JP2000019204A - Noise source searching equipment for printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise source searching equipment for printed board in which noise intensity distribution dependent on the fluctuation of frequency can be analyzed in a short time by decreasing the number of measuring times. SOLUTION: An image of a printed board 1 to be measured is taken into a personal computer 11 and a micro antenna probe 13b is scanned, at a scanning section 13, along the two-dimensional plane of the printed board 1 in order to detect a radiation noise. The radiation noise is subjected to frequency analysis by means of a spectrum analyzer 14 and the intensity level is stored in the memory of the personal computer 11 along with the positional information of each measuring section. Subsequently, map data are generated and displayed on a display 21 while being superposed on image data. The personal computer 11 generates the map data based on the spectrum data over the entire frequency range and the positional information.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an improvement in a device for searching for a noise source of a board that can display a source of electromagnetic noise radiated from a printed board on which an electronic circuit is mounted on a display.

[0001]

TECHNICAL FIELD OF THE INVENTION

[0002]

2. Description of the Related Art Recent printed circuit boards have been increasing in packing density with the miniaturization of electronic devices, and have become more susceptible to radiating electromagnetic wave noise due to higher operating frequency. Therefore, measures against electromagnetic interference (EMI) have been taken. Is becoming more and more difficult. Most of the sources of electromagnetic wave noise on printed circuit boards are electronic elements that are components of electronic circuits.
This EMI countermeasure for the printed circuit board largely depends on the pattern design, and its evaluation requires a great deal of time and effort.

In order to search for a source of electromagnetic wave noise on the printed circuit board, a large number of loop antennas are arranged in a grid to form an electromagnetic wave noise detecting section, and the printed circuit board to be measured is operated to measure near-field radiation. Devices for measuring the frequency intensity distribution have been developed. However, in this device, there is a limit to the arrangement density of a large number of loop antennas, which may cause inaccuracy in grasping the position, and there is a problem in that it is expensive because the characteristics of each loop antenna must be uniform. .

Meanwhile, Japanese Patent Application Laid-Open No. Hei 5-31286 discloses this.
In Japanese Patent Publication No. 7 (1999), a small antenna probe is scanned along the surface of a printed circuit board to be measured, a noise intensity at each scanning position is detected, and a noise intensity distribution diagram is created. There has been proposed a noise finder device for simultaneously displaying images on a printed circuit board. In this device, the noise intensity distribution diagram and the image of the printed circuit board to be measured are combined and displayed, so that the noise source can be easily specified.However, it is necessary to repeatedly scan to obtain the noise intensity distribution diagram for each frequency band. Therefore, there is a possibility that the number of measurement steps may be increased, and it takes time to perform a comparative study.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and makes it possible to accumulate data over the entire measurement frequency range generated from a printed circuit board to be measured in one measurement, and to obtain a noise intensity distribution for each frequency band. By simply specifying the frequency band, the noise intensity distribution diagram of the printed circuit board to be measured and the image can be superimposed and displayed, making it possible to reduce the number of measurements and easily analyze the noise intensity distribution due to frequency changes in a short time. It is an object of the present invention to provide an apparatus for searching for a noise source of a substrate.

[0006]

In order to achieve the above object, a device for detecting a noise source of a printed circuit board according to the present invention comprises: an image data generating section for generating image data of a measured printed circuit board; A scanning unit having a small antenna probe for noise detection that scans with a motor along the surface of the surface, a spectrum analyzer that performs frequency analysis of noise at each scanning position of the small antenna probe, and a scanning position of the scanning unit with the motor And generates a noise intensity distribution map based on the intensity level for each frequency input from the spectrum analyzer for each scanning position, and superimposes the noise intensity on the image data input from the image data generation unit. A personal computer that displays the distribution map on a display In the apparatus for searching for a noise source of a printed circuit board, the personal computer specifies a memory that stores intensity levels and position information over the entire range of the measurement frequency input from the spectrum analyzer, and specifies a specific frequency band within the range of the measurement frequency. The measurement condition setting means, and the intensity level and the position information in the specific frequency band designated by the measurement condition setting means are read from the memory to obtain a peak value of the intensity level, and the noise intensity distribution is obtained by the peak value and the position information. And data analysis means for generating the data. Reduces the number of measurements by storing in the memory the spectrum data of the entire measurement frequency generated from the printed circuit board to be measured, creating map data with the data analysis means, and superimposing the noise intensity distribution diagram and the camera image on the display. Noise distribution analysis due to a change in frequency is facilitated in a short time.

[0007] The data analysis means includes: a level value detection section for obtaining a maximum value of intensity levels in a specific frequency band designated by the measurement condition setting means;
It is preferable to have a map data creation unit that creates a noise intensity distribution based on the intensity level obtained by the level value detection unit and its position information, in that noise distribution analysis due to a change in frequency can be easily performed in a short time.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. FIGS. 1 to 4 are diagrams for explaining a printed circuit board noise source detecting apparatus according to an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of the apparatus, FIG. 2 is a schematic external view showing the configuration of the apparatus, and FIG. FIG. 4 is a diagram for explaining a movement interval of a probe in the device, and FIG. 4 is a diagram for explaining a measurement frequency and an intensity level at each scanning position of the device.

In these figures, the printed circuit board noise source detecting apparatus 10 of the present embodiment simultaneously displays the distribution of electromagnetic noise radiated from the measured printed board 1 on the camera image of the measured printed board 1. A personal computer 11 that performs various types of data processing, an image data generator 12 that obtains image data of the printed circuit board 1 to be measured, and scans the minute antenna probe 13b along the surface of the printed circuit board 1 to be measured. A scanning unit 13 for obtaining the positional information, a spectrum data generating unit 14 for analyzing the frequency of noise detected by the small antenna probe 13b of the scanning unit 13, and the like.

The image data generating unit 12 includes a CCD camera 12a for projecting a component mounting surface (front surface) or a pattern surface (back surface) of the printed circuit board 1 to be measured, and a CCD camera 12a.
An image processing unit 12b that converts image data projected by the camera 12b into image data that can be captured by the personal computer 11. The CCD camera 12a can adjust a zoom ratio, a focus, and the like according to, for example, the size and the measurement range of the printed circuit board 1 to be measured. As shown in FIG. A column 29 is provided on the scanning section main body 13a so as to be disposed above the measurement printed circuit board 1, and is attached to an end of the column 29.

The scanning section 13 includes a scanning section main body 13a on which the printed circuit board 1 to be measured can be mounted on the upper surface by a set plate or the like and in which a scanning mechanism or the like is housed.
A small antenna probe 13b for detecting a noise signal, which is attached to a scanning mechanism in the scanning unit body 13a.
And a motor 13c composed of a stepping motor or the like for driving a scanning mechanism for moving the minute antenna probe 13b on a horizontal two-dimensional plane in the X-axis and Y-axis directions.
And an amplifier 13d for amplifying a noise signal detected by the minute antenna probe 13b to a value suitable for the spectrum data generating unit 14, an encoder 13e for detecting a scanning position, and the like. The small antenna probe 13b is a small-diameter loop coil, and
A magnetic flux generated by a current flowing therethrough passes through the loop coil to generate an electromotive force.
It is necessary to reduce the size so that the difference from the neighborhood of the mm square area can be detected. The frequency characteristic of a typical small antenna probe 13b is, for example, 30 MHz to 3 GHz.
One that can cover the normal measurement frequency range is used. The small antenna probe 13b preferably has a substantially flat characteristic in the entire measurement frequency range. However, the measurement data may be corrected by the correction data. The amplifier 13d performs impedance matching and further obtains a gain of about 40 dB. The standard frequency characteristic of the amplifier 13d is, for example, 300
The frequency is from KHz to 1.5 GHz, and can be changed to 25 MHz to 3 GHz by replacing the option.

The spectrum data generator 14 comprises a spectrum analyzer 14a for analyzing the frequency of noise detected by the minute antenna probe 13b and outputting an intensity level with respect to the frequency as spectrum data. The signal from the spectrum analyzer 14a is taken into the personal computer 11 by GPIP.

The personal computer 11 is a data processing unit 1 constituting a central processing unit of a computer main body.
5, an image data memory 16 for storing image data from the image data generation unit 12, a position data memory 17 for storing position information from the encoder 13e of the scanning unit 13, and a spectrum data from the spectrum data generation unit 14. Spectrum data memory 18 to be stored
And a program memory 19 for storing a program for data processing executed by the data processing unit 15, a keyboard 20 for operating various settings, data input or start and end, and display of analysis results and the like. And a printer 22 for printing data or display contents.

The data processing section 15 is a section for performing various data processings executed by a program stored in the program memory 19 or the like. A data input / output unit 23 for controlling input / output, a motor control unit 24 for controlling operation of the motor 13c in the scanning unit 13, a measurement condition setting unit 25 for setting various measurement conditions, and a display / printing unit Data analysis means 26 for analyzing the data, and output processing means 27 for outputting the image data and the noise intensity distribution of the analyzed spectrum data to the display 21 or the printer 22.

The measurement condition setting means 25 is a selection of the small antenna probe 13b or the spectrum analyzer 14a, setting of a measurement range in an image, and a moving pitch of the small antenna probe 13b according to a width and a height in the measurement range of the image. A frequency specification unit 25a having a part for setting a measurement section, etc., and setting a measurement frequency range and specifying a specific frequency band within the frequency range;
Having. Then, as shown in FIG. 3, for example, the motor control means 24 divides the width direction (X-axis direction) equally into m and the height direction (Y-axis direction) equally into n, as shown in FIG. Is a part for controlling the motor 13c so as to automatically and automatically move each section (the central part indicated by a circle in the figure) within the range set in the above. The movement of the small antenna probe 13b by the motor 13c is, for example, 0.
It can be controlled in units of 1 mm. The setting of the measurement frequency range in the frequency designation unit 25a includes a start frequency at which measurement is started, a stop frequency at which measurement is stopped,
By setting the frequency step and the like, the number of measurement points within the image range is determined. The specification of the specific frequency band in the frequency specification unit 25a is to specify a frequency band to be observed within the measurement frequency range. The data analysis unit 26 includes a level value detection unit 26a that calculates a peak value of the measured intensity level for each frequency step, and a two-dimensional intensity distribution based on the peak value calculated by the level value detection unit 26a and position information. And a map data creating unit 26b for creating That is, the level value detector 26
3A shows each frequency step (f1 to fk) of the measurement frequency range (range shown in FIG. 4A) while the small antenna probe 13b sequentially moves in each section in the range shown in FIG. 3 and stops in each section. Of the intensity level shown in FIG.
Lmnk), the peak value of the intensity level of the specific frequency band (range shown in FIG. 4B) designated by the frequency designation unit 25a is calculated. Then, the map data creation unit 26b assigns the peak value calculated by the level value detection unit 26a to, for example, one of a plurality of stage divisions corresponding to color classification, and combines the stage division with the position information of the division. Creates map data corresponding to the plane intensity distribution. The output processing unit 27 superimposes the map data created by the data analysis unit 26 and the image data from the image data generation unit 12 on the display 21 or enables the printer 22 to print the map data. This is the part that performs output processing.

Next, the operation procedure of the noise source locating apparatus having the above configuration will be described. FIG. 5 is a flowchart showing an operation procedure by the device according to the embodiment of the present invention.

In FIG. 1, first, the printed circuit board 1 to be measured is mounted on the upper surface of the scanning section main body 13a with a set plate or the like, and the personal computer 11 is started.
The power of the image data generation unit 12, the scanning unit 13, and the spectrum data generation unit 14 is turned on, and the power of the printer 22 is turned on as necessary (ST1). Next, before the measurement, the personal computer 11 selects an antenna probe and a spectrum analyzer (ST2). That is, a setting for selecting the same one as the small antenna probe 13b attached to the scanning mechanism of the scanning unit 13 is performed.
a, setting for selecting the resolution bandwidth, the video band, the attenuator, the number of measurements, and the like. Next, an image position is set in the image data generation unit 12 (ST3).
In setting the image position, the CCD camera 12a adjusts the zoom ratio and focus according to the size of the printed circuit board 1 to be measured and the measurement range, and adjusts the aperture and the like according to the illumination. The still image of the CCD camera 12a is taken into the personal computer 11 via the image processing unit 12b and stored in the image data memory 16. next,
The measurement condition setting means 25 sets measurement conditions such as setting of a measurement frequency range, setting of a measurement range, setting of alignment and emission measurement (ST4). That is, the start frequency, the stop frequency, and the frequency step are set, the measurement range in the image is set, and the image is aligned with the minute antenna probe 13b. Then, the setting of the width, the height, the division and the number of times in the image, and the setting of the emission measurement for recording data of the entire frequency range set for each measurement position are performed.

Next, the printed circuit board 1 to be measured is operated and measurement is performed (ST5). That is, when the measurement start is operated from the keyboard 20 or the like, the scanning unit 13 starts scanning the sections of the range where the small antenna probe 13b is set by controlling the motor 13c by the motor control unit 24 in a predetermined order, At the same time, the position information is detected by the encoder 13e. Small antenna probe 13b
Detects the radiation noise from the measured printed circuit board 1 while each section is stopped, a signal of the detected radiation noise is amplified by the amplifier 13d, and then the frequency analysis is performed by the spectrum analyzer 14a. Output as spectrum data. Position information and spectrum analyzer 1 from encoder 13e
4a is taken into the personal computer 11 and stored in the position data memory 17a.
And stored in the spectrum data memory 18. Next, after scanning the entire measurement range, the data analysis unit 26 performs data analysis by detecting a level value and creating map data (ST6). Then, the output processing means 27
The map data created by the data analysis means 26 and the image data from the image data generator 12 are superimposed and displayed on the display 21 (ST7). Next, a comparative study is performed based on the display (ST8), and after a predetermined measure is taken (ST9), the same measurement is repeated again. The display image on the display 21 is printed by the printer 22 as necessary.

FIG. 6 shows a display example by the apparatus according to the embodiment of the present invention. A noise distribution diagram 32 based on map data is displayed on the display 21 so as to be superimposed on a camera image 31 of the printed circuit board 1 to be measured. In the lower part, a spectrum diagram 33 for each position is displayed with the horizontal axis as the measurement frequency and the vertical axis as the intensity level value. Noise distribution diagram 3
In 2, the same area surrounded by the curve is displayed as a color-coded distribution diagram because the peak values belong to the same color step classification. The spectrum diagram 33 displays the spectrum data at the point P in the noise distribution diagram 32, and when a specific frequency band is designated, the shaded zone band 34 is displayed in the spectrum diagram 33 by color coding or the like. By moving the zone band 34 within the entire measurement frequency range and changing the frequency band, it is possible to easily know the change in the noise distribution diagram 32 on the camera image 31.

As described above, according to the printed circuit board noise source detecting apparatus 10 having the above-described configuration, the image data of the component mounting surface or the pattern surface of the measured printed circuit board 1 generated by the image data generating unit 12 is transmitted to the personal computer. 11, the scanning unit 13 scans the small antenna probe 13a along the two-dimensional plane of the printed circuit board 1 to be detected, detects radiation noise from the printed circuit board 1, and outputs the detected radiation noise. The frequency analysis is performed by the spectrum data generation unit 14 to obtain an intensity level for the frequency. The intensity level and the position information of each measurement section are taken into the personal computer 11 and stored in the memories 17 and 18. Map data of two-dimensional distribution map from values and their location information Form, by superimposing the map data to the image data by displaying on the display 21 by the output processing unit 27, a camera image 31 of the measurement printed circuit board 1
And the noise distribution diagram 32 can be visually grasped. Measurement condition setting means 25 of data processing unit 15
Can specify a specific frequency band within the range of all measurement frequencies, and the data analysis means 26 uses the spectrum data and position information of the entire measurement frequency range stored in the spectrum data memory 18 and the position data memory 17 in advance. In order to create the map data, the intensity distribution and intensity tendency of the radiation noise of the measured printed circuit board 1 can be grasped in a short time only by moving the specific frequency band within the entire measurement frequency range and changing the frequency band. In addition, it is easy to narrow down the points to be dealt with, and the number of measurements can be reduced.

In the apparatus of the present invention, the measurement frequency range can be set arbitrarily by setting the start frequency and the stop frequency. However, it is preferable that the measurement frequency range be set so as to cover at least the entire frequency range to be measured. The specific frequency band may be arbitrarily specified within the entire measurement frequency range. Further, the map data only needs to be displayed in such a manner that at least the intensity level is color-coded by color or the like, and the color, the number of steps, and the like can be arbitrarily set. Furthermore, the scanning of the minute antenna probe 13b may be performed on an arbitrary trajectory as needed, and is not limited to the embodiment.

In this embodiment, the scanning unit 13 is provided with the encoder 13e for detecting the scanning position, but the position information is calculated based on, for example, control information from the motor control unit 24. If you do
The encoder 13e may not be provided.

[0023]

As described above, the apparatus for detecting a noise source of a printed circuit board according to the present invention enables the accumulation of spectrum data over the entire measurement frequency range generated from a printed circuit board to be measured in one measurement, and By simply specifying the frequency band, the noise intensity distribution diagram can be displayed by superimposing the noise intensity distribution diagram on the measured PCB and the camera image, reducing the number of measurements and simplifying the noise distribution analysis by changing the frequency in a short time. become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a printed circuit board noise source searching apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic external view showing the configuration of a printed circuit board noise source searching apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a probe movement interval in the printed circuit board noise source searching apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram for explaining a measurement frequency and an intensity level at each scanning position of the printed circuit board noise source searching apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation procedure of the printed circuit board noise source searching apparatus according to the embodiment of the present invention.

FIG. 6 is a diagram showing a display example of the printed circuit board noise source searching apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printed circuit board to be measured 10 apparatus for detecting noise source of printed circuit board 11 personal computer 12 image data generation unit 12a CCD camera 12b image processing unit 13 scanning unit 13b micro antenna probe 13c motor 13d amplifier 13e encoder 14 spectrum data generation unit 15 data processing unit 16 Image data memory 17 Position data memory 18 Spectrum data memory 19 Program memory 20 Keyboard 21 Display 22 Printer 23 Data input / output means 24 Motor control means 25 Measurement condition setting means 25a Frequency designation unit 26 Data analysis unit 26a Level detection unit 26b Map data Creation unit 27 Output processing unit 29 Support 31 Camera image 32 Noise distribution diagram 33 Spectrum diagram 34 Zone band

Claims (2)

[Claims] An image data generating unit for generating image data of the measured printed circuit board; a scanning unit having a small antenna probe for noise detection scanned by a motor along a surface of the measured printed circuit board; A spectrum analyzer that performs frequency analysis of noise at each scanning position of the minute antenna probe, and a scanning position controlled by a motor of the scanning unit is controlled, and based on an intensity level for each frequency input from the spectrum analyzer for each scanning position. A noise intensity distribution map, and a personal computer for displaying the noise intensity distribution map on a display by superimposing the noise intensity distribution map on the image data input from the image data generator. The computer A memory for storing the intensity level and position information over the entire range of the measurement frequency input from the ram analyzer, a measurement condition setting unit for specifying a specific frequency band within the range of the measurement frequency, and a specification specified by the measurement condition setting unit. A printing method comprising: reading out the intensity level in the frequency band and its position information from the memory to obtain a peak value of the intensity level; and generating a noise intensity distribution based on the peak value and the position information. Equipment for detecting noise sources on substrates. 2. The data analysis means according to claim 1, wherein: a level value detection unit for obtaining a maximum value among intensity levels in a specific frequency band designated by said measurement condition setting means; and an intensity level obtained by said level value detection unit. 2. The apparatus according to claim 1, further comprising a map data creation unit for creating a noise intensity distribution based on the position information.