JP2652975B2 - Board inspection equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board inspection apparatus, and more particularly to a board inspection apparatus for inspecting the continuity and disconnection of a circuit pattern and a through hole of a circuit board such as a printed wiring board used for mounting electronic equipment. About.

[Conventional technology]

A conventional substrate inspection apparatus will be described in detail with reference to the drawings.

 FIG. 8 is a block diagram showing an example of the prior art.

2. Description of the Related Art A conventional substrate inspection apparatus is an apparatus that inspects whether a circuit pattern formed inside a substrate to be inspected (hereinafter, a substrate) is correctly connected. The method is based on the inspection of continuity and disconnection between terminals of the circuit pattern for all terminals.

Next, the configuration of the apparatus will be described. The board inspection apparatus shown in FIG. 8 inspects fixtures 16 and 17 in which probes that respectively come into contact with all of the terminal portions 11, 12, 13, 14, and 15 of the circuit pattern of the board 8 and the continuity disconnection. A probe that contacts two terminals of the circuit pattern, a scanner 19 that connects the measuring device 18, and a control unit 1 that controls the scanner 19 and the measuring device 18.
It consists of.

The scanner 19 is a group of switches, and selectively connects a measuring terminal of a measuring instrument to a probe. The measuring device mainly comprises a device capable of measuring a resistance value.

Next, an inspection method will be described. First, when inspecting the continuity of the circuit pattern 10, the probe in contact with the terminals 14 and 15 and the measurement terminal of the measuring device 18 are connected by the scanner 19. In this state, the resistance value is measured, and if the measured value is sufficiently low, it is determined that the conduction is established.

Next, to check that the circuit pattern 10 is not short-circuited with another circuit pattern, connect one measuring terminal of the measuring device to a probe that contacts the terminal 14 or 15 of the circuit pattern 10, and The other terminal is connected to all the other probes and measures the resistance value. If the resistance value is sufficiently large, it is determined that there is no short circuit with another circuit pattern.
In this way, the probes are switched one after another by the scanner 19,
Inspect all circuit patterns.

[Problems to be solved by the invention]

In the above-described conventional board inspection apparatus, a fixture in which a probe corresponding to one-to-one is implanted in the terminal portion of the circuit pattern is required. Therefore, it is necessary to prepare the fixture every time the type of the board changes. There is a disadvantage that there is.

[Means for solving the problem]

According to a first aspect of the present invention, there is provided a substrate inspection apparatus comprising: an ultrasonic generator configured to converge and irradiate an ultrasonic wave to an arbitrary point on a substrate to be inspected; A sheet, a sheet-like electrode in close contact with the sheet, an electrode in contact with a surface of the substrate to be inspected on which the sheet is not connected, a detection circuit for detecting a current flowing between the two electrodes, It is configured to include an ultrasonic generator and a controller that controls the detection circuit.

A substrate inspection apparatus according to a second aspect of the present invention includes an ultrasonic generator that converges and irradiates an ultrasonic wave to an arbitrary point on a substrate to be inspected, and an ultrasonic wave generated by the ultrasonic generator, on the substrate to be inspected. A sheet of a piezoelectric material that connects the block portion to be propagated, the substrate to be inspected and the block portion, a sheet-like electrode that is in close contact with the sheet, an ultrasonic detection unit that detects ultrasonic vibrations from the substrate to be inspected, It is configured to include an ultrasonic generator and a controller that controls the ultrasonic detector.

A substrate inspection apparatus according to a third aspect of the present invention includes an ultrasonic detection unit that detects ultrasonic waves from an arbitrary point on a substrate to be inspected, a sheet of piezoelectric material that connects the substrate to be inspected and the ultrasonic detection unit, A sheet-like electrode that is in close contact with the sheet, an electrode that contacts a surface of the substrate to be inspected that is not connected to the sheet, a power supply that applies a voltage between the two electrodes, and the ultrasonic detection. And a control unit for controlling the power supply unit.

A substrate inspection apparatus according to a fourth aspect of the present invention includes an ultrasonic generator that irradiates an ultrasonic wave to an arbitrary point on a substrate to be inspected, a sheet of a piezoelectric material that connects the substrate to be inspected and the ultrasonic generator,
A sheet-like electrode that is in close contact with the sheet, an electrode that contacts a surface of the substrate to be inspected on which the sheet is not connected, and a switch, a resistor, a capacitor, and a phase detector that are connected to the electrode that contacts the substrate. The circuit includes a circuit and a control unit for controlling the ultrasonic wave generation unit, the phase detection circuit, and the switch.

〔Example〕

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

FIG. 1 is a block diagram showing a first embodiment of the present invention.

The substrate 108 is placed in close contact with the piezoelectric material sheet 107 and the electrode 109. The electrode 106 is brought into close contact with the sheet 107, and further, the ultrasonic transducer 104 is brought into close contact with the sheet 105 via a block 105 for transmitting ultrasonic waves. The ultrasonic transducer 104 and the block 105 together constitute an ultrasonic generator.

By exciting the ultrasonic transducer 104 in this state,
The surface of the substrate 108 is irradiated with ultrasonic waves. The block 105 is made of a material having low attenuation of ultrasonic wave propagation, for example, a block made of duralumin or water. The electrodes 106 and 109 are made of a metal thin film. In place of the electrode 109, a circuit pattern having a large area such as a GND electrode inside the substrate can be used.

FIG. 2 is a perspective view showing one embodiment of the ultrasonic transducer 104,
FIG. 3 is a block diagram showing a driving method of the ultrasonic transducer 104.

The ultrasonic transducer 104 is, for example, a plate 12 of a piezoelectric element such as PZT.
1 is provided with electrodes 122 and 123.

The electrode 122 is a group of small mutually insulated electrodes,
They are arranged regularly in the horizontal direction. Each of the electrodes 122 is individually provided with a wiring for driving a vibrator, and a different voltage can be applied to each electrode. The electrode 122 is formed by, for example, depositing an electrode on one surface of the plate 121 of the piezoelectric element and then leaving only the necessary portion of the electrode by photolithography.

The ultrasonic transducer driving circuit 103 includes a transducer driving power amplifier 124 that is individually connected to the electrode 122 and a phase control circuit 125 that supplies a signal to each power amplifier 124.

The phase control circuit 125 inputs an appropriate signal to the power amplifier 124 so that a voltage having a different phase can be applied to each electrode 122 in order to generate an ultrasonic vibration focused on the surface of the substrate 108. A method of controlling the phase of a signal to be applied to generate a vibration that converges once is a so-called phased array method, which is a known method, and is not particularly described here.

The sheet 107 is made of a piezoelectric material, for example, PVDF or the like. At this time, the thickness of the sheet 107 is, for example, an odd multiple of half the wavelength of the vibration generated by the ultrasonic transducer 104.

The electrodes 106 and 109 are connected to the detection circuit 102, respectively. The detection circuit 102 is composed of, for example, an ammeter, and checks the quality of the circuit pattern by measuring a current generated between both electrodes.

 Next, the inspection method will be described.

First, the procedure of the continuity test of the terminals 112 and 113 of the circuit pattern 111 will be described. First, the ultrasonic vibrator 104 is driven to excite vibration converged on the terminal 113 of the circuit pattern. Then, strong vibration is applied to the portion of the sheet 107 sandwiched between the terminal 113 and the electrode 106, so that a voltage is generated between the terminal 113 and the electrode 106 by the piezoelectric effect.

If the terminal 112 and the terminal 113 are connected, the terminal 112 is connected to the electrode 1
Since it is connected to 09, a voltage is generated between the electrode 106 and the electrode 109. Therefore, a current flows through the detection circuit 102.

On the other hand, when the terminals 112 and 113 are disconnected, no voltage is generated at the terminal 112, so that no current flows through the detection circuit 102. This makes it possible to determine whether the circuit pattern 111 is disconnected.

Next, a procedure of a continuity test of the terminals 114 and 115 of the circuit pattern 110 will be described.

The vibration that converges on the terminal 114 of the ultrasonic transducer is excited.
Then, a voltage is generated in the circuit pattern 110 for the same reason as described above. Here, since there is a capacitance between the circuit pattern 110 and the electrode 109, a current is generated in the detection circuit, and the magnitude of the current increases as the capacitance increases.

On the other hand, the capacitance between the circuit pattern 110 and the electrode 109 is proportional to the overlapping area of each other, and is a fixed value for each circuit pattern. Accordingly, when the circuit pattern is broken, it corresponds to the decrease in the area of the circuit pattern, and the capacitance becomes small, and the detection circuit 10
The current generated in 2 is smaller than when the circuit pattern is correct.

Further, when the circuit pattern 110 is short-circuited with another circuit pattern, the capacitance generated in the detection circuit 102 is increased because the capacitance is larger than in the case where the circuit pattern is correct. In the inspection, a detection current expected in the case of a non-defective product is obtained in advance, and a disconnection or short circuit of the circuit pattern can be detected by comparing the detection current with the detection current.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

A piezoelectric material sheet 207 is placed on the substrate 208 in close contact therewith.
The electrode 206 is brought into close contact with the sheet 207, and further, the ultrasonic transducers 204 and 209 are brought into close contact with each other via a block 205 that transmits ultrasonic waves.

In this state, the ultrasonic wave is transmitted to the surface of the substrate 208 by exciting the ultrasonic oscillator 204 for transmission. Block 2
05 is made of a material having a low attenuation of ultrasonic wave propagation, such as duralumin block or water. The ultrasonic transducer 209 for receiving waves is used to receive ultrasonic vibrations propagating from the substrate 208 through the block 205.

FIG. 5 is a block diagram showing an embodiment of the ultrasonic vibration detection circuit 202.

The ultrasonic vibration detecting circuit 202 includes a voltage amplifier 225 individually connected to the electrode 220 of the ultrasonic transducer 209 for receiving a wave, and a synthesizing circuit 226 for synthesizing the output of the voltage amplifier.

Since the detection circuit wants to selectively receive the ultrasonic vibration radiated from one point on the substrate, the synthesis circuit 225 outputs the output of each of the voltage amplifiers 225 so that the directivity increases at one point on the substrate surface. Change the phase and add. This technique is
Since it is the same as the method of the so-called phased array antenna, it is not particularly described here.

The sheet 207 is made of a piezoelectric material, for example, PVDF. At this time, the thickness of the sheet 207 is, for example, an odd multiple of half the wavelength of the vibration generated by the ultrasonic transducer 204.

Next, the inspection method will be described. First, a procedure of a continuity test between the terminals 212 and 213 of the circuit pattern 210 will be described. First, the ultrasonic transducer 204 for transmitting waves is driven to excite vibration converged on the terminal 212 of the circuit pattern. Then, a strong vibration is applied to the portion of the sheet 207 sandwiched between the terminal 212 and the electrode 206, so that a voltage is generated between the terminal 212 and the electrode 206 by the piezoelectric effect.

If the terminal 212 and the terminal 213 are connected, the terminal 213 and the electrode 2
Since the above voltage is applied during the period 06, the portion of the sheet 207 sandwiched between the terminal 217 and the electrode 206 is excited.

Therefore, when the directivity of the wave receiving vibrator 209 is adjusted to the position of the terminal 213, vibration at the electrode 213 is detected. This indicates that the electrode 212 and the electrode 213 are connected. On the other hand, when the terminals 212 and 213 are disconnected, since no voltage is generated at the terminal 213, no vibration occurs at the electrode 213, and no vibration of the electrode 213 is detected at the wave receiving vibrator 209. . This allows the circuit pattern 21
It is possible to determine the disconnection of one conduction.

Next, to determine that the other pattern 211 and the pattern 210 do not cause a short circuit, the ultrasonic vibration is transmitted to the terminal 212 or 213 of the pattern 210, and the terminal of the circuit pattern 211 is determined.
Receive the wave from 214 or 215 and confirm that no vibration is detected.

When the inspection is performed on all the patterns on the substrate, the terminal positions of the patterns for which the connection relationship is to be inspected are stored in the control unit in advance, and the positions of the transmitting and receiving waves are sequentially determined by the ultrasonic vibrator drive circuit and the ultrasonic The inspection is performed by instructing the sound wave vibration detection circuit.

FIG. 6 is a block diagram showing a third embodiment of the present invention.

A substrate 308 is placed in close contact with a piezoelectric material sheet 307 and an electrode 309. The electrode 306 is brought into close contact with the sheet 307, and further, the ultrasonic transducer 304 is brought into close contact with the sheet 307 via a block 305 for transmitting ultrasonic waves. The ultrasonic transducer 304 and the block 305 together constitute an ultrasonic detecting unit. Block 305
Is a portion for transmitting the ultrasonic vibration generated on the substrate to the ultrasonic vibrator 304, and is made of a material with small propagation attenuation of the ultrasonic wave, for example, a duralumin block or water. The electrodes 306 and 309 are made of a metal thin film.

 Next, the inspection method will be described.

The continuity test between the terminals 312 and 313 of the through hole 311 will be described. First, a voltage is generated between the electrodes 306 and 309 by the power supply unit 302. If terminals 312 and 313 are connected,
Since the terminal 309 is connected to the terminal 312, a voltage of the electrode 307 is generated at the terminal 312.

Accordingly, a voltage is applied to the portion of the piezoelectric sheet sandwiched between the terminal 312 and the electrode 206, and this portion causes vibration. Therefore, when the directivity of the ultrasonic detection unit is set to the terminal 312, vibration is detected.

On the other hand, if the terminals 312 and 313 are disconnected,
Since no voltage is generated at the terminal 312, no vibration occurs, and no vibration is detected by the ultrasonic detection unit. This makes it possible to determine the disconnection of conduction in the through hole 311.

The inspection procedure is based on a procedure stored in advance in the control unit 301, and sequentially detecting the vibrations while adjusting the directivity to the terminal unit to be inspected. At this time, the power supply unit 302 may be driven once in a pulsed manner each time one terminal is inspected, or may be continuously driven in a sine wave irrespective of timing for detecting vibration. .

FIG. 7 is a block diagram showing a fourth embodiment of the present invention.

The substrate 408 is placed between the piezoelectric material sheet 407 and the electrode 409 in close contact with each other. The electrode 406 is brought into close contact with the sheet 407, and the ultrasonic vibrator 404 is brought into close contact with the sheet 407 via a block 405 that transmits ultrasonic waves. The ultrasonic vibrator 404, the block 405, and the ultrasonic vibrator drive circuit 403 together form an ultrasonic generator.

The block 405 transmits the ultrasonic vibration generated by the ultrasonic vibrator 404 to the surface of the substrate 408, and is made of a material with little ultrasonic wave propagation and decay, for example, a duralumin block or water. The electrodes 406 and 409 are made of a metal thin film.

 Next, the inspection method will be described.

The procedure of the continuity test between the terminals 412 and 413 of the through hole 411 will be described. First, switch 410 is turned to the resistor side. In this state, the ultrasonic transducer 404 is driven by a sine wave to converge and irradiate the ultrasonic wave to the position of the terminal 412. Then, a strong vibration is transmitted to the portion of the piezoelectric material sandwiched between the terminal 412 and the electrode 406, so that a voltage is generated between the electrode 406 and the terminal 412.

If the terminals 412 and 413 are connected, a current flows through the resistor 414 due to the generated voltage. Since the portion between the terminals 412 and 413 can be regarded as a pure resistance, the phase difference between the voltage measured at the electrode 409 and the vibrator drive signal matches the phase difference between the voltage generated at the terminal portion 412 and the vibrator drive signal.

Next, the switch 410 is moved to the capacitor side. When the phase difference between the voltage of the electrode 409 and the transducer drive signal is measured in this state, a difference occurs from the phase difference measured by connecting the resistor earlier. The difference is that the voltage generated at the capacitor is
This is because it is behind the voltage generated in 2.

From this difference, the size of the capacitor 415, and the frequency of the drive signal, the resistance between the terminals 412 and 413 is calculated by AC logic. If the difference between the measured phase differences is small,
It is determined that the terminals 412 and 413 are disconnected or have a high resistance value.

The inspection procedure is a procedure stored in advance in the control unit 401, and sequentially converges and irradiates the vibration to the terminal unit to be inspected.
Transducer drive signal before and after switching switch 410 and electrode 4
By measuring the phase difference of the voltage of 09.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION The board | substrate inspection apparatus of this invention has the effect that it is not necessary to perform a dedicated fixture for every board | substrate type.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIG.
FIG. 3 is a perspective view showing one embodiment of the ultrasonic transducer shown in FIG. 1, FIG. 3 is a block diagram showing a driving method of the ultrasonic transducer, and FIG. 4 shows a second embodiment of the present invention. Block Diagram,
FIG. 5 is a block diagram showing an example of the ultrasonic vibration detection circuit shown in FIG. 4, FIG. 6 is a block diagram showing a third embodiment of the present invention, and FIG. 7 is a fourth embodiment of the present invention. FIG. 8 is a block diagram showing a conventional example. 101 control unit, 102 detection circuit, 103 ultrasonic transducer drive circuit, 104 ultrasonic transducer, 105 block,
106 ... electrodes, 107 ... sheet of piezoelectric material, 108 ... substrate to be inspected, 109 ... electrodes, 110,111 ... circuit pattern, 112
~ 115 ... Terminal.

Claims (4)

(57) [Claims] 1. An ultrasonic generator for converging and irradiating an ultrasonic wave to an arbitrary point on a substrate to be inspected, a sheet of piezoelectric material connecting the substrate to be inspected and the ultrasonic generator, and the sheet A sheet-like electrode that is in close contact with the electrode, an electrode that contacts the surface of the test substrate that is not connected to the sheet, a detection circuit that detects a current that flows between the two electrodes, and the ultrasonic wave generator. And a control unit for controlling the detection circuit. 2. An ultrasonic generator for converging and irradiating an ultrasonic wave to an arbitrary point on a substrate to be inspected, and a block for transmitting ultrasonic waves generated by the ultrasonic generator on the substrate to be inspected. A sheet of piezoelectric material that connects the substrate to be inspected and the block unit, a sheet-like electrode that is in close contact with the sheet, an ultrasonic detector that detects ultrasonic vibrations from the substrate to be inspected, and the ultrasonic generator, A board inspection apparatus comprising: a control unit that controls an ultrasonic detection unit. 3. An ultrasonic detecting section for detecting ultrasonic waves from an arbitrary point on a substrate to be inspected, a sheet of a piezoelectric material connecting the substrate to be inspected and the ultrasonic detecting section, and a close contact with the sheet. A sheet-like electrode, an electrode in contact with the surface of the substrate to be inspected on which the sheet is not connected, a power supply unit for applying a voltage between the two electrodes, the ultrasonic detection unit, and a power supply unit. A board inspection apparatus characterized by including a control unit for controlling. 4. An ultrasonic generator for irradiating an ultrasonic wave to an arbitrary point on a substrate to be inspected, a sheet of a piezoelectric material connecting the substrate to be inspected and the ultrasonic generator, and a sheet in close contact with the sheet. A sheet-like electrode, an electrode that contacts the surface of the substrate to be inspected on which the sheet is not connected, a switch, a resistor, a capacitor, a phase detection circuit, and a switch that are connected to the electrode that contacts the substrate. Generator, phase detection circuit,
A board inspection apparatus comprising: a control unit that controls a switch.