JPH1038984A - Method and apparatus for detecting failure site - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for enabling a failure site to be detected without contact and with high resolution and high sensitivity without professional knowledge on design which can be applied to a wide range of electronic circuit devices of interest. SOLUTION: A magnet 11 for applying a magnetic field to an electronic circuit device 10 to be inspected which is in operation is provided. The magnet 11 is scanned by a scanning means 12 along a surface of the circuit device 10. Reaction force functioning to the magnet 11 when the magnetic field is applied by the scanning means 12 is detected as an electric signal by a reaction detection means 13. The electric signal detected by the means 13 is analyzed by an analyzing means 17 to express it in numeral. Reaction force data expressed in numeral is compared by a comparison means 17 with reaction force data corresponding to normal operation of the electronic circuit device 10 stored in a database in advance, thereby detecting a failure site.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a failed part which automatically performs a failure analysis of an electronic circuit device such as an IC or an electronic substrate.

[0002]

2. Description of the Related Art In failure analysis of ICs and electronic boards,
Identifying the failure site is of utmost importance. Conventionally, in the case of IC, liquid crystal analysis method, emission microscope,
EB (electron beam) tester, 0BIC method (photo-induced current method), OBIRCH method (light-heating resistance change detection method), and the like. In the case of an electronic substrate, a method using an infrared image or an electronic component is extracted. There is a method for measuring characteristics, and the like.
In the liquid crystal analysis method, a liquid crystal is applied to a faulty IC and energized, and abnormal heat generation due to a leak current or the like is detected. When the applied liquid crystal is kept at a temperature just below the phase transition temperature and is energized, only the leak portion exceeds the phase transition temperature due to heat generation. At this time, only the liquid crystal on the leak part has a different molecular arrangement from the surroundings,
The light transmittance of that portion changes and can be specified by a microscope image. The emission microscope detects a minute light emission from a minute portion on the IC chip by using a high-sensitivity photo-counting camera through an optical microscope and forms an image. Then, the detected minute light emission is taken into an image processor, subjected to image processing, and displayed on a monitor. By superimposing this on an optical microscope image, a light emitting portion is specified. E
The B-tester utilizes the fact that the amount of secondary electrons generated when irradiating a sample with an electron beam to the detector depends on the surface potential of the electron beam-irradiated area, and uses an electron pulse synchronized with the operation of the LSI. With the use of the beam, the potential of the wiring at a specific timing can be observed. In the OBIC method, an electron-hole pair generated when a semiconductor is irradiated with a laser beam drifts due to an externally applied electric field or an internal electric field to detect an OBIC that flows to the outside. Then, by detecting a change in the OBIC in correspondence with the laser irradiation position, the defective portion is specified. The OBIRCH method is
Utilizing the fact that when a laser is irradiated to the wiring, the wiring temperature at that portion rises and the resistance increases. In a portion where the heat conduction is deteriorated due to the occurrence of a void or the like, the temperature rise is particularly large and the resistance increases. Therefore, this is detected as a current change, and the location of the defect is specified in correspondence with the laser irradiation position. On the other hand, in the method using an infrared image, the infrared temperature emitted from the object to be diagnosed is captured and its surface temperature is observed.
Identify the abnormal heat generation part as a failure part in the temperature map. In the method of extracting electronic components and measuring their electrical characteristics, a general method is to check the input / output characteristics of the extracted components and find abnormal characteristics. There is a method for detecting a failure on the digital board, and a method for detecting a failure on the digital board using the marginal voltage of the digital IC as an index.

[0003]

SUMMARY OF THE INVENTION So far, I
There are few failure site detection devices applicable to both C and electronic boards. A current example is a method using an infrared image, but using this method for an IC is inferior to a liquid crystal analysis method and other methods in terms of sensitivity and resolution. Also,
Even when used for an electronic substrate, there is a risk that a misdiagnosis may occur due to heat transfer between a normal component and an abnormal component, a variation in the amount of heat generated between similar components, and the like. Then, IC
Regarding a dedicated failure site detection device, the liquid crystal analysis method is simple and relatively inexpensive, but has a very poor spatial resolution of several μm. Further, since the EB tester uses the SEM, there is a disadvantage that the sample must be kept in a vacuum. On the other hand, for the emission microscope, the spatial resolution is 1 μm or more, and the detectable current is 10 nA.
~, Detectable current: several tens pA ~, OBIRCH method
Spatial resolution: The resolution and sensitivity are as good as several hundred nm, respectively. However, these devices have the disadvantage that they cannot be applied to electronic substrates. As a method for an electronic substrate, there is a method of extracting electronic components on the electronic substrate and measuring electrical characteristics in addition to a method using an infrared image. But,
In this method, not only knowledge of the circuit is required but also time is required, and the efficiency of the failure analysis is reduced.

Therefore, the present invention can be applied to a wide range of objects such as ICs and electronic boards, and does not require specialized design knowledge.
An object of the present invention is to enable non-contact sampling to enable high-resolution and high-sensitivity failure detection.

[0005]

According to the present invention, there is provided a magnet for applying a magnetic field to a target electronic circuit device in an operating state, and scanning means for scanning the magnet along the surface of the target electronic circuit device. A reaction detecting means for detecting a reaction force acting on the magnet as an electric signal when a magnetic field is applied by the scanning means, an analyzing means for analyzing the electric signal detected by this means to quantify the reaction force, and A failure portion detecting method and device comprising comparing means for comparing the digitized reaction force data with the corresponding reaction force data in a normal state of the target electronic circuit device stored in a database in advance. You.

[0006] In the method and apparatus for detecting a failed part configured as described above, the force generated between the magnetic field of the magnet and the current flowing through the circuit on the target surface is detected as the force that the magnet receives from the target. This is based on Fleming's left-hand rule, and enables non-contact measurement. Therefore, there is no problem of abrasion of the object or the apparatus itself, no trouble of wiring, and the like, and the speed of surface scanning by the scanning means can be increased. In addition, by changing the size of the magnet and the size of the applied magnetic field, and having the scanning means corresponding thereto, the failure site detecting device can be applied to ICs and electronic substrates without limiting the target. Applicable.

Further, according to the present invention, there is provided the above-mentioned faulty part detecting apparatus, characterized in that the magnet used for applying the magnetic field uses a minute single pole head or an induction type head. By using a minute single-pole head or an inductive head, a minute area can be scanned, and the reaction force applied to the single-pole head or the inductive head on a fine circuit such as an IC chip is detected. In this device, the width is 0.1 mm.
A magnetic field is applied on the order of 1 μm to the wiring of a fine circuit on an IC or LSl. Therefore, a higher resolution analysis such as a liquid crystal analysis method can be performed. Further, high-speed head scanning can be realized by applying the technology of the magnetic head of the hard disk.

Further, according to the present invention, there is provided the faulty site detecting device, wherein the magnet is an electromagnet. In this device, when it is difficult to detect the reaction force that the electromagnet receives from the target, a strong magnetic field is generated to make it easier to detect.In addition, when there is an area where the magnetic field is not desired to be applied, the target is demagnetized to adversely affect the target. Can have no effect.

Further, according to the present invention, a magnetic field detector for detecting a magnetic field generated on the surface of a target electronic circuit device in an operating state as an electric signal, and the magnetic field detector is mounted on the surface of the target electronic circuit device. Scanning means for scanning along, analysis means for analyzing an electric signal detected by this means and quantifying it as a value of a magnetic field, and said target electronic circuit device in which magnetic field data quantified by this means is stored in a database in advance And a comparison means for comparing the magnetic field data with the corresponding magnetic field data.

In the method and apparatus configured as described above, the magnetic sensor detects the magnetic field generated in the space above the target surface by the current flowing through the target circuit during the operation of the target to be diagnosed by the magnetic sensor in a non-contact manner. At this time, since no external action such as light or a magnetic field is applied to the target from the failure site detection device side, the state can be detected over the entire surface of the target regardless of the circuit configuration of the target. In addition, depending on the shape of the magnetic sensor, a diagnosis target can be broadly expanded from an IC to an electronic substrate and other devices. Furthermore, in this method and apparatus for detecting a failed part, the magnetic sensor scans the entire target surface by the scanning means, and the result of mapping the magnetic field distribution is compared with the result of mapping in the normal state to detect a failed part or an abnormal part. Therefore, there is no need for design information or circuit knowledge.

Further, according to the present invention, the magnetic field detector comprises three MR heads or GMR heads for independently detecting a magnetic field component in each of three-dimensional axial directions. An apparatus is provided. This device has three MR heads or GMR heads corresponding to the detection of the magnetic field components in the respective axial directions in order to independently detect the magnetic field components in the three-dimensional axial (x, y, z) directions. The three MR heads or GMR heads are respectively scanned to detect magnetic field components at respective points on the surface of the measured object as magnetoresistive changes. It is possible to measure the magnitude and direction of the magnetic field at each point three-dimensionally, and to measure the magnetic field with high sensitivity since an MR head or GMR head is used. Furthermore, since MR heads and GMR heads can be made of thin films, they have a large degree of freedom in size and shape, and measure the surface magnetic field of a wide range of objects using ICs, electronic substrates, and other devices. It becomes possible. Further, each of three-dimensional axes (xyz) using three MR heads or GMR heads
Since the magnetic field components in the directions are measured independently, there is also an advantage that a subtle change in the magnetic field can be easily detected.

Further, according to the present invention, there is provided the faulty part detecting device, wherein a flux gate magnetometer is used as the magnetic field detector. In this apparatus, an external magnetic field is detected as a change in the output of an operational amplifier by a fluxgate magnetometer, thereby realizing high-sensitivity and high-resolution magnetic field detection. Also,
The use of fluxgate magnetometers contributes to downsizing of the equipment and widening of the target.

[0013]

As described above, according to the present invention, a failure analysis of an electronic circuit device such as an IC or an electronic substrate is performed by a magnet based on Fleming's law. A method of detecting a magnetic field generated on the surface as a state quantity, and detecting a change in the state quantity caused by a change in a current state of a target to detect an abnormal part or a faulty part. An apparatus for detecting a failed part according to the present invention will be described below with reference to FIGS. 1 to 11.

FIG. 1 is a block diagram of a faulty part detecting apparatus according to a first embodiment of the present invention. The failure site detection device of this embodiment is an electronic circuit device 1 that is a failure site detection target.
A magnet 11 for applying a magnetic field to the surface of the electronic circuit device 1
Scanning means 12 for scanning this magnet 11 along the surface of
A reaction detecting means 13 for detecting a reaction force received by the magnet 11 from a target; an amplifying means 14 for amplifying a small signal detected by the reaction detecting means 13; and converting the amplified signal into a magnitude and direction of force by calculation. And a database 16 for storing, as normal data, the results of measuring the reaction force applied to the magnet 11 at each measurement point on the surface of the normal target electronic circuit device 10 by the analysis means 15 from the magnet 11 in advance. A comparison / judgment unit 17 for comparing and comparing the analysis result obtained by the analysis unit 15 with the normal data in the database 16 to determine a failed part, and an output unit 18 for outputting the analysis result and the comparison / judgment result And a holder 1 for fixing an object to unify the coordinate system of measurement
9. FIG. 2 is an enlarged perspective view showing a main part of FIG. 1, in which the target electronic circuit device 10 is operated by a magnet 11 and a force generated when a magnetic field is applied thereto is described by Fleming's left-hand rule. FIG. In the figure, portions corresponding to the configuration of FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the figure, the target electronic circuit device 10
When a magnetic flux B indicated by a white arrow of the magnet 11 is applied to a current I indicated by a thick arrow flowing in a specific portion of the above-mentioned case, a force F indicated by a thin arrow acts on the magnet 11 according to Fleming's left-hand rule. Here, the force F is expressed as F = I × B × l (1). Here, F, I, and B each represent a vector, and 1 is a dimension of a side of the magnet 11 parallel to the current I.

FIG. 3 shows the reaction detecting means 13 shown in FIG.
FIG. 2 is a perspective view for explaining a schematic configuration example of FIG. (A) shows a method in which an external force is applied to the magnet by expanding and contracting a spring 21 so as to cancel the displacement of the magnet 11 due to the reaction force, and the expansion and contraction of the spring at that time is detected as a change in the capacitance of the capacitors 22 and 23. (B) shows the magnet 1 by the reaction force.
The electromagnets 25 and 26 are attached to the magnet 24 so as to cancel the displacement of 1.
Currents I ₁ , I ₂ flowing through the electromagnets 25, 26
Is a method of detecting a change in

The changes in the capacitances of the capacitors 22 and 23 or the changes in the currents I ₁ and I ₂ applied to the electromagnets 25 and 26 obtained by the reaction detecting means 13 are analyzed by the analyzing means 15. It is performed as follows. First,
The case of FIG. 3A will be described. Δ in the x-axis direction
It is assumed that the force acting on the magnet 11 is balanced by compressing the spring 21 by d ₁ and Δd _{2 in the} y-axis direction (Δd ₁ and Δd ₂ can take both positive and negative values). At this time, the capacitor 22,
The capacitance of 23 was determined by electrical measurement to be C ₁ ′ and C ₂ ′, respectively.
Then, C ₁ ′ = εS ₁ / (d ₁ + Δd ₁ ) (2) C ₂ ′ = εS ₂ / (d ₁ + Δd ₂ ) (3) Therefore, Δd ₁ = εS ₁ / C ₁ ′ −d ₁ = D ₁ (C ₁ / C ₁ ′ −1) (4) Δd ₂ = εS ₂ / C ₂ ′ −d ₂ = d ₂ (C ₂ / C ₂ ′ −1) (5) Therefore, the magnitude of the force F Is

(Equation 1) Further, if an angle between the force F and the x axis in the xy plane is θ,
θ is

(Equation 2) Is the angle that satisfies.

Next, the case of FIG. 3B will be described. The magnetic field created by the electromagnets 25 and 26 is
, The function of the magnetic field in the x-axis direction and the function of the magnetic field in the y-axis direction are Hx (I) and Hy, respectively.
(I). Assuming that the currents of the electromagnets 25 and 26 when the forces acting on the magnet 11 are balanced are I ₁ and I ₂ , respectively, the components Fx and Fy of the force F in the x-axis direction and the y-axis direction at the time of balancing are Fx = q _m Hx (I ₁ ) (8) Fy = q _m Hy (I ₂ ) (9) Therefore, the magnitude F and the direction θ of the force F are given by the following equations.

[0018]

(Equation 3)

(Equation 4) FIG. 4 is a diagram for explaining a method of comparing / determining the analysis result with the normal data in the database 16. Data corresponding to the same measurement point is compared, and if the analysis result is within the measurement error of the normal data, it is determined to be a normal part, and if not, it is determined to be a failure part.

FIG. 5 shows an example of an output image as a result output by the output means 18. The magnitude and direction of the measured reaction are displayed in a vector, and normal data and analysis data are output side by side. The abnormal part vector is displayed in different colors, and numerical data corresponding to each vector is also output.

The faulty part detecting device of the present invention thus configured detects a faulty part as follows. First,
The object is fixed to the holder 19 in order to unify the coordinate system for measurement. Then, the magnet 11 is moved to the position where the reaction force is to be detected by the scanning means 12, and a magnetic field is applied to the current flowing through the target electronic circuit device 10 during operation. At this time, the magnet 11 receives the reaction force F as shown in FIG. The force F is detected by the reaction detecting means 13 as shown in FIG. 3 as a change in the capacitance of the capacitor or the magnitude of the current flowing through the electromagnet. These detection signals are amplified by the amplification means 14 and input to the analysis means 15. The analysis means 15 converts the detection signal into the magnitude of the force F and the direction θ as described above. Scanning unit 1 performs a series of measurements up to this point.
Repeat for each measurement point selected in 2. At this time, the scan interval of the measurement points by the scanning means 12 and the size of the scan area are standardized for each type of the target electronic circuit device 10 so that such information can be input. When all the measurements are completed, the analysis result is input to the comparison / judgment means 17 and collated and compared with the normal data stored in the database 16 as shown in FIG. Determine whether the analysis result and the normal data match within the range of the measurement error,
The analysis result and the determination result are displayed on the display by the output means 18 as shown in FIG. Further, these results are recorded on the storage medium as failure site data so that the results can be reused as failure analysis information.

In this embodiment, the magnitude of the magnet and the applied magnetic field are adjusted, and scanning means corresponding to the magnet is provided.
The present invention can be applied to an IC and an electronic substrate without limiting the target. In addition, since an optical system such as a vacuum system or a laser is not required, the configuration of the apparatus can be simplified. Furthermore, the value of the current flowing through the circuit can be measured without contact from the value of the reaction force and the value of the applied magnetic field.

FIG. 6 is a schematic diagram showing another embodiment of the magnet scanning means suitable for a microelectronic circuit device such as an IC. In this embodiment, a micro head 31 for a hard disk such as a single pole head or an induction type head is used as a magnet. As the scanning means, a mechanism used for a seek operation of a hard disk is applied. In order to float the micro head 31 on the order of 0.1 μm on the IC, air is sent from the outside to the surface of the IC chip and attached to the micro head. The slider 32 generates buoyancy, and balances the force of the spring of the suspension arm 33. As the reaction detecting means 13, the amplifying means 14, the analyzing means 15, the database 16, the comparing / judging means 17, and the output means 18, the same means as those in the first embodiment are used. The scan interval of the measurement point and the size of the scan area by the slider 32 as the scanning means are determined by the target I
Each type of C is unified so that such information can be input to the scanning unit.

In the present embodiment, it is possible to scan a minute area, and it is possible to detect a failure portion of a minute circuit on an IC. Further, the size of the scanning means and the reaction detecting means can be reduced, and high-speed scanning by the head can be realized.

In the above embodiment, the magnet 11
Alternatively, although an example in which a permanent magnet is used as the micro head 31 has been described, it is also possible to use an electromagnet and make the applied magnetic field variable. By adjusting the current value of this electromagnet, demagnetize the part on the target surface where you do not want to apply a magnetic field, and generate a strong magnetic field in the part where the reaction force is difficult to detect because the target circuit current is small. , Making it easier to detect the reaction force. According to such a configuration, the electronic circuit device to be subjected to the failure portion detection may be a target including a component or a circuit for which no magnetic field is to be applied, and the electromagnet can be continuously scanned over the entire surface. Further, since a strong magnetic field can be generated, the reaction force can be easily detected.

FIG. 7 is a schematic diagram showing a faulty part detecting apparatus according to still another embodiment of the present invention. In this embodiment, a magnetic field detector 4 that detects a magnetic field generated from the surface of the target electronic circuit device 40 as any signal.
Scanning means 42 for scanning the magnetic field detector 41 over the entire surface of the target electronic circuit device 40;
Analysis means 4 for analyzing the detection signal detected by 1 and digitizing it
3, a database 46 in which the results of measuring the magnetic field at each measurement point in the surface of the normal target electronic circuit device 40 from the magnetic field detector 41 by the analysis means 43 in advance are stored as normal data, and the analysis results Is compared with a normal result stored in the database 46 to determine whether or not there is a failure; an output means 45 that outputs an analysis result and a comparison / determination result; And a holder 47 for fixing an object to unify the objects.

This faulty part detecting device detects a faulty part as follows. First, the target electronic circuit device 40 is fixed to the holder 47 in order to unify the coordinate system for measurement. Then, the magnetic field detector 41 is scanned on the surface of the target electronic circuit device 40 by the scanning means 42, and a magnetic field generated by a current flowing through the target electronic circuit device 40 is captured as a current change by a Hall element or a coil, It is detected as a change in magnetostriction or magnetoresistance of a ferromagnetic material. These detection signals are input to the analysis means 43, and the detection signals are converted into the magnitude and direction of the magnetic field. The series of measurements up to this point is repeated for each measurement point selected by the scanning means 42. At this time, the scan interval of the measurement points by the scanning unit 42 and the size of the scan area are unified for each type of the target electronic circuit device 40,
Be prepared to enter such information. When all the measurements are completed, the analysis result is input to the comparison / judgment means 44, and collated and compared with the normal data stored in the database 46. It is determined whether the analysis result is normal or abnormal based on whether or not the analysis result and the normal data match within the range of the measurement error, and outputs the analysis result and the determination result to the output unit 4.
At 5, the numerical value or vector is displayed on the display. Further, these results are recorded on the storage medium as failure site data so that the results can be reused as failure analysis information.

In this embodiment, there is no need to apply an external action such as light or a magnetic field to the target electronic circuit device 40 from the faulty part detection device, so that no device for that purpose is required.
The device can be simplified and miniaturized. Further, since no influence is exerted on the circuit, the state can be detected over the entire surface of the target electronic circuit device irrespective of the circuit configuration of the target electronic circuit device 40. Further, depending on the shape of the magnetic field detector 41, the diagnosis target can be widely extended from an IC to an electronic circuit board and other devices.

FIG. 8 is a schematic configuration diagram showing still another embodiment of the magnetic field measuring means used in the failure site detecting device of the present invention. This magnetic field measuring apparatus includes a three-dimensional head 51 that independently detects a magnetic field component in each of the three-dimensional coordinate axes (x, y, z). The three-dimensional magnetic head 51
It is constituted by three MR heads or GMR heads 52, 53, 54 arranged on three surfaces of a cube so as to independently detect magnetic field components in the x, y, and z axis directions. These three MR heads or GMR heads 5
A current is supplied from the current source / voltmeter 56 to the electrodes 2, 53, and 54 via the respective electrodes 55, and a change in the magnetic resistance of the magnetic head 51 is detected as a voltage change. That is, the current source / voltmeter 56 obtains a magnetoresistance change from a voltage change detected by each electrode 55. The obtained magnetoresistance change signal is sent to the analyzing means 57, where x, y, z
A magnetic field component in each axis direction is detected.

FIG. 9 is a diagram for explaining the magnetic field dependence of the magnetoresistance of the MR or GMR head. When an MR film or GMR film receives a magnetic field from an object, the magnetization direction in the film changes. Thereby, the resistance value of the MR film or the GMR film changes. As shown in FIG. 3A, when the current direction indicated by a thin arrow is parallel to the magnetization direction indicated by a thick arrow, that is, the current direction is the same as or completely opposite to the magnetization direction. Sometimes the maximum is reached, and FIG.
As shown in the figure, the minimum value is obtained at the right angle. FIG. 4C is a graph showing the relationship between the angle between the current direction and the magnetization direction on the horizontal axis and the resistance value on the vertical axis. By observing the voltage between the terminals while flowing a current from the terminals connected to both ends of the film constituting the MR or GMR head, a change in the resistance of the MR film or the GMR film can be detected as a voltage change. Therefore, if this film is arranged as three magnetic heads 52, 53, 54 so as to be perpendicular to the magnetic field components in the directions of each axis (x, v, z) of the three-dimensional orthogonal system,
The magnetic field generated by the object can be measured three-dimensionally.
Thereafter, the detected magnetoresistance change is input to the analysis means 57, and each magnetoresistance change is converted into each magnetic field component from the magnetic field dependence of the magnetoresistance of this film. Then, the magnitude and direction of the magnetic field are calculated. The analysis result is similar to the embodiment shown in FIG. 1 or FIG. 7, and the magnetic field detection and analysis are repeated while scanning the three-dimensional magnetic head 51 on the surface of the target electronic circuit device by the scanning means. It is compared with the normal result stored in the database to determine whether or not a failure has occurred, and the measurement result and the determination result are output and stored.

The magnetic field measuring apparatus according to this embodiment has an M
Since the R head or GMR head is used, the magnetic field can be measured with high sensitivity. Further, since the MR head and the GMR head can be made of a thin film, their sizes and shapes can be changed relatively freely. Therefore, it is possible to measure the surface magnetic field of a wide range of objects using an IC, an electronic substrate, or a device having a size and shape suitable for other devices. In addition, 3
Since the three-dimensional magnetic field components in each axial direction are measured independently by using one MR head or GMR head, it is easy to detect a subtle change in the magnetic field.

In the faulty part detecting device of the present invention, in addition to the means described above as the magnetic field detecting means, a flux gate
It is also possible to use a magnetometer. FIG. 11 is a basic configuration diagram of a flux magnetometer. The minimum components are a basic block 60 and a CR smoothing circuit 61 surrounded by a chain line. The principle of magnetic field detection is as follows. A primary winding and a secondary winding are applied to a rod-shaped magnetic core 62, and a resonance capacitor Cs is connected to the secondary side. The resonance voltage is input to an operational amplifier 63 that operates as a comparator, and the output of the operational amplifier supplies an excitation current to the primary side through a resistor Rf. Normally, when there is no external magnetic field, the output of this operational amplifier is a trapezoidal wave with positive and negative targets.
The bias effect causes a difference between the positive and negative excitation periods of the rod-shaped magnetic core 621. Since the amplitude of the trapezoidal wave during the positive and negative excitation periods is limited by the saturation voltage of the operational amplifier 63,
By generating a DC component and smoothing it by a CR smoothing circuit 61 including a capacitor Co and a resistor Ro, a DC voltage proportional to the difference between the positive and negative periods can be obtained. Since this DC voltage has an output proportional to the external magnetic field, the magnetic field can be measured by detecting the DC voltage.

In the faulty part detecting device according to this embodiment, a high sensitivity magnetic field can be detected by the flux magnetometer, so that the faulty part can be easily detected. For example, an amorphous magnetostrictive core (Fe4C066Si15
When B15) is used, a sensitivity of 12.4 V / Oe and a maximum resolution of about 1.3 × 10−60e are possible. Further, this flux magnetometer has a size similar to that of an IC, and can be used for detecting a magnetic field of a relatively small object. Therefore, this failure site detecting device can be applied to a wide range of objects. Further, the size of the device can be reduced.

[0033]

According to the present invention described above, the size of the magnet and the applied magnetic field are adjusted, and the scanning means corresponding to the magnet is provided. The present invention can be applied to the detection and diagnosis of a circuit board as well as those failure parts. Further, since an optical system such as a vacuum system or a laser is not required, the size of the apparatus can be reduced.

Further, according to the present invention, since there is no need to apply an external action such as an electron, light or a magnetic field to the object from the faulty part detecting device side, an external input system such as an electron gun or a laser is not required. Since the magnetic field, which is generated spontaneously by the current flowing through the circuit of the target device in the surface space of the target electronic circuit device, is simply detected by a magnetic sensor in a non-contact manner, the configuration of the device system can be simplified and downsized. It is.

Also, depending on the shape of the magnetic sensor, the object to be diagnosed can be widely extended from ICs to electronic boards and other devices.

[Brief description of the drawings]

FIG. 1 is a block diagram of a failure site detecting device according to a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a main part of FIG. 1;

FIG. 3 is a perspective view for explaining a schematic configuration example of the reaction detection means 13 of FIG. 1;

FIG. 4 is a diagram illustrating a comparison / judgment method by the comparison / judgment means 17 of FIG. 1;

FIG. 5 is a diagram showing an example of an output image of an output unit 18 in FIG. 1;

FIG. 6 is a schematic configuration diagram showing another embodiment of the magnet scanning means in the failure site detecting device of the present invention.

FIG. 7 is a schematic configuration diagram showing a failure site detecting device according to still another embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing still another embodiment of the magnetic field measuring means used in the failure site detecting device of the present invention.

FIG. 9 is a diagram for explaining the magnetic field dependence of the magnetic resistance of the MR head or GMR head used for the magnetic field measuring means in the failure site detecting device of the present invention.

FIG. 10 is a circuit diagram showing a basic configuration of a flux magnetometer as still another embodiment of the magnetic field measuring means in the faulty part detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electronic circuit device 11 Magnet 12 Scanning means 13 Reaction detection means 14 Amplification means 15 Analysis means 16 Database 17 Comparison / judgment means 18 Output means 19 Holder

Claims (8)

[Claims] A magnet applies a magnetic field to a target electronic circuit device in an operating state, scans the magnet along the surface of the target electronic circuit device, and applies a reaction force acting on the magnet when the magnetic field is applied to the target electronic circuit device. It is detected as a signal, the detected electric signal is analyzed and the reaction force is quantified, and the quantified reaction force data is stored in advance in the database as the corresponding reaction force data at the time of normal operation of the target electronic circuit device. A method for detecting a failed part, wherein the method includes comparing. 2. A magnet for applying a magnetic field to a target electronic circuit device in an operating state, scanning means for scanning the magnet along the surface of the target electronic circuit device, and the magnet when the magnetic field is applied by the scanning means. Reaction detection means for detecting the reaction force acting on the reaction signal as an electric signal, analysis means for analyzing the electric signal detected by this means and quantifying the reaction force, and database of the reaction force data quantified by this means in advance. And a comparing means for comparing the target electronic circuit device with corresponding reaction force data stored in the target electronic circuit device in a normal state. 3. The failure site detecting device according to claim 2, wherein the magnet used for applying the magnetic field uses a minute single pole head or an inductive head. 4. The faulty part detecting device according to claim 2, wherein said magnet is an electromagnet. 5. A magnetic field detector which detects a magnetic field generated on the surface of the target electronic circuit device in an operating state as an electric signal is scanned along the surface of the target electronic circuit device, and the detected electric signal is analyzed. And digitize it as the value of the magnetic field,
A method for detecting a failed part, wherein the digitized magnetic field data is compared with corresponding magnetic field data of the target electronic circuit device stored in a database in advance. 6. A magnetic field detector for detecting a magnetic field generated on a surface of a target electronic circuit device in an operating state as an electric signal, and a scanning unit for scanning the magnetic field detector along a surface of the target electronic circuit device. Analysis means for analyzing the electric signal detected by this means and quantifying it as a value of a magnetic field,
A failure portion detection device comprising comparison means for comparing the magnetic field data quantified by this means with the corresponding magnetic field data of the target electronic circuit device stored in a database in advance. 7. The faulty part detecting apparatus according to claim 6, wherein said magnetic field detector is three MR heads or GMR heads for independently detecting magnetic field components in three-dimensional axial directions. 8. The method according to claim 6, wherein a flux gate magnetometer is used as the magnetic field detector.
The failure part detection device according to the above.