WO2009101750A1

WO2009101750A1 - Loop antenna and immunity test method

Info

Publication number: WO2009101750A1
Application number: PCT/JP2008/072937
Authority: WO
Inventors: Norio Masuda
Original assignee: Nec Corporation
Priority date: 2008-02-12
Filing date: 2008-12-17
Publication date: 2009-08-20
Also published as: JPWO2009101750A1; JP5504894B2

Abstract

Provided is a loop antenna capable of accurately identifying circuits and components having low immunity performances. The loop antenna is provided with a first ring-shaped conductor and one or more second ring-shaped conductors smaller than the first ring-shaped conductor and disposed inside the ring of the first ring-shaped conductor. The first ring-shaped conductor and the second ring-shaped conductors are connected in series and disposed in the same plane. In this case, in the area surrounded by the first ring-shaped conductor and the second ring-shaped conductors, the direction of a magnetic field generated by the first ring-shaped conductor is opposite to those generated by the second ring-shaped conductors.

Description

Loop antenna and immunity test method

The present invention relates to a loop antenna, and more particularly to an antenna that is irradiated with a magnetic field to test electromagnetic sensitivity and immunity performance, or a compact loop antenna that generates a magnetic field to communicate.

When an electronic device operates, an electromagnetic field generated along with the operation of another electronic device or mechanical device arrives, and the electromagnetic field causes an electromagnetic interference to cause an electromagnetic interference (EMI: Electromagnetic Interference), and the performance of the electronic device May cause deterioration. On the other hand, in an environment where such electromagnetic interference exists, in order to improve the immunity with which the electronic device can operate without the performance deterioration and to prevent the performance deterioration due to the electromagnetic interference, at the design stage of the electronic device, It is important to identify locations where electromagnetic sensitivity is high, to elucidate the mechanism of occurrence of electromagnetic interference, and to design with improved immunity.

An antenna is installed near a large scale integrated circuit (LSI) or a printed wiring board (PWB: Printed Wiring Board) in order to identify a portion where electromagnetic sensitivity is weak, and an electromagnetic field is irradiated to cause malfunction or performance degradation. Tests are underway to determine the condition. Such a test helps to identify circuits and mounting components that are weak in electromagnetic immunity.

FIG. 11 shows a configuration example when evaluating an immunity performance by installing an antenna for irradiating a magnetic field right above the LSI.

FIG. 11A is a diagram of the LSI viewed from directly above, and the antenna 10 is installed directly above the QFP (Quad Flat Pack) 1 on which the LSI is mounted so as to be at a certain height from the QFP 1. In the example of FIG. 11A, the antenna 10 is made of a multilayer substrate, and the loop wiring 11 for generating a magnetic field is formed of a printed wiring. FIG. 11B is a side view of the same configuration as FIG. 11A. Peripheral circuits necessary for operating the LSI are also mounted on the mounting board 5. A circuit for monitoring the operation of the LSI is also mounted on the mounting board 5.

In FIG. 1, 2 is a chip portion of

QFP

1, and 3 is a lead frame of QFP 1.

As shown in FIG. 12, the antenna 10 is composed of a loop wiring 11 formed by printed wiring on a printed wiring board 13, a lead 12 and a connector 14. The high frequency signal sent from the signal generator 17 is transmitted by the coaxial cable 16, the connector 14 and the lead 12, and is finally supplied to the loop wiring 11. A magnetic field is generated around the loop surface around the loop wiring 11 in accordance with the laws of electromagnetism. At this time, in general, the magnetic field in the direction perpendicular to the loop surface is dominant. Therefore, as shown in FIG. 11B, when the antenna 10 is disposed at an appropriate distance so as to be parallel to the QFP mounted on the mounting board 5, a magnetic field with little change in intensity is irradiated over the entire surface of the QFP. it can. While changing the setting of the signal generator 17 and controlling the intensity, modulation, waveform, etc. of the generated magnetic field, the cause of the malfunction of the LSI is identified. In FIG. 11A, an antenna of approximately the same size as the QFP is used, but some test methods use a smaller antenna than the QFP to provide limited coverage. In this case, a magnetic field is irradiated while scanning a small antenna at a predetermined height on the QFP, and a circuit with weak immunity is identified.

FIG. 13 is an explanatory view of a method of measuring the magnetic field of the surface of the antenna 10 of FIG. As shown in FIGS. 13A and 13B, FIG. 14A is a view obtained by measuring and visualizing the magnetic field while installing the small-sized magnetic field probe 15 in the vicinity of the loop wiring 11 and scanning in the XY axis direction at a constant height. In FIG. 14A, since the magnetic field in the vicinity of the loop wiring 11 has components in the X, Y, Z directions, the X direction component (Hx), the Y direction component (Hy), Z direction while changing the installation axis of the small magnetic field probe 15 The intensity of the component (Hz) is measured and synthesized and displayed as Hxyz = (x ² + y ² + z ² ) ^(1/2) .

The measurement was performed by connecting the small magnetic field probe 15 to a measuring instrument such as a spectrum analyzer, oscillating the antenna 10 at 10 MHz, and measuring the output of the small magnetic field probe 15. In FIG. 14A and (b), the result of scanning and measuring the small magnetic field probe 15 over the whole loop surface is displayed. In FIG. 14A, (b), the center of the loop wiring 11 is (x, y) = (18 mm, 18 mm). The external shape of the loop wiring 11 of FIG. 13B is 24 mm square, and the width of the loop wiring 11 is 1 mm, and the small magnetic field probes 15 were measured 6 mm apart. In FIG. 14A, it can be seen that a strong magnetic field is generated over the entire surface in the range surrounded by the loop wiring 11. FIG. 14B shows the result of measurement of the magnetic field while making the Y and Z coordinates constant and one-dimensionally scanning on the line AA ′ passing the center of the loop wiring 11 of FIG. 13B. The position of X = 18 mm in FIG. 14B means that the small magnetic field probe 15 is located at the center of the loop wiring 11. Although the asymmetry due to the measurement error etc. is recognized, it has a nearly symmetrical distribution.

As can be seen from FIG. 14B, Hz is dominant in the area surrounded by the loop wiring 11. There is also a region where Hx becomes strong near the loop wiring 11, but the intensity is lower than Hz. If the measurement distance of the small magnetic field probe 15 is further reduced, and becomes smaller than 1 mm, Hx may become dominant compared to Hz, but the distance between the loop and the object under normal use conditions is taken into consideration Then, the distribution in FIG. 14A is a typical distribution. Since Hy is in principle the direction in which the magnetic field is not observed, it has a very low value. The magnitude of the combined magnetic field Hxyz = (x ² + y ² + z ² ) ^{(1/2) in} the x, y, and z directions is roughly similar to the distribution in Hz, but in the region where Hx is strong Hxyz Will be greater than Hz. Therefore, in the case of FIG. 14B, Hxyz is approximately a combination of Hz and Hx. In the area surrounded by the loop wiring 11, the change in the intensity of the synthetic magnetic field Hxyz is small, and remains at about 8%. Both FIGS. 14A and 14B are normalized and displayed at the maximum value. If the loop wiring 11 is manufactured to the same size as that of the QFP and placed on the QFP as shown in FIG. 11A, it is possible to irradiate a magnetic field of almost constant strength over the entire surface of the QFP.

FIG. 15A schematically shows the test method of irradiating the magnetic field described above. The hatched portion is a region that generates a strong magnetic field, and the inside of the loop wire 11 substantially belongs to this region. Although changing the distance between the QFP 1 and the antenna 11 changes the distribution, it is general to conduct the test at a measurement distance close to a uniform distribution. Specifically, when the antenna 10 is very close to the LSI chip 1 and the lead frame 3 to be tested, a strong magnetic field is generated only in the vicinity of the loop wiring 11 and the magnetic field strength at the central portion of the loop wiring 11 is low. That is, an annular magnetic field distribution occurs. However, in the case of the QFP, since the thickness of the package is large, the loop wiring 11 can not but be installed away from the chip 1 and the lead frame 3. In this case, the magnetic field in the vicinity of the center of the loop wiring 11 becomes strong, and as a result, a strong magnetic field is generated in the loop plane illustrated in FIG. 14A. Therefore, changing the installation distance of the antenna 10 to generate an annular magnetic field is very limited.

Although the case where a test is performed by irradiating a magnetic field is illustrated above, if the antenna which generate | occur | produces a uniform electric field is used, it can apply to the malfunction test by an electric field.

In FIG. 15A, since the magnetic field is irradiated over the entire surface of the QFP 1, the immunity of the entire QFP 1 can be evaluated, but the evaluation of each part can not be performed. As shown in FIG. 15B, it is possible to irradiate the magnetic field only to the chip 2 on which the LSI is formed by creating the loop wiring 11 having a small external dimension, but connecting the lead frame 3 and QFP 1 to the pads on the chip Only the bonding wire 4 can not be irradiated with the magnetic field. In particular, in the frequency band of 1 GHz or less, noise may be generated in the lead frame 3 or the bonding wire 4 by the electromagnetic field coming from the outside, and may be larger than the noise generated inside the chip 2 by the same external electromagnetic field. In this case, noise generated in the lead frame 3 or the bonding wire 4 becomes conductive noise, and is mixed into the inside of the chip 2 from the terminal portion to cause a malfunction. Therefore, even if an electromagnetic field does not enter the chip 2 from the outside I can not expect an effect. Therefore, it is important to select and test the lead frame 3 and the bonding wires 4 in order to select the correct noise countermeasure.

FIG. 15C shows the case where the magnetic field irradiation test is performed by selecting the portion where bonding wire 4 and bonding wire 4 are connected to lead frame 3 (that is, the portion where lead frame 3 is tapered), and FIG. This is the case where the test is performed to irradiate the magnetic field including the wiring 6 on the board 5. As described above, by using a magnetic field generation method that generates a strong magnetic field in an annular shape, it becomes possible to test by combining the chip 2, the bonding wire 4, the lead frame 3, and the wiring 6 on the mounting board. It becomes possible to identify the mounted component that causes the decrease in immunity.

FIG. 16 shows an example in which a magnetic field is selected for each circuit. In FIG. 16A, the test is performed including all the parts connected to the circuit to be tested, rather than selecting at the mounting part level. Examples of circuits include power supply circuits, data ports, I / O ports for signal transmission, etc. However, pins connected to similar circuits are often adjacent on the QFP. In that case, as shown in FIG. 16B, for example, it may not be desirable to irradiate a specific lead frame 3.

As described above, in the prior art, it is not possible to select a mounted part or circuit and irradiate a magnetic field from the outside, and there is a drawback that it is not possible to sufficiently identify a circuit or part having low immunity performance.

Next, known documents recognized by the applicant will be described.

Patent document 1 connects a first half loop 3c, a circular loop 3e, and a second half loop 3g in series, and forms a first annular shape including a first half loop 3c and a second half loop 3g. A loop antenna is disclosed in which the antenna portion and the second annular antenna portion consisting of the circular loop 3e are formed in the same shape and the same size, and the first and second annular antenna portions are adhered.

In the patent document 1 described above, it is described that signal transmission can be performed without a problem in the Radio Law. This is considered to be the problem of the magnetic field distribution at a distance where the magnetic fields generated by the loop antenna are sufficiently combined.

Further, FIG. 2C of Patent Document 2 discloses a coil antenna for a noncontact communication device in which the magnetic field strength is increased by winding a loop portion of a loop antenna a plurality of times.

In addition, neither patent document 1 nor 2 is used for the measurement of immunity.

Moreover, in the said patent document 1, it is described that signal transmission can be performed, without the problem in a Radio Law arises. This is considered to be a problem of the magnetic field generated by the loop antenna being sufficiently synthesized, that is, the magnetic field distribution at a distance sufficiently away from the loop antenna. On the other hand, the present invention addresses the magnetic field distribution in the vicinity of the loop antenna and controls the magnetic field distribution in the vicinity of the loop antenna.
Japanese Patent Application Laid-Open No. 62-61430 JP, 2006-74348, A (2nd example)

The present invention has been made in view of the above-described point, and its object is to control the magnetic field distribution in the vicinity of the loop antenna to enable generation of an annular magnetic field distribution adapted to the measurement object, The present invention provides a novel loop antenna that can accurately identify circuits and components with low immunity performance.

Another object of the present invention is to provide an electronic device having an extremely short distance communication function, capable of preventing a malfunction by selectively attenuating a magnetic field around components which are not desired to be irradiated with a magnetic field. It is.

The present invention basically adopts the technical configuration as described below in order to achieve the above-mentioned object.
That is, the first aspect of the loop antenna according to the present invention is
A first annular conductor,
One or more second annular conductors smaller than the first annular conductor and located inside the ring of the first annular conductor,
Said second annular conductor is connected in series with said first annular conductor;
The first annular conductor and the second annular conductor are disposed on the same plane, and
In the second aspect,
A first annular conductor formed on the substrate;
One or more second annular conductors smaller than the first annular conductor and located inside the ring of the first annular conductor,
Said second annular conductor is connected in series with said first annular conductor;
The first annular conductor and the second annular conductor are disposed on different sides of the substrate,
In the third aspect,
An annular conductor,
And a metal plate disposed inside the ring of the annular conductor,
The annular conductor and the metal plate are disposed on the same plane, and
In the fourth aspect,
An annular conductor formed on a substrate,
And a metal plate disposed inside the ring of the annular conductor,
The annular conductor and the metal plate are disposed on different sides of the substrate,
In the fifth aspect,
A substrate,
An annular conductor provided on the first surface of the substrate;
A metal pad provided inside the ring of the annular conductor on the first surface of the substrate and connecting the inner conductor or the outer conductor of the coaxial cable;
It comprises a metal plate provided on a second surface different from the first surface of the substrate and connected with the metal pad and a plurality of vias,
The coaxial cable is vertically connected to the substrate surface, and
In the sixth aspect,
A substrate,
An annular conductor provided on the first surface of the substrate;
A metal pad provided on the inside of the ring of the annular conductor at a second surface different from the first surface of the substrate and connecting the inner conductor or the outer conductor of the coaxial cable;
It comprises a metal plate provided on the first surface of the substrate and connected to the metal pad by a plurality of vias,
The coaxial cable is vertically connected to the substrate surface.

Further, the aspect of the magnetic field generation method according to the present invention is
A first annular conductor and one or more second annular conductors smaller than the first annular conductor and located inside the annulus of the first annular conductor, the second annular conductor comprising A loop antenna connected in series to the first annular conductor is driven at a frequency having a wavelength sufficiently longer than the total length of the first annular conductor and the second annular conductor, and an annular magnetic field distribution It is characterized in that

Since the loop antenna of the present invention is configured as described above, the magnetic field can be selectively irradiated, and it becomes easy to identify parts having low immunity performance.

Further, according to the mounting method of the loop antenna of the present invention, in the electronic device having the extremely short distance communication function, since the magnetic field around the parts which are not desired to be irradiated with the magnetic field can be selectively attenuated, malfunction can be prevented.

It is a figure which shows an example of a structure of the loop antenna of this invention. It is a side view of FIG. 1A. It is a figure which shows magnetic field distribution of the vicinity of the loop antenna of this invention. It is a figure which shows magnetic field distribution of the vicinity of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the structure of the loop antenna which has a conductor board of this invention. It is a figure which shows the example which has arrange | positioned the connection pad in the inside of a cyclic | annular conductor in the figure of FIG. 4A. It is a figure which shows the conductor board provided in the other side of the printed wiring board of FIG. 4B. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure which shows that a lead frame does not exist in 45 degree direction of QFP. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure explaining the other structural example of the loop antenna of this invention. It is a figure which applied the loop antenna of the present invention to SiP. It is a side view of FIG. 9A. It is a figure which shows that both chips shown to FIG. 9A are connected by the wiring on an interposer. It is a figure which compares the magnetic field distribution of the loop antenna of this invention, and the conventional loop antenna. It is a figure explaining the conventional immunity test method. FIG. 11B is a side view of FIG. 11A. It is a figure explaining the conventional loop antenna. It is a figure explaining the measuring method of the magnetic field distribution of the conventional loop antenna vicinity. It is a top view of FIG. 13A. It is a figure which shows an example of the magnetic field distribution of the conventional loop antenna vicinity. It is a figure which shows an example of the magnetic field distribution of the conventional loop antenna vicinity. It is a figure which shows the case where a magnetic field is irradiated over the QFP whole surface in a magnetic field irradiation method. It is a figure which shows the case where a magnetic field is irradiated only to the chip | tip in which small loop wiring of an outer-diameter dimension is created in magnetic field irradiation method, and LSI is formed. It is a figure which shows the case where a part which a bonding wire and a bonding wire are connected to a lead frame in a magnetic field irradiation method is selected, and a magnetic field is irradiated. It is a figure which shows the case where a magnetic field is irradiated including the wiring on a mounting board in a magnetic field irradiation method. It is a figure which shows the case where the test including all the components connected to the circuit under test in a magnetic field irradiation method is performed. It is a figure which shows the case where a magnetic field is not irradiated to a specific lead frame in a magnetic field irradiation method.

Explanation of sign

1 QFP
Reference Signs List 2 chip 3 lead frame 4 bonding wire 5 mounting board 6 wiring 10 antenna 11 loop wiring 12 lead 13 printed wiring board 14 connector 15 small magnetic field probe 16 coaxial cable 17 signal generator 18 probe head 20 loop antenna 21 printed wiring board 22 annular conductor 23 ring conductor 24 connection wiring 25 connection wiring 26 coaxial cable 27 sleeve 28 conductor pattern 30 a pad 30 a pad 31 a current 31 b current 32 conductor plate 33 via 34 via 50 interposer 51 chip 52 chip 58 wiring 59 wiring 60 spacer 61 annular conductor 62 annular conductor

The loop antenna of the present invention comprises a first annular conductor and one or more second annular conductors smaller than the first annular conductor and located inside the ring of the first annular conductor, Configured to generate an annular magnetic field in a region between the annular conductor and the second annular conductor, thereby selectively irradiating the magnetic field and identifying a component having low immunity performance. It is.

In the loop antenna of the present invention, the first annular conductor and the second annular conductor may be connected in series and driven by one signal source, or the first annular conductor Each of the second annular conductors may be driven by another signal source.

In addition, as a shape of the annular conductor of this invention, a polygon including a rectangle and a circle | round | yen is included.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining an embodiment of a loop antenna 20 of the present invention.

The loop antenna 20 of the present invention comprises a printed wiring board 21 and a conductor pattern 28 formed thereon. The conductor pattern 28 includes an annular conductor 22 formed so as to go around the outside, an annular conductor 23 connected in series to a part of the conductor pattern 28, and a connection wire 24 connecting the respective annular conductors. The annular conductor 23 has a smaller outside dimension than the annular conductor 22 and is disposed inside the annular conductor 22. The annular conductor 22 is connected to the connection wiring 25, and the other end of the connection wiring 25 is connected to the

pads

30a and 30b. The side view of FIG. 1B shows a state in which the coaxial cable 26 is vertically connected to the printed wiring board 21, but the center conductor of the coaxial cable is electrically connected to the pad 30a using a method such as soldering. It is fixed. On the other hand, the outer conductor of the coaxial cable is connected to the pad 30 b via the sleeve 27. By performing such connection, it is possible to vertically connect with the conductor pattern 28 while suppressing the collapse of the coaxial structure. The other end of the coaxial cable 26 is connected to the signal generator 17, and the signal transmitted from the signal generator 17 is transmitted to the

annular conductors

22 and 23 to generate a magnetic field around the

annular conductors

22 and 23 according to the laws of electromagnetism. . By fixing the coaxial cable 26 vertically, the antenna 20 can be brought close to the QFP 1 at a fixed height as shown in FIG. 11B.

FIGS. 2A and 2B show the results of measuring the magnetic field on the loop antenna 20 in the same measurement system as in FIGS. 13A and 13B. Each figure is shown normalized with the maximum value. In FIG. 2A, the center of the annular conductor of the loop antenna 20 is at (x, y) = (18 mm, 18 mm). The outer dimensions of the annular conductor 24 are 24 mm, the outer dimensions of the annular conductor 23 are 15 mm, and the wiring width is 1 mm. In FIG. 2A, it can be seen that the magnetic field strength at the central portion is reduced, and a strong magnetic field is generated in the ring. FIG. 2B shows the result of measuring the distribution on the AA ′ line of FIG. 13B, but two peaks are observed.

This peak is approximately located in the region sandwiched by the annular conductor 22 and the annular conductor 23. In FIG. 1A, assuming that the current 31a supplied from the signal generator 17 flows in the annular conductor 22, the annular conductor 22 generates a magnetic field at its center in a direction from the front to the back of the paper. At this time, since the current 31b flowing through the annular conductor 23 is in the opposite direction to the current 31a, a magnetic field is generated at the central portion in the direction of penetrating from the back side to the front side of the drawing.

In FIG. 1A, since the centers of the annular conductor 22 and the annular conductor 23 coincide with each other, the combined magnetic field of the annular conductor 22 and the annular conductor 23 decreases in strength near its center. It can also be considered that the conductor pattern 28 includes two loop antennas having different directions of oscillation with the same phase.

The above results are shown in FIG. 1A in which two loop antennas are driven by a signal having a wavelength sufficiently longer than the total length of the

annular conductors

22 and 23. Such a frequency is selected. As a result, since the

annular conductors

22 and 23 are driven in phase to generate a magnetic field, an annular magnetic field distribution shown in FIG. 2A can be obtained. When the wavelength is shorter than the total length of the annular conductor, the influence of voltage and current distribution on the annular conductor becomes large, and it becomes impossible to generate an annular magnetic field distribution having uniform magnetic field strength.

In FIG. 1A, the

annular conductors

22, 23 have a near rectangular shape. Assuming that the measurement object is a QFP, it is possible to conduct the test over the entire surface of the object by making it square. Usually, the QFP 1 and the chip 2 are substantially square, and the sides are parallel to each other. Therefore, as shown in FIG. 1A, by arranging the annular conductor 23 at the center of the annular conductor 22 so that the sides are parallel to each other, the irradiation range shown in FIG. 15 can be selected and irradiated.

When the object to be measured is circular or when it is desired to irradiate a magnetic field to a part of the object to be measured, the conductor pattern 28 may be designed according to the shape. Therefore, the conductor pattern 28 is manufactured in a rectangle, a trapezoid, a circle, an ellipse, or a polygon according to the purpose. The annular conductor 22 and the annular conductor 23 do not have to have the same shape, and a combination of different shapes is also acceptable as shown in FIG. 3A. FIG. 3C is an example in which a plurality of annular conductors 23 are arranged.

Further, the center of the annular conductor 22 and the center of the annular conductor 23 do not have to be aligned, and the annular conductor 23 can be disposed at an asymmetric position with respect to the annular conductor 22. In packages such as SiP (System in Package), the chip is often mounted at an asymmetric position, and such a mounting method is also possible.

By using the loop antenna 20 described above, it becomes possible to irradiate a magnetic field to the annular region shown in FIG. 15C and FIG. 15D, which helps to identify components and circuits having high electromagnetic sensitivity.

If the chip 2, the bonding wire 4, the lead frame 3, and the printed wiring 6 are respectively assigned to the factor A, the factor B, the factor C, and the factor D, the factor A is always included in the conventional test method using the antenna 10. That is, if the test is performed while changing the outer dimensions of the loop wiring 11, it is necessary to measure the electromagnetic immunity in the combination such as factor A, factor (A + B), factor (A + B + C), factor (A + B + C), factor (A + B + C + D) become. In the method of selecting the irradiation area in such an addition formula, for example, if contribution to the immunity of factor A is large, the contribution of other factors can not be separated, and if the interaction between each factor is large There is a disadvantage that the effect of is difficult to separate. In the present invention, it is possible to conduct a test in which factors in adjacent places such as factor (B + C), factor (C + D) and factor C, for example, are partially excluded, so factor analysis is facilitated and electromagnetic sensitivity is improved. Helps to identify expensive components and circuits.

In FIG. 4A, the inner annular conductor 23 is replaced with a conductor plate 32 made of a metal plate having a predetermined area. In FIG. 4A, the conductor plate 32 is disposed at the center of the annular conductor 22. When the annular conductor 22 is driven at a predetermined frequency, a strong magnetic field is generated inside the ring, but if the conductor plate 32 is thick enough to prevent the magnetic field from penetrating, the magnetic field at the central portion of the conductor plate 32 is attenuated. Although the loop antenna 20 does not operate to cancel the magnetic field positively, an annular distribution similar to that of the loop antenna 20 can be obtained. If each side of the conductor plate 32 is formed so as to be parallel to each side of the annular conductor 22, the magnetic field distribution shown in FIGS. 15B and 15C can be generated. The shape of the conductor plate 32 may be any shape such as a trapezoid in accordance with the measurement condition. Further, the shape of the annular conductor may be different from the shape of the metal plate.

In FIG. 4A, the

pads

30a and 30b for connecting the coaxial cable 26 are disposed outside the annular conductor 22 provided on one surface of the printed wiring board 21. In this example, the

connection pads

31 a and 31 b are disposed inside the annular conductor 22.

FIG. 4C shows a conductor plate 32 provided on the other surface of the printed wiring board 21 of FIG. 4B. The conductor plate 32 is connected to the pad 31 b by the via 33, and the ground conductor of the coaxial cable 26 together with the pad 31 b. Connected to Also in this case, the magnetic field attenuates around the conductor plate 32 as in FIG. 4A. Since the coaxial cable 26 can be installed inside the annular conductor 22, the size can be reduced.

Although not shown, the conductor plate 32 is disposed on the inner side of the annular conductor 22, and the conductor plate 32 is formed on the same surface as the annular conductor 22, and the

pads

31a and 31b are opposed to the conductor plate 32 to be a conductor. It may be configured to be provided on a surface different from the surface on which the plate 32 is provided.

In FIG. 5A, the shape of the annular conductor 22 is polygonal, and a magnetic field is applied only to the hatched area in FIG. 16A. Usually, the loop antenna is rectangular or annular, but as shown in FIG. 5A, the magnetic field can be irradiated only to the lead frame to be tested if the shape of the lead frame of the QFP is matched. Furthermore, as shown in FIG. 5B, if an annular conductor is formed inside, it is possible to attenuate the magnetic field strength around the lead frame that you do not want to test, as shown in FIG. 16B.

FIG. 6A shows an embodiment of the present invention in which the

connection wirings

24 and 25 are disposed in parallel with the side of the QFP. When the connection wiring 25 is formed in this manner, a distribution which does not originally require a magnetic field is formed around the connection wiring 25, the magnetic field strength is lowered, and a part of the lead frames may not be irradiated with the magnetic field of sufficient strength. . On the other hand, in FIG. 1A or FIG. 6B, the connection wiring 25 is connected to the corner of the annular conductor 22 formed in a rectangular shape, and drawn out so as to form an angle of 45 degrees with each side of the annular wiring. On the other hand, the connection wiring 24 is disposed adjacent to the connection wiring 25 and the angle between the

connection wirings

24 and 25 is 0 degree. If the measurement object is QFP, the lead frame is often not placed at the corners. Therefore, as shown in FIG. 1A and FIG. 6C, the lead frame inside the QFP is extended with respect to the adjacent side of the QFP, so the distance in the 45 degree direction becomes wider. By arranging the connection wiring 25 in a diagonal direction in which the lead frame does not exist, a uniform magnetic field can be irradiated to a region required for the test. The connection wiring 25 does not have to be arranged linearly with the connection wiring 24 and may form an angle of 45 degrees. In FIG. 6B, the connection wiring 24 and the connection wiring 25 are partially shared.

When the annular conductor is a polygon, it is preferable to provide the connection wiring 25 at the corner where the two sides of the polygon intersect.

In FIG. 7, an annular conductor 22 and an annular conductor 23 are formed in different layers. The annular conductor 23 is disposed inside the annular conductor 22, and the annular conductor 22 and the annular conductor 23 are connected in series at the vias 34. It is possible to change the distance in the direction perpendicular to the loop surface of the annular conductor 22 and the annular conductor 23 by controlling the thickness of the printed board 21 and to control the intensity distribution on the QFP 1.

As described above, a characteristic magnetic field distribution can be generated by using the antenna of the present invention in a frequency band of a wavelength sufficiently longer than the total length of the annular conductor. By using the loop antenna 20 in which two annular conductors illustrated in FIG. 1A are connected in series, it is possible to immediately generate an annular magnetic field distribution.

Further, as shown in FIG. 8, if the two annular conductors are operated independently, the strength of the magnetic field can be locally adjusted, and the same effect as the loop antenna 20 can be obtained. In the case of FIG. 8, since the annular conductors 61 and 62 can be controlled independently, the phase of the supplied signal can be reversed or the amplitude can be changed, and the generated magnetic field distribution can be efficiently controlled. Therefore, precise control is possible as compared with the integrated type of FIG. 1A.

By using these magnetic field distribution generation methods, as described above, it becomes possible to test the QFP 1 and chip 2 that constitute the LSI package, and the wiring on the printed circuit board, and the immunity test to analyze the state of malfunction of the LSI It can be efficient.

Next, another embodiment of the present invention will be described.

The loop antenna of the present invention described above can also be applied to a transmitting / receiving antenna incorporated on a printed wiring board or in an LSI package.

FIGS. 9A and 9B show a device in which a printed wiring board 21 in which a loop antenna is formed is mounted on a system in package (SiP) via a spacer 60. FIG.

The reason for mounting a planar antenna on a printed circuit board is to realize thinning and downsizing. For this reason, the distance between the SiP and the antenna conductor is very close, for example, 1 mm or less. Two

chips

51 and 52 are mounted on the interposer 50 by BGA. The

chips

51, 52 are connected to each other by

wires

58, 59 on the interposer, as shown in FIG. 9C. This is to recombine the wiring on the interposer 50. When the number of connected wiring increases, the wiring 58 becomes a first layer, the wiring 59 becomes a second layer, and so on.

Such an SiP is used in a wireless medium for reading and writing information without contact, such as an IC card or a wireless tag. Moreover, it may be mounted in the inside of information terminal devices, such as a mobile telephone. The loop antenna 20 of this embodiment is used when transmitting and receiving information with an external device wirelessly. As a typical example of the conventional antenna, the loop antenna 10 illustrated in FIG. 12 is given. As described above, such a loop antenna 10 produces a substantially uniform magnetic field distribution as shown in FIG. 14A.

The loop antenna 20 of the present invention is driven by the chip 51 to generate a magnetic field, and performs communication with an external LSI over an extremely short distance. At this time, the wires formed on the interposer such as the

wires

58 and 59 are longer than the on-chip wires, and thus are susceptible to the influence of the external electromagnetic field in a frequency band lower than the

chips

51 and 52. Therefore, when the conventional antenna 10 is used in place of the loop antenna 20, a large noise voltage is generated in the

wires

58 and 59, which becomes conductive noise and intrudes into the circuits in the

chips

51 and 52, causing the circuit to malfunction. That is, the

wires

58 and 59 which are more sensitive to the electromagnetic field coming from the outside than the

chips

51 and 52 alone will eventually allow the entry of noise.

As described above, the loop antenna 20 of the present invention generates an annular magnetic field distribution near the loop antenna 20, and the magnetic field strength at the central portion is weak. That is, since the magnetic field strength is weak in the region where the wiring with high electromagnetic sensitivity in the central portion of FIG. 9A is present, it is possible to reduce the risk of occurrence of a malfunction.

In an IC card or the like, a receiving antenna is installed to face the antenna 20, and communication is performed at an extremely short distance. When the loop antenna 10 having substantially the same outer dimensions is used as the receiving antenna, when the antenna 10 and the loop antenna 20 are excited with the same power, the output of the receiving antenna of the loop antenna 20 is lowered. This is because the magnetic field strength at the central portion of the loop antenna 20 is attenuated. If the total amount of magnetic field in the loop of the receiving antenna is equal, the gain in transmission and reception does not decrease. Comparing the integrated value of the magnetic field in the loop with the external dimensions of the receiving antenna being the same as on the transmitting side, if the transmission power of the loop antenna 20 is multiplied by 1.8, a magnetic field equivalent to the antenna 10 is generated Are equal. FIG. 10 compares the magnetic field distribution at this time. Even in this case, the magnetic field strength near the center of the loop antenna 20 is about 30% smaller than the magnetic field strength near the center of the loop antenna 10 and about 10 dB smaller in decibel notation. Therefore, the effect of protecting the parts near the center can be expected while providing the same gain as the conventional type. FIG. 10 is a result of measuring the magnetic field distribution generated by the antenna 10 and the loop antenna 20, and is normalized by the maximum value of the loop antenna 20.

This application claims priority based on Japanese Patent Application No. 2008-30739 filed on February 12, 2008, the entire disclosure of which is incorporated herein.

The present invention is applicable to a loop antenna, an electronic device having an extremely short distance communication function, and various other related devices.

Claims

A first annular conductor,
One or more second annular conductors smaller than the first annular conductor and located inside the ring of the first annular conductor,
Said second annular conductor is connected in series with said first annular conductor;
A loop antenna characterized in that the first annular conductor and the second annular conductor are disposed on the same plane.
A first annular conductor formed on the substrate;
One or more second annular conductors smaller than the first annular conductor and located inside the ring of the first annular conductor,
Said second annular conductor is connected in series with said first annular conductor;
A loop antenna, wherein the first annular conductor and the second annular conductor are disposed on different sides of the substrate.
In the portion surrounded by the first annular conductor and the second annular conductor, the direction of the magnetic field generated by the first annular conductor and the direction of the magnetic field generated by the second annular conductor are opposite to each other. The loop antenna according to claim 1 or 2, characterized in that
The loop antenna according to any one of claims 1 to 3, wherein the first annular conductor and the second annular conductor are rectangular.
The loop antenna according to claim 4, wherein a conductor for connecting the first annular conductor and the second annular conductor is disposed at a corner of the rectangle.
The loop antenna according to any one of claims 1 to 5, wherein each side of the first annular conductor and each side of the second annular conductor are parallel.
The loop antenna according to any one of claims 1 to 3, wherein the shape of the first annular conductor and the shape of the second annular conductor are different.
The loop antenna according to any one of claims 1 to 3, wherein at least one of the first annular conductor and the second annular conductor has a circular shape or a polygonal shape including a trapezoidal shape.
The loop antenna according to claim 8, wherein a conductor for connecting the first annular conductor and the second annular conductor is disposed at a corner of the polygonal shape.
An annular conductor,
And a metal plate disposed inside the ring of the annular conductor,
A loop antenna characterized in that the annular conductor and the metal plate are disposed on the same plane.
An annular conductor formed on a substrate,
And a metal plate disposed inside the ring of the annular conductor,
The loop antenna, wherein the annular conductor and the metal plate are disposed on different surfaces of the substrate.
A substrate,
An annular conductor provided on the first surface of the substrate;
A metal pad provided inside the ring of the annular conductor on the first surface of the substrate and connecting the inner conductor or the outer conductor of the coaxial cable;
It comprises a metal plate provided on a second surface different from the first surface of the substrate and connected with the metal pad and a plurality of vias,
A loop antenna characterized by connecting the coaxial cable perpendicularly to the substrate surface.
A substrate,
An annular conductor provided on the first surface of the substrate;
A metal pad provided on the inside of the ring of the annular conductor at a second surface different from the first surface of the substrate and connecting the inner conductor or the outer conductor of the coaxial cable;
It comprises a metal plate provided on the first surface of the substrate and connected to the metal pad by a plurality of vias,
A loop antenna characterized by connecting the coaxial cable perpendicularly to the substrate surface.
The loop antenna according to any one of claims 11 to 13, wherein the annular conductor and the metal plate are rectangular, and each side of the annular conductor is parallel to each side of the metal plate.
The loop antenna according to any one of claims 11 to 13, wherein the shape of the annular conductor is different from the shape of the metal plate.
The loop antenna according to any one of claims 11 to 13, wherein the annular conductor has a circular shape or a polygonal shape including a trapezoidal shape.
A first annular conductor and one or more second annular conductors smaller than the first annular conductor and located inside the annulus of the first annular conductor, the second annular conductor comprising A loop antenna connected in series to the first annular conductor is driven at a frequency having a wavelength sufficiently longer than the total length of the first annular conductor and the second annular conductor, and an annular magnetic field distribution A magnetic field generating method characterized by generating
An immunity test method characterized in that an annular magnetic field distribution is generated in the vicinity of a loop surface using the loop antenna according to any one of claims 1 to 16 to investigate malfunction of an electronic device.
The electronic device having an ultra short distance communication function using the loop antenna according to any one of claims 1 to 16, wherein the magnetic field strength of the loop antenna in the area where the circuit or component having high electromagnetic sensitivity is arranged is weaker than the magnetic field strength in other areas. A mounting method of a loop antenna characterized by mounting as follows.