0625 MHz to 1609.375 MHz, the specific wiring length for the surface layer is specifically within the range of 28.0 mm to 28.4 mm, and the specific wiring length for the inner layer is within the range of 23.5 mm to 23.9 mm. It should be noted that, although an example where the specific wiring length is λ / 4 was described above, the specific wiring length can also be λ / 2. In this case, the specific wiring length for the surface layer, corresponding to the GLONASS band (1.60 GHz), is approximately 56.2 mm to 56.4 mm, and the specific wiring length for the inner layer is approximately 47.4 mm to 47.6 mm. Since the GLONASS band is a band from 1594.0625 MHz to 1609.375 MHz, the specific wiring length for the surface layer, in particular, lies within the range of 56.0 mm to 56.8 mm, and the specific wiring length for the inner layer lies within the range of 47.0 mm to 47.8 mm. Additionally, both λ / 4 and λ / 2 can be used as the specific wiring length. When λ / 2 is used, in the example above, the specific wiring length for the surface layer corresponding to the BDS band (1.56 GHz) is approximately 57.8 mm, and the specific wiring length for the inner layer is approximately 48.6 mm. For example, the specific wiring length for the surface layer corresponding to the BDS band is in the range of 57.6 mm to 58.0 mm, and the specific wiring length for the inner layer is in the range of 48.4 mm to 48.8 mm. Furthermore, the specific wiring length for the surface layer, corresponding to the GLONASS band (1.60 GHz), is approximately 56.3 mm to 56.5 mm, and the specific wiring length for the inner layer is approximately 47.3 mm to 47.5 mm. For example, the specific wiring length for the surface layer is in the range of 56.0 mm to 56.8 mm, and the specific wiring length for the inner layer is in the range of 47.0 mm to 47.8 mm. It should be noted that the numerical ranges given above are only examples. If the number of parts on the circuit board varies, the dielectric constant εr changes due to the different base material, and therefore the wiring length must be controlled. Furthermore, to ensure greater flexibility, the range of specific wiring lengths described above can be expanded. Conversely, to increase the range of usable wiring lengths, the range of specific wiring lengths described above can be narrowed. It should be noted that, although the BDS band and the GLONASS band are given as examples of the specific band in the preceding description, the specific band can be a different frequency band. Furthermore, the specific band is not limited to the GHz band. For example, the specific band can be the operating frequency of a circuit or the like contained in the electronic device 10, or the operating frequency of a device connected to the electronic device 10. Furthermore, the specific band can be a frequency that is n times (n being a natural number) these operating frequencies. For example, the specific band can be a frequency that is an odd multiple of these operating frequencies. Furthermore, there can be a large number of specific bands. In this case, the unused wiring length for each specific band is determined, and the wiring pattern is generated so that it does not include any wiring with any of the specified wiring lengths. [Advantageous effects, etc.] Inventions resulting from the disclosure of this description include, for example, the inventions described below. The following section describes the inventions resulting from the disclosure of this description, together with the advantageous effects and the like obtained by the inventions. For example, according to one aspect of the present disclosure, the circuit board 12 is the circuit board 12 comprising a plurality of wiring layers. At least a portion of the wiring 31 (or wiring 32) arranged in the plurality of wiring layers comprises a meandering pattern 33 (or meandering pattern 34). The meandering pattern is designed based on different parameters for wiring arranged in different wiring layers of the plurality of wiring layers. Here, the circuit board 12 is an example of a wiring circuit board. Here, the parameters are, for example, the propagation speed v, the wavelength λ, or the wiring length corresponding to a specific band. Accordingly, a meandering pattern can be formed for each wiring layer using parameters suitable for that layer. Therefore, for example, noise corresponding to a specific band can be suppressed. For example, the meandering pattern can be included to give the wiring a length that is not 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). This prevents the wiring from becoming a specific wiring length corresponding to the specific band, and thus noise corresponding to the specific band can be suppressed. For example, different specific wiring lengths can be designed for the different wiring layers. Accordingly, the length of wiring corresponding to a specific band can be calculated for each wiring layer using parameters suitable for that layer. Therefore, noise corresponding to the specific band can be suppressed. For example, the different wiring layers can be a surface layer and an inner layer. Accordingly, the length of wiring corresponding to a specific band can be appropriately calculated for both the surface and inner layers. Therefore, noise corresponding to that specific band can be suppressed. For example, a specific wiring length for the surface layer can be determined based on a wavelength λ1, which is calculated using the following equations: εe = ((εr1 + 1) / 2) + ((εr1 - 1) / 2) × 1 / (√(1 + (10 × h) / w); v1 = c / √εe; and λ1 = v1 / f. A specific wiring length for the inner layer can be determined based on a wavelength λ2, which is calculated using the following equations: v2 = c / √εr2; and λ2 = v2 / f.Here, εe is the effective relative permittivity of a first insulating layer contained in the surface layer; εr1 is the relative permittivity of the first insulating layer; h is the thickness of the first insulating layer; w is the wiring width for the surface layer; c is the speed of light; v1 is the propagation speed in the surface layer; f is the specific frequency band; εr2 is the relative permittivity of a second insulating layer contained in the inner layer; and v2 is the propagation speed in the inner layer. Accordingly, noise corresponding to the specific band can be adequately suppressed for both the surface layer and the inner layer. For example, the specific frequency band may be contained within a band ranging from 1559.052 MHz to 1563.144 MHz, or within a band ranging from 1594.0625 MHz to 1609.375 MHz. In other words, the specific frequency band may be the BDS band or the GLONASS band. For example, a specific wiring length for the surface layer may be in the range of 28.8 mm to 29.0 mm, and a specific wiring length for the inner layer may be in the range of 24.2 mm to 24.4 mm. Accordingly, noise corresponding to the specific band can be adequately suppressed for both the surface and inner layers. For example, a specific wiring length for the surface layer may be in the range of 28.0 mm to 28.4 mm, and a specific wiring length for the inner layer may be in the range of 23.5 mm to 23.9 mm. Accordingly, noise corresponding to the specific band can be adequately suppressed for both the surface and inner layers. For example, the specific wiring length can be designed based on the specific frequency band, wiring width, and thickness of an insulator prepreg. For instance, the specific wiring length is calculated using equations 3 through 5 as described above. Accordingly, the specific wiring length can be calculated with high accuracy by considering multiple parameters. For example, the wiring board can be designed for use in a vehicle. For example, the wiring board can be used in an electronic control unit (ECU) that includes an active sound control unit (ASC) and / or an active noise control unit (ANC). For example, a wiring method according to one aspect of the present disclosure is a wiring method for use in the circuit board 12, which comprises a plurality of wiring layers, each containing a wiring 31 (or a wiring 32), wherein the wiring at least partially comprises a meandering pattern 33 (or a meandering pattern 34). The wiring method comprises: designing the meandering pattern based on different parameters for a wiring arranged in different wiring layers of the plurality of wiring layers. Here, the parameters are, for example, the propagation speed v, the wavelength λ, or the wiring length corresponding to a specific band. Accordingly, a meandering pattern can be formed for each wiring layer using parameters suitable for that layer. Therefore, for example, noise corresponding to a specific band can be suppressed. [Other embodiments] Although exemplary embodiments have been described above, the present disclosure is not limited to the embodiments described above. For example, the electronic device according to the foregoing embodiments can be provided for a mobile device other than a vehicle. The mobile device can be, for example, an aircraft or a ship. Furthermore, the present disclosure can be implemented as such a mobile device other than a vehicle. Furthermore, the general or specific aspects of this disclosure can be implemented as a system, a device, a method, an integrated circuit, a computer program, or a non-volatile, computer-readable recording medium, such as a CD-ROM. Furthermore, the general or specific aspects of this disclosure can be implemented as any combination of a system, a device, a method, an integrated circuit, a computer program, and a non-volatile, computer-readable recording medium. Apart from the foregoing, forms obtained by making various modifications to respective embodiments that can be conceived by those skilled in the field, or forms realized by any combination of structural elements and functions in the respective embodiments within the core of the present disclosure, are included in the present disclosure. [Commercial Applicability] An electronic device according to the present disclosure is, for example, useful as an electronic device in a vehicle. [List of reference symbols] 10 electronic device 11 housing 12 circuit board 13 upper chassis 14 lower chassis 21, 22, 31, 32 wiring 33, 34 meandering pattern 41, 51, 54 grounding conductor 42, 52 insulating layer 43, 53 wiring QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature JP 2017-116348

[0003]

Claims

Wiring board comprising: a plurality of wiring layers, wherein at least a portion of the wiring arranged in the plurality of wiring layers comprises a meandering pattern, and the meandering pattern is designed based on different parameters for wiring arranged in different wiring layers of the plurality of wiring layers. Wiring board according to claim 1, wherein the meandering pattern is included to give the wiring a length that is not a specific wiring length corresponding to a specific frequency band. Wiring board according to claim 2, wherein different specific wiring lengths are designed for the different wiring layers. Wiring board according to claim 3, wherein the different wiring layers are a surface layer and an inner layer. Wiring board according to claim 4, wherein a specific wiring length for the surface layer is determined based on a wavelength λ1, which is determined based on the following equations: ε e = ( ( ε r + 1 ) / 2 ) + ( ( ε r − 1 ) / 2 ) × 1 / ( √ ( 1 + ( 10 × h ) / w ) ; v1 = c / √ ε e; and λ 1 = v1 / f , and A specific wiring length for the inner layer is determined based on a wavelength λ2, which is determined based on the following equations: v2 = c / √ ε r2; and λ 2 = v2 / f , where: εe is an effective relative dielectric constant of a first insulating layer contained in the surface layer; εr1 is a relative dielectric constant of the first insulating layer; h is the thickness of the first insulating layer; w is a wiring width for the surface layer; c is the speed of light; v1 is a propagation speed in the surface layer; f is the specific frequency band; εr2 is a relative dielectric constant of a second insulating layer contained within the inner layer; and v2 is a propagation speed in the inner layer. Wiring board according to claim 5, wherein the specific frequency band is contained in a band ranging from 1559.052 MHz to 1563.144 MHz, or in a band ranging from 1594.0625 MHz to 1609.375 MHz. Wiring board according to claim 4, wherein a specific wiring length for the surface layer is included in a range of 28.8 mm to 29.0 mm, and a specific wiring length for the inner layer is included in a range of 24.2 mm to 24.4 mm. Wiring board according to claim 4, wherein a specific wiring length for the surface layer is included in a range of 28.0 mm to 28.4 mm, and a specific wiring length for the inner layer is included in a range of 23.5 mm to 23.9 mm. Wiring board according to claim 2, wherein the specific wiring length is designed based on the specific frequency band, a wiring width and a thickness of an insulator prepreg. Wiring board according to any one of claims 1 to 9, wherein the wiring board is designed for use in a vehicle. Wiring board according to claim 10, wherein the wiring board is used in an electronic control unit (ECU) comprising an active sound control unit (ASC) and / or an active noise control unit (ANC). Wiring method for use in a wiring board comprising a plurality of wiring layers, each in which a wiring arrangement is provided, wherein the wiring at least partially comprises a meandering pattern, wherein the wiring method comprises: designing the meandering pattern based on different parameters for a wiring arrangement in different wiring layers of the plurality of wiring layers.

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