JPH11211799A - Device and method for detecting faulty parts for printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether mounted parts are good or not with sufficient accuracy even if a radiation noise changes depending on a height from a printed circuit board by moving a detection probe to an arbitrary position in the directions of X, Y, and Z axes of a printed circuit board. SOLUTION: A first rail 9a is extended in the direction of X axis of a printed circuit board 1 to be inspected, and a detection probe 3 is moved along it. Similarly, a second rail 9b is extended in the direction of Y axis, and the first rail 9a is moved along with it. Further, a third rail 9c is extended in the direction of Z axis, and the second rail 9b is moved along with it. In this manner, by moving the detection probe 3 along the first rail 9a, the second rail 9b, and the third rail 9c, the detection probe 3 can reach an arbitrary position within the plane of the printed circuit board 1 and an arbitrary height position. Especially, by moving the detection probe 3 in the direction of Z axis of the printed circuit board 1, both surfaces of the parts surface and the soldering surface of the printed circuit board 1 can be researched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting a defective component for a printed circuit board.

[0002]

2. Description of the Related Art Usually, a printed circuit board on which electric components are mounted is mounted inside an information processing apparatus. This printed circuit board is manufactured by fixing components on a printed circuit board on which circuit wiring is printed by soldering, and an operation test is performed before the printed circuit board is mounted on an information processing device.

FIG. 6 is a schematic view of a general tester for performing an operation test of a printed circuit board. As shown in FIG.
A printed circuit board 51 on which components are mounted is fixed on a board checker 52. A controller 53 is connected to the board checker 52 via a control cable 54. The controller 53 determines the quality of the circuit operation of the printed circuit board 51 by applying a voltage to the printed circuit board 51 and controlling the circuit operation. As a result of the judgment,
A printed circuit board that does not operate normally is discarded as a defective printed circuit board.

[0006] In addition to the tester shown in FIG. 6, there have been proposed many devices for judging the quality of a printed circuit board as shown below. Japanese Patent Laying-Open No. 6-324122 discloses a non-contact type test apparatus for an electronic circuit board. In this test apparatus, an electromagnetic radiation detection probe is arranged at a short distance from an electronic circuit board to be inspected, and the electromagnetic radiation detection probe detects electromagnetic waves radiated from an electronic circuit board near the probe. .

[0005] US Patent No. 5,067,788 also discloses a non-contact test apparatus for an electronic circuit board. The test apparatus includes a wire loop probe arranged in a rectangular shape, a tuned receiver, and an address circuit for connecting each probe to the receiver. The wire loop probe is located adjacent to the electronic circuit board. Wire
Inspection of the electronic circuit board is performed by inducing a current in the loop probe and continuously detecting this current with a tuning receiver.

Japanese Patent Application Laid-Open No. 3-39989 discloses a method for inspecting a transparent conductive circuit board for defects. This inspection method is characterized in that a magnetic field generated in the transparent electrode is detected by scanning the magnetic field detection unit so as to be orthogonal to the transparent electrode. Japanese Patent Application Laid-Open No. 2-62975 discloses that an AC signal of a predetermined frequency is supplied between two short-circuited circuit patterns of a plurality of circuit patterns formed on an insulating substrate, and the AC signal is A method for inspecting a printed circuit board, wherein a generated magnetic field is tracked by a magnetic field detection sensor is disclosed.

Japanese Patent Application Laid-Open No. 1-63878 discloses a detecting coil for detecting a change in a magnetic field generated from a pulsating current flowing through a short-circuited portion and converting it into a voltage, and a display means for amplifying and displaying the voltage from the detecting coil. And a short-circuit position detecting device having the following. Japanese Patent Application Laid-Open No. 9-72947 discloses an inspection device for checking a solder connection state of an electronic component. According to this inspection device, the electric field intensity of the lead shoulder is detected by the EO sensor, and according to the magnitude of the signal level representing the electric field intensity,
A signal processing unit inspects a solder connection state between the lead and a pad on the circuit board.

Japanese Patent Application Laid-Open No. 61-89174 discloses a magnetic sensor for scanning the surface of a printed circuit board and detecting a magnetic field on the surface of the printed circuit board, and processing an output signal of the magnetic sensor to determine a position where the magnetic field intensity is maximum. A printed circuit board inspection apparatus is disclosed which includes signal processing means for detecting, and display means for indicating a position where the magnetic field intensity is maximum based on a signal from the signal processing means.

Japanese Patent Application Laid-Open No. 8-327708 discloses that
An electronic circuit operation test apparatus is disclosed. According to this test apparatus, the signal from the point to be measured is temporally changed, and the signal to be measured is induced in the electrostatically coupled detection electrode by disposing the sensor array close to the substrate to be tested. Let it. In this way, the operating state of the electronic circuit is tested by detecting the two-dimensional or one-dimensional potential distribution on the entire surface of the substrate under test and comparing it with the reference potential distribution.

[0010]

All of the above-mentioned conventional test apparatuses are of the type in which only the surface to be inspected is inspected using, for example, a probe or other similar means. That is, the surface of the printed circuit board to be inspected is two-dimensionally scanned, thereby determining the quality of the printed circuit board or a specific portion or component on the printed circuit board.

For example, when the intensity of radiation noise from a printed circuit board is measured and the quality of the printed circuit board is determined based on the intensity, the accuracy of the determination of the quality depends on the accuracy of the measurement of the intensity of the radiation noise. Decided. The intensity of the radiation noise from the printed circuit board depends on the area of a region surrounded by a path (current loop) of a circuit current flowing through the printed circuit board. Therefore, when the area changes, the intensity of the radiation noise also changes. However, in the conventional two-dimensional measurement, it is impossible to measure the change in the intensity of the radiation noise due to the change in the area with sufficient accuracy.

Further, as described above, since various components are mounted on the printed circuit board, the intensity of radiated noise may change in accordance with the height from the printed circuit board. Such a change due to the height from the printed circuit board cannot be dealt with at all by a conventional test apparatus that only proposes two-dimensional measurement. The present invention has been made in view of the problems of such a conventional printed circuit board testing apparatus, and the factors of the inspection of the printed circuit board (for example, radiation noise in the above case) are within the plane of the printed circuit board. Defective parts for printed circuit boards that can judge the quality of components mounted on the printed circuit board with sufficient accuracy even if they change depending on the height from the printed circuit board. It is an object to provide a detection device and a detection method.

[0013]

According to the present invention, at least one detection probe is provided on a printed circuit board, and the detection probe is connected to the X-axis of the printed circuit board. Means for moving to a desired position in the direction, the Y-axis direction, and the Z-axis direction.

According to the defective component detection device of the present invention, not only one-dimensional or two-dimensional measurement but also three-dimensional measurement of the circuit board to be inspected is enabled. For this reason,
When radiated noise is used as a test factor for a printed circuit board, even if the radiated noise varies depending on the height from the printed circuit board, the defective component detection device measures the change in the radiated noise according to the height. to enable.
For this reason, the change of the radiation noise can be measured accurately, and the quality of the component to be inspected can be accurately determined.

In particular, according to the defective component detection device, when the radiation noise changes in accordance with the area of the region surrounded by the circuit current path (current loop), the measurement can be performed from above the region. In general, a change in a two-dimensional region can be accurately grasped by measuring the change three-dimensionally. For this reason, it is possible to accurately grasp the change in the radiation noise caused by the change in the area, and to accurately determine the quality of the component to be inspected.

According to a second aspect of the present invention, there is provided a defective component detecting apparatus for a printed circuit board, comprising: an inspecting means for judging the quality of an inspected component based on sideband noise of a detection signal transmitted from a detection probe. It is preferred to have.
In this case, as described in claim 3, the quality of the inspection target component can be inspected using the loop band of the phase synchronization signal as the quality standard.

The inspection means for judging the quality of the component to be inspected may include comparing a waveform of a clock signal from the component to be inspected with a predetermined standard waveform. Inspection means for judging the quality of the inspection target component based on the comparison result may be used. According to the present invention, the printed circuit board is moved by the at least one detection probe in the X-axis direction of the printed circuit board.
A first process of scanning in the Y-axis direction and the Z-axis direction;
A method for detecting a defective component on a printed circuit board, comprising: a second step of determining the quality of a component to be inspected based on a detection signal transmitted from a detection probe.

According to this method, the same effect as that of the defective component detecting device according to the first aspect can be obtained.
For example, in the second step, the quality of the inspection target component can be determined using the sideband noise of the detection signal.

In this case, as described in claim 7, it is preferable that the quality of the component to be inspected is determined based on the loop band of the phase synchronization signal. Alternatively, in the second step, as described in claim 8,
By comparing the waveform of the clock signal from the circuit component to be inspected with a predetermined standard waveform, the quality of the component to be inspected can be determined.

[0020]

1 and 2 show an apparatus for detecting a defective component for a printed circuit board according to an embodiment of the present invention.
As shown in FIG. 1, a printed circuit board driving power supply 2 is connected to a printed circuit board 1 to which components are fixed by soldering. The detection probe 3 is arranged on the printed circuit board 1. The position where the detection probe 3 is arranged is determined by the detection probe search circuit 4 connected to the detection probe 3.

An amplifier 5 is connected to the detection probe 3, and a detection signal from the detection probe 3 is amplified by the amplifier 5. The output of the amplifier 5 is input to the spectrum analyzer 6, and the detection signal from the detection probe 3 is analyzed by the spectrum analyzer 6. The analysis result is displayed on the spectrum analyzer 6. The operations of the spectrum analyzer 6 and the detection probe search circuit 4 are controlled by the controller 7.

As shown in FIG. 2, the detection probe 3 is attached to and supported by a probe moving device 8, and the probe moving device 8 moves the detection probe 3 to the printed circuit board 1.
It is configured to be able to move in the direction. As shown in FIG. 2A, a first rail 9a extends in the X-axis direction of the printed circuit board 1 to be inspected, and the detection probe 3 moves on the first rail 9a along the first rail 9a. Mounted as possible.

A second rail 9b extends in the Y-axis direction of the printed circuit board 1 to be inspected, and the first rail 9a
At one end, it is attached to the second rail 9b. The first rail 9a is configured to be movable along the second rail 9b. Further, as shown in FIG. 2 (b), the printed circuit board 1
A third rail 9c extends along the Z-axis direction, and the second rail 9b is attached to the third rail 9c at one end. The second rail 9b is configured to be movable along the third rail 9c.

As described above, the detection probe 3 moves along the first rail 9a, and the first rail 9a moves to the second rail 9b.
Along with the second rail 9b along the third rail 9c.
Can reach any position in the plane of the printed circuit board 1 and any position on the printed circuit board 1. In particular, by moving the detection probe 3 in the Z-axis direction of the printed circuit board 1, it is possible to search both the component surface (front surface) and the solder surface (back surface) of the printed circuit board 1.

The term "Z-axis direction" includes not only a direction orthogonal to the printed circuit board 1 but also a direction inclined with respect to the printed circuit board 1. The probe moving device 8 is driven via the controller 7 and moves the detection probe 3 to a position defined by three coordinates (X, Y, Z coordinates) specified by the detection probe search circuit 4.

Next, the operation of the defective component detecting device according to the present embodiment will be described with reference to FIG. By activating the printed circuit board drive power supply 2, power is applied to the printed circuit board 1 to be measured (step 21),
The measured printed circuit board 1 enters an operating state (step 22).

On the other hand, the controller 7 drives the probe moving device 8 to scan the printed circuit board 1 with the detection probe 3 (step 23). The scanning by the detection probe 3 causes the detection probe search circuit 4 to search for a component to be inspected on the printed circuit board 1, and transmits a signal representing three-axis coordinates indicating the position of the component to be inspected to the controller 7. Controller 7 receiving this signal
Drives the probe moving device 8 to dispose the detection probe 3 at the position of the inspection target component (step 2).
4).

When the printed circuit board 1 operates (step 22), an electromagnetic wave is radiated from the printed circuit board 1 and the detection probe 3
(Step 25), and transmits an electromagnetic radiation detection signal corresponding to the intensity of the electromagnetic wave. The electromagnetic radiation detection signal transmitted from the detection probe 3 is amplified by the amplifier 5 (Step 26). The amplified signal is sent to the spectrum analyzer 6, and the spectrum analyzer 6 displays the waveform of the electromagnetic radiation detection signal (step 27).

The waveform of the electromagnetic radiation detection signal generated when the printed circuit board 1 operates normally is stored in the spectrum analyzer 6 in advance. The spectrum analyzer 6 compares the waveform detected by the detection probe 3 with the stored waveform to determine whether the waveform is good (step 28). If the result of the waveform quality determination is that the detected waveform is normal, the determination result is YES, that is, the inspected component is not defective, and the process proceeds to the next step 30. That is, it is determined whether the search position of the detection probe 3 is the end position of the search range specified by the detection probe search circuit 4 (Step 30).

If the position is the end position of the search range, the determination for yes / no of the part to be inspected is ended. If it is not the end position of the search range, that is, if there is still a range to be searched, steps 23 to 28 are repeated. If the waveform detected in the waveform quality determination (step 28) is determined to be an abnormal waveform, the determination result is no, and a failure alarm indicating that the inspection target component is defective is posted (step 29). .

After posting the component failure alarm, the process proceeds to step 30. That is, it is determined whether the search position of the detection probe 3 is the end position of the search range specified by the detection probe search circuit (step 30). Based on the result of this determination, the measurement is terminated, or steps 23 to 28 are repeated. Hereinafter, referring to FIG.
The determination conditions for determining the quality of the waveform performed in step 28 will be described.

FIG. 4 shows a sideband noise characteristic of an electromagnetic radiation detection signal generated when a clock signal from the printed circuit board 1 is detected. The sideband noise of the clock signal having the frequency f0 is the reference signal multiplication noise 41
And a phase-locked oscillator noise 42. The offset frequency f1 at the intersection of the reference signal multiplication noise 41 and the phase locked oscillator noise 42 is the loop band frequency 43 of the clock signal that is the phase locked signal.

The level of the reference signal multiplication noise 41 is a value degraded by the multiplication order obtained by dividing the clock frequency by the reference signal frequency from the phase noise characteristic of the reference signal. The phase locked oscillator noise 42 is determined by the phase noise characteristics of the phase locked oscillator used. Since the values of the reference signal multiplication noise 41, the phase locked oscillator noise 42, and the loop band frequency 43 are known, it is possible to determine the sideband noise of the detected electromagnetic radiation detection signal in advance. This sideband noise is stored in the spectrum analyzer 6 as a normal waveform.

FIG. 5 shows an example of the procedure for judging the quality of a component to be inspected based on the electromagnetic radiation detection signal detected by the detection probe 3 using the sideband noise determined in this way. First, the controller 7 operates the probe moving device 8 to cause the detection probe 3 to scan the printed circuit board 1 in the X-axis direction, the Y-axis direction, and the Z-axis direction of the printed circuit board 1 to be inspected (step 41). ).

The detection probe 3 detects radiation noise emitted from the printed circuit board 1 and transmits a detection signal corresponding to the magnitude of the radiation noise. This detection signal is amplified by the amplifier 5 and then sent to the spectrum analyzer 6, where the distribution of the detection signal is displayed on the spectrum analyzer 6. Next, the controller 7 specifies a position where the radiation noise has a peak value (maximum value) based on the distribution display of the detection signals in the spectrum analyzer 6 (step 42). Further, the frequency F of the detection signal representing the radiation noise indicating the peak value is measured (step 43).

Next, it is determined whether or not the measured frequency F is a harmonic of the clock signal (step 44).
If the measured frequency F is not a clock signal harmonic, the process returns to step 41, and the printed circuit board 1
Is performed in three axial directions. If the measured frequency F is a harmonic of the clock signal, the sideband noise characteristic of the radiation noise detection signal is measured (step 45).
A sideband noise characteristic diagram as shown in FIG. 4 is obtained.

In the sideband noise characteristic diagram obtained in this manner, whether the deviation A of the loop band frequency 43 is larger than the predetermined deviation B with reference to the sideband noise of the clock signal having the frequency f0. It is determined whether or not it is (step 46). If the deviation A of the loop band frequency 43 is equal to or larger than the deviation B set in advance (A ≧ B), it is determined that the inspection target component whose radiation noise has the peak value is defective. (Step 47). On the other hand, if the deviation A of the loop band frequency 43 is smaller than the preset deviation B (A <B), it is determined that the inspection target component is non-defective, and steps 41 to 46 are repeated.
In other words, the same pass / fail determination as described above is performed on other inspection target components.

As described above, according to the defective component detection apparatus according to the present embodiment, even if the radiation noise emitted from the printed circuit board to be inspected changes in the height direction of the printed circuit board. It is possible to judge the quality of components based on the radiation noise with sufficient accuracy.

[0039]

According to the defective component detection apparatus and the defective component detection method of the present invention, the factor of the inspection of the printed circuit board (for example, the radiation noise in the above case) is not only in the plane of the printed circuit board but also in the plane. Even if it changes depending on the height from the printed circuit board, it is possible to judge the quality of the components mounted on the printed circuit board with sufficient accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a component defect detection device according to an embodiment of the present invention.

FIG. 2A is a plan view of the component defect detection device shown in FIG. 1;
And a side view (b).

FIG. 3 is a flowchart of a pass / fail judgment of the defect detection device shown in FIG. 1;

FIG. 4 is a sideband noise characteristic diagram of an electromagnetic radiation detection signal.

FIG. 5 is a flowchart of a pass / fail judgment using sideband noise characteristics.

FIG. 6 is a schematic view of a conventional printed circuit board operation tester.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printed circuit board 2 printed circuit board drive power supply 3 detection probe 4 detection probe search circuit 5 amplifier 6 spectrum analyzer 7 controller 8 probe moving device 9 a first rail 9 b second rail 9 c third rail 41 reference signal reference signal multiplication noise 42 phase Synchronous oscillator noise 43 Loop band frequency 51 Printed circuit board 52 Board checker 53 Controller 54 Control cable

Claims (8)

[Claims] 1. At least one detection probe arranged on a printed circuit board, and the detection probe is arranged in an X-axis direction of the printed circuit board.
Means for moving to an arbitrary position in the Y-axis direction and the Z-axis direction; and a defective component detection device for a printed circuit board. 2. A defective component detecting apparatus for a printed circuit board according to claim 1, further comprising inspection means for judging the quality of a component to be inspected based on sideband noise of a detection signal transmitted from said detection probe. . 3. The defective component detecting device for a printed circuit board according to claim 2, wherein the inspection unit performs an inspection of the quality of the component to be inspected based on a loop band of the phase synchronization signal. 4. An inspection means for comparing a waveform of a clock signal from a component to be inspected with a predetermined standard waveform and judging pass / fail of the component to be inspected based on a result of the comparison. A defective component detection device for a printed circuit board according to the above. 5. A first step of scanning a printed circuit board with at least one detection probe in the X-axis direction, the Y-axis direction, and the Z-axis direction of the printed circuit board, and detecting a detection signal transmitted from the detection probe. On the basis of,
A second process of determining the quality of a component to be inspected; and a method of detecting a defective component on a printed circuit board. 6. The method according to claim 5, wherein in the second step, the quality of the component to be inspected is determined based on sideband noise of the detection signal. 7. The method for detecting a defective component on a printed circuit board according to claim 6, wherein the quality of the component to be inspected is determined based on a loop band of the phase synchronization signal. 8. The method according to claim 1, wherein in the second step, the quality of the inspection target component is determined by comparing a waveform of a clock signal from the inspection target circuit component with a predetermined standard waveform. Item 6. The method for detecting a defective component of a printed circuit board according to Item 5.