JPH10253686A - Inspection apparatus for printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection apparatus, for a printed-wiring board, by which an open part and a short-circuited part can be detected without mechanically damaging a part to be measured. SOLUTION: All electrode 1 which is used to apply a voltage, from the outside, to a part of an object 3, to be inspected, formed on a printed-wiring board 2 is installed. A probe 5 which is used to detect a voltage generated in another part of the object to be inspected is installed. At least one out of the electrode 1 and the probe 5 is set to a noncontact state. In the electrode 1, a voltage is induced in the object 3, to be inspected, by using a capacitance across itself and the object 3 to be inspected. As the probe 5, a probe which uses an electro- optical element whose refractive index is changed according to an electric field can be utilized. When an insulator whose relative permittivity is larger than the relative permittivity of the air is interposed between the electrode 1 and the object 3 to be inspected, a large voltage can be induced in the object 3, to be inspected, by using a small voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board inspection apparatus, and more particularly, to an electrical inspection such as open or short circuit by applying a voltage to a conductor portion to be inspected on a printed wiring board. The present invention relates to a printed wiring board inspection apparatus having a configuration.

[0002]

2. Description of the Related Art It is well known that a printed circuit board inspection apparatus of this type inspects a wiring pattern on a wiring board or a portion to be inspected such as a connector such as an open circuit or a short circuit. A metal needle called a probe is used. That is, two of the above-described probes are set up at a distance above the portion to be inspected, a voltage is applied to the portion to be inspected by one of the two probes, and a voltage is detected by the other probe. Then, the conduction state of the portion to be inspected is detected based on the relationship between the two voltages. At that time, in the conventional inspection apparatus, the two probes are brought into direct mechanical contact with a connector, a wiring, a pad or a through hole on the printed wiring board.

[0003]

A problem with the above-mentioned conventional printed wiring board inspection apparatus is that the wiring, pads or through holes are damaged. In order to make selective contact with a portion to be inspected on a printed wiring board, which has become extremely fine in recent years, the tip of the pin probe must be as thin and sharp as possible. On the other hand, in order to increase the inspection accuracy, the contact resistance between the portion to be inspected and the probe must be sufficiently reduced. As described above, in the probe having a small contact area with the inspected portion, in order to lower the contact resistance with respect to the inspected portion, the contact pressure must be increased,
Eventually, the wiring, pads, or through holes are damaged for inspection.

Accordingly, an object of the present invention is to provide a printed wiring board inspection apparatus which does not cause mechanical damage to a portion to be measured.

[0005]

According to the present invention, there is provided a printed wiring board inspection apparatus comprising: voltage applying means for externally applying a voltage to a part of a conductor to be inspected formed on a printed wiring board to be inspected; In a printed wiring board inspection apparatus comprising: voltage detection means for detecting a voltage generated in another part of the conductor to be inspected in response to the application of the voltage, application of a voltage to the conductor to be inspected by the voltage application means and At least one of the detection of the voltage of the conductor to be inspected by the voltage detection means is performed in a non-contact manner.

In the printed wiring board inspection apparatus according to the present invention, a part of a conductor to be inspected formed on a printed wiring board to be inspected is externally applied by using a capacitance between the conductor and the inspection conductor. Voltage applying means for inducing a voltage by a voltage, and a voltage generated in another portion of the conductor to be inspected in response to induction of a voltage on the inspected conductor by the voltage applying means,
At least one of voltage detecting means for detecting the conductor to be inspected in a non-contact manner is provided.

In the above printed wiring board inspection apparatus,
A probe using an electro-optical element is used as the voltage detecting means. Alternatively, a metal needle probe that mechanically contacts the conductor to be inspected is used.

[0008] An insulator having a relative dielectric constant greater than 1 is interposed between the voltage applying means and the conductor to be inspected.

In the printed wiring board inspection apparatus according to the present invention, a voltage is supplied to the device under test by utilizing the capacitance between the voltage supply electrode and the device under test. This allows
The mechanical contact portion with the object to be measured, which has conventionally been two places, can be reduced by at least one place.

Further, by using a probe using an electro-optical element whose refractive index changes according to an external electric field as a voltage detecting means, the voltage detecting side is also brought into non-contact, so that the mechanical connection between the inspection apparatus and the inspection object can be achieved. Contact can be completely eliminated.

By interposing an insulator having a relative permittivity greater than that of air between the voltage detecting means and the device under test, a larger voltage can be induced to the device under test even with the same voltage. Like that.

A voltage is induced in the device under test by utilizing the capacitance between the electrode for voltage application and the device under test. Therefore, voltage can be applied in a non-contact manner, and inspection can be performed without damaging the printed wiring board.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the relationship between a probe and a printed wiring board for explaining the operation principle of the present invention. Referring to FIG. 1, a voltage application electrode 1 and a voltage detection probe 5 are arranged at a distance from an object 3 on a printed wiring board 2. A voltage is externally applied to the electrode 1, and the voltage of the device under test 3 is detected using the probe 5. The electrode 1 and the probe 5
At least one is not in contact with the device under test. FIG.
FIG. 2 is a sectional view taken along the line Aa in FIG. 1. FIG.
In the printed wiring board inspection apparatus shown in FIG. 1 as an example, the voltage application electrode 1 is not in contact with the DUT 3, while the voltage detection probe 7 is different from a conventional pin probe. Similarly, it is in direct contact with the device under test. In the inspection apparatus shown in FIG. 1, when a voltage is externally applied to the electrode 1, the voltage is applied to the DUT 3 by the capacitance existing in the space gap 6 between the DUT 3 on the printed wiring board and the electrode 1. Induced. A good conductor is desirable as a material of the electrode. The voltage generated on the DUT 3 in response to the voltage application by the electrode 1 is detected by a voltmeter or the like using the electric probe 7. Hereinafter, three embodiments will be described.

FIG. 2 is a sectional view showing a state during inspection of the printed wiring board according to the first embodiment of the present invention. In the present embodiment, as described above, the voltage is applied in a non-contact manner. Therefore, at the time of pattern inspection or open,
The pad, wiring or through-hole on the side that supplies the voltage during short-circuit inspection can be protected from being damaged.
Damage to the inspection object can be reduced as compared with the related art.

Next, FIG. 3 is a sectional view showing a state at the time of inspection of a printed wiring board according to a second embodiment of the present invention. Referring to FIG. 3, both the voltage application electrode 1 and the voltage detection probe 8 are not in contact with the DUT 3 on the printed wiring board. As the voltage detecting probe 8, a probe using a so-called electro-optical element whose refractive index changes due to an externally applied electric field is used. Thereby, the first
In addition to the effects of the first embodiment, at the time of pattern inspection and open / short inspection, pads, wirings, and through holes can be prevented from being damaged at all. It can be further reduced than in the form.

FIG. 4 is a sectional view showing a state at the time of inspection of a printed wiring board according to a third embodiment of the present invention. Referring to FIG. 4, the present embodiment is different from the second embodiment in that an insulator 4 is interposed between DUT 3 and voltage applying electrode 1. In the present embodiment, the voltage applied to the electrode 1 is induced in the device 3 by the capacitance of the insulator 4 between the electrode 1 and the device 3. On the other hand, the voltage applied to the DUT 3 is detected by the voltage detection probe 5. Examples of the insulator 4 include a photoresist and the like. The photoresist has a relative permittivity of 3 to 4 and a relative permittivity greater than that of air having a relative permittivity of 1. Accordingly, the voltage applied to the device under test 3 can be made higher than in the first embodiment in which only air exists between the electrode 1 and the device under test 3. This embodiment has an effect of enabling higher-sensitivity measurement in addition to the effects of the first and second embodiments.

[0017]

As described above, according to the present invention, when inspecting the electrical characteristics of a conductor on a printed wiring board, the present invention relates to a method of detecting a voltage between an electrode for applying a voltage and an object to be measured, and detecting a voltage between an object to be measured and voltage detection. And at least one of them is in non-contact.

Thus, according to the present invention, the printed wiring board can be inspected without damaging it.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining the operation principle of a printed wiring board inspection apparatus according to the present invention.

FIG. 2 is a sectional view showing a state at the time of inspection according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a state at the time of inspection according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a state at the time of inspection according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage application electrode 2 Printed wiring board 3 DUT 4 Insulator 5 Voltage detection probe 6 Space gap 7 Probe using electro-optical element 8 Pin probe

Claims (5)

[Claims] 1. A voltage applying means for externally applying a voltage to a part of a conductor to be inspected formed on a printed wiring board to be inspected, and another voltage applying means for applying another voltage to the conductor to be inspected in response to the application of the voltage. A printed wiring board inspection device comprising: voltage detection means for detecting a voltage generated in a portion; at least one of application of a voltage to the inspected conductor by the voltage applying means and detection of a voltage of the inspected conductor by the voltage detection means Is performed in a non-contact manner. 2. A non-contact voltage induced by a voltage externally applied to a part of a conductor to be inspected formed on a printed wiring board to be inspected, using a capacitance between the conductor and the inspected conductor. Voltage applying means, and a voltage detecting means for detecting a voltage generated in another portion of the conductor to be inspected in response to induction of a voltage on the conductor to be inspected by the voltage applying means, in a non-contact manner with the conductor to be inspected, A printed wiring board inspection device comprising at least one. 3. The printed wiring board inspection apparatus according to claim 1, wherein a probe using an electro-optical element is used as the voltage detecting means. 4. The printed wiring board inspection apparatus according to claim 1, wherein a metal needle probe mechanically in contact with the conductor to be inspected is used as the voltage detection means. Printed wiring board inspection equipment. 5. The printed wiring board inspection apparatus according to claim 1, wherein the insulation between the voltage applying means and the conductor to be inspected has a relative dielectric constant larger than that of air. A printed wiring board inspection device characterized by having an object interposed.