JP3195195B2 - Method and apparatus for testing operation of electronic circuit on substrate under test - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit on a board under test for testing the operation of an electronic circuit on a board under test in which electronic parts such as an LSI are mounted on a circuit board such as a printed board to form an electronic circuit. The present invention relates to an operation test method and an apparatus thereof.

[0002]

2. Description of the Related Art Conventionally, an electrical test for testing the operation of an electronic circuit on a board under test in which an electronic component such as an LSI is mounted on a circuit board such as a printed board to form an electronic circuit, that is, an in-circuit test, has been known. , With a contact probe
This is done by directly detecting the signal at the point to be measured.
In general, the number of measurement points per substrate is as high as several thousands, so the positioning of the probe to each measurement point is performed by a jig in which needle-like probes are arranged side by side like a sword mountain, that is, a fixture. Is going. Since the position on the substrate plane to be measured differs depending on the type of substrate, a fixture must be manufactured for each type of substrate. For this reason, the time and cost required for producing the fixture and the space and cost for storing the fixture are wasted. In order to compensate for the above-mentioned problem, it is assumed that a fixture is not used, for example, as described in Electronics Packaging Technology Vol. 10, No. 7, pp33-36, “Fixtureless double-sided printed circuit board inspection device”
There is a method of testing while moving a small number of probes to a necessary place, that is, a method called a moving probe (or flying probe) method. However, this moving probe method takes time each time the probe is moved to the point to be measured, and the test time of the substrate becomes longer. Therefore, it is difficult to apply the method to mass-produced products. There has been a problem that it is difficult to cope with a substrate having a fine pattern such as a high-density mounting substrate or a component such as an IC having a narrow lead pitch.

Japanese Patent Laid-Open Publication No. Hei 5-264672 discloses a method of coping with a substrate having a fine pattern and components such as an IC having a narrow lead pitch by coupling a point to be measured and a detection probe capacitively. A method of detecting a signal by contact is shown. However, this prior art only discloses the details of the detection probe and the incorporation of the probe into the above-mentioned sword-shaped fixture or use as a moving probe. That is, only the non-contact signal detection method is described.

In addition, a magnetic field or electric field detection sensor is arranged,
Japanese Patent Laid-Open Publication No.
No. 324122. The publication discloses a method of performing an operation test of a board by arranging mainly magnetic field detection sensors, detecting a magnetic field generated from the board under test, and comparing the electromagnetic radiation of a known circuit board with a time domain. Have been.
However, in this prior art, the distance between the magnetic field detection sensor and the substrate is kept constant by contacting the spacer element attached to the magnetic field sensor with the substrate so that the sensor position matches the surface shape of the substrate. Therefore, when the arrangement position (or pitch) of the sensor does not match the detected point (or pitch) on the substrate, the sensor unit is retracted from the substrate surface, that is, once separated, the sensor unit is moved in the substrate plane direction. It is necessary to move and make contact with each other. In order to deal with various types of products, that is, to flexibly correspond to different measurement points for each type of substrate, an inspection time may be required. Further, in this conventional technique, the quality of a board is determined by comparing the electromagnetic radiation of a known circuit board with that of a known circuit board in the time domain, so that it is necessary to sufficiently reduce the variation in the electromagnetic radiation between the boards. However, even if the board is large and the circuit is complicated,
Variations between components occur due to component variations (eg, digital signal voltage amplitude, rise / fall time, etc.) and interference between signals, so it is not possible to accurately determine the quality of the board under test. difficult.

[0005]

In the above prior art, the operating state of an electronic circuit on a substrate under test in which an electronic circuit such as an LSI is mounted on a circuit board such as a printed circuit board to form an electronic circuit is efficiently measured in a non-contact manner. Good measurements were not sufficiently considered.

[0006] An object of the present invention is to solve the above problems.
The operating state (in-circuit test) of the electronic circuit on the board under test, in which an electronic component such as an LSI is mounted on a circuit board such as a printed board to form an electronic circuit, is measured by an electric field distribution detection electrode.
The Ru near to provide an electronic circuit performance test method and apparatus in the test substrate which is to be able to efficiently measure without contact with the sensor array which is arranged in an array.

[0007]

In order to achieve the above object, the present invention provides an electronic circuit operation test method for testing the operation of an electronic circuit on a substrate under test on which electronic components are mounted to form an electronic circuit. wherein temporally changing the test signal to the electronic circuit in the tested substrate is applied, the electronic times in the tested substrate in a state where a sensor array arranged the electric field distribution detection electrodes in an array is brought close to the tested substrate
The electrostatically coupled between each measured point of the road
Non-contact with the substrate under test by each electric field distribution detection electrode
Potential or phase at each measured point of electronic circuit
Function of the components mounted on the
The test given to the board under test based on the mounting information on the position
Signal state around each fixed point on the board under test from the test signal
Is estimated, and each of the above
Potential at each fixed point detected by the detection electrode or
The phase is corrected, and the potential or potential at each corrected fixed point is corrected.
Is the distribution information and the reference
Distribution information on the substrate under test consisting of different potentials or phases
A method for testing the operation of an electronic circuit on a substrate under test, characterized in that an operation state of the electronic circuit on the substrate under test is tested by comparing the information with a test report . In addition , the present invention provides the above-mentioned
In the electronic circuit operation test method for a board, the electric field
Each of the electronic circuits on the substrate under test is
When detecting the potential or phase at the measurement point, the sensor
At least the detection electrode
It is characterized in that it is moved within the range of the h .

[0008]

[0009]

[0010] The present invention also provides an electronic component mounted electronic component.
Test the operation of the electronic circuit on the circuit board under test.
In the electronic circuit operation test apparatus to be tested,
Of the board under test so that the state of the electronic circuit at
The test signal is changed over time from the outside to the electronic circuit.
A test signal applying means for applying a test signal
Each measured point of the electronic circuit and each electric field distribution detection electrode
Close to the substrate under test so that
A sensor array in which field distribution detection electrodes are arranged in an array,
Between each measured point of the electronic circuit on the substrate under test
Each electric field component of the sensor array electrostatically coupled at
Electrons on the substrate under test in a non-contact manner by the cloth detection electrode
Detection that detects the potential or phase at each measured point in the circuit
Means and the functions and functions of the components mounted on the board under test.
On the board under test based on
From the given test signal, the signal around the fixed point on the
Signal state, and based on the estimated surrounding signal state,
For each measured point of the electronic circuit detected by the detecting means
Correction means for correcting the potential or phase in the circuit, and the correction means
Potential or phase at each target fixed point corrected by
Information on the substrate to be tested and the reference potential
Or the distribution information on the substrate
Test the operation of the electronic circuit on the board under test.
And a comparing means.
This is an electronic circuit operation test apparatus . In addition, the present invention
In the electronic circuit operation test device on the substrate under test,
Each measurement of the electronic circuit on the substrate under test by the detection means
When detecting the potential or phase at a point, the sensor array
A at least the electric field distribution detection electrode
Characterized by having moving means for moving within the range of the pitch
And

[0011]

[0012]

[0013]

[0014]

According to the above configuration, the electronic circuit on the substrate under test is provided.
Electrostatically coupled to each of the measured points
Non-contact test by the electric field distribution detection electrodes of the array
Potential or potential at each measured point of the electronic circuit on the substrate
The phase is detected and the functions and functions of the components mounted on the board under test are determined.
On the board under test based on
From the given test signal, the signal around the fixed point on the
Signal state, and based on the estimated surrounding signal state,
The potential at each measured point of the detected electronic circuit or
By correcting the phase, it is possible to accurately measure the two-dimensional or one-dimensional potential distribution (including the phase distribution of the potential) of the entire surface or a part of the substrate under test without contact, so that the electronic circuit on the substrate under test can be accurately measured. Can be tested very efficiently.

[0015]

According to the above construction, an electric field distribution detecting electrode or an electric field distribution detecting sensor composed of an electrostatic capacitance, an electro-optic crystal, or the like, or an electromagnetic field distribution detecting electrode, such as a coil, is arranged in an array on a substrate to be tested. By measuring the two-dimensional or one-dimensional potential distribution (including potential phase distribution) or electromagnetic field distribution over the entire surface or a part of the substrate under test in a non-contact manner by disposing the array close to the substrate under test This makes it possible to test the operation state (failure or the like) of the electronic circuit on the substrate under test very efficiently.

[0016]

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, an in-circuit test (testing the operation of an electronic circuit on a board under test in which electronic parts such as an LSI were mounted on a circuit board such as a printed board to form an electronic circuit). Will be briefly described with reference to FIG. The in-circuit test is a test to check whether the circuit board has been manufactured correctly or, if it is faulty, where it is faulty. This is due to various factors such as a defective board, a defective part itself, and a failure. Hereinafter, a description will be given by taking, as an example, the substrate under test 3 that includes two logic circuits of NOT (logical NOT) circuits 102 and 103 having a very simple circuit configuration. The substrate under test 3 is
When the input terminal 107 is set to “H” level, the output terminal 10
Reference numeral 8 denotes a substrate having a function of outputting an "H" level, that is, a logic signal of the same level as the input. To test this board, at least 104, 10 as shown in FIG.
5, 106 three probes are required. That is,
A probe 104 for applying a test signal to an input terminal 107 of the substrate, a probe 106 for detecting a signal at an output terminal 108 of the substrate, and a NOT (logical NOT) circuit 10
3 (or NOT (logical NOT) circuit 10)
2) is a probe 105 for detecting the output (2). Here, if there is no probe 105, if the output terminal 1
At 08, when a level different from the expected level appears, for example, when “H” level is applied to the input terminal 107 and “L” level is output to the output terminal 108, if there is no probe 105, the NOT (logical negation) circuit 102 , 103, it is impossible to know which of them is faulty or where there is a mounting defect. However, with the probe 105,
If the value is “H” level (the expected value here is “L” level), the first stage including the printed circuit board pattern from the input terminal 107 to the input of the second stage NOT (logical NOT) circuit It can be diagnosed that the failure is around the NOT (logical negation) circuit 102. When it is desired to specify a failure point in more detail, a NOT (logical NOT) circuit 102, 1
Probes may be arranged at the remaining input / output terminals 03, but at that time, the cost of the fixture increases and the test time also increases.

Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG. First, the outline of the present invention will be described with reference to FIG. 2, and then the details of each unit will be described below. In FIG. 2, reference numeral 1 denotes a non-contact signal detection sensor array in which m × n sensor electrodes (electric field distribution detection electrodes) 2 for non-contact detection of a signal of a substrate under test are arranged in an array at a pitch p. Although not shown, the non-contact signal detection sensor array 2 has at least a sensor pitch p in the XY axis 31 direction.
It is configured to be able to move like 32a, 32b within the range. That is, the non-contact signal detection sensor array 2
It is possible to detect the substrate under test 3 with a resolution equal to or less than the pitch p of the sensor electrodes 2. Reference numeral 3 denotes a substrate to be tested, which is arranged in the direction 30 shown in FIG. Reference numeral 5 denotes a signal processing circuit for processing an input signal 21 which is connected to the sensor electrode 2 and input, and is specifically configured as shown in FIG.
The output signal 53 of the OP amplifier 50 is converted by the A / D converter 65 into A
/ D conversion and outputs a detection signal 23. The details will be described later. Reference numeral 6 denotes a test signal generator, which applies one or more test signals 25 to the board 3 to be tested via the board connector 12 and uses the movable contact type probe 9 to make one or more test signals. 26 to control the signal level at an arbitrary point in the substrate under test 3. Reference numeral 7 denotes a potential distribution determining process for determining a potential distribution in the substrate under test based on the detection signal 23 of the signal processing circuit 5 and the component mounting information 8. Reference numeral 9 denotes a movable contact type probe by an automatic positioning mechanism (omitted in the drawing), which applies a test signal 26 to an arbitrary point on the substrate under test or detects a signal at an arbitrary point. . The movable contact probe 9 will be described later, but is not an essential item in the present invention. Reference numeral 10 controls the entire test system, and includes a computer system such as a microprocessor and a signal interface circuit between the functional blocks such as the signal processing circuit 5 and the like. 12
Denotes a board connector, which allows a test signal 25 to be applied to a pin of an arbitrary connector number of the connector of the board under test 3, and a signal of an arbitrary connector number as indicated by a signal 27. It can be read into a computer system (control device) 10.

Next, the signal processing circuit 5 will be described.
FIG. 3 shows a specific configuration of the signal processing circuit 5. 3, the signal processing circuit 5 includes an OP amplifier 50 and a resistor 5
1 is a high amplification rate non-inverting amplifier. OP amplifier 5
0 is desirably a high input impedance, for example, LH0 of National Semiconductor, USA
032 etc. can be used. 52 is an equivalent representation of the substrate 3 to be tested, 52a is a representation of a wiring pattern of a printed circuit board or a lead wire of a component as an electrode facing the sensor electrode 2, and 52b is an electronic circuit. The component is represented as a signal source V1. As previously described with reference to FIG. 2, the substrate under test 3 and the non-contact signal detection sensor array 1 are arranged close to each other. Therefore, as shown in FIG. 52a corresponding to each other are opposed and capacitively coupled. Therefore, the circuit shown in FIG. 3 is an equivalent circuit as shown in FIG. In FIG. 4A, reference numeral 54 denotes a capacitive coupling C1 between 51a and 2; 55, an input capacitance C2 of the OP amplifier 50; and 56, a resistance component R of the input impedance of the OP amplifier 50. The input / output characteristics V2 / V1 with respect to the frequency of the circuit shown in FIG. 4A are as shown in FIG. 4B (for example, transistor technology, November 1993).
Monthly issue, p. 232, CQ Publisher), cutoff frequency f
Since it becomes a high-pass filter of c, frequencies higher than fc can be transmitted in a non-contact manner. Therefore, at a frequency sufficiently higher than fc at the signal source 52b, a square wave 5 as shown in FIG.
7 is generated, as shown in FIG.
A similar square wave 58 can be detected in the output signal 53 of 0. Further, as its magnitude is proportional to the output voltage of the signal source 52b, as apparent from FIG.
The output voltage of the signal source 52b can be estimated from the peak-to-peak voltage. Note that in FIG.
Is an A / D converter for converting the signal 53 into a digital value, 6
Reference numeral 6 denotes a timing signal generator for giving a conversion timing 67 to the A / D converter, and generates a timing signal 67 based on a signal 68 from the test signal generator 6. Also,
The number of the signal processing circuits 5 is equal to the number of the sensor electrodes 2.

Next, the potential distribution determination processing 7 will be described. As can be clearly seen from FIG. 4B, a signal that can be detected as the output signal 53 is larger as C2 is smaller than C1, which is advantageous for the test. For example, assuming that C1 is approximated as a parallel plate, the capacitance C can be obtained by the following (Equation 1).

[0021]

(Equation 1)

Where ε is the dielectric constant, A is the area of the electrode, d
Is the distance between the electrodes. As is clear from the expression (1), in order to increase the capacitance C, the distance d may be reduced, that is, the distance between the substrate 3 and the sensor electrode 2 may be reduced. There is a limit due to the height of the projections. Another method is to increase the area A. That is, the size of the sensor electrode 2 may be increased to the same size as the pad of the substrate under test 3. However, when the size of the sensor electrode 2 is increased, the sensor electrode 2 is also connected to an adjacent pad, and the influence of the signal of the adjacent pad is exerted. For example, in the case of a DIP (dual in-line package), which is a general IC package,
The pitch of the lead wire of C is 2.54 mm, and the pad to which the lead wire is soldered has a diameter of about 1.6 mm. In addition, the distance between the substrate under test 3 and the sensor electrode 2 needs to be separated by about 1.5 mm because the protrusion of the lead wire of the component penetrating the substrate is about 1 mm. When the circuit of FIG. 1 is mounted as shown in FIG. 6 and a square wave signal is input from the lead wire 61a, an output signal 53 to be detected is detected.
Are as shown in FIG. Here, the minus on the vertical axis indicates the inversion of the phase. As the influence of the adjacent signal, the difference between the center of the lead wire 61d and the detection signal, and the peak value of the lead wires 61b and 61c to which the same signal is applied and the same type of signal are applied only to pin 1 only. And the peak value of 61d is different. Since these influences cause measurement errors, the potential distribution determination processing 7 is a processing for correcting and accurately obtaining the value of each point. As a specific processing example, the test signal generator 6 outputs a test signal based on the mounting information 8 of the board shown in FIG. Is given, the detection signal 23 is corrected by estimating what kind of signal is generated around the point to be measured. For example, in the example described above with reference to FIG.
When measuring the signal of the lead wire 61d, it is estimated from the mounting information 8 that a signal having an opposite phase is applied to the right side and the signal is detected to be slightly smaller, and the detection signal 23 is corrected by a correction coefficient determined in advance. can do.

Hereinafter, a test flow according to the present embodiment will be described. First, the substrate under test 3 is arranged close to the non-contact signal detection array 1 in the direction indicated by the direction 30. At this time, the positioning is also performed at a predetermined position in the XY direction 31 shown in FIG. Next, a test signal is generated from the test signal generator 6 so that the location where the test of the substrate under test 3 is desired has a desired value. For example, FIG. 1 used in the above description
(Logical NOT) circuit 1
When it is desired to test whether the signal is normal up to the input of 03, a test signal 25 (for example, a square wave signal 57 as shown in FIG. 5A) is generated by the test signal generator 6 and applied via the board connector 12. . At this time, if the logic from the board connector 12 to the input of the NOT (logical NOT) circuit 103 is complicated or the test signal is input from the board connector 12 for other reasons, the NOT (logical NOT) circuit 103 When the input cannot be made into a square wave, the test signal 26 is applied directly to the output pin of the NOT (logical negation) circuit 102 by the movable contact probe 9.

Next, an arbitrary sensor electrode 2 of the non-contact signal detection array 1 is moved so as to be immediately below an input pin (lead wire 61c) of a NOT (logical negation) circuit 103, and an output signal 53 is A / D converted. The signal is converted into a digital signal by the detector 65, the peak-to-peak voltage is measured, the measured value is corrected by the potential distribution determination processing 7, and the magnitude and the phase relationship with the signal added from the board connector 12 are checked to determine the NOT (logical No) It is possible to check whether a desired signal is applied to the input pin (lead 61c) of the circuit 103. However, generally, it is rare to examine only one point, that is, one pin, and often examine a plurality of points. As described above, the non-contact signal detection array 1 is movable in the XY directions at least within the range of the pitch p of the sensor electrodes 2. Therefore, by moving the non-contact signal detection array 1 as shown by 70 in FIG.
1 can be detected by one sensor electrode 2a. For example, in the case of the non-contact signal detection array 1 shown in FIG. 7, a range of 72 can be detected. Therefore, while moving the non-contact signal detection array 1 like 70, the signals from the sensor electrodes 2 are measured at appropriate intervals, and the potential distribution determination processing 7 is performed.
If the measured value is corrected and stored, the potential distribution over the entire 72 range can be obtained. The control unit 10 compares the potential at a required position and the like with the design information 11 so that
Diagnosis of a failure of the substrate under test 3 and detection of a failure location can be performed. Here, if the amount of movement is larger than the pitch p, it is possible to detect even a substrate under test that is sufficiently larger than the size of the non-contact sensor array 1. In the case where the output is directly output to the board connector 12, such as a NOT (logical negation) circuit 103 in FIG. 6, the value may be directly read into the control unit 10 through the signal line 27 and used for diagnosis. good. When the potential around the measurement point is not determined and the measured value cannot be corrected by the potential distribution determination processing 7, the signal of the measurement point is directly read into the control unit through the signal line 33 by the movable contact probe 9. But it is good.

According to this embodiment, the electrical test of the substrate under test can be performed without the fixture, and
Since the voltage of each point to be detected can be accurately obtained, it is possible to judge whether the circuit operation is good or not in consideration of the range of variation inherent in a good board (component). In addition, there is an effect that a failure location can be accurately specified. Further, since the signals are detected by moving the non-contact signal detection array, signals can be detected with a resolution equal to or less than the sensor electrode interval, and the number of sensor electrodes and signal processing circuits can be reduced. This has the effect. Next, a second embodiment according to the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that the potential distribution determining process 7, the component mounting information 8, and the design information 11 are changed to a storage device 75 and a comparing process 76. The storage device 75 converts the detection signal 23 detected by A / D conversion of the output signal 53 of the OP amplifier 50 in the signal processing circuit 5 by the A / D converter 65 and detects the detection signal 23 on the entire surface of one substrate or a part thereof as a unit. One or more can be memorized,
The data can be read to the comparison process 76. The storage device 75 is specifically configured using a semiconductor memory or a magnetic disk device. In general, the storage device 75 stores a two-dimensional voltage (potential) distribution of the entire surface or a part of a substrate when a specific test signal is applied to a non-defective substrate. In the comparison process 71, the detection signal 23 detected by the signal processing circuit 5 when the test target substrate 3 is actually tested and the characteristics of a good board stored in the storage device 75 in advance are determined. It compares the reference detection signal 23 detected from the board that is present for each corresponding position, and outputs information on the mismatch between the two signals to the computer system (control device) 10. As the comparison device 76, for example, a method described in JP-A-63-32666, “Pattern Defect Detection Method” can be used. That is, Japanese Patent Application Laid-Open No. 63-32666 discloses a comparison of two-dimensional grayscale image signals, which can be compared by replacing the grayscale image signal with a voltage (potential) distribution signal.

Next, a test flow according to the second embodiment will be described. The steps up to the application of the test signal to the substrate under test 3 and the detection of the output signal 53 while moving the non-contact sensor array 1 in this state are the same as in the first embodiment. The potential distribution (a kind of image) data of the entire surface or a part of the substrate under test 3 obtained in this way is compared with the potential distribution of a reference substrate such as a non-defective substrate stored in the storage device 75 for comparison processing 7.
6, it is found that if there is no difference, there is a good product, and if there is a difference, there is a failure in the vicinity. Also,
At this time, if the potential distribution of the substrate for which the failure information such as the failure location is known is used as the reference potential distribution, it is possible to specify that the test target board 3 is in the already known failure state. it can. According to this embodiment, since the potential distribution determination processing is unnecessary, there is an effect that an electrical test of the board can be performed without component mounting information. Next, a second embodiment of the signal processing circuit 5 will be described.
FIG. 9 shows a second embodiment of the signal processing circuit 5. In FIG. 9, the dotted line of the signal processing circuit 5 is a current-voltage conversion amplifier using an OP amplifier 80 and a resistor 81. OP
It is desirable to use a low input bias current for the amplifier 80. For example, LH0032 manufactured by National Semiconductor of the United States can be used. Reference numeral 52 denotes the substrate under test 3 equivalently as in FIG. The circuit in FIG. 9 is an equivalent circuit as shown in FIG. 10, that is, the voltage i from the voltage source 52b is used to change the current i flowing through the coupling capacitance 100 of the sensor electrode 2 and the wiring pattern 52a of the substrate 3 under test. Into a circuit for detection. At this time, the current i has the relationship of the following (Equation 2).

[0027]

(Equation 2)

That is, the current i is obtained by differentiating the voltage v, and the output 82 of the current-voltage conversion amplifier is
A waveform 112 as shown in FIG. That is, the signal source 5
If a square wave 111 as shown in FIG. 11A is generated at a sufficiently large frequency in 2b, a waveform 112 is output from the output 82 of the current-voltage conversion amplifier as shown in FIG. 11B. become. The waveform 112 of the output 82 of this current-voltage conversion amplifier is compared with the comparators 85 and 8 shown in FIG.
6, the rising edge of the signal under measurement is signal 90,
The falling is detected as a signal 91, and these signals are
By using the set signal and the reset signal of the S flip-flop 87, the signal under measurement can be reproduced in the detection signal 23a. By comparing this output with a reference signal under measurement expected by the test signal given to the substrate under test 3,
The operating state of the substrate under test can be tested. According to this embodiment, since the digital signal of the signal under measurement can be reproduced from the detection signal, there is an effect that it is easy to compare with the test signal which is the reference signal.

Next, a third embodiment of the signal processing circuit 5 will be described. FIG. 13 shows a third embodiment of the signal processing circuit 5. In FIG. 13, the input 82 of the BPF (bandpass filter) 110 is the output 82 of FIG. 9 described earlier in the second embodiment of the signal processing circuit 5, and the operation up to this point is the same. Is omitted. The signal 82 is a differentiated waveform 112, as described above, which comprises several sinusoidal signals. For example, when the voltage source 52b in FIG. 10 described above, that is, the signal under measurement is a repetitive square wave 111 having a duty ratio of 50%, the signal is expressed by the following equation (3). Can be expanded to a Fourier series.

[0030]

(Equation 3)

Here, ω is the angular frequency of the square wave. If this signal is differentiated, the following equation (4) is obtained.

[0032]

(Equation 4)

That is, it can be seen that the sum is the sum of the repetition frequency of the square wave and the sine wave of an odd multiple of that frequency. Therefore, if only a specific frequency is extracted by the BPF 110 and its magnitude is measured by the A / D converter 111 using the detection signal 23b, the magnitude of the signal to be measured can be estimated. According to the present embodiment, since only a specific frequency is extracted and measured, there is an effect that it is hardly affected by external noise and the magnitude of the signal to be measured can be estimated.

Next, in the above embodiment, the sensor electrode 2
Has described the case where the electric field distribution at the measurement point (terminal or lead) of the electronic circuit on the test substrate 3 is measured by capacitive coupling, but the coil is formed as the sensor electrode 2 by a thin film forming technique by sputtering and etching. (Electromagnetic field distribution detection electrode) is formed, and the electromagnetic field distribution of the measured point (terminal or lead) of the electronic circuit on the substrate under test 3 is measured by electromagnetic field coupling for detecting a current flowing through the coil. Even in this case, the operation state (failure state) of the electronic circuit can be detected in the same manner as in the above embodiment. The current measuring circuit can measure the current flowing through the coil if it is configured as shown in FIG. 9, for example.

In the above-described embodiment, the case where the sensor electrode 2 measures the electric field distribution at the measured point (terminal or lead) of the electronic circuit on the test substrate 3 by the capacitive coupling has been described. The electrode is composed of an electro-optic crystal (electric field distribution detection sensor), and the electro-optic crystal is irradiated with light such as a laser beam, and the change in the refractive index of the electro-optic crystal is changed by a photoelectric conversion element. By receiving the light, the electric field distribution of the measured point (terminal or lead) of the electronic circuit on the substrate under test 3 can be measured, and the operation state (failure state) of the electronic circuit can be detected in the same manner as in the above embodiment. it can. In this embodiment, since the electro-optic crystals are arranged in an array, it is necessary to provide a laser light source (semiconductor laser light source) and a photoelectric conversion element corresponding to the electro-optic crystals. If a laser beam deflection scanning mechanism such as a galvanometer mirror is provided, the number of laser light sources to be installed can be reduced.

[0036]

According to the present invention, an electrical test of the operation state (including a failure state) of an electronic circuit on a substrate under test on which an electronic circuit such as an LSI is mounted can be efficiently implemented without contact. It works.

Further, according to the present invention, it is difficult to arrange needle-like probes in a sword-like manner due to size and shape problems. This has the effect that a test of the state (including the failure state) can be performed.

Further, according to the present invention, it is not necessary to use a jig in which needle-shaped probes are arranged side by side like a sword, that is, a fixture, so that the cost of the fixture can be reduced.

Further, according to the present invention, an electrical test of the operation state (including a failure state) of an electronic circuit on a test board on which an electronic circuit such as an LSI is mounted can be efficiently implemented without contact. As a result, there is an effect that the number of manufacturing steps of the substrate to be tested can be reduced and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an electronic circuit for explaining an outline of an in-circuit test according to the present invention.

FIG. 2 is a diagram showing an overall configuration of a first example of an in-circuit test according to the present invention.

FIG. 3 is a diagram showing a first embodiment of a signal processing circuit according to the present invention.

4 is a diagram showing an equivalent circuit (shown in (a)) and its characteristics (shown in (b)) in the first embodiment of the signal processing circuit shown in FIG. 3;

FIG. 5 shows a waveform of a signal under test (shown in (a)) and a waveform of a detection signal (shown in (b)) in the first embodiment of the signal processing circuit shown in FIGS. 3 and 4; FIG.

FIG. 6 is a diagram illustrating signal intensity detected based on the signal processing circuit illustrated in FIG. 3 for an electronic circuit on a substrate under test.

FIG. 7 is a diagram illustrating a relationship between a moving method of a non-contact signal detection sensor array and a detection range.

FIG. 8 is a diagram showing an overall configuration of a second example of the in-circuit test according to the present invention.

FIG. 9 is a diagram showing a detection amplifier unit in a second embodiment of the signal processing circuit according to the present invention.

FIG. 10 is a diagram showing an equivalent circuit in a second embodiment of the signal processing circuit shown in FIG. 9;

11 shows a waveform of a signal under test (shown in (a)) and a waveform of a detection signal (shown in (b)) applied in the second embodiment of the signal processing circuit shown in FIGS. 9 and 10; FIG.

FIG. 12 is a diagram showing one embodiment of a post-processing circuit in the second embodiment of the signal processing circuit shown in FIG. 9;

FIG. 13 is a diagram showing another embodiment of the post-processing circuit in the second embodiment of the signal processing circuit shown in FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Non-contact signal detection sensor array, 2, 2a ... Sensor electrode, 3 ... Substrate under test 5 ... Signal processing circuit, 6 ... Test signal generator, 7 ... Potential distribution determination processing 8 ... Component mounting information, 10 ... Computer system (Control and determination unit) 11 design information, 12 board connector 50 OP amplifier, 51 resistors 61 a, 61 b, 61 c, 61 d lead wire, 65 A
/ D converter 66 timing signal generator, 75 storage device, 76
Comparison device 101 ... substrate under test, 102, 103 ... NOT (logical NOT) circuit 104, 105, 106 ... contact type probe

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-119778 (JP, A) JP-A-6-213955 (JP, A) JP-A-2-2967 (JP, A) JP-A-6-12967 331710 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01R 31/302 H01L 21/66

Claims (4)

(57) [Claims] An electronic circuit operation test method for testing the operation of an electronic circuit on a substrate under test on which electronic components are formed by mounting electronic components, wherein a test signal is temporally changed by the electronic circuit on the substrate under test. applying Te, place the electric field distribution detection electrodes in an array
At the sensor array state the brought close to the test substrate
Between each measured point of the electronic circuit on the substrate under test
At each of the electric field distribution detecting electrodes electrostatically coupled at
Each of the electronic circuits on the substrate under test
Detects the potential or phase at a point and mounts it on the board under test.
Mounting information on the functions and locations of the components
From the test signal given to the board under test
Of the signal around each fixed point of
Each electric field distribution detection electrode based on the signal state of the surrounding
Correct the potential or phase at each detected fixed point,
Consisting of the corrected potential or phase at each side fixed point
Distribution information on the substrate under test and reference potential or potential
A method for testing the operation of an electronic circuit on a substrate under test , comprising comparing the distribution information on the substrate under test consisting of phases with each other to test the operation state of the electronic circuit on the substrate under test. 2. A substrate to be tested by each of said electric field distribution detecting electrodes.
Potential or phase at each measured point of the electronic circuit at
When detecting, the sensor array is slightly moved with respect to the substrate under test.
At least within the pitch range of the detection electrode.
2. The operation of an electronic circuit on a substrate under test according to claim 1.
Test method . 3. A substrate on which an electronic circuit is formed by mounting electronic components.
Electronic circuit operation to test the operation of the electronic circuit on the test board
In the test device, the state of the electronic circuit on the substrate under test changes.
A test signal from the outside to the electronic circuit of the board under test
A test signal applying means for applying the electric signal while changing the electric field between the electric circuit and each of the measured points and electric fields of the electronic circuit on the substrate under test.
The substrate under test is electrostatically coupled to the distribution detection electrode.
The electric field distribution detection electrodes are arranged in an array in close proximity to the plate
Between the measured sensor array and each measured point of the electronic circuit on the substrate under test.
Each electric field component of the sensor array electrostatically coupled at
Electrons on the substrate under test in a non-contact manner by the cloth detection electrode
Detection that detects the potential or phase at each measured point in the circuit
Means, the function of the component mounted on the substrate under test, and its function.
The test given to the board under test based on the mounting information on the position
From the test signal, the signal status around the fixed point on the
Estimating and performing the detection based on the estimated surrounding signal state.
At each measured point of the electronic circuit detected by the
Correction means for correcting the position or phase, and the potential at each fixed point to be corrected corrected by the correction means
Or the distribution information and reference on the substrate under test consisting of phases
Distribution on the substrate under test consisting of the potential or phase
Compared with the information, the operation state of the electronic circuit on the board under test
Test means characterized by comprising comparison means for testing the condition
Electronic circuit operation test equipment on test boards . 4. The apparatus according to claim 1, wherein said detecting means detects a voltage on the substrate under test.
Detect potential or phase at each measured point of slave circuit
The sensor array at least with respect to the substrate under test.
Moving means for moving within the range of the pitch of the electric field distribution detection electrode
4. The substrate under test according to claim 3, further comprising:
Electronic circuit operation test equipment .