JP2009043052A - Printed-circuit board design support device, method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily design an arrangement of a ground via so as to suppress unwanted electromagnetic radiation from between a power supply and a ground layers which is caused by a signal via penetrating a power supply plane and a ground plane of a printed-circuit board. <P>SOLUTION: Signal via information showing a configuration of a signal via which penetrates two ground planes clamping a power supply plane corresponding to extracted power supply plane information is extracted from layout information. An inter-via distance calculation part 105 calculates a distance between a signal via and the ground via shown in the signal via information extracted by a signal via extraction part 104 according to an approximation stored in an emission suppression quantity storage part 102. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a printed circuit board design support for supporting a design related to arrangement of ground vias for suppressing unnecessary electromagnetic radiation generated between a power plane and a ground plane due to a signal via penetrating the power plane and the ground plane of the printed circuit board. The present invention relates to an apparatus, a method, and a program.

  Unnecessary electromagnetic waves radiated from a printed circuit board on which an LSI or IC is mounted cause troubles in broadcasting and communication, and may cause malfunctions in other electronic devices. For this reason, unnecessary electromagnetic radiation from the printed circuit board must be kept low. The main electromagnetic radiation from a printed circuit board is radiation from a power supply system composed of a power plane and a ground plane. Specifically, due to voltage fluctuations generated between the power plane and the ground plane, both planes become parallel plate antennas, and electromagnetic waves are radiated. One of the causes of voltage fluctuations between the power plane and the ground plane is generally known as a signal via disposed through both planes.

  FIG. 23 is a cross-sectional view schematically showing the configuration of the printed circuit board 2304 showing that the signal via 2301 is disposed through the power plane 2302 and the ground plane 2303. A signal wiring 2305 is formed on the front and back surfaces of the printed board 2304, and an internal signal wiring 2306 is arranged in a layer between the power plane 2302 and the ground plane 2303 inside the printed board 2304.

  The current flowing through the signal wiring 2305 uses either the power plane 2302 or the ground plane 2303 as a return path. In the signal via 2301 penetrating the power plane 2302 and the ground plane 2303, the return path for the signal current becomes discontinuous, thereby causing a voltage variation between the two planes. The signal via 2302 is necessary for electrically connecting the signal wirings 2305 wired in different layers, but it is preferable to avoid the signal vias 2302 as much as possible because it increases unnecessary electromagnetic radiation. However, with downsizing and high-density mounting of electronic devices, the area for wiring signal wiring on a printed circuit board is limited, and the arrangement of signal vias is inevitable.

  To suppress unnecessary electromagnetic radiation from the power plane and ground plane, a capacitor is placed between the power plane and the ground plane as a return path in the vicinity of the signal via, and a ground via that connects the ground planes is placed. To be done. There has been proposed a method for checking whether or not the capacitor and the ground via are arranged at an appropriate position in order to suppress unnecessary electromagnetic radiation (see Patent Document 1 and Patent Document 2).

In Patent Document 1, from the viewpoint of suppressing the voltage fluctuation between the power plane and the ground plane, the voltage fluctuation is suppressed by issuing a warning when the distance between the signal via and the capacitor is larger than the allowable range. Radiation is suppressed.
In Patent Document 2, unnecessary electromagnetic wave emission is suppressed by determining whether or not a path serving as a return path exists within a range specified for a signal via.

WO2004 / 111890 JP 2007-011629 A

  However, there are several problems with these techniques. First, in the method of Patent Document 1, a signal current return path is secured by a capacitor. However, since there is an inductance of the capacitor itself and an inductance by a pad at the time of mounting, the capacitor has a return path for a high-frequency signal current. Not. In addition, the resonance frequency of the power supply system may shift to the high frequency side due to the placement of the capacitor, and unnecessary electromagnetic radiation due to unexpected resonance may occur. For this reason, it is difficult to suppress unnecessary electromagnetic radiation in a wide frequency band by arranging a capacitor in the vicinity of the signal via.

  On the other hand, the ground via is an effective means that does not require a pad for mounting and has a small inductance component and functions as a return path up to a high frequency. Further, from the viewpoint of the return path of the signal current, the unnecessary electromagnetic radiation from the power supply system can be suppressed as the ground via is arranged closer to the signal via.

  In the method of Patent Document 2, it is checked whether or not the ground via exists within a specified range around the signal via, but there is a problem that the amount of suppression of unnecessary electromagnetic radiation cannot be quantitatively grasped. For this reason, unnecessary electromagnetic radiation cannot be suppressed sufficiently low, and it may be necessary to change the design or add countermeasure parts after the printed circuit board is manufactured. Alternatively, although the unnecessary electromagnetic radiation can be sufficiently suppressed, the designer may decide to add and place a ground via near the signal via. This lowers the degree of freedom of printed circuit board design, and is not desirable as a printed circuit board method for realizing downsizing and high-density mounting of electronic devices.

  The present invention has been made to solve the above-described problems. Unnecessary electromagnetic radiation from the power-ground layer caused by signal vias arranged through the power plane and the ground plane of the printed circuit board is provided. The purpose of this is to make it possible to more easily perform a design that can suppress the above.

  A printed circuit board design support apparatus according to the present invention includes layout information storage means for storing layout information including at least information indicating a ground plane structure, a power plane structure, and a signal via structure, and a power plane and a ground plane. Radiation suppression amount storage means for storing an approximate expression indicating the relationship between the amount of suppression of unnecessary electromagnetic radiation generated from the configured power supply system and the distance between the signal via and the ground via connecting the two ground planes, and layout information Power plane extraction means for extracting power plane information indicating the structure of the power plane arranged between the two ground planes, and two ground planes sandwiching the power plane corresponding to the power plane information from the layout information Signal to extract signal via information indicating the structure of signal via And A extraction means, the approximate expression is obtained by a via distance calculation means for calculating the distance between the signal via and ground vias represented by signal vias information as provided at least.

  Also, the printed circuit board support method according to the present invention includes a layout information storing step for storing layout information including at least information indicating a ground plane structure, a power plane structure, and a signal via structure, and a power plane and a ground plane. A radiation suppression amount storage step stored by an approximate expression indicating a relationship between a suppression amount of unnecessary electromagnetic radiation generated from a power supply system configured by the distance between a signal via and a ground via connecting two ground planes, and layout information From the layout information, the power plane extraction step for extracting power plane information indicating the structure of the power plane arranged between the two ground planes, and the two ground planes sandwiching the power plane corresponding to the power plane information from the layout information. Signal via information indicating the structure of the signal via A signal via extracting, by the approximate expression is obtained by a via distance calculation step of calculating a distance between the signal via and ground vias represented by signal vias information as provided at least.

  In addition, the program according to the present invention includes a layout information storage function for storing layout information including at least information indicating a ground plane structure, a power plane structure, and a signal via structure, a power plane, and a ground plane. A radiation suppression amount storage function stored by an approximate expression indicating a relationship between a suppression amount of unnecessary electromagnetic radiation generated from a power supply system configured by the distance between a signal via and a distance of a ground via connecting two ground planes, and layout information From the layout information, the power plane extraction function that extracts the power plane information indicating the structure of the power plane arranged between the two ground planes, and the two ground planes sandwiching the power plane corresponding to the power plane information from the layout information Extract signal via information indicating the structure of the signal via A signal via extraction function that, by approximate expression is intended for causing the at least achieve a via distance calculation function of calculating a distance between the signal via and ground vias represented by signal vias information.

  As described above, according to the present invention, the distance between the signal via indicated by the signal via information extracted by the signal via extraction unit and the ground via is calculated by the stored approximate expression. A design that can suppress unnecessary electromagnetic radiation from the power-ground layer caused by signal vias that are arranged through the power plane and ground plane of the printed circuit board can be more easily achieved. It is done.

  Embodiments of the present invention will be described below with reference to the drawings.

[Example 1]
First, Example 1 according to the present invention will be described. FIG. 1 is a configuration diagram illustrating a configuration example of a printed circuit board design support apparatus in Embodiment 1 of the present invention. This apparatus includes a layout information storage unit 101, a radiation suppression amount storage unit 102, a power plane extraction unit 103, a signal via extraction unit 104, and a via distance calculation unit 105.

  The layout information storage unit 101 stores information (layout information) indicating the structure of the ground plane, the structure of the power supply plane, and the structure of the signal via constituting the printed circuit board. The radiation suppression amount storage unit 102 is a relationship between a suppression amount of unnecessary electromagnetic radiation generated from a power supply system including a power plane and a ground plane of a printed circuit board and a distance between a signal via and a ground via connecting two ground planes. Is stored. In the radiation suppression amount storage unit 102, for example, a desired amount of suppression of unnecessary electromagnetic radiation is stored.

  The power plane extraction unit 103 also extracts power plane information indicating the structure of the power plane formed between the two ground planes from the layout information stored in the layout information storage unit 101. The signal via extraction unit 104 extracts signal via information indicating the structure of the signal via passing through the two ground planes sandwiching the power plane corresponding to the extracted power plane information from the layout information. The via distance calculation unit 105 calculates the distance between the signal via indicated by the signal via information extracted by the signal via extraction unit 104 and the ground via by the approximate expression stored in the radiation suppression amount storage unit 102.

  The printed circuit board design support apparatus according to the first embodiment is, for example, a computer device including a CPU, a main storage device, an external storage device, a network connection device, and the like. The CPU operates according to a program developed in the main storage device. By doing so, the above-described functions are realized. Each function may be distributed among a plurality of computer devices.

  In the printed circuit board design support apparatus according to the first embodiment, the distance calculated by the inter-via distance calculation unit 105 is the distance between the signal via and the ground via that causes the unnecessary electromagnetic radiation to be suppressed to the set suppression amount. It is. Therefore, if the ground via is arranged at a distance greater than the distance calculated by the inter-via distance calculation unit 105 with respect to the signal via of the target printed circuit board, the amount of unnecessary electromagnetic radiation can be suppressed to a desired value. Become. As described above, according to the first embodiment, the design that can suppress unnecessary electromagnetic radiation from the power-ground layer due to the signal vias arranged through the power plane and the ground plane of the printed circuit board is more improved. It will be easy.

[Example 2]
Next, a second embodiment according to the present invention will be described. FIG. 2 is a block diagram illustrating a configuration of a main part of the printed circuit board design support apparatus according to the second embodiment of the present invention. The printed circuit board design support apparatus 201 includes a layout information input unit 202, a radiation suppression amount input unit 203, a power plane extraction unit 204, a signal via extraction unit 205, a radiation suppression amount database 206, a via distance calculation unit 207, and a ground via extraction. A unit 208 and a display unit 209;

  The layout information input unit 202 receives and stores input of layout information of a printed circuit board input by, for example, a user (designer) operating the apparatus. The radiation suppression amount input unit 203 receives and stores an input of a suppression amount of unnecessary electromagnetic radiation generated from the power supply system, which is input by, for example, an operation of the apparatus by a designer. The power plane extraction unit 204 extracts power planes formed between two or more ground planes from the layout information input from the layout information input unit 202.

  The signal via extraction unit 205 extracts signal vias arranged through the power supply plane extracted by the power supply plane extraction unit 204. The radiation suppression amount database 206 stores a relational approximate expression and a constant (proportional coefficient) of the amount of suppression of unnecessary electromagnetic radiation with respect to the distance between the signal via and the ground via. The via-to-via distance calculation unit 207 is a distance between a signal via and a ground via for satisfying the radiation suppression amount input from the radiation suppression amount input unit 203 using the approximate expression stored in the radiation suppression amount database 206. Is calculated.

  The ground via extraction unit 208 extracts ground vias arranged in a circle having the radius between the via distances calculated by the inter-via distance calculation unit 207 with the signal vias extracted by the signal via extraction unit 205 as the center. . The display unit 209 displays the printed circuit board layout information input by the layout information input unit 202, the power plane extracted by the power plane extraction unit 204, and the signal via extracted by the signal via extraction unit 205.

  In addition, when there is no power plane to be extracted by the power plane extraction unit 204 or when there is no signal via to be extracted by the signal via extraction unit 205, the design support apparatus is targeted in the layout information. That no layout exists. Further, a warning is displayed when a ground via is not extracted by the ground via extraction unit 208.

  FIG. 3 is a block diagram showing a hardware configuration of a computer device for realizing each functional block of the printed circuit board design support apparatus 1 shown in FIG. Referring to FIG. 3, the printed circuit board design support apparatus 101 includes a printed circuit board design support program, a storage medium 301 in which various data necessary for calculation in the support program are stored, and a printed circuit board design support apparatus main body 302. .

  The storage medium 301 is a storage medium represented by, for example, a CD-ROM or a DVD. The storage medium 301 includes a power plane extraction, a signal via extraction, a calculation of a distance between vias, a program used for ground via extraction, and a relationship between a distance between a signal via and a ground via and a suppression amount of unnecessary electromagnetic radiation. Is stored. The storage medium stores a plurality of coefficient values included in this approximate expression.

  The printed circuit board design support apparatus main body 302 includes an input / output device 303 for inputting / outputting data, a storage device 304 for storing a program read from the storage medium 301, data input by the input / output device 303, and the like. An arithmetic unit (CPU) 305 that performs overall control and calculation, and a display unit 306 for displaying processing status and warnings are provided. A device (not shown) that reads / writes data from / to the storage medium 301, an input / output device 303, a storage device 304, an arithmetic device 305, and a display device 306 are connected to each other via a bus 307.

  The input / output device 303 corresponds to the layout information input unit 202 and the radiation suppression amount input unit 203 illustrated in FIG. The arithmetic device 305 includes a plurality of functional units such as the power plane extraction unit 204, the signal via extraction unit 205, the via distance calculation unit 207, and the ground via extraction unit 208 illustrated in FIG. Each functional unit is provided by the CPU executing a program stored in the storage medium 301. The display device 306 corresponds to the display unit 209 illustrated in FIG.

  In the hardware configuration illustrated in FIG. 3, the layout information of the printed circuit board and the amount of suppression of unnecessary electromagnetic radiation are input by the input / output device 303. This input information is stored in the storage device 304 from the input device 33 via the bus 307. The storage device 304 also stores a program read from the storage medium 301. The arithmetic device 305 uses the information (printed circuit board layout information, suppression amount of unnecessary electromagnetic radiation) and a program stored in the storage device 304 so that the ground via for the signal via satisfies the suppression amount of unnecessary electromagnetic radiation. Check that it is placed in. This result is displayed on the display device 306.

  Next, the operation of the printed circuit board design support apparatus 101 of this embodiment will be described in detail. FIG. 4 is a flowchart showing the operation of the printed circuit board design support apparatus 201 shown in FIG. The operation will be described below with reference to FIGS. When the printed circuit board design support apparatus 101 is activated, the arithmetic device 305 reads and executes a program stored in the storage device 304. Thereby, each functional block shown in FIG. 2 is realized.

  After the printed circuit board design support apparatus 101 is activated, a printed circuit board such as a structure of a power plane and a ground plane, an electronic device such as an LSI or an IC, and a mounting position of a decoupling capacitor is input to the layout information input unit 202 by a designer's operation. The data (layout information) relating to the layout is input (step S401). The layout information input unit 202 stores the input layout information. This input data is output from the layout information input unit 202 to the power plane extraction unit 204. Also, based on the coordinates and connection information included in the layout information, an image of the printed circuit board layout is generated and output to the display unit 209.

  Next, the amount of suppression of unnecessary electromagnetic radiation by placing a ground via serving as a return path with respect to the signal via is input to the radiation suppression amount input unit 203 by the operation of the designer (step S402). This input data is output to via distance calculation section 207.

  Next, the power plane extraction unit 204 extracts power planes formed between two or more ground planes from the layout information supplied from the layout information input unit 202 (step S403). This is because ground vias connect two or more ground planes, and in order to suppress unnecessary electromagnetic radiation from the power supply system by forming a return path for signal current by the ground vias. This is because the power plane needs to be formed between two or more ground planes.

  When extraction by the power plane extraction unit 204 includes a power plane formed between two or more ground planes (step S404), information about the extracted power plane is obtained as a signal via extraction unit. It is output to 205. On the other hand, when the power plane does not exist (step S404), the display unit 209 displays that the target power plane does not exist (step S411).

  Next, the signal via extraction unit 205 extracts signal vias arranged through the power plane from the information of the power plane supplied from the power plane extraction unit 204 (step S405). Here, when a signal via arranged through the power supply plane exists and is extracted (step S406), the signal via extraction unit 205 outputs the extracted information to the ground via extraction unit 208. On the other hand, when the signal via is not extracted (step S406), it is displayed on the display unit 209 that there is no problematic signal via (step S411).

  Next, in step S407, the inter-via distance calculation unit 207 calculates the distance between the signal via and the ground via for satisfying the input suppression amount of unnecessary electromagnetic radiation as shown below.

First, in the radiation suppression amount database 206, an approximate expression shown in the following equation (1) representing the relationship between the distance between vias and the suppression amount of unnecessary electromagnetic radiation, and a plurality of coefficient values (A, B) is set.
d = exp (ΔE−B) / A (1)
Here, d is the distance between the signal via and the ground via, and ΔE indicates the amount of suppression of unnecessary electromagnetic radiation.

  The via-to-via distance calculation unit 207 calculates the distance between the signal via and the ground via that satisfies the suppression amount of unnecessary electromagnetic radiation using the above formula (1). The calculation result is output to the ground via extraction unit 208 and also displayed on the display unit 209.

  As described above, when the distance between the signal via and the ground via for satisfying the input suppression amount of unnecessary electromagnetic radiation is calculated, the ground via extraction unit 208 outputs the distance from the signal via extraction unit 205. The ground vias arranged around the signal vias are extracted based on the information on the signal vias and the information on the via distance output from the via distance calculation unit 207 (step S408). That is, ground vias arranged in a circle centered on a signal via are extracted with a distance between vias as a radius.

  If a target ground via is extracted (step S409), the display unit 209 is notified that there is no problematic signal via (step S411). On the other hand, if the ground via is not extracted, information on the name and arrangement position of the corresponding signal via is output to the display unit 209 (step S411). Further, a circle whose radius is the distance between vias output from the via distance calculation unit 207 centered on the signal via from which the ground via has not been extracted is displayed in the layout image of the printed circuit board displayed on the display unit 209. Generate by adding to.

  As described above, according to the printed circuit board design support apparatus 201 of the present embodiment, it is confirmed at the design stage that the ground via for the signal via is arranged so as to satisfy the amount of suppression of unnecessary electromagnetic radiation. Is possible. In particular, the amount of unwanted electromagnetic radiation that can be suppressed can be specified quantitatively, and the layout of ground vias can be confirmed.Therefore, the design should be made while simultaneously considering high-density mounting of signal wiring and component placement and suppression of unnecessary electromagnetic radiation. Can be done. Even when the ground via is not properly arranged, the arrangement range of the ground via that satisfies the radiation suppression amount is displayed in the layout image, so that correction for suppressing unnecessary electromagnetic radiation can be easily performed.

  In addition, since the calculation of the distance between vias in the present invention uses an approximate expression, the time spent for the calculation can be very short, so that the design optimization process can be performed easily and in a short time.

  Here, the results of the three-dimensional electromagnetic field simulation and the actual measurement performed to derive an approximate expression for calculating the distance between the signal via and the ground via satisfying this from the amount of suppression of unnecessary electromagnetic radiation will be described.

  FIG. 5 is a plan view showing the configuration of the model used for the simulation by the printed circuit board design support apparatus 201. 6 shows the A-A ′ cross section of FIG. 5, and FIG. 7 shows the B-B ′ cross section of FIG. 5. In this example, as shown in the figure, the model printed board includes a dielectric substrate 501 having two ground planes 502, a ground plane 503, and one power supply plane 504. The dielectric substrate 501 has a relative dielectric constant of 4.3 by simulating FR-4 which is generally used.

  The printed board includes a signal via 505 penetrating the printed circuit board, and also includes a ground via A 506 and a ground via B 507 connecting the two ground planes 502, the ground plane 503. Further, a signal wiring 508 having a characteristic impedance of 50Ω connected to the signal via 505 is arranged on the surface of the printed circuit board, and the signal power 508 has a signal whose input power is normalized to 1 mW at all frequencies. A source 509 was connected. The signal wiring 508 has a characteristic impedance of 50Ω. A signal wiring 510 connected to the signal via 505 is disposed on the back surface of the printed board, and the signal wiring 510 is terminated by connecting a 50Ω termination resistor 511.

  In consideration of the fact that a normal printed circuit board is provided with screw holes for connection to a housing, two ground planes 502 and 503 are connected to each other at six ground plane connection points 512 on the outer periphery of the substrate. Note that the ground via A 506 and the ground via B 507 were arranged at a position d (mm) away from the signal via 505. By modeling in this way, voltage fluctuation is induced between the power plane and the ground plane by the current flowing through the signal via, and electromagnetic radiation using both planes as parallel plate antennas can be calculated.

  In this simulation, there are 3m points for three examples: a) when no ground via is placed, b) when either ground via A or ground via B is placed, and c) when two ground vias are placed. The radiated electric field strength of was calculated. An example of the simulation result is shown in FIG. In FIG. 8, the horizontal axis represents the frequency and the vertical axis represents the maximum value of the radiated electric field intensity at the point of 3 m. When the solid line does not arrange the ground via, the broken line shows the case where the ground via A is arranged at the position of d = 1 mm. The calculation results are shown. In FIG. 8, black circles indicate points where the radiation electric field intensity peaks due to resonance between the power plane and the ground plane. Here, four radiation peaks are observed.

  From FIG. 8, it can be confirmed that the radiation electric field intensity is suppressed by arranging the ground via. Further, when attention is paid to changes in the four radiation peaks, it can be seen that each is suppressed by about 10 dB. From this, it was confirmed that the arrangement of the ground via can suppress the radiation electric field intensity almost independent of the frequency. Moreover, although the resonant frequency has moved to the high frequency side by arrange | positioning a ground via, it has also confirmed that this change was small.

  In FIG. 9, the horizontal axis represents the distance between the signal via and the ground via, the vertical axis represents the amount of suppression of unnecessary electromagnetic radiation, the calculation result of the amount of suppression of unnecessary electromagnetic radiation with respect to the distance between vias, and the unnecessary electromagnetic radiation with respect to the distance between vias. It is a figure which shows the approximate expression which shows the relationship of the suppression amount of. In FIG. 9, first, the black square indicates the result when only the ground via A is disposed, and the black triangle indicates the result when both the ground via A and the ground via B are disposed. The solid line and the broken line will be described later. The electromagnetic wave radiated from the power plane and the ground plane is most prominently observed at the radiation peak caused by the resonance of both planes. For this reason, here, the fluctuation amount of the radiation peak intensity due to the arrangement of the ground via is defined as the amount of suppression of unnecessary electromagnetic radiation.

  Note that a normal printed circuit board generates a plurality of radiation peaks as described with reference to FIG. 8, but the amount of suppression of each radiation peak due to the arrangement of ground vias can be regarded as substantially constant. Here, the average value of the fluctuation amounts of a plurality of generated radiation peaks is used as the suppression amount of unnecessary electromagnetic radiation. By the way, in this simulation, even when only the ground via B is arranged, it is confirmed that the same result as that obtained when only the ground via A is arranged can be obtained.

  FIG. 9 shows that unnecessary electromagnetic radiation is greatly suppressed as the distance between the signal via and the ground via is shorter. Further, it can be seen that unnecessary electromagnetic radiation is greatly suppressed when both the ground vias A and B are arranged, compared to the case where only the ground via A is arranged.

The relationship between the distance between vias and the amount of suppression of unnecessary electromagnetic radiation can be approximated by a linear function with respect to the logarithmic value of the distance between vias, and the amount of radiation suppression is ΔE (dB) and the distance between vias is d (mm). Then, these relationships can be expressed by the following formula (2).
ΔE = A · ln (d) + B (2)

  The coefficient (constant) of the linear function (relational approximate expression) shown in this equation (2) can be determined from the above-described simulation result, and can be determined in advance by measurement. FIG. 9 also shows the approximate straight line determined in this way. When the solid line of FIG. 9 arranges only the ground via A, the broken line is an approximate straight line for the radiation suppression amount when both the ground via A and the ground via B are arranged. By solving the equation (2) for the inter-via distance d, the equation (1) is obtained, and the distance between vias that satisfies the radiation suppression amount inputted in advance can be calculated. As FIG. 9 shows, the shorter the distance between vias, the more the unnecessary electromagnetic radiation can be suppressed. Therefore, ground vias are arranged in a circle whose radius is the distance d between vias obtained by Equation (1) with the signal via as the center. For example, it is clear that a predetermined amount of suppression of unnecessary electromagnetic radiation is satisfied.

  As described above, the radiated electromagnetic waves generated from the power plane and the ground plane have a plurality of radiation peaks corresponding to the resonance modes of both planes. The amount of fluctuation of each radiation peak due to the arrangement of ground vias can be considered to be almost constant.However, when it is necessary to take into account the slight difference between each fluctuation amount, or when designing with an allowance for the amount of suppression of unwanted electromagnetic radiation The coefficients A and B in equation (1) may have a predetermined width (range).

  Next, in order to confirm the simulation result, a result obtained by making a prototype of a printed board and performing evaluation by actual measurement will be described. FIG. 10 is a plan view schematically showing the configuration of a prototype printed circuit board. 11 shows the A-A ′ cross section of FIG. 10, and FIG. 12 shows the B-B ′ cross section of FIG. 10. This printed circuit board has substantially the same configuration as that of the above-described simulation model described with reference to FIGS. 5, 6, and 7, and includes two ground planes 1002 and 1003 on a dielectric substrate (FR-4) 1001. , And one power plane 1004.

  Further, two ground planes 1002 and 1003 are connected by screw holes 1012 provided at six locations on the outer periphery of the substrate. In the substrate 1001, signal vias 1005 and 1015 penetrating the power plane 1004 and the ground planes 1002 and 1003 are provided at two locations. For these signal vias 1005 and 1015, the following three types of substrates were prepared.

  First, a prototype substrate 1 in which no ground via was arranged was produced. In addition, the prototype substrate 2 on which only the ground via A1006 and the ground via A′1016 were arranged was produced. In addition, the prototype substrate 3 on which the ground via A1006, the ground via A'1016, the ground via B1007, and the ground via B'1017 are arranged is produced.

  Here, arranging only the ground via A1006 and the ground via A′1016 means arranging only one ground via for the signal vias 1005 and 1015. In FIG. The same effect as arranging only the via A can be obtained. In addition, the arrangement of the ground via A1006, the ground via A′1016, the ground via B1007, and the ground via B′1017 means that two ground vias are arranged for each of the signal vias 1005 and 1015. FIG. The same effect as that of arranging both the ground via A and the ground via B in FIG.

  There are two types of via distances d of 1 mm and 5 mm. The signal wirings 1008, 1010, and 1018 have a characteristic impedance of 50Ω, an SMA connector 1013 is attached to one end, and the other end is terminated with a resistor 1023 of 50Ω. A signal source was connected via the SMA connector 1013, and the radiated electric field intensity at a point of 3 m was measured in a six-sided anechoic chamber. Note that the input power from the signal source is 1 mW at each measurement frequency, as in the simulation.

  An example of the measurement result is shown in FIG. In FIG. 13, when the horizontal axis indicates the frequency and the vertical axis indicates the maximum value of the radiated electric field intensity at the point of 3 m, the solid line indicates no ground via, and the broken lines indicate the ground via A′1016, the ground via B 1007, and the ground via B. The measurement result when '1017 is arranged at the position of d = 1 mm with respect to the signal vias 1005 and 1015 is shown. In FIG. 13, black circles indicate points where the radiation electric field intensity peaks due to resonance between the power plane and the ground plane. As shown in FIG. 13, as a result of evaluation measurement by actual measurement using a prototype substrate, a radiation electric field strength almost the same as that in the simulation was observed.

  As can be seen from FIG. 5 and FIG. 10, the distance between the signal wiring and the ground plane is different between the simulation and the prototype board. For this reason, a difference occurs in the intensity of electromagnetic wave radiation from the signal wiring, and the absolute value of the radiation electric field strength in the simulation result shown in FIG. 8 and the measurement result shown in FIG. 13 is different. Although there is a difference in the intensity of the radiated electric field due to the influence of the signal current, the same result is obtained in the simulation and the actual measurement result of the prototype board with respect to the radiation peak caused by the resonance between the power plane and the ground plane. That is, by arranging the ground via at a position 1 mm from the signal via, the electric field intensity at the radiation peak is suppressed by about 10 dB.

  FIG. 14 shows the measurement result of the amount of suppression of unnecessary electromagnetic radiation with respect to the distance between vias, where the horizontal axis represents the distance between the signal via and the ground via, and the vertical axis represents the amount of suppression of unnecessary electromagnetic radiation. In FIG. 14, first, when only the ground via A1006 and the ground via A′1016 are arranged in the black square, the black triangle shows the ground via A1006, the ground via A′1016, the ground via B1007, and the ground via B′1017. The result when arranged is shown.

  Further, in FIG. 9, the solid line and the broken line indicate a relational approximate expression between the distance between vias and the amount of radiation suppression obtained in the above-described simulation, and the solid line indicates that when only the ground via A1006 and the ground via A′1016 are arranged, A broken line indicates an approximate expression when both the ground via A1006, the ground via A′1016, the ground via B1007, and the ground via B′1017 are arranged.

  From FIG. 14, it can be confirmed that the radiation suppression amount obtained from the measurement result of the printed circuit board is in good agreement with the approximate expression obtained by the previous simulation with a difference within 1 dB.

  From the above results, it can be seen that the amount of suppression of unnecessary electromagnetic radiation with respect to the distance between the signal via and the ground via can be calculated using an approximate expression determined by simulation or actual measurement and its coefficient. In order to suppress unwanted electromagnetic radiation on various printed circuit boards by changing the combination of the layer configuration and the dielectric constant of the board material, etc., and determining the approximate expression and its coefficient as described above and storing them in the database The distance between the signal via and the ground via can be calculated.

  The radiation suppression amount database 206 according to the second embodiment of the present invention may store a relational approximate expression of the radiation suppression amount with respect to the distance between vias when a plurality of ground vias are arranged. For example, as in the above simulation, when one and two ground vias are arranged with respect to the signal via, an approximate straight line of the radiation suppression amount with respect to the distance between vias and a coefficient of this approximate straight line (approximate expression) are calculated. These are stored in the radiation suppression amount database 206. At this time, the via distance calculation unit 207 calculates the distance between vias required for satisfying the radiation suppression amount input from the radiation suppression amount input unit 203 for each number of ground vias arranged, and the ground via extraction unit. It outputs to 208. The ground via extraction unit 208 extracts the total number of ground vias arranged in a circle centered on the signal vias extracted by the signal via extraction unit 205 and having a radius between vias corresponding to the number of ground vias arranged. .

  Specifically, the distance between vias obtained from the relational approximate expression when one ground via is arranged is d1, and the distance between vias obtained from the relational approximate expression when two ground vias are arranged is d2. . First, when one or more ground vias are extracted in a circle having a radius d1 centered on the signal via extracted by the signal via extraction unit 205, there is no signal via that causes a problem in the display unit 209. Is output and the process is terminated. If ground vias are not extracted, the next step is to extract ground vias arranged in a circle having a radius d2 with the signal via as the center. Outputs that there are no vias and ends the process. Even in this processing, when the number of ground vias necessary for suppressing the radiation amount is not extracted, information on the name and arrangement position of the corresponding signal via is output to the display unit 209.

[Example 3]
Next, a third embodiment according to the present invention will be described. FIG. 15 is a configuration diagram showing the configuration of the main part of the printed circuit board design support apparatus 1501 according to the third embodiment of the present invention. A printed circuit board design support apparatus 1501 according to the third embodiment is obtained by adding a layout information changing unit 210 to the apparatus according to the second embodiment described above. The layout information changing unit 210 changes the information related to the layout of the printed circuit board output from the layout information input unit 202, and outputs the changed information to the power plane extraction unit 204. In FIG. 15, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted here.

  The hardware configuration of the printed circuit board design support apparatus of the present embodiment is basically the same as the configuration shown in FIG. The layout information input unit 10 is provided in the input / output device 303. Other functional units are the same as those in the second embodiment.

  Next, the operation of the printed circuit board design support apparatus 1501 of this embodiment will be described in detail. FIG. 16 is a flowchart illustrating an operation example of the printed circuit board design support apparatus 1501 according to the third embodiment. The operation will be described below with reference to FIGS.

  After the printed circuit board design support device 1501 is activated, a printed circuit board such as the layout of the power plane and ground plane, the mounting position of an electronic device such as an LSI or an IC, and a decoupling capacitor is input to the layout information input unit 202 by the operation of the designer. Data relating to the layout (layout information) is input (step S1601). The layout information input unit 202 stores the input layout information. This input data is supplied from the layout information input unit 202 to the layout information change unit 210. Also, based on the coordinates and connection information included in the layout information, an image of the printed circuit board layout is generated and output to the display unit 209.

  Next, in order to suppress voltage fluctuation between the power supply plane and the ground plane in the layout information changing unit 210 by the operation of the designer, the structure of the power supply plane and the ground plane, electronic devices such as LSI and IC, and decoupling capacitors, etc. The layout is changed, such as changing the mounting position, changing the wiring path of the signal wiring, adding or deleting the ground via, and changing the arrangement position (step S1602). The changed layout information is supplied to the power plane extraction unit 204. Further, based on the changed layout information, an image of the printed circuit board layout is generated and output to the display unit 209.

  Next, the amount of suppression of unnecessary electromagnetic radiation by placing a ground via serving as a return path with respect to the signal via is input to the radiation suppression amount input unit 203 by the operation of the designer (step S1602). This input data is output to via distance calculation section 207.

  Next, the power plane extraction unit 204 extracts a power plane formed between two or more ground planes from the layout information supplied from the layout information change unit 210 (step S1603). When extraction by the power plane extraction unit 204 includes a power plane formed between two or more ground planes (step S1604), information about the extracted power plane is obtained as a signal via extraction unit. It is output to 205. On the other hand, if there is no power plane (step S1604), the display unit 209 displays that there is no target power plane (step S1612).

  Next, the signal via extraction unit 205 extracts signal vias arranged through the power plane from the information of the power plane supplied from the power plane extraction unit 204 (step S1605). Here, when a signal via arranged through the power supply plane exists and is extracted (step S1606), the signal via extraction unit 205 outputs the extracted information to the ground via extraction unit 208. On the other hand, if no signal via is extracted (step S1606), it is displayed on the display unit 209 that there is no problematic signal via (step S1612).

  In step S1607, the via distance calculation unit 207 calculates the distance between the signal via and the ground via to satisfy the suppression amount of unnecessary electromagnetic radiation input in step S1602. First, an approximate expression (Expression (1)) and a plurality of coefficient values (A, B) included in Expression (1) representing the relationship between the distance between vias and the amount of suppression of unnecessary electromagnetic radiation are set. Expression (1) and the plurality of coefficient values (A, B) are stored in advance in the radiation suppression amount database 206. Using Equation (1), the distance between the signal via and the ground via that satisfies the suppression amount of unnecessary electromagnetic radiation is calculated, and the calculation result is output to the ground via extraction unit 208 and displayed on the display unit 209. .

  In the ground via extraction unit 208, ground vias arranged around the signal via based on the information on the signal via output from the signal via extraction unit 205 and the information on the inter-via distance output from the inter-via distance calculation unit 207. Is extracted (step S1608). That is, ground vias arranged in a circle centered on a signal via are extracted with a distance between vias as a radius.

  If a target ground via is extracted (step S1609), the display unit 209 is output that there is no problematic signal via (step S1612). On the other hand, when the ground via is not extracted, information on the name and arrangement position of the corresponding signal via is output to the display unit 209 (step S1610). Further, a circle whose radius is the distance between vias output from the via distance calculation unit 207 centered on the signal via from which the ground via has not been extracted is displayed in the layout image of the printed circuit board displayed on the display unit 209. Generate by adding to.

  Thereafter, the designer determines whether the layout needs to be changed based on the result displayed on the display unit 209. Here, if it is determined that there are no signal vias that pose a problem in order to suppress unnecessary electromagnetic radiation, or that ground vias are appropriately arranged, there is no need to change the layout information for this device. Enter a message. With this input, the printed circuit board design support apparatus 1501 ends all the processes (step S1611). On the other hand, if it is determined that the ground via is not properly arranged with respect to the signal via and it is necessary to change the layout, it is input that the layout information needs to be changed. With this input, the printed circuit board design support apparatus 1501 returns to step S1602 (step S1611).

  According to the printed circuit board design support apparatus 1501 of the third embodiment, in order to suppress unnecessary electromagnetic radiation generated from the power plane and the ground plane, the layout information changing unit 210 performs the structure of the power plane and ground plane, LSI, and IC. It is possible to change the mounting position of the electronic device and the decoupling capacitor, change the wiring path of the signal wiring, add or delete the ground via, and change the arrangement position. As a result, the design can be performed while confirming the effect of measures for suppressing unnecessary electromagnetic radiation from the power plane and the ground plane. Thereby, the printed circuit board which suppressed the unnecessary electromagnetic radiation can be designed.

[Example 4]
Next, a fourth embodiment according to the present invention will be described. FIG. 17 is a configuration diagram showing the configuration of the main part of the printed circuit board design support apparatus 1701 according to the fourth embodiment of the present invention. The printed circuit board design support apparatus 1701 of the fourth embodiment is obtained by changing the ground via extraction unit 208 to a signal via selection unit 1708 in the configuration shown in FIG. Based on the signal via information output from the signal via extraction unit 205, the signal via selection unit 1708 generates a layout image centered on an arbitrary signal via selected by the designer, and an inter-via distance calculation unit 207. A circle whose radius is the distance between the signal via and the ground via supplied from is further generated in the layout image and output to the display unit 209. In FIG. 17, the same components as those shown in FIG.

  The hardware configuration of the printed circuit board design support apparatus 1701 of the fourth embodiment is basically the same as the configuration shown in FIG. The signal via selection unit 1708 is provided in the input / output device 303. Other functional units are the same as those in the second embodiment.

  Next, the operation of the printed circuit board design support apparatus 1701 of this embodiment will be described in detail. FIG. 18 is a flowchart showing an operation example of the printed circuit board design support apparatus 1701 shown in FIG. The operation will be described below with reference to FIGS.

  After the printed circuit board design support device 1701 is activated, a printed circuit board such as the layout of the power plane and the ground plane, the mounting position of an electronic device such as an LSI or IC, and a decoupling capacitor is input to the layout information input unit 202 by a designer's operation. Data relating to the layout (layout information) is input (step S1801). The layout information input unit 202 stores the input layout information. This input data is supplied from the layout information input unit 202 to the power plane extraction unit 204. Also, based on the coordinates and connection information included in the layout information, an image of the printed circuit board layout is generated and output to the display unit 209.

  Next, an amount of suppression of unnecessary electromagnetic radiation by arranging a ground via serving as a return path with respect to the signal via is input to the radiation suppression amount input unit 203 by the operation of the designer (step S1802). This input data is output to via distance calculation section 207.

Next, the power plane extraction unit 204 extracts power planes formed between two or more ground planes from the layout information supplied from the layout information input unit 202 (step S1803).
When extraction by the power plane extraction unit 204 includes a power plane formed between two or more ground planes (step S1804), information about the extracted power plane is obtained as a signal via extraction unit. It is output to 205. On the other hand, if there is no power plane (step S1804), the display unit 209 displays that there is no target power plane (step S1810).

  Next, the signal via extraction unit 205 extracts signal vias arranged through the power plane from the information of the power plane supplied from the power plane extraction unit 204 (step S1805). Here, when a signal via arranged through the power plane exists and is extracted (step S1806), the signal via extraction unit 205 outputs the extracted information to the signal via selection unit 1708 (step S1807). . Further, the extracted information about the signal via is output in a list format to the display unit 209. The display unit 209 displays the information about the signal via in a state that can be operated by the operator. On the other hand, if no signal via is extracted (step S1806), the display unit 209 displays that there is no target signal via (step S1810).

  Next, in step S1808, the via distance calculation unit 207 calculates the distance between the signal via and the ground via to satisfy the suppression amount of unnecessary electromagnetic radiation input in step S1802. First, an approximate expression (Expression (1)) and a plurality of coefficient values (A, B) included in Expression (1) representing the relationship between the distance between vias and the amount of suppression of unnecessary electromagnetic radiation are set. Expression (1) and the plurality of coefficient values (A, B) are stored in advance in the radiation suppression amount database 206. Using Equation (1), the distance between the signal via and the ground via that satisfies the suppression amount of unnecessary electromagnetic radiation is calculated, and the calculation result is output to the ground via extraction unit 208 and displayed on the display unit 209. .

  Next, when the operator selects an arbitrary signal via from the list of signal vias displayed on the display unit 209, the signal via selection unit 1708 selects an operation from among the information about the signal via input from the signal via extraction unit 205. The signal via selected by the user is extracted. Then, a circle whose radius is the distance between vias supplied from the via distance calculation unit 207 with this signal via as the center is added to the layout image of the printed circuit board displayed on the display unit 209 (step S19809). .

  According to the printed circuit board design support apparatus 1701 of the fourth embodiment, in order to suppress unnecessary electromagnetic radiation generated from the power plane and the ground plane, the ground via should be arranged for any signal via selected by the designer. A range can be displayed. As a result, the designer checks whether the arrangement of the ground vias is appropriate, and adjusts the arrangement positions of the ground vias appropriately so that, for example, signal wiring and components can be arranged at high density while suppressing unnecessary electromagnetic radiation. can do. As a result, the degree of freedom in the layout design of the printed circuit board is increased, and a printed circuit board that achieves both high-density mounting and suppression of unnecessary electromagnetic radiation can be designed.

  Next, a simulation example by the printed circuit board design support apparatus 201 according to the second embodiment of the present invention will be described. In the following, the printed circuit board shown in FIG. This printed circuit board has a size of 145 mm × 210 mm in plan view. Further, as shown in a partial cross-sectional view of FIG. 20, the dielectric substrate 1901 includes two ground planes 1902, a ground plane 1903, and one power supply plane 1904. The ground plane 1902, the ground plane 1903, and the power plane 1904 have a size of 145 mm × 210 mm, like the printed circuit board.

  The printed circuit board includes signal vias 1905a and 1905b penetrating therethrough, and also includes a ground via 1906 that connects the two ground planes 1902 and 1903. The first LSI 1909 and the first LSI 1910 are mounted on the surface of the printed circuit board, the signal wiring 1908a having a width of 1.8 mm for connecting the first LSI 1909 and the signal via 1905a, and the width 1 for connecting the signal via 1905b and the second LSI 1910. .8 mm signal wiring 1908b. On the other hand, the back surface of the printed circuit board is provided with back surface signal wiring 1911 that connects the signal via 1905a and the signal via 1905b. In consideration of the fact that the printed board is provided with screw holes for connecting to the housing, the two ground planes 1902 and 1903 are connected to each other through six screw holes 1912 on the outer periphery of the board.

  A printed circuit board configured as described above is prepared. First, in the printed circuit board design support apparatus 201 according to the second embodiment, the layout information input unit 202 is input with the dimensions (145 mm × 210 mm) of the printed circuit board and the dielectric by the designer's operation. The dielectric constant of the substrate material of the body substrate 1901 (4.3), the plane dimensions of the power plane 1904 (145 mm × 210 mm), the plane dimensions of the two ground planes 1902 and 1903 (145 mm × 210 mm), the signal wirings 1908a and 1908b, and the back surface Information on the width (1.8 mm) of the signal wiring 1911 and these wiring routes, screw holes 1912 (six locations on the outer periphery of the substrate), ground vias 1906, and layout information indicating the positional relationship between them and the mounting positions of the first LSI 1909 and the second LSI 1910. input. When this layout information is input, a layout image generated based on the input information is displayed on the display unit 209.

  Next, the power plane extraction unit 204 extracts the power plane 1904 formed between the two ground planes 1902 and 1903, and the extracted information is output to the signal via extraction unit 205. In the signal via extraction unit 205, the signal via 1905 a and the signal via 1905 b are extracted as signal vias arranged through the power supply plane, and the extracted information is output to the ground via extraction unit 208.

  Next, when −10 dB was input as a suppression amount of unnecessary electromagnetic radiation to the radiation suppression amount input unit 203 by the operation of the designer, the input suppression amount was output to the via distance calculation unit 207. Next, an approximate expression having a plurality of coefficients corresponding to the input layout information of the printed circuit board is extracted from the radiation suppression amount database 206, and the via distance calculation unit 207 satisfies −10 dB which is the suppression amount of unnecessary electromagnetic radiation. The distance between the signal via 1905b and the ground via 1906 was calculated. The distance between vias calculated as a result was displayed as 1.2 mm when arranging one ground via and 6.3 mm when arranging two ground vias. Data on the number of ground vias arranged and the distance between vias is output to the ground via extraction unit 208.

  Next, the ground via extraction unit 208 first searches for ground vias arranged in a circle having a radius of 1.2 mm with the signal via 1905a as the center. As a result, ground vias were not extracted, and ground vias arranged in a circle with a radius of 6.3 mm were searched. Here, since the ground via was not extracted, the information of the signal via 1905a was displayed and output on the display unit 209. Further, as shown in FIG. 21, a circle 2101 having a radius of 1.2 mm and a circle 2102 having a radius of 6.3 mm are generated in addition to the layout image 2110 around the signal via 1905a, and these are displayed on the display unit 209. It was done.

  Next, the ground via extraction unit 208 searches for ground vias arranged in a circle having a radius of 1.2 mm with the signal via 1905b as the center. As a result, ground vias were not extracted, and ground vias arranged in a circle with a radius of 6.3 mm were searched. As a result, the number of extracted ground vias is one, and since two or more ground vias are not arranged in a circle with a radius of 6.3 mm, the information of the signal via 1905b is output to the display unit 209. Further, as shown in FIG. 22, a circle 2201 having a radius of 1.2 mm and a circle 2202 having a radius of 6.3 mm are generated in addition to the layout image 2210 around the signal via 1905b, and these are displayed on the display unit 209. It was done.

  As a result of the above, it was confirmed that the ground vias were not properly disposed in both the signal via 1905a and the signal via 1905b with respect to the radiation suppression amount −10 dB.

  Further, when the same operation as described above was performed with the radiation suppression amount set to −6 dB, the via distance calculated by the via distance calculation unit 207 was 3.7 mm when one ground via was arranged, and 2 ground vias were arranged. When placed individually, it was displayed as 13.1 mm. The ground via extraction unit 208 first extracts ground vias arranged in a circle having a radius of 3.7 mm with the signal via 1905a as the center. As a result, no ground via was extracted, and therefore, a ground via arranged in a circle having a radius of 13.1 mm was extracted. Here, since the ground via was not extracted, the information of the signal via 1905a was displayed and output on the display unit 209. Further, a circle having a radius of 3.7 mm and a radius of 6.3 mm around the signal via 1905 a is further generated in the layout image and displayed on the display unit 209. Next, ground vias arranged in a circle having a radius of 3.7 mm with the signal via 1905b as the center were extracted. As a result, since one ground via was extracted, the processing was terminated.

  Next, a simulation example by the printed circuit board design support apparatus 1701 in the fourth embodiment of the present invention will be described. As described above, the printed circuit board shown in FIG.

  First, in the layout information input unit 202 of the printed circuit board design support apparatus 1701, the dimensions of the printed circuit board (145 mm × 210 mm), the dielectric constant of the substrate material of the dielectric substrate 1901 (4.3), and the planar dimensions of the power plane 1904 (145 mm × 210 mm), the plane dimensions (145 mm × 210 mm) of the two ground planes 1902 and 1903, the widths (1.8 mm) of the signal wirings 1908 a and 1908 b and the back surface signal wiring 1911, information on these wiring paths, screw holes 1912 (board periphery 6 ), Ground vias 1906, and layout information indicating the positional relationship between them and the mounting positions of the first LSI 1909 and the second LSI 1910. When this layout information is input, a layout image generated based on the input information is displayed on the display unit 209.

  Next, the power plane extraction unit 204 extracts the power plane 1904 formed between the two ground planes 1902 and 1903, and the extracted information is output to the signal via extraction unit 205. In the signal via extraction unit 205, the signal via 1905 a and the signal via 1905 b are extracted as signal vias arranged through the power supply plane, and the extracted information is output to the signal via selection unit 1708. In addition, information regarding the extracted signal via 1905a and the signal via 1905b is converted into a list format and output to the display unit 209 in an operable state.

  Next, when −10 dB was input as a suppression amount of unnecessary electromagnetic radiation to the radiation suppression amount input unit 203 by the operation of the designer, the input suppression amount was output to the via distance calculation unit 207. Next, an approximate expression having a plurality of coefficients corresponding to the input layout information of the printed circuit board is extracted from the radiation suppression amount database 206, and the via distance calculation unit 207 satisfies −10 dB which is the suppression amount of unnecessary electromagnetic radiation. The distance between the signal via and the ground via was calculated. The distance between vias calculated as a result was displayed as 1.2 mm when arranging one ground via and 6.3 mm when arranging two ground vias. Data on the number of ground vias arranged and the distance between the vias was output to the signal via selection unit 1708.

  Next, when the signal via 1905a is selected from the list of signal vias displayed on the display unit 209 by the operation of the designer, the signal via 1905a is extracted by the signal via selection unit 1708, as shown in FIG. In addition, a circle 2101 having a radius of 1.2 mm and a circle 2102 having a radius of 6.3 mm centered on the signal via 1905 a are generated in the layout image 2110, and these are displayed on the display unit 209.

  Next, when the signal via 1905b is selected from the list of signal vias displayed on the display unit 209 by the operation of the designer, the signal via 1905b is extracted by the signal via selection unit 1708, as shown in FIG. In addition, a circle 2201 having a radius of 1.2 mm and a circle 2202 having a radius of 6.3 mm are additionally generated in the layout image 2210 with the signal via 1905 b as the center, and these are displayed on the display unit 209.

  Thereby, in the signal via 1905a and the signal via 1905b, the arrangement range of the ground via satisfying the radiation suppression amount −10 dB was confirmed. Further, it was found that the signal via 1905b can satisfy the radiation suppression amount by bringing the currently disposed ground via close to the signal via or adding one ground via within 6.3 mm from the signal via.

It is a block diagram which shows the structural example of the printed circuit board design assistance apparatus in Example 1 of this invention. It is a block diagram which shows the structure of the principal part of the printed circuit board design assistance apparatus in Example 2 of this invention. It is a block diagram which shows the structure of the principal part of the printed circuit board design assistance apparatus in Example 2 of this invention. 3 is a flowchart showing an operation of the printed circuit board design support apparatus 201 shown in FIG. 3 is a plan view illustrating a configuration of a model used for simulation by the printed circuit board design support apparatus 201. FIG. It is sectional drawing which shows the A-A 'cross section of FIG. It is sectional drawing which shows the B-B 'cross section of FIG. It is a characteristic view showing the result of having calculated the radiation electric field intensity by the simulation by the printed circuit board design support apparatus 201. It is explanatory drawing which shows the approximate expression which shows the result of having calculated the suppression amount of the unnecessary electromagnetic radiation with respect to the distance between vias, and the relationship of the suppression amount of the unnecessary electromagnetic radiation with respect to the distance between vias. It is a top view which shows typically the structure of the prototype printed circuit board. It is sectional drawing which shows the A-A 'cross section of FIG. It is sectional drawing which shows the B-B 'cross section of FIG. It is a characteristic view showing the result of having calculated the radiated electric field strength of the trial printed circuit board by the printed circuit board design support apparatus 201. It is explanatory drawing which shows the approximate expression which shows the result of calculating the suppression amount of the unnecessary electromagnetic radiation with respect to the distance between vias by the prototype printed circuit board, and the relationship of the suppression amount of the unnecessary electromagnetic radiation with respect to the distance between vias. It is a block diagram which shows the structure of the principal part of the printed circuit board design assistance apparatus 1501 in Example 3 which concerns on this invention. 10 is a flowchart illustrating an operation example of a printed circuit board design support apparatus 1501 according to the third embodiment. It is a block diagram which shows the structure of the principal part of the printed circuit board design assistance apparatus 1701 in Example 4 which concerns on this invention. 18 is a flowchart illustrating an operation example of the printed circuit board design support apparatus 1701 illustrated in FIG. 17. 3 is a plan view showing a configuration of a printed circuit board to be simulated by the printed circuit board design support apparatus 201. FIG. It is sectional drawing which shows the partial cross section of FIG. 6 is an explanatory diagram illustrating a display example displayed by the printed circuit board design support apparatus 201. FIG. 6 is an explanatory diagram illustrating a display example displayed by the printed circuit board design support apparatus 201. FIG. FIG. 11 is a cross-sectional view schematically showing a configuration of a printed circuit board 2304 showing that signal vias 2301 are disposed through a power plane 2302 and a ground plane 2303.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Layout information storage part, 102 ... Radiation suppression amount storage part, 103 ... Power supply plane extraction part, 104 ... Signal via extraction part, 105 ... Via distance calculation part, 201 ... Printed circuit board design support apparatus, 202 ... Layout information input , 203 ... Radiation suppression amount input unit, 204 ... Power plane extraction unit, 205 ... Signal via extraction unit, 206 ... Radiation suppression amount database, 207 ... Inter-via distance calculation unit, 208 ... Ground via extraction unit, 209 ... Display unit .

Claims (12)

Layout information storage means for storing layout information including at least information indicating a structure of a ground plane, a structure of a power plane, and a structure of a signal via;
Radiation suppression amount storage for storing an approximate expression indicating the relationship between the suppression amount of unnecessary electromagnetic radiation generated from a power supply system composed of a power plane and a ground plane and the distance between a signal via and a ground via connecting two ground planes Means,
Power plane extraction means for extracting power plane information indicating the structure of the power plane disposed between the two ground planes from the layout information;
A signal via extraction means for extracting signal via information indicating a structure of a signal via penetrating two ground planes sandwiching a power plane corresponding to the power plane information from the layout information;
A printed circuit board design support apparatus comprising at least via distance calculation means for calculating a distance between the signal via indicated by the signal via information and the ground via by the approximate expression. The printed circuit board design support apparatus according to claim 1,
Ground via extraction means for extracting, from the layout information, ground via information indicating the structure of ground vias arranged within the distance calculated by the inter-via distance calculation means for the signal via indicated by the signal via information. A printed circuit board design support apparatus comprising: In the printed circuit board design support device according to claim 1 or 2,
Display means for displaying a circle whose radius is the distance calculated by the inter-via distance calculation means centered on the signal via indicated by the signal via information together with a layout diagram generated from the layout information. Printed circuit board design support device. In the printed circuit board design support device according to claim 3,
Comprising a signal via selection means for selecting the signal via information to be input instruction;
The printed circuit board design support apparatus, wherein the display unit displays the circle corresponding to the signal via information selected by the signal via selection unit. A layout information storage step for storing layout information including at least information indicating a structure of a ground plane, a structure of a power plane, and a structure of a signal via;
Radiation suppression amount storage stored by an approximate expression indicating the relationship between the suppression amount of unnecessary electromagnetic radiation generated from a power supply system composed of a power plane and a ground plane and the distance between the signal via and the ground via connecting the two ground planes Steps,
A power plane extraction step for extracting power plane information indicating a structure of a power plane arranged between the two ground planes from the layout information;
A signal via extraction step for extracting signal via information indicating a structure of a signal via penetrating two ground planes sandwiching a power plane corresponding to the power plane information from the layout information;
A printed circuit board design support method comprising at least an inter-via distance calculating step of calculating a distance between the signal via indicated by the signal via information and the ground via by the approximate expression. The printed circuit board design support method according to claim 5,
A ground via extraction step for extracting, from the layout information, ground via information indicating a structure of a ground via disposed within the distance calculated in the inter-via distance calculation step with respect to the signal via indicated by the signal via information. A printed circuit board design support method, comprising: The printed circuit board design support method according to claim 5 or 6,
A display step of displaying a circle having a radius of the distance calculated by the inter-via distance calculation step centered on the signal via indicated by the signal via information together with a layout diagram generated from the layout information. Printed circuit board design support method. The printed circuit board design support method according to claim 7,
A signal via selection step for selecting the signal via information to be input instruction;
In the display step, the circle corresponding to the signal via information selected in the signal via selection step is displayed. On the computer,
A layout information storage function for storing layout information including at least information indicating a structure of a ground plane, a structure of a power plane, and a structure of a signal via;
Radiation suppression amount storage stored by an approximate expression indicating the relationship between the suppression amount of unnecessary electromagnetic radiation generated from a power supply system composed of a power plane and a ground plane and the distance between the signal via and the ground via connecting the two ground planes Function and
A power plane extraction function that extracts power plane information indicating a structure of a power plane arranged between the two ground planes from the layout information;
A signal via extraction function for extracting signal via information indicating a structure of a signal via penetrating two ground planes sandwiching a power plane corresponding to the power plane information from the layout information;
A program for realizing at least an inter-via distance calculation function for calculating a distance between a signal via indicated by the signal via information and the ground via by the approximate expression. The program according to claim 9, wherein
A ground via extraction function for extracting, from the layout information, ground via information indicating a structure of a ground via disposed within a distance calculated by the inter-via distance calculation function with respect to the signal via indicated by the signal via information; A program characterized by comprising. The program according to claim 9 or 10,
A display function for displaying a circle whose radius is the distance calculated by the inter-via distance calculation function centered on the signal via indicated by the signal via information together with a layout diagram generated from the layout information. program. The program according to claim 11, wherein
Provided with a signal via selection function for selecting the signal via information to be input instructions,
In the display function, the circle corresponding to the signal via information selected by the signal via selection function is displayed.

Images