JP2007155597A - Magnetic field sensor used for measuring magnetic field and current and current measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve non-symmetry of a signal layer or to strengthen shield. <P>SOLUTION: A magnetic field sensor has a linear conductor pattern 1a, and first and second conductor patterns 1b, 1c branched from an end by being connected to the end of the linear conductor pattern. The magnetic field sensor has a first layer 1 arranged oppositely by separating the edges of the first and second conductor patterns from a prescribed distance, a second layer 3 having the same shape conductor pattern as the first layer, a third conductor pattern 2b opposed to the first conductor pattern by making it finer than the width of the first conductor pattern, and a fourth conductor pattern 2c opposed to the second conductor pattern by being connected to the third conductor pattern and the edge part. The magnetic field sensor has a third layer arranged between the first layer and the second layer by possessing a notch in the vicinity of a linear conductor by the fourth conductor pattern and a first via conductor 4 electrically connecting the first layer, the second layer and the third layer with the edge part of the third conductor pattern. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic field detector and a current measuring method used for magnetic field and current measurement, and more particularly, to a magnetic field detector based on a shielded loop type magnetic field detector manufactured from a multilayer substrate. The present invention also relates to a technique for measuring a current or a magnetic field in a non-contact manner using a wiring on a semiconductor chip, a ball portion or a bonding wire portion of a semiconductor package as a measurement target.

Conventionally, magnetic field detectors used for magnetic field detection and current measurement for printed circuit board wiring and the like have been devised and actually commercialized. For example, in Patent Document 1, a magnetic field probe using a multilayer board for measuring a high-frequency current in printed circuit board wiring is devised. Patent Documents 2 and 3 devise a shielded loop by a thin film process. As an example of application of these magnetic field detectors, there is a current sensor that measures a magnetic field on a wiring and converts it into a current as disclosed in Patent Document 4. Patent Document 5 proposes a shielded loop coil for measuring permeability. Patent Document 6 has a shield-enhanced structure. Patent Document 7 describes an example in which vias are arranged around a printed wiring pattern forming a loop to improve characteristics.
Japanese Patent No. 2970615 Japanese Patent No. 3173501 Japanese Patent No. 3104420 JP 2000-171504 A Japanese Patent No. 3085651 Japanese Patent No. 3633593 JP 2004-69337 A

  FIG. 14 shows the basic structure of the shielded loop type magnetic field detector. The wiring pattern of each layer is a thin film made of a metal such as copper. Between each layer is filled with a dielectric. The signal wiring 2 is sandwiched between the ground wiring 1 of the first layer and the ground wiring 3 of the third layer, and each layer is electrically connected by a via 4 at the tip. The first, second, and third layers have a shielded loop structure that shields the electric field while detecting the magnetic field as a whole. Although this shielded loop structure can constitute a very good magnetic field detector in the high frequency band, since the ground layer on the side where the C-shaped portion 2b of the signal layer does not exist is opened, the electromagnetic field wraps around and the magnetic field output It has been pointed out that it affects the signal transmission of the C-shaped part that constitutes the stripline for transmitting. Such a multilayer structure has been conventionally produced using a semi-rigid coaxial cable, but is due to imperfections caused by replacing it with a multilayer substrate. John D. Dyson, “Measurement of Near Fields of Antenna and Scatters”, IEEE Transactions on Antenna and Propagation, Vol.AP-21, No.4, pp.446-461 (1973.7) 15 shows a shielded loop composed of a semicircular portion 6b having a coaxial structure and a semicircular portion 6c made of a non-hollow circular conductor, as shown in FIG. This non-hollow circular conductor was replaced with a multilayer substrate, which caused an error.

  In order to solve this, Patent Document 6 proposes a shield reinforcing structure by via connection as shown in FIG. Shield reinforcement is possible with this structure, but when using a printed circuit board etc., there is a limit to the miniaturization of the manufacturing process and the pitch of via formation is limited, so the number of vias that can be arranged is limited. there were. Further, when the distance between the ground wirings 1 and 3 is large, the direction along the vias 4, 9, and 10 is slit in the thickness direction of the printed circuit board, and there is a disadvantage that electric field shielding is difficult.

  Furthermore, since the signal layer and the ground layer are connected by vias, reflection occurs at high frequencies, which may cause measurement errors.

  As described in Patent Document 4, such a magnetic field detector is installed perpendicular to a printed circuit wiring or a wiring on an IC chip as shown in FIG. The measured magnetic field can be converted to a current flowing through the wiring using an appropriate conversion formula. However, since the wiring exists in the lower layer, it cannot be measured near the surface layer, or if the face-down mounting is performed with the IC chip surface facing the package side, the wiring on the IC chip surface will be hidden. There is a problem that measurement cannot be performed by the method shown in FIG. Even in face-up mounting, when the wiring to be measured is in the lower layer, the magnetic field appearing on the surface of the IC chip cannot be measured with high accuracy.

  It is an object of the present invention to provide a means for resolving signal layer asymmetry or strengthening the shield. Another object of the present invention is to provide means for preventing reflection and unnecessary electromagnetic field wraparound. Another object of the present invention is to provide a technique for detecting a magnetic field in the vicinity of a BGA (Ball Grid Allay) or a bonding wire. Another object of the present invention is to provide a non-contact current measuring method for calculating a current from a magnetic field.

The magnetic field detector of the present invention includes a first linear conductor pattern and first and second conductor patterns that are connected to an end portion of the first linear conductor pattern and branch from the end portion. A first layer in which the tip portions of the first and second conductor patterns are spaced apart from each other by a predetermined distance; and
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A second linear conductor pattern facing the first linear conductor pattern, and a first conductor pattern that is narrower than a width of the first conductor pattern and connected to a tip of the linear conductor pattern. A third conductor pattern facing and extending to a position facing the tip of the first or second conductor pattern, and the second conductive connected to the first tip of the third conductor pattern A fourth conductor pattern opposite to the pattern, the fourth conductor pattern having a notch near the second linear conductor pattern, and disposed between the first layer and the second layer. A third layer,
The first layer, the second layer, and the third layer are electrically connected through the first tip of the third conductor pattern or the second tip of the fourth conductor pattern that is cut away. And a first via conductor.

The magnetic field detector of the present invention includes a linear conductor pattern, and first and second conductor patterns that are connected to an end portion of the linear conductor pattern and branch from the end portion. A first layer in which the tip of the second conductor pattern is spaced by a predetermined distance and is opposed to the first layer;
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A third conductor pattern that is narrower than a width of the first conductor pattern and that opposes the first conductor pattern, or a third and fourth conductor pattern that opposes the first and second conductor patterns, and A third layer disposed between the first layer and the second layer,
A resistor is inserted between the first layer and the third layer and between the second layer and the third layer at the tip of the third or fourth conductor pattern. And

In particular, the characteristic impedance of the portion forming the transmission line by the first layer, the second layer, and the third layer is R, the resistance value of the resistor between the first layer and the third layer is R1, the first layer When the resistance value of the resistor between the second layer and the third layer is R2,
R = (R1 · R2) / (R1 + R2)
It is desirable to satisfy this relationship.

The magnetic field detector of the present invention includes a linear conductor pattern, and first and second conductor patterns that are connected to an end portion of the linear conductor pattern and branch from the end portion. A first layer in which the tip of the second conductor pattern is spaced by a predetermined distance and is opposed to the first layer;
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A third conductor pattern that is narrower than a width of the first conductor pattern and that opposes the first conductor pattern, or a third and fourth conductor pattern that opposes the first and second conductor patterns, and A third layer disposed between the first layer and the second layer, and a third layer disposed between the first layer and the second layer,
An electromagnetic absorber is inserted between the first layer and the third layer and between the second layer and the third layer at the tip of the third or fourth conductor pattern. It is characterized by.

  According to the present invention, unnecessary wraparound of an electromagnetic field can be prevented, and a decrease in accuracy of magnetic field measurement at a high frequency due to asymmetry of a conductor and reflection at a terminal portion can be prevented.

  In addition, according to the present invention, a method capable of non-contact measurement of the current flowing through the ball is provided, so that it can be applied to a mounting method such as BGA.

  In addition, according to the present invention, since a technique capable of measuring a non-contact current with a bonding wire can be provided, it is possible to cope with a case where there is no wiring measured on the upper layer of the IC chip.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, a conventional magnetic field detector shown in FIG. 14 will be described as a reference example. Such a magnetic field detector is used for non-contact current measurement that detects a magnetic field in the vicinity of an electronic component such as a printed circuit board or a semiconductor package, visualizes the magnetic field distribution, and calculates a current flowing through the wiring from the magnetic field. Normally, when such a magnetic field detector is exposed to an electromagnetic field to be measured, a voltage is induced in each conductor according to the electromagnetic law. At this time, a voltage due to the magnetic field is induced in a direction in which current flows mainly clockwise or counterclockwise in the wiring conductor patterns 1b, 1c, 3b, and 3c. The flowing current is transmitted through the conductor 2 through the via 4 at the tip, further transmitted through the wiring 1, and detected as a voltage at the input stage of the measuring instrument. This is a typical operation when using this type of magnetic field detector. At this time, there is usually not only a magnetic field around the object to be measured but also an electric field, and a voltage is induced along the longitudinal direction of each conductor. Usually, components other than the measurement target are mounted on such a printed circuit board, and therefore an electromagnetic field that is not intended to be measured is generated. At this time, since the magnetic field detector has a substantially symmetric shape with respect to the conductor 1, the voltage due to the electric field is canceled or becomes a very small value compared to the voltage output due to the magnetic field. In this way, the electric field can be shielded and a magnetic field detector can be configured.
However, in the conventional magnetic field detector of FIG. 14, the inner-layer signal wiring 2 exists only on one side and is not symmetrical with respect to the longitudinal direction (transmission direction) of the ground wiring 1. Since the entire magnetic field detector is composed of a multilayer substrate, the side surface of the ground layer is open, and a slight electric field penetrates into the interior, causing a measurement error to increase. Such a phenomenon is not always observed with this type of magnetic field detector, and the width of the ground wirings 1 and 3 is sufficiently larger than the signal wiring 2 and the interlayer thickness of each layer for reasons of miniaturization and prevention of the lens effect. This occurs when it cannot be widely used.

[Embodiment 1]
1A and 1B are a perspective view and a plan view showing a magnetic field detector according to a first embodiment of the present invention.

  In FIG. 1, the first-layer wiring conductor pattern 1 serving as a ground wiring (basically a wiring having a constant potential is not limited to GND) is branched from the linear conductor pattern 1a and the linear conductor pattern 1a. It has a conductor pattern 1b and a conductor pattern 1c. The leading ends of the conductor pattern 1b and the conductor pattern 1c are spaced apart from each other by a predetermined distance. Each of the conductor patterns 1b and 1c is a “C” -shaped or “U” -shaped conductor pattern, and the conductor patterns 1b and 1c together constitute a “C” -shaped conductor pattern. The conductor patterns 1b and 1c have the same length, and the gap between the tips of the conductor patterns 1b and 1c is arranged at the approximate center of the magnetic field detector. The gap may be long and deviated from the center. The gap is desirably arranged at or near the center of the magnetic field detector due to the characteristics, but basically, at any position from the center of the magnetic field detector to the vicinity of the connection portion of the linear conductor pattern 1a. Since the magnetic field can be detected, the position of the gap may be appropriately changed in consideration of performance required as a magnetic field detector.

  The second-layer wiring conductor pattern 2 serving as a signal wiring includes a linear conductor pattern 2a, a conductor pattern 2b connected to the linear conductor pattern 2a, and a conductor pattern 2c connected to the tip of the conductor pattern 2b. The conductor patterns 2b and 2c together form a “C” shape, and the conductor pattern 2c has a notch in the vicinity of the linear conductor pattern. The linear conductor pattern 2a, the conductor pattern 2b, and the conductor pattern 2c are provided so as to face the linear conductor pattern 1a, the conductor pattern 1b, and the conductor pattern 1c, and the linear conductor pattern 1a, the conductor pattern 1b, and the conductor pattern 1c are provided. The width is narrower than the width. The width of the conductor pattern 2c is the same as that of the conductor pattern 2b.

  The third-layer wiring conductor pattern 3 serving as a ground wiring (basically a wiring having a constant potential as well as GND) has the same shape as the first-layer wiring conductor pattern. That is, the wiring conductor pattern 3 includes a linear conductor pattern 3a, a conductor pattern 3b branched from the linear conductor pattern 3a, and a conductor pattern 3c. Each of the conductor patterns 3b and 3c is a “C” -shaped or “U” -shaped conductor pattern, and the conductor patterns 3b and 3c together constitute a “C” -shaped conductor pattern.

The wiring conductor pattern 1, the wiring conductor pattern 2, and the wiring conductor pattern 3 are electrically connected by the via conductor 4 through the leading end portion of the conductor pattern 2b. The via conductor 4 may pass through the end portion of the conductor pattern 2c (in the vicinity of the conductor pattern 2a) (the same applies to each embodiment described later). The via conductor 4 may be provided so as to pass through a neighboring region that is away from the tip of the conductor pattern 2b or 2c to the extent that there is no problem in characteristics (this region is also included in the tip). Here, the via conductor 4 passes through the tip portions (one tip portion that creates a gap) of the conductor patterns 1c and 3c, but passes through the tip portions (the other tip portion that creates a gap) of the conductor patterns 1b and 3b. May be.
As shown in FIG. 18, the wiring conductor pattern 1 and the wiring conductor pattern 2 are opposed to each other via the insulating layer 41, and the wiring conductor pattern 2 and the wiring conductor pattern 23 are opposed to each other via the insulating layer 42. The wiring conductor patterns 1, 2, and 3 can be formed of a metal layer such as AgPd or Au, and the insulating layer 41 can be a glass ceramic sheet. FIG. 19 shows a magnetic field detector of another configuration example, and FIG. 20 shows a cross-sectional view taken along line AA ′ of FIG. As shown in FIG. 20, the magnetic field detector of this configuration example has a multilayer board configuration in which the wiring conductor pattern 2 and the wiring conductor pattern 3 are provided in the substrate, and the wiring conductor pattern 1 is provided on the substrate. The wiring conductor pattern 1, the wiring conductor pattern 2, and the wiring conductor pattern 3 may be provided in the substrate.
18 and 19, d1 indicates the length of the wiring conductor patterns 1 and 3, d2 indicates the width of the wiring conductor patterns 1 and 3, and d1 / d2 is preferably 1 or more.

  The difference between the magnetic field detector of this embodiment and the conventional magnetic field detector of FIG. 14 is that the wiring conductor pattern 2 serving as a signal wiring extends beyond the via conductor 4 and has a C-shaped conductor pattern 2c. The wiring conductor pattern 2 serving as a signal wiring is opposed to the wiring conductor pattern 1, and the signal wiring has a substantially symmetrical shape when viewed from the linear conductor pattern 1 a of the wiring conductor pattern 1. With such a configuration, even if a slight electric field enters from the side surface, a voltage of the same level is induced, so that the voltage due to the electric field is easily canceled.

  In addition, the structure of the magnetic field detector according to the present embodiment arranges the wiring conductor pattern 2 serving as the signal wiring so as to be symmetric with respect to the linear conductor pattern 1a of the wiring conductor pattern 1, thereby preventing disturbance of the electromagnetic field distribution. It has the effect of symmetrizing and suppressing the induction of asymmetric voltage components due to disturbance of the electromagnetic field. Therefore, the ratio of the output of the electric field to the output by the magnetic field is reduced, and the so-called S / N ratio is improved.

[Embodiment 2]
2A and 2B are a perspective view and a plan view showing a magnetic field detector according to a second embodiment of the present invention. In this embodiment, in FIG. 2 (a), (b), the same component as the component shown in FIG. 1 (a), (b) is attached | subjected, and description is abbreviate | omitted.

  In the magnetic field detector shown in FIGS. 2A and 2B, as in the first embodiment, an unwanted electromagnetic field invades from the side surface of the C-shaped portion where no signal wiring exists and an undesirable voltage or current is generated. When induced by an electromagnetic field, one side is brought close to 6c in FIG.

  Further, in the magnetic field detector shown in FIGS. 2A and 2B, the via conductor 9 is also provided at the terminal portion near the notch 14 of the conductor pattern 2c serving as the signal wiring as shown in FIGS. 2A and 2B. By providing this, it is possible to have a structure integrated with the wiring conductor patterns 1 and 3 that become the upper and lower ground wirings, and one side of the C-shaped portion approaches a complete metal body. When such a magnetic field detector is manufactured on a printed circuit board, the interval between layers may not be narrowed in order to match the characteristic impedance to a predetermined value. In some cases, the pitch of vias cannot be reduced for reasons such as yield. Therefore, a slit-like gap is formed in the direction along the via, and unnecessary electromagnetic fields may enter, or unnecessary voltage may be induced in the direction along the via. As shown in FIG. 2, by providing a wiring pattern along the upper and lower ground wirings and further increasing the number of via connections such as the via 9, the shield can be further strengthened.

[Embodiment 3]
FIG. 3 is a perspective view showing a magnetic field detector according to a third embodiment of the present invention. In the present embodiment, in FIG. 3, the same components as those shown in FIGS. 2A and 2B are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, unlike the second embodiment, the width of the conductor pattern 2d connected to the conductor pattern 2b is expanded to the same width as that of the conductor patterns 1c and 3c serving as upper and lower ground wirings. If the area of the conductor is thus increased, it becomes possible to approximate the configuration of FIG. The width of the conductor pattern 2d may be smaller than the conductor patterns 1c and 3c.

[Embodiment 4]
FIG. 4 is a perspective view showing a magnetic field detector according to a fourth embodiment of the present invention. FIG. 4 shows a structure in which via conductors are arranged on the entire surface of the half-circumferential portion, and the conductors are arranged in a lattice shape in the direction along the ground and in the direction connecting the ground, and the opening when viewed from the side is shown. Since the area is reduced, the structure of FIG. 15 can be further approximated. In FIG. 4, only via conductors 4 and 9 are shown as via conductors, and other via conductors are shown with only via holes on the conductor pattern 1c for simplification, but in reality, as in FIG. The via conductors similar to the via conductors 4 and 9 are provided under the via holes. In FIG. 4, the same components as those shown in FIGS. 2A and 2B are denoted by the same reference numerals, and description thereof is omitted.

[Embodiment 5]
FIG. 5 is a perspective view showing a magnetic field detector according to a fifth embodiment of the present invention. In FIG. 5, the same components as those shown in FIG. In FIG. 5, by providing the intermediate layer (conductor layer) 11 and increasing the number of conductors, the metal portion can be increased without changing the overall thickness. As in the case of FIG. 4, it is also possible to provide vias that connect the upper and lower ground lines and the intermediate layer. In FIG. 5, two intermediate layers 11 are provided between the ground wiring 1 and the signal wiring 2, and between the ground wiring 3 and the signal wiring, respectively. One or three or more intermediate layers 11 may be provided between the ground wiring 1 and the signal wiring 2 and between the ground wiring 3 and the signal wiring.
FIG. 5 shows a result of comparison between the magnetic field detector having the above-described shield reinforcing structure and the conventional magnetic field detector. As shown in FIG. 17, when a magnetic field detector is installed on the microstrip line, an output by a magnetic field can be obtained. Here, when the direction of the magnetic field detector is rotated 180 degrees around the installation ground wiring 1, the output due to the magnetic field is reversed, but the output due to the electric field which is an error factor is not reversed. Therefore, it is ideal that there is no difference between the output when the magnetic field detector is installed at 0 degrees and the output when it is installed at 180 degrees. FIG. 6 is a graph showing the output difference between 0 degrees and 180 degrees. The conventional type of FIG. 6 shows the characteristics of the magnetic field detector of FIG. 14, and the new type of FIG. 6 is the magnetic field detector of FIG. It can be seen that the new type is close to 0 decibels, particularly in the frequency band of 4 GHz or higher, and the performance is improved.

[Embodiment 6]
FIG. 7 shows that there is no via conductor connecting the wiring conductor pattern 2 serving as the signal layer and the wiring conductor patterns 1 and 3 serving as the ground layer, and between the wiring conductor patterns 1 and 3 serving as the ground wiring through the tip of the conductor pattern 2b. A resistor 12 is inserted.
A characteristic impedance of a portion where the transmission line is formed by the wiring conductor pattern 1, the wiring conductor pattern 2, and the wiring conductor pattern 3 is R, and a resistance value of the resistor 12 between the wiring conductor pattern 2 and the wiring conductor pattern 1 is R1. When the resistance value of the resistor 12 between the wiring conductor pattern 2 and the wiring conductor pattern 3 is R2,
R = (R1 · R2) / (R1 + R2)
It is desirable to set the resistance values R1 and R2 so as to satisfy the relationship. When viewed from the transmission line side, the resistor having the resistance value R1 and the resistor having the resistance value R2 are grounded in parallel so that the characteristic impedance of the transmission line and the combined resistance value of the two resistors are equal. This is because reflection of a transmitted signal can be suppressed.

  For example, when the characteristic impedance of the strip line formed by the wiring conductor patterns 1 and 3 serving as the ground layer and the wiring conductor pattern 2 serving as the signal layer is 50Ω, the resistance value of the resistor 12 is designed to be 100Ω. . When such a resistor 12 is inserted, reflection of transmitted signals can be suppressed particularly in a high frequency band exceeding gigahertz.

Such insertion of the resistor is also performed in the conventional magnetic field detector of FIG. 15, but it is manufactured using the multilayer substrate by inserting the resistor into the multilayer substrate as in this embodiment. The same function can be realized with a magnetic field detector, which helps to improve measurement accuracy. It is also possible to detect a DC magnetic field.
The conductor pattern 2c may be omitted. Also, the position of the resistor can be changed. In FIG. 2, the via conductor 4 is not provided, and the resistor can be arranged by inserting a resistor instead of the via conductor 9 of FIG.

[Embodiment 7]
If the resistor 12 in the sixth embodiment is replaced with an electromagnetic absorber, a more accurate non-reflection termination condition can be realized. By providing the absorber with a resistance component or inserting it in parallel with the resistor, a magnetic field detector that can be used in a wide band can be configured. The absorber may be any material that can absorb electromagnetism. For example, a ferrite material or a polymer material mixed with a ferrite material can be used.

[Embodiment 8]
When measuring the current flowing through the wiring on the IC chip, as shown in FIG. 17, a magnetic field detector is installed vertically from the top surface of the IC chip to detect a magnetic field in a direction around the wiring and convert it into a current. Is a common usage. However, when the IC chip is mounted by a mounting method called face-down, there is no wiring that can bring the magnetic field detector close to the surface, so it is difficult to measure the magnetic field and current with the method shown in FIG. .

  FIG. 8 is a diagram for explaining a magnetic field detector for measuring a magnetic field and a current in such a case. In FIG. 8, 21 is a ball, 22 is an IC chip, 23 is an IC package, 24 is a magnetic field, 25 is a printed circuit board, 26 is a linear lead wire, 27 is a lead wire, 28 is a connector, and 30 is a current.

  Since the magnetic field cannot be measured on the IC chip, the magnetic field is measured around a connection ball such as a solder ball or a gold ball for connecting the IC chip to the package. Such balls are often spherical or cylindrical. Since the current flows in the ball connecting the IC package and the printed board, a magnetic field is generated around the ball surface in the vicinity of the ball. In order to detect this magnetic field, a minute magnetic field detector must be installed in the vicinity of the ball. FIG. 8 shows an embodiment of such a magnetic field detector.

  This magnetic field detector has a magnetic field detector made of a multilayer substrate at the tip. A transmission line (strip line) constituted by the ground wirings 1 and 3 and the signal wiring 2 as the lead lines is extended to a necessary length. This is because the tip of the magnetic field detector is inserted with a gap between the balls. Normally, in the case of a BGA package as shown in FIG. 8, the height of the ball is from several tens of micrometers to several hundreds of micrometers, and the magnetic field detector must be inserted into a narrow gap. In this case, it is required to bring out the lead line directly, but there is no problem if the external dimension of the connector for connecting to a measuring instrument such as a spectrum analyzer attached to the tip of the lead line is sufficiently small. However, in general, since an SMA type connector or the like is used, it is difficult to insert the connector straight into the gap. Therefore, in this embodiment, physical interference between the connector and the printed circuit board is avoided by connecting a lead wire 2 having an angle with respect to the lead wire 1 to form a transmission line. Note that a substrate on which an amplifier or the like is integrated may be mounted instead of the connector. With such a configuration, the magnetic field detector can be directed in the direction of the magnetic field generated in the vicinity of the ball, and there is an effect of improving the S / N and improving the accuracy of current calculation. In addition, the operability when inserting the magnetic field detector is improved.

  FIG. 9 is a diagram showing an application example to a bonding wire. In FIG. 9, 29 is a bonding wire, and 30 is an electric current.

  Although the IC chip is mounted face up in FIG. 9, the measurement error becomes large when the wiring to be measured exists below the IC chip. Therefore, it may be necessary to measure the current with a bonding wire. Usually, such a wire has a straight portion, but if a magnetic field detector can be brought close to that portion, the magnetic field around the wire can be detected and converted into a current. At this time, as shown in FIG. 9, by providing a lead wire having an angle corresponding to the shape of the measurement object, the magnetic field detector can be easily supported and the operability is improved. Such a measurement method can be applied to some implementations of SiP (System in a package) which has been widely used in recent years, and its application range is wide.

[Embodiment 9]
As described above, if the magnetic field around the ball and the bonding wire is measured, the current flowing through the ball and the wire can be calculated.
If a wire and a ball are approximated by a line current model as shown in FIG. 10, as an example, the magnetic field and current can be associated from the following equation.

この式は電磁気学の最も基礎的な式の一つであり、Ｈはボールあるいはワイヤ近傍を周回する磁界であり、Ｉはボールあるいはワイヤ中を流れる電流である。

This equation is one of the most basic equations in electromagnetism, H is a magnetic field that circulates in the vicinity of the ball or wire, and I is a current flowing in the ball or wire.

  When the magnetic field detector detects a magnetic field, its output is measured as a voltage Vp by a measuring instrument such as a spectrum analyzer. If the magnetic field calibration coefficient of the magnetic field detector is Cf, the magnetic field H can be obtained from the voltage Vp. This magnetic field calibration coefficient can be obtained by measurement or calculation.

この式を（１）式に代入すれば次の式が得られる。

Substituting this equation into equation (1) gives the following equation:

（３）式より最終的にワイヤあるいはボールを流れる電流値を求めることができる。

The value of the current flowing through the wire or ball can be finally obtained from the equation (3).

  When currents are equally distributed on the ball or wire surface as shown in FIG. 11, equation (4) is used instead of equation (1). Reference numeral 31 denotes a surface current flowing in the divided area.

  FIG. 12 is a view of FIG. 11 as viewed from the top surface of the ball, where rk is a distance from the current existing in the divided kth region, and θk is a magnetic field component in the direction of the opening of the magnetic field detector. It is an angle for. Further, 32 is a divided kth surface current, 33 is the center of the central opening of the magnetic field detector, and 34 is a magnetic field component perpendicular to the central opening of the magnetic field detector.

ここでＮはワイヤ表面の分割数であるため、分割された領域での電流値はＩ／Ｎという値を持つ。（２）式を（４）式に適用すれば、次の式が得られ、測定された電圧から電流を求めることができる。

Here, N is the number of divisions on the wire surface, so the current value in the divided area has a value of I / N. When the formula (2) is applied to the formula (4), the following formula is obtained, and the current can be obtained from the measured voltage.

以上述べた通り、測定対象物の形状に応じて適切な電流モデルを設定すれば、測定された近傍磁界からボールやワイヤを流れる総電流値を算出することができ、磁界検出器を利用した非接触電流測定システムを構築することが可能となる。

As described above, if an appropriate current model is set according to the shape of the object to be measured, the total current value flowing through the ball or wire can be calculated from the measured nearby magnetic field. It becomes possible to construct a contact current measurement system.

  When the divided current is also set inside the ball or the wire, it can be calculated by assuming the divided current in each region with the same capacity as dividing the surface.

  If current exists only near the surface due to the skin effect, etc., the total current flowing through the ball or wire from the magnetic field measured by the same procedure can be obtained by calculating the current distribution in the depth direction using an appropriate calculation method. Can be calculated.

  When these calculations are performed, the calculation is further simplified if the concept of current calibration coefficient is introduced.

  Many other methods for expressing the calculation formula of the magnetic field as described above are conceivable. For example, in the equation described above, the magnetic field generated at the center of the opening at the center of the magnetic field detection unit is calculated, but when the region for detecting the magnetic field is represented by a certain area, FIG. For example, a method of integrating the magnetic field over an equivalent magnetic field detection range including the central opening and its periphery as shown in FIG. In FIG. 13, reference numeral 35 denotes an integration range.

  The present invention is used for a magnetic field detector used for magnetic field and current measurement, and particularly for a magnetic field detector based on a shielded loop type magnetic field detector manufactured by a multilayer substrate. Further, it is used in a technique for measuring a current or a magnetic field in a non-contact manner using a wiring on a semiconductor chip, a ball portion or a bonding wire portion of a semiconductor package as a measurement target.

(A), (b) is the perspective view and top view which show the magnetic field detector of 1st Embodiment of this invention. (A), (b) is the perspective view and top view which show the magnetic field detector of 2nd Embodiment of this invention. It is a perspective view which shows the magnetic field detector of 3rd Embodiment of this invention. It is a perspective view which shows the magnetic field detector of 4th Embodiment of this invention. It is a perspective view which shows the magnetic field detector of 5th Embodiment of this invention. It is a characteristic view which shows the output difference at the time of installing the output when a magnetic field detector is installed at 180 degree | times, and 180 degree | times. It is a perspective view which shows the magnetic field detector of 6th Embodiment of this invention. It is a figure which shows the magnetic field detector which measures a magnetic field and an electric current. It is a figure which shows the magnetic field detector which measures an electric current with a bonding wire. It is a figure explaining the method of calculating the electric current which flows through a ball | bowl and a wire with a line current model. It is a figure explaining the method of calculating an electric current when an electric current is equally distributed on the surface of a ball | bowl or a wire. It is the figure which looked at the ball | bowl of FIG. 11 from the upper surface. It is a figure explaining the method of calculating the electric current which flows through a ball | bowl and a wire. It is a figure which shows the basic structure of a shielded loop type magnetic field detector. It is a figure which shows the shielded loop comprised by the semicircle part of a coaxial structure and the semicircle part by the circular conductor which is not hollow. It is a figure which shows the shield reinforcement structure by via | veer connection. It is a figure which shows the measurement which detects the magnetic field which is installed perpendicularly | vertically to the printed circuit wiring and the wiring on an IC chip, and goes around a wiring. It is a disassembled perspective view of a magnetic field detector. FIG. 19 is a plan view showing a magnetic field detector of another configuration example. FIG. 20 is a cross-sectional view taken along line A-A ′ of FIG. 19.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground wiring pattern of 1st layer 1a Straight line part of ground wiring of 1st layer 1b C-shaped part which forms strip line of ground wiring of 1st layer 1c C character which does not form strip line of ground wiring of 1st layer Part 2 Second layer signal wiring pattern 2a Second layer signal wiring pattern straight line portion 2b Second layer ground wiring pattern and C-shaped part forming strip line 2c Side not forming second layer strip line C-shaped part 2d C-shaped part with wider width on the side where the second layer strip line is not formed 3 Ground wiring pattern of the third layer 3a Straight line portion of the ground wiring of the third layer 3b Ground wiring of the third layer C-shaped part 3c forming the strip line of the third layer C-shaped part not forming the strip line of the ground wiring of the third layer 4 Signal line pattern tip of the second layer Vias connecting the first, second, and third layers 5 Gap 6 Outer conductor of coaxial cable 6a Straight portion of outer conductor 6b C-shaped portion 6c on the side forming the coaxial of the outer conductor 6c C-shape on the side not forming the coaxial Form part 7 Center conductor 8 Gap 9 Via connecting the first and third layers in the vicinity of the notch 10 Via disposed between the via 4 and the via 9 11 Inserted between the first, second and second layers C-shaped pattern 12 Resistor or absorber 13 Printed circuit board (outer shape)
DESCRIPTION OF SYMBOLS 14 Notch 15 Magnetic field detector 16 Magnetic field around wiring 17 Current of wiring 18 Strip conductor 19 Ground conductor 20 Dielectric 21 Ball 22 IC chip 23 IC package 24 Magnetic field 25 Printed circuit board 26 Leader line 1
27 Leader 2
28 Connector 29 Bonding Wire 30 Current 31 Surface Current Flowing in Divided Region 32 Divided kth Surface Current 33 Center of Center Opening of Magnetic Field Detector 34 Magnetic Field Component Vertical to Central Opening of Magnetic Field Detector 35 Integration range

Claims (11)

A first linear conductor pattern; and first and second conductor patterns connected to an end of the first linear conductor pattern and branched from the end; and the first and second conductor patterns A first layer in which the tip of the conductor pattern is spaced a predetermined distance away from the first layer;
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A second linear conductor pattern facing the first linear conductor pattern, and a first conductor pattern that is narrower than a width of the first conductor pattern and connected to a tip of the linear conductor pattern. A third conductor pattern facing and extending to a position facing the tip of the first or second conductor pattern, and the second conductive connected to the first tip of the third conductor pattern A fourth conductor pattern opposite to the pattern, the fourth conductor pattern having a notch near the second linear conductor pattern, and disposed between the first layer and the second layer. A third layer,
The first layer, the second layer, and the third layer are electrically connected through the first tip of the third conductor pattern or the second tip of the fourth conductor pattern that is cut away. A magnetic field detector comprising: a first via conductor.   The first via conductor passes through one of the first tip portion and the second tip portion, and the second via conductor passes through the other of the first tip portion and the second tip portion. The magnetic field detector according to claim 1, wherein the first layer, the second layer, and the third layer are electrically connected by a second via conductor.   The magnetic field detector according to claim 1, wherein the fourth conductor pattern has the same width as the third conductor pattern.   The width of the fourth conductor pattern is larger than the width of the third conductor pattern and is the same width as the second conductor pattern or smaller than the second conductor pattern. The magnetic field detector according to 1 or 2.   5. A plurality of via conductors for connecting the first, second, and third layers are provided between the first via conductor and the second via conductor. The magnetic field detector according to item.   Each of the first and third layers and the second and third layers has a width opposite to the fourth conductor pattern and the same width as the fourth conductor pattern or smaller than the fourth conductor pattern. The magnetic field detector according to claim 1, wherein at least one conductor layer is provided, and the conductor layer is connected to the first or / and second via conductor. A linear conductor pattern; and first and second conductor patterns connected to an end of the linear conductor pattern and branched from the end; and tip portions of the first and second conductor patterns A first layer spaced apart by a predetermined distance and disposed opposite to each other;
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A third conductor pattern that is narrower than a width of the first conductor pattern and that opposes the first conductor pattern, or a third and fourth conductor pattern that opposes the first and second conductor patterns, and A third layer disposed between the first layer and the second layer,
A resistor is inserted between the first layer and the third layer and between the second layer and the third layer at the tip of the third or fourth conductor pattern. Magnetic field detector. A characteristic impedance of a portion that forms a transmission line by the first layer, the second layer, and the third layer is R, a resistance value of a resistor between the first layer and the third layer is R1, and the second layer When the resistance value of the resistor between the first layer and the third layer is R2,
R = (R1 · R2) / (R1 + R2)
The magnetic field detector according to claim 7, wherein the following relationship is satisfied. A linear conductor pattern; and first and second conductor patterns connected to an end of the linear conductor pattern and branched from the end; and tip portions of the first and second conductor patterns A first layer spaced apart by a predetermined distance and disposed opposite to each other;
A second layer having a conductor pattern of the same shape as the first layer and disposed opposite the first layer;
A third conductor pattern that is narrower than a width of the first conductor pattern and that opposes the first conductor pattern, or a third and fourth conductor pattern that opposes the first and second conductor patterns, and A third layer disposed between the first layer and the second layer, and a third layer disposed between the first layer and the second layer,
An electromagnetic absorber is inserted between the first layer and the third layer and between the second layer and the third layer at the tip of the third or fourth conductor pattern. Magnetic field detector characterized by.   A magnetic field detector, wherein a strip line having an angle is connected to a linear strip line included in the magnetic field detector according to claim 1.   A current measurement method for measuring a magnetic field around a ball or a bonding wire using the magnetic field detector according to any one of claims 1 to 10 and converting it into a current.

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