JP2005017024A - Inspection apparatus of circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus for a circuit board for quickly performing an electric inspection of the circuit board that is highly integrated and allows a circuit pattern net to be composed of a plurality of pads, by the application of electro-optical effects. <P>SOLUTION: In the inspection apparatus of the circuit board, a probe 8 is brought into contact with a specified pad on one surface of the circuit board 2, and an electro-optical element 1 is arranged on pads 2-5, 2-6 on the other surface, and the voltage of the pads is subjected to image detection. In the inspection apparatus, disconnections among pads 2-2, 2-3, and 2-4, where the probe 8 is brought into contact, are inspected, voltage is applied from the pad, where the probes are in contact, and the voltage of the pads on the other surface, where the electro-optical element is arranged, is subjected to image detection for inspecting disconnection. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for inspecting an electrical defect portion of a circuit board, and more specifically, an image is detected by bringing a probe into contact with a specific pad on one side of a circuit pattern and applying the electro-optic effect to the voltage of the pad on the other side. It relates to the device to inspect.
[0002]
[Prior art]
As a method for inspecting a circuit board for disconnection, short circuit, etc., conventionally, a method has been employed in which a dedicated jig is formed with a spring probe and the pads are collectively contacted to perform electrical inspection. However, in recent years, with the increase in the number of pads, a large number of expensive spring probes are required, and the cost of dedicated jigs has increased. In addition, due to the high density of the pad spacing, it is difficult to physically ensure contact, and pad damage due to contact with a sharp spring probe is also a problem. Therefore, an inspection method corresponding to a high-density pad interval has become necessary, and there is a method of performing a disconnection inspection or a short-circuit inspection by detecting an image of a voltage distribution by applying an electro-optic effect.
[0003]
In the electrical inspection method using the electro-optic effect, a voltage is applied to a circuit pattern, an electric field generated from the voltage of the circuit pattern is detected, and a voltage is generated at a place to be conducted or insulated. Check for disconnection and short circuit depending on whether or not they are present.
[0004]
Conventionally, as a method for inspecting a voltage distribution of a circuit pattern using an electro-optic effect, for example, an electric field strength at a specific position is detected in a non-contact manner using an EO sensor, and a solder connection state of a circuit board is inspected. There is a thing (refer patent document 1). However, this method can detect only the electric field at the tip of the EO sensor, and it is necessary to move the EO sensor in order to obtain the voltage distribution of the circuit pattern. Therefore, there is a problem that it takes time to measure voltages at a plurality of locations to be inspected.
[0005]
In addition, for example, there is a method in which a voltage distribution is measured in a non-contact manner, and a defect of a transparent conductive film of a liquid crystal display is electrically inspected (see Patent Document 2). This is a method of irradiating an electro-optic element arranged in the vicinity of a circuit board with a parallel light beam and two-dimensionally detecting the voltage distribution of the circuit pattern from the reflected light.
[0006]
In the case of the transparent conductive film of the liquid crystal display, the pads are electrically connected one-to-one in the circuit pattern net. However, in the circuit board, the circuit pattern may have a large number of pads, and the plurality of pads may be electrically connected to the plurality of pads. Therefore, when a voltage distribution of a specific pad is detected and inspected by a method applying an electro-optic effect, a two-dimensional imaging device such as a CCD that is commonly used takes a long time to detect. It is necessary to inspect in a short time by reducing the number of detections.
[0007]
In this method, when a voltage is applied to the circuit pattern, there is a problem that charges are diffused in the surface direction in the electro-optic element and the voltage distribution is deteriorated. However, as shown in Patent Document 3 below, the problem has already been solved by the present inventor and a resolution of voltage distribution on the order of μm has been obtained.
[0008]
[Patent Document 1]
Japanese Patent Application No. 7-248861 [Patent Document 2]
JP-A-5-256794 [Patent Document 3]
JP 2002-286812 A [0009]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and applies an electro-optic effect to an electrical inspection of a circuit board that is highly integrated and a circuit pattern net is configured by a plurality of pads. Another object of the present invention is to provide a circuit board inspection apparatus capable of inspecting in a short time.
[0010]
[Means for Solving the Problems]
The present invention relates to a circuit board inspection apparatus in which a probe is brought into contact with a specific pad on one side of a circuit board and an electro-optic element is arranged on the pad on the other side to detect an image of the voltage of the pad. A circuit characterized in that a disconnection inspection is performed by performing a disconnection inspection between adjacent pads, applying a voltage from a pad in contact with a probe, and detecting an image of the voltage of the pad on the other surface on which the electro-optic element is disposed. This is a substrate inspection apparatus.
[0011]
According to another aspect of the present invention, there is provided a circuit pattern in an inspection apparatus for a circuit board in which a probe is brought into contact with a specific pad on one side of a circuit board and an electro-optic element is disposed on the pad on the other side to detect the voltage of the pad. When inspecting a circuit board having a portion where the pads are arranged at a high density and a portion where the pads are arranged at a low density, the probes are individually brought into contact with the pads arranged at a low density on one side, Perform short circuit inspection between circuit pattern nets, disconnection inspection between pads arranged at low density, apply voltage from pads arranged at low density for each circuit pattern net, The circuit board inspection apparatus is characterized in that the voltage of the pads on the other surface disposed at a high density is image-detected for disconnection inspection.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1A is a block diagram showing an embodiment of a circuit board inspection apparatus according to the present invention. FIG. 1B is an explanatory view showing the electro-optical element 1 and the circuit board 2 in FIG. 1A in an enlarged manner.
As shown in FIGS. 1A and 1B, a voltage is applied by bringing a probe 8 into contact with the circuit pattern 2-1 of the circuit board 2. The scanner device 7 can turn ON / OFF the power supply to the individual pads 2-2, 2-3, and 2-4 of the circuit pattern 2-1 that is in contact with the probe 8. The power feeding / electrical inspection device 5 inspects the voltage application to the circuit pattern 2-1 and the disconnection and short circuit between the pads of the circuit pattern 2-1 contacting the probe 8.
[0013]
For the electro-optic element 1, Bi ₁₂ SiO ₂₀ or the like that exhibits sensitivity to a longitudinal electric field is used as the electro-optic crystal 1-1. The electro-optic crystal 1-1 is desirably about 10 to 500 μm. A transparent conductive film 1-2 is provided on one side, and a dielectric reflection film 1-3 is provided on the opposite side.
[0014]
The electro-optical element 1 is disposed in the vicinity of the pads 2-5 and 2-6 of the circuit pattern 2-1 that are not in contact with the probe 8. The electro-optical element 1 may be brought into contact with the circuit board 2 or may be non-contact at a distance of about 20 μm.
[0015]
The light emitted from the illuminating device 6 is polarized by the polarizer 3 and is irradiated to the electro-optic element 1 by changing the optical path by the beam splitter 4. The lighting device 6 uses a halogen light source, an LED light source, or the like. Irradiation light incident on the electro-optic element 1 is reflected by the bottom surface of the dielectric reflecting film 1-3 and emitted. The ITO film 1-2 is grounded to the ground.
[0016]
When a voltage is applied from the power feeding / electrical inspection apparatus 5, an electric field distribution is generated between the circuit pattern 2-1 and the ITO film 1-2 by the voltage distribution of the circuit pattern 2-1, and the electro-optic crystal 1-1. The refractive index changes according to the electric field distribution.
By applying an alternating voltage as the applied voltage, it is possible to suppress the diffusion of electric charges generated in the surface direction of the electro-optic element 1. The reflected light from the electro-optical element 1-1 changes its polarization state according to the voltage distribution of the circuit pattern 2-1.
[0017]
The analyzer 9 is orthogonal to the polarizer 3, and the reflected light whose polarization state is changed by the electric field is used as the light intensity distribution according to the voltage distribution. At this time, phase compensation is performed by the quarter-wave plate 10 to achieve linearization and high sensitivity. By detecting the reflected light with the CCD 11, an image of the voltage distribution can be detected.
[0018]
The CCD 11 requires several m to several hundred ms for one detection. A general-purpose device capable of detecting 30 frames per second takes about 33 ms, and when the number of integrations is increased in order to detect the voltage distribution with a good S / N ratio, further detection time is required. Therefore, it is necessary to inspect the disconnection of the circuit pattern 2-1 by reducing the number of detections by the CCD 11 and combining the analysis result of the voltage distribution image and the disconnection inspection by the power supply / electricity inspection device 5.
[0019]
When the disconnection inspection of the circuit pattern 2-1 is performed, the determination is made based on whether or not the pads 2-2, 2-3, 2-4, 2-5, and 2-6 are all conductive. When the voltage distribution of the pads 2-5 and 2-6 is detected by the CCD 11 each time a voltage is applied to the pad 2-2, the pad 2-3, or the pad 2-4, the number of detections of the CCD 11 increases and the detection time is increased. become longer.
[0020]
Therefore, in the present invention, first, the power supply / electrical inspection device 5 inspects whether the pads 2-2, 2-3, and 2-4 contacting the probe 8 are all conductive. Here, when conduction between any of the pads is not obtained, it is determined to be defective.
[0021]
Next, a voltage is applied to any of the pads 2-2, 2-3, and 2-4, and the voltage distribution is detected by the CCD 11. The image processing device 12 determines the continuity of the pads 2-5 and 2-6 depending on whether or not a voltage distribution exists at the positions of the pads 2-5 and 2-6 in the voltage distribution image.
Since it has already been inspected that all of the pads 2-2, 2-3, and 2-4 are conducting, here, when voltage distribution exists in both the pads 2-5 and 2-6 Therefore, all the pads of the circuit pattern 2-1 are conductive, and are determined to be non-defective products. Otherwise, it is determined as defective. These operations are integrated and controlled by the control device 13.
[0022]
The inspection flow related to the disconnection inspection of the circuit pattern 2-1 is as shown in FIG. In this way, the CCD 11 can be inspected with a single detection.
[0023]
FIG. 3 is an explanatory view of a circuit board inspection apparatus according to claim 2. The circuit board 16 to be inspected is shown mounted on the inspection apparatus, but components other than the electro-optical element 1 and the CCD 11 are omitted.
In recent years, in a BGA substrate or the like, a portion in which the pads are arranged at high density, such as the pads 14-3, 14-4, 15-3, and 15-4 of the circuit board 16, and the pads 14- There are portions arranged at low density, such as 1, 14-2, 15-1, and 15-2. In recent years, the pad spacing has become less than 100 μm in the portion where the pads are arranged at high density, and physically, the probe contact is difficult at 150 μm or less. There is a need for an inspection method.
[0024]
When there is a possibility of short-circuiting, such as when the circuit pattern nets 14 and 15 shown in FIG. 3 are adjacent to each other, it is necessary to conduct a short-circuit inspection in addition to a disconnection inspection as an electrical inspection. Again, since the CCD 11 requires detection time, it is desirable to carry out with a small number of detections.
[0025]
First, it is inspected that the nets 14 and 15 of the circuit pattern are not short-circuited. Both the pad 14-1 and the pad 14-2 are inspected by the power feeding / electrical inspection device 5 to check whether the pad 15-1 or the pad 15-2 is short-circuited. Here, when short-circuited in any case, a short-circuit failure occurs.
[0026]
Next, in each of the circuit pattern nets 14 and 15, disconnection inspection is performed between the pads with which the probe 8 is in contact. When the pads 14-1 and 14-2 or the pads 15-1 and 15-2 are not conductive, a disconnection failure occurs.
[0027]
Next, a voltage is applied to an arbitrary pad of the pads 14-1 and 14-2 and an arbitrary pad of the pads 15-1 and 15-2, and the voltage distribution is image-detected by the CCD 11. The image processing device 12 determines whether or not there is a voltage distribution at the positions of the pads 14-3, 14-4, 15-3, and 15-4 in the voltage distribution image. The continuity with is determined.
Here, since the voltage distribution exists at all the positions of the pads 14-3, 14-3, 15-3, and 15-4, all the pads are conductive in the nets 14 and 15 of the circuit pattern. It becomes. In this way, the CCD 11 can perform an electrical inspection with a single detection, and if it passes the above inspection, it is determined that the short circuit / disconnection inspection of the circuit board 16 is normal. The above inspection flow is shown in FIG.
[0028]
【The invention's effect】
According to the present invention, an electro-inspection can be performed by limiting the number of captures to an image sensor that requires time for detection, such as a CCD, by detecting the voltage distribution by applying the electro-optic effect.
In addition, according to the present invention, the voltage distribution of the pad portion arranged at high density is detected by the electro-optic element, the probe is brought into contact with the pad arranged at low density where contact is easy, and the contacted probes By inspecting a part of the short circuit and the disconnection, the disconnection inspection on the other surface can be realized by a single CCD detection and can be realized in a short inspection time.
[Brief description of the drawings]
FIG. 1A is a configuration diagram showing an embodiment of a circuit board inspection apparatus according to the present invention.
(B) is an explanatory view showing an electro-optic element and a circuit board in an enlarged manner.
FIG. 2 is an inspection flow related to a disconnection inspection according to an embodiment;
FIG. 3 is an explanatory view of a circuit board inspection apparatus according to claim 2;
4 is an inspection flow of the circuit board inspection apparatus shown in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electro-optical element 1-1 ... Electro-optical crystal 1-2 ... ITO film 1-3 ... Dielectric reflection film 2, 16 ... Circuit board 2-1 ... Circuit pattern 2-2, 3, 4, 5, 6 ... pad 3 ... polarizer 4 ... beam splitter 5 ... feeding / electrical inspection device 6 ... illumination device 7 ... scanner device 8 ... .... Probe 9 ... Analyzer 10 ... 1/4 wavelength plate 11 ... CCD
DESCRIPTION OF SYMBOLS 12 ... Image processing apparatus 13 ... Control apparatus 14, 15 ... Net 14-1, 2, 3, 4, 15-1, 2, 3, 4, ... pad of circuit pattern

Claims (2)

In a circuit board inspection apparatus in which a probe is brought into contact with a specific pad on one side of the circuit board and an electro-optic element is arranged on the pad on the other side to detect the voltage of the pad, between the pads in contact with the probe Circuit board inspection apparatus, characterized in that a disconnection inspection is performed by applying a voltage from a pad in contact with a probe and detecting a voltage of a pad on the other surface on which the electro-optic element is arranged to detect a disconnection . In a circuit board inspection apparatus in which a probe is brought into contact with a specific pad on one side of a circuit board and an electro-optic element is arranged on the pad on the other side to detect the voltage of the pad, the pads of the circuit pattern have a high density. When inspecting a circuit board having a portion disposed and a portion disposed at a low density, the probe is individually brought into contact with a pad disposed at a low density on one side, so that the circuit pattern between the nets Short circuit inspection, disconnection inspection between pads arranged at low density, voltage is applied from pads arranged at low density for each net of circuit pattern, and electro-optic elements are arranged at high density A circuit board inspection apparatus characterized in that a disconnection inspection is performed by detecting an image of a voltage of a pad on the other surface arranged.

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